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allpaths.c
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1 /*-------------------------------------------------------------------------
2  *
3  * allpaths.c
4  * Routines to find possible search paths for processing a query
5  *
6  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/backend/optimizer/path/allpaths.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 
16 #include "postgres.h"
17 
18 #include <limits.h>
19 #include <math.h>
20 
21 #include "access/sysattr.h"
22 #include "access/tsmapi.h"
23 #include "catalog/pg_class.h"
24 #include "catalog/pg_operator.h"
25 #include "catalog/pg_proc.h"
26 #include "foreign/fdwapi.h"
27 #include "miscadmin.h"
28 #include "nodes/makefuncs.h"
29 #include "nodes/nodeFuncs.h"
30 #include "nodes/supportnodes.h"
31 #ifdef OPTIMIZER_DEBUG
32 #include "nodes/print.h"
33 #endif
34 #include "optimizer/appendinfo.h"
35 #include "optimizer/clauses.h"
36 #include "optimizer/cost.h"
37 #include "optimizer/geqo.h"
38 #include "optimizer/optimizer.h"
39 #include "optimizer/pathnode.h"
40 #include "optimizer/paths.h"
41 #include "optimizer/plancat.h"
42 #include "optimizer/planner.h"
43 #include "optimizer/tlist.h"
44 #include "parser/parse_clause.h"
45 #include "parser/parsetree.h"
46 #include "partitioning/partbounds.h"
47 #include "port/pg_bitutils.h"
48 #include "rewrite/rewriteManip.h"
49 #include "utils/lsyscache.h"
50 
51 
52 /* Bitmask flags for pushdown_safety_info.unsafeFlags */
53 #define UNSAFE_HAS_VOLATILE_FUNC (1 << 0)
54 #define UNSAFE_HAS_SET_FUNC (1 << 1)
55 #define UNSAFE_NOTIN_DISTINCTON_CLAUSE (1 << 2)
56 #define UNSAFE_NOTIN_PARTITIONBY_CLAUSE (1 << 3)
57 #define UNSAFE_TYPE_MISMATCH (1 << 4)
58 
59 /* results of subquery_is_pushdown_safe */
60 typedef struct pushdown_safety_info
61 {
62  unsigned char *unsafeFlags; /* bitmask of reasons why this target list
63  * column is unsafe for qual pushdown, or 0 if
64  * no reason. */
65  bool unsafeVolatile; /* don't push down volatile quals */
66  bool unsafeLeaky; /* don't push down leaky quals */
67 } pushdown_safety_info;
68 
69 /* Return type for qual_is_pushdown_safe */
70 typedef enum pushdown_safe_type
71 {
72  PUSHDOWN_UNSAFE, /* unsafe to push qual into subquery */
73  PUSHDOWN_SAFE, /* safe to push qual into subquery */
74  PUSHDOWN_WINDOWCLAUSE_RUNCOND, /* unsafe, but may work as WindowClause
75  * run condition */
76 } pushdown_safe_type;
77 
78 /* These parameters are set by GUC */
79 bool enable_geqo = false; /* just in case GUC doesn't set it */
80 int geqo_threshold;
81 int min_parallel_table_scan_size;
82 int min_parallel_index_scan_size;
83 
84 /* Hook for plugins to get control in set_rel_pathlist() */
85 set_rel_pathlist_hook_type set_rel_pathlist_hook = NULL;
86 
87 /* Hook for plugins to replace standard_join_search() */
88 join_search_hook_type join_search_hook = NULL;
89 
90 
91 static void set_base_rel_consider_startup(PlannerInfo *root);
92 static void set_base_rel_sizes(PlannerInfo *root);
93 static void set_base_rel_pathlists(PlannerInfo *root);
94 static void set_rel_size(PlannerInfo *root, RelOptInfo *rel,
95  Index rti, RangeTblEntry *rte);
96 static void set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
97  Index rti, RangeTblEntry *rte);
98 static void set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel,
99  RangeTblEntry *rte);
100 static void create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel);
101 static void set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel,
102  RangeTblEntry *rte);
103 static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
104  RangeTblEntry *rte);
105 static void set_tablesample_rel_size(PlannerInfo *root, RelOptInfo *rel,
106  RangeTblEntry *rte);
107 static void set_tablesample_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
108  RangeTblEntry *rte);
109 static void set_foreign_size(PlannerInfo *root, RelOptInfo *rel,
110  RangeTblEntry *rte);
111 static void set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel,
112  RangeTblEntry *rte);
113 static void set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
114  Index rti, RangeTblEntry *rte);
115 static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
116  Index rti, RangeTblEntry *rte);
117 static void generate_orderedappend_paths(PlannerInfo *root, RelOptInfo *rel,
118  List *live_childrels,
119  List *all_child_pathkeys);
120 static Path *get_cheapest_parameterized_child_path(PlannerInfo *root,
121  RelOptInfo *rel,
122  Relids required_outer);
123 static void accumulate_append_subpath(Path *path,
124  List **subpaths,
125  List **special_subpaths);
126 static Path *get_singleton_append_subpath(Path *path);
127 static void set_dummy_rel_pathlist(RelOptInfo *rel);
128 static void set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
129  Index rti, RangeTblEntry *rte);
130 static void set_function_pathlist(PlannerInfo *root, RelOptInfo *rel,
131  RangeTblEntry *rte);
132 static void set_values_pathlist(PlannerInfo *root, RelOptInfo *rel,
133  RangeTblEntry *rte);
134 static void set_tablefunc_pathlist(PlannerInfo *root, RelOptInfo *rel,
135  RangeTblEntry *rte);
136 static void set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel,
137  RangeTblEntry *rte);
138 static void set_namedtuplestore_pathlist(PlannerInfo *root, RelOptInfo *rel,
139  RangeTblEntry *rte);
140 static void set_result_pathlist(PlannerInfo *root, RelOptInfo *rel,
141  RangeTblEntry *rte);
142 static void set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel,
143  RangeTblEntry *rte);
144 static RelOptInfo *make_rel_from_joinlist(PlannerInfo *root, List *joinlist);
145 static bool subquery_is_pushdown_safe(Query *subquery, Query *topquery,
146  pushdown_safety_info *safetyInfo);
147 static bool recurse_pushdown_safe(Node *setOp, Query *topquery,
148  pushdown_safety_info *safetyInfo);
149 static void check_output_expressions(Query *subquery,
150  pushdown_safety_info *safetyInfo);
151 static void compare_tlist_datatypes(List *tlist, List *colTypes,
152  pushdown_safety_info *safetyInfo);
153 static bool targetIsInAllPartitionLists(TargetEntry *tle, Query *query);
154 static pushdown_safe_type qual_is_pushdown_safe(Query *subquery, Index rti,
155  RestrictInfo *rinfo,
156  pushdown_safety_info *safetyInfo);
157 static void subquery_push_qual(Query *subquery,
158  RangeTblEntry *rte, Index rti, Node *qual);
159 static void recurse_push_qual(Node *setOp, Query *topquery,
160  RangeTblEntry *rte, Index rti, Node *qual);
161 static void remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel,
162  Bitmapset *extra_used_attrs);
163 
164 
165 /*
166  * make_one_rel
167  * Finds all possible access paths for executing a query, returning a
168  * single rel that represents the join of all base rels in the query.
169  */
170 RelOptInfo *
171 make_one_rel(PlannerInfo *root, List *joinlist)
172 {
173  RelOptInfo *rel;
174  Index rti;
175  double total_pages;
176 
177  /* Mark base rels as to whether we care about fast-start plans */
178  set_base_rel_consider_startup(root);
179 
180  /*
181  * Compute size estimates and consider_parallel flags for each base rel.
182  */
183  set_base_rel_sizes(root);
184 
185  /*
186  * We should now have size estimates for every actual table involved in
187  * the query, and we also know which if any have been deleted from the
188  * query by join removal, pruned by partition pruning, or eliminated by
189  * constraint exclusion. So we can now compute total_table_pages.
190  *
191  * Note that appendrels are not double-counted here, even though we don't
192  * bother to distinguish RelOptInfos for appendrel parents, because the
193  * parents will have pages = 0.
194  *
195  * XXX if a table is self-joined, we will count it once per appearance,
196  * which perhaps is the wrong thing ... but that's not completely clear,
197  * and detecting self-joins here is difficult, so ignore it for now.
198  */
199  total_pages = 0;
200  for (rti = 1; rti < root->simple_rel_array_size; rti++)
201  {
202  RelOptInfo *brel = root->simple_rel_array[rti];
203 
204  /* there may be empty slots corresponding to non-baserel RTEs */
205  if (brel == NULL)
206  continue;
207 
208  Assert(brel->relid == rti); /* sanity check on array */
209 
210  if (IS_DUMMY_REL(brel))
211  continue;
212 
213  if (IS_SIMPLE_REL(brel))
214  total_pages += (double) brel->pages;
215  }
216  root->total_table_pages = total_pages;
217 
218  /*
219  * Generate access paths for each base rel.
220  */
221  set_base_rel_pathlists(root);
222 
223  /*
224  * Generate access paths for the entire join tree.
225  */
226  rel = make_rel_from_joinlist(root, joinlist);
227 
228  /*
229  * The result should join all and only the query's base + outer-join rels.
230  */
231  Assert(bms_equal(rel->relids, root->all_query_rels));
232 
233  return rel;
234 }
235 
236 /*
237  * set_base_rel_consider_startup
238  * Set the consider_[param_]startup flags for each base-relation entry.
239  *
240  * For the moment, we only deal with consider_param_startup here; because the
241  * logic for consider_startup is pretty trivial and is the same for every base
242  * relation, we just let build_simple_rel() initialize that flag correctly to
243  * start with. If that logic ever gets more complicated it would probably
244  * be better to move it here.
245  */
246 static void
247 set_base_rel_consider_startup(PlannerInfo *root)
248 {
249  /*
250  * Since parameterized paths can only be used on the inside of a nestloop
251  * join plan, there is usually little value in considering fast-start
252  * plans for them. However, for relations that are on the RHS of a SEMI
253  * or ANTI join, a fast-start plan can be useful because we're only going
254  * to care about fetching one tuple anyway.
255  *
256  * To minimize growth of planning time, we currently restrict this to
257  * cases where the RHS is a single base relation, not a join; there is no
258  * provision for consider_param_startup to get set at all on joinrels.
259  * Also we don't worry about appendrels. costsize.c's costing rules for
260  * nestloop semi/antijoins don't consider such cases either.
261  */
262  ListCell *lc;
263 
264  foreach(lc, root->join_info_list)
265  {
266  SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
267  int varno;
268 
269  if ((sjinfo->jointype == JOIN_SEMI || sjinfo->jointype == JOIN_ANTI) &&
270  bms_get_singleton_member(sjinfo->syn_righthand, &varno))
271  {
272  RelOptInfo *rel = find_base_rel(root, varno);
273 
274  rel->consider_param_startup = true;
275  }
276  }
277 }
278 
279 /*
280  * set_base_rel_sizes
281  * Set the size estimates (rows and widths) for each base-relation entry.
282  * Also determine whether to consider parallel paths for base relations.
283  *
284  * We do this in a separate pass over the base rels so that rowcount
285  * estimates are available for parameterized path generation, and also so
286  * that each rel's consider_parallel flag is set correctly before we begin to
287  * generate paths.
288  */
289 static void
290 set_base_rel_sizes(PlannerInfo *root)
291 {
292  Index rti;
293 
294  for (rti = 1; rti < root->simple_rel_array_size; rti++)
295  {
296  RelOptInfo *rel = root->simple_rel_array[rti];
297  RangeTblEntry *rte;
298 
299  /* there may be empty slots corresponding to non-baserel RTEs */
300  if (rel == NULL)
301  continue;
302 
303  Assert(rel->relid == rti); /* sanity check on array */
304 
305  /* ignore RTEs that are "other rels" */
306  if (rel->reloptkind != RELOPT_BASEREL)
307  continue;
308 
309  rte = root->simple_rte_array[rti];
310 
311  /*
312  * If parallelism is allowable for this query in general, see whether
313  * it's allowable for this rel in particular. We have to do this
314  * before set_rel_size(), because (a) if this rel is an inheritance
315  * parent, set_append_rel_size() will use and perhaps change the rel's
316  * consider_parallel flag, and (b) for some RTE types, set_rel_size()
317  * goes ahead and makes paths immediately.
318  */
319  if (root->glob->parallelModeOK)
320  set_rel_consider_parallel(root, rel, rte);
321 
322  set_rel_size(root, rel, rti, rte);
323  }
324 }
325 
326 /*
327  * set_base_rel_pathlists
328  * Finds all paths available for scanning each base-relation entry.
329  * Sequential scan and any available indices are considered.
330  * Each useful path is attached to its relation's 'pathlist' field.
331  */
332 static void
333 set_base_rel_pathlists(PlannerInfo *root)
334 {
335  Index rti;
336 
337  for (rti = 1; rti < root->simple_rel_array_size; rti++)
338  {
339  RelOptInfo *rel = root->simple_rel_array[rti];
340 
341  /* there may be empty slots corresponding to non-baserel RTEs */
342  if (rel == NULL)
343  continue;
344 
345  Assert(rel->relid == rti); /* sanity check on array */
346 
347  /* ignore RTEs that are "other rels" */
348  if (rel->reloptkind != RELOPT_BASEREL)
349  continue;
350 
351  set_rel_pathlist(root, rel, rti, root->simple_rte_array[rti]);
352  }
353 }
354 
355 /*
356  * set_rel_size
357  * Set size estimates for a base relation
358  */
359 static void
360 set_rel_size(PlannerInfo *root, RelOptInfo *rel,
361  Index rti, RangeTblEntry *rte)
362 {
363  if (rel->reloptkind == RELOPT_BASEREL &&
364  relation_excluded_by_constraints(root, rel, rte))
365  {
366  /*
367  * We proved we don't need to scan the rel via constraint exclusion,
368  * so set up a single dummy path for it. Here we only check this for
369  * regular baserels; if it's an otherrel, CE was already checked in
370  * set_append_rel_size().
371  *
372  * In this case, we go ahead and set up the relation's path right away
373  * instead of leaving it for set_rel_pathlist to do. This is because
374  * we don't have a convention for marking a rel as dummy except by
375  * assigning a dummy path to it.
376  */
377  set_dummy_rel_pathlist(rel);
378  }
379  else if (rte->inh)
380  {
381  /* It's an "append relation", process accordingly */
382  set_append_rel_size(root, rel, rti, rte);
383  }
384  else
385  {
386  switch (rel->rtekind)
387  {
388  case RTE_RELATION:
389  if (rte->relkind == RELKIND_FOREIGN_TABLE)
390  {
391  /* Foreign table */
392  set_foreign_size(root, rel, rte);
393  }
394  else if (rte->relkind == RELKIND_PARTITIONED_TABLE)
395  {
396  /*
397  * We could get here if asked to scan a partitioned table
398  * with ONLY. In that case we shouldn't scan any of the
399  * partitions, so mark it as a dummy rel.
400  */
401  set_dummy_rel_pathlist(rel);
402  }
403  else if (rte->tablesample != NULL)
404  {
405  /* Sampled relation */
406  set_tablesample_rel_size(root, rel, rte);
407  }
408  else
409  {
410  /* Plain relation */
411  set_plain_rel_size(root, rel, rte);
412  }
413  break;
414  case RTE_SUBQUERY:
415 
416  /*
417  * Subqueries don't support making a choice between
418  * parameterized and unparameterized paths, so just go ahead
419  * and build their paths immediately.
420  */
421  set_subquery_pathlist(root, rel, rti, rte);
422  break;
423  case RTE_FUNCTION:
424  set_function_size_estimates(root, rel);
425  break;
426  case RTE_TABLEFUNC:
427  set_tablefunc_size_estimates(root, rel);
428  break;
429  case RTE_VALUES:
430  set_values_size_estimates(root, rel);
431  break;
432  case RTE_CTE:
433 
434  /*
435  * CTEs don't support making a choice between parameterized
436  * and unparameterized paths, so just go ahead and build their
437  * paths immediately.
438  */
439  if (rte->self_reference)
440  set_worktable_pathlist(root, rel, rte);
441  else
442  set_cte_pathlist(root, rel, rte);
443  break;
444  case RTE_NAMEDTUPLESTORE:
445  /* Might as well just build the path immediately */
446  set_namedtuplestore_pathlist(root, rel, rte);
447  break;
448  case RTE_RESULT:
449  /* Might as well just build the path immediately */
450  set_result_pathlist(root, rel, rte);
451  break;
452  default:
453  elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
454  break;
455  }
456  }
457 
458  /*
459  * We insist that all non-dummy rels have a nonzero rowcount estimate.
460  */
461  Assert(rel->rows > 0 || IS_DUMMY_REL(rel));
462 }
463 
464 /*
465  * set_rel_pathlist
466  * Build access paths for a base relation
467  */
468 static void
469 set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
470  Index rti, RangeTblEntry *rte)
471 {
472  if (IS_DUMMY_REL(rel))
473  {
474  /* We already proved the relation empty, so nothing more to do */
475  }
476  else if (rte->inh)
477  {
478  /* It's an "append relation", process accordingly */
479  set_append_rel_pathlist(root, rel, rti, rte);
480  }
481  else
482  {
483  switch (rel->rtekind)
484  {
485  case RTE_RELATION:
486  if (rte->relkind == RELKIND_FOREIGN_TABLE)
487  {
488  /* Foreign table */
489  set_foreign_pathlist(root, rel, rte);
490  }
491  else if (rte->tablesample != NULL)
492  {
493  /* Sampled relation */
494  set_tablesample_rel_pathlist(root, rel, rte);
495  }
496  else
497  {
498  /* Plain relation */
499  set_plain_rel_pathlist(root, rel, rte);
500  }
501  break;
502  case RTE_SUBQUERY:
503  /* Subquery --- fully handled during set_rel_size */
504  break;
505  case RTE_FUNCTION:
506  /* RangeFunction */
507  set_function_pathlist(root, rel, rte);
508  break;
509  case RTE_TABLEFUNC:
510  /* Table Function */
511  set_tablefunc_pathlist(root, rel, rte);
512  break;
513  case RTE_VALUES:
514  /* Values list */
515  set_values_pathlist(root, rel, rte);
516  break;
517  case RTE_CTE:
518  /* CTE reference --- fully handled during set_rel_size */
519  break;
520  case RTE_NAMEDTUPLESTORE:
521  /* tuplestore reference --- fully handled during set_rel_size */
522  break;
523  case RTE_RESULT:
524  /* simple Result --- fully handled during set_rel_size */
525  break;
526  default:
527  elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
528  break;
529  }
530  }
531 
532  /*
533  * Allow a plugin to editorialize on the set of Paths for this base
534  * relation. It could add new paths (such as CustomPaths) by calling
535  * add_path(), or add_partial_path() if parallel aware. It could also
536  * delete or modify paths added by the core code.
537  */
538  if (set_rel_pathlist_hook)
539  (*set_rel_pathlist_hook) (root, rel, rti, rte);
540 
541  /*
542  * If this is a baserel, we should normally consider gathering any partial
543  * paths we may have created for it. We have to do this after calling the
544  * set_rel_pathlist_hook, else it cannot add partial paths to be included
545  * here.
546  *
547  * However, if this is an inheritance child, skip it. Otherwise, we could
548  * end up with a very large number of gather nodes, each trying to grab
549  * its own pool of workers. Instead, we'll consider gathering partial
550  * paths for the parent appendrel.
551  *
552  * Also, if this is the topmost scan/join rel, we postpone gathering until
553  * the final scan/join targetlist is available (see grouping_planner).
554  */
555  if (rel->reloptkind == RELOPT_BASEREL &&
556  !bms_equal(rel->relids, root->all_query_rels))
557  generate_useful_gather_paths(root, rel, false);
558 
559  /* Now find the cheapest of the paths for this rel */
560  set_cheapest(rel);
561 
562 #ifdef OPTIMIZER_DEBUG
563  pprint(rel);
564 #endif
565 }
566 
567 /*
568  * set_plain_rel_size
569  * Set size estimates for a plain relation (no subquery, no inheritance)
570  */
571 static void
572 set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
573 {
574  /*
575  * Test any partial indexes of rel for applicability. We must do this
576  * first since partial unique indexes can affect size estimates.
577  */
578  check_index_predicates(root, rel);
579 
580  /* Mark rel with estimated output rows, width, etc */
581  set_baserel_size_estimates(root, rel);
582 }
583 
584 /*
585  * If this relation could possibly be scanned from within a worker, then set
586  * its consider_parallel flag.
587  */
588 static void
589 set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel,
590  RangeTblEntry *rte)
591 {
592  /*
593  * The flag has previously been initialized to false, so we can just
594  * return if it becomes clear that we can't safely set it.
595  */
596  Assert(!rel->consider_parallel);
597 
598  /* Don't call this if parallelism is disallowed for the entire query. */
599  Assert(root->glob->parallelModeOK);
600 
601  /* This should only be called for baserels and appendrel children. */
602  Assert(IS_SIMPLE_REL(rel));
603 
604  /* Assorted checks based on rtekind. */
605  switch (rte->rtekind)
606  {
607  case RTE_RELATION:
608 
609  /*
610  * Currently, parallel workers can't access the leader's temporary
611  * tables. We could possibly relax this if we wrote all of its
612  * local buffers at the start of the query and made no changes
613  * thereafter (maybe we could allow hint bit changes), and if we
614  * taught the workers to read them. Writing a large number of
615  * temporary buffers could be expensive, though, and we don't have
616  * the rest of the necessary infrastructure right now anyway. So
617  * for now, bail out if we see a temporary table.
618  */
619  if (get_rel_persistence(rte->relid) == RELPERSISTENCE_TEMP)
620  return;
621 
622  /*
623  * Table sampling can be pushed down to workers if the sample
624  * function and its arguments are safe.
625  */
626  if (rte->tablesample != NULL)
627  {
628  char proparallel = func_parallel(rte->tablesample->tsmhandler);
629 
630  if (proparallel != PROPARALLEL_SAFE)
631  return;
632  if (!is_parallel_safe(root, (Node *) rte->tablesample->args))
633  return;
634  }
635 
636  /*
637  * Ask FDWs whether they can support performing a ForeignScan
638  * within a worker. Most often, the answer will be no. For
639  * example, if the nature of the FDW is such that it opens a TCP
640  * connection with a remote server, each parallel worker would end
641  * up with a separate connection, and these connections might not
642  * be appropriately coordinated between workers and the leader.
643  */
644  if (rte->relkind == RELKIND_FOREIGN_TABLE)
645  {
646  Assert(rel->fdwroutine);
647  if (!rel->fdwroutine->IsForeignScanParallelSafe)
648  return;
649  if (!rel->fdwroutine->IsForeignScanParallelSafe(root, rel, rte))
650  return;
651  }
652 
653  /*
654  * There are additional considerations for appendrels, which we'll
655  * deal with in set_append_rel_size and set_append_rel_pathlist.
656  * For now, just set consider_parallel based on the rel's own
657  * quals and targetlist.
658  */
659  break;
660 
661  case RTE_SUBQUERY:
662 
663  /*
664  * There's no intrinsic problem with scanning a subquery-in-FROM
665  * (as distinct from a SubPlan or InitPlan) in a parallel worker.
666  * If the subquery doesn't happen to have any parallel-safe paths,
667  * then flagging it as consider_parallel won't change anything,
668  * but that's true for plain tables, too. We must set
669  * consider_parallel based on the rel's own quals and targetlist,
670  * so that if a subquery path is parallel-safe but the quals and
671  * projection we're sticking onto it are not, we correctly mark
672  * the SubqueryScanPath as not parallel-safe. (Note that
673  * set_subquery_pathlist() might push some of these quals down
674  * into the subquery itself, but that doesn't change anything.)
675  *
676  * We can't push sub-select containing LIMIT/OFFSET to workers as
677  * there is no guarantee that the row order will be fully
678  * deterministic, and applying LIMIT/OFFSET will lead to
679  * inconsistent results at the top-level. (In some cases, where
680  * the result is ordered, we could relax this restriction. But it
681  * doesn't currently seem worth expending extra effort to do so.)
682  */
683  {
684  Query *subquery = castNode(Query, rte->subquery);
685 
686  if (limit_needed(subquery))
687  return;
688  }
689  break;
690 
691  case RTE_JOIN:
692  /* Shouldn't happen; we're only considering baserels here. */
693  Assert(false);
694  return;
695 
696  case RTE_FUNCTION:
697  /* Check for parallel-restricted functions. */
698  if (!is_parallel_safe(root, (Node *) rte->functions))
699  return;
700  break;
701 
702  case RTE_TABLEFUNC:
703  /* not parallel safe */
704  return;
705 
706  case RTE_VALUES:
707  /* Check for parallel-restricted functions. */
708  if (!is_parallel_safe(root, (Node *) rte->values_lists))
709  return;
710  break;
711 
712  case RTE_CTE:
713 
714  /*
715  * CTE tuplestores aren't shared among parallel workers, so we
716  * force all CTE scans to happen in the leader. Also, populating
717  * the CTE would require executing a subplan that's not available
718  * in the worker, might be parallel-restricted, and must get
719  * executed only once.
720  */
721  return;
722 
723  case RTE_NAMEDTUPLESTORE:
724 
725  /*
726  * tuplestore cannot be shared, at least without more
727  * infrastructure to support that.
728  */
729  return;
730 
731  case RTE_RESULT:
732  /* RESULT RTEs, in themselves, are no problem. */
733  break;
734  }
735 
736  /*
737  * If there's anything in baserestrictinfo that's parallel-restricted, we
738  * give up on parallelizing access to this relation. We could consider
739  * instead postponing application of the restricted quals until we're
740  * above all the parallelism in the plan tree, but it's not clear that
741  * that would be a win in very many cases, and it might be tricky to make
742  * outer join clauses work correctly. It would likely break equivalence
743  * classes, too.
744  */
745  if (!is_parallel_safe(root, (Node *) rel->baserestrictinfo))
746  return;
747 
748  /*
749  * Likewise, if the relation's outputs are not parallel-safe, give up.
750  * (Usually, they're just Vars, but sometimes they're not.)
751  */
752  if (!is_parallel_safe(root, (Node *) rel->reltarget->exprs))
753  return;
754 
755  /* We have a winner. */
756  rel->consider_parallel = true;
757 }
758 
759 /*
760  * set_plain_rel_pathlist
761  * Build access paths for a plain relation (no subquery, no inheritance)
762  */
763 static void
764 set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
765 {
766  Relids required_outer;
767 
768  /*
769  * We don't support pushing join clauses into the quals of a seqscan, but
770  * it could still have required parameterization due to LATERAL refs in
771  * its tlist.
772  */
773  required_outer = rel->lateral_relids;
774 
775  /*
776  * Consider TID scans.
777  *
778  * If create_tidscan_paths returns true, then a TID scan path is forced.
779  * This happens when rel->baserestrictinfo contains CurrentOfExpr, because
780  * the executor can't handle any other type of path for such queries.
781  * Hence, we return without adding any other paths.
782  */
783  if (create_tidscan_paths(root, rel))
784  return;
785 
786  /* Consider sequential scan */
787  add_path(rel, create_seqscan_path(root, rel, required_outer, 0));
788 
789  /* If appropriate, consider parallel sequential scan */
790  if (rel->consider_parallel && required_outer == NULL)
791  create_plain_partial_paths(root, rel);
792 
793  /* Consider index scans */
794  create_index_paths(root, rel);
795 }
796 
797 /*
798  * create_plain_partial_paths
799  * Build partial access paths for parallel scan of a plain relation
800  */
801 static void
802 create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
803 {
804  int parallel_workers;
805 
806  parallel_workers = compute_parallel_worker(rel, rel->pages, -1,
807  max_parallel_workers_per_gather);
808 
809  /* If any limit was set to zero, the user doesn't want a parallel scan. */
810  if (parallel_workers <= 0)
811  return;
812 
813  /* Add an unordered partial path based on a parallel sequential scan. */
814  add_partial_path(rel, create_seqscan_path(root, rel, NULL, parallel_workers));
815 }
816 
817 /*
818  * set_tablesample_rel_size
819  * Set size estimates for a sampled relation
820  */
821 static void
822 set_tablesample_rel_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
823 {
824  TableSampleClause *tsc = rte->tablesample;
825  TsmRoutine *tsm;
826  BlockNumber pages;
827  double tuples;
828 
829  /*
830  * Test any partial indexes of rel for applicability. We must do this
831  * first since partial unique indexes can affect size estimates.
832  */
833  check_index_predicates(root, rel);
834 
835  /*
836  * Call the sampling method's estimation function to estimate the number
837  * of pages it will read and the number of tuples it will return. (Note:
838  * we assume the function returns sane values.)
839  */
840  tsm = GetTsmRoutine(tsc->tsmhandler);
841  tsm->SampleScanGetSampleSize(root, rel, tsc->args,
842  &pages, &tuples);
843 
844  /*
845  * For the moment, because we will only consider a SampleScan path for the
846  * rel, it's okay to just overwrite the pages and tuples estimates for the
847  * whole relation. If we ever consider multiple path types for sampled
848  * rels, we'll need more complication.
849  */
850  rel->pages = pages;
851  rel->tuples = tuples;
852 
853  /* Mark rel with estimated output rows, width, etc */
854  set_baserel_size_estimates(root, rel);
855 }
856 
857 /*
858  * set_tablesample_rel_pathlist
859  * Build access paths for a sampled relation
860  */
861 static void
862 set_tablesample_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
863 {
864  Relids required_outer;
865  Path *path;
866 
867  /*
868  * We don't support pushing join clauses into the quals of a samplescan,
869  * but it could still have required parameterization due to LATERAL refs
870  * in its tlist or TABLESAMPLE arguments.
871  */
872  required_outer = rel->lateral_relids;
873 
874  /* Consider sampled scan */
875  path = create_samplescan_path(root, rel, required_outer);
876 
877  /*
878  * If the sampling method does not support repeatable scans, we must avoid
879  * plans that would scan the rel multiple times. Ideally, we'd simply
880  * avoid putting the rel on the inside of a nestloop join; but adding such
881  * a consideration to the planner seems like a great deal of complication
882  * to support an uncommon usage of second-rate sampling methods. Instead,
883  * if there is a risk that the query might perform an unsafe join, just
884  * wrap the SampleScan in a Materialize node. We can check for joins by
885  * counting the membership of all_query_rels (note that this correctly
886  * counts inheritance trees as single rels). If we're inside a subquery,
887  * we can't easily check whether a join might occur in the outer query, so
888  * just assume one is possible.
889  *
890  * GetTsmRoutine is relatively expensive compared to the other tests here,
891  * so check repeatable_across_scans last, even though that's a bit odd.
892  */
893  if ((root->query_level > 1 ||
894  bms_membership(root->all_query_rels) != BMS_SINGLETON) &&
895  !(GetTsmRoutine(rte->tablesample->tsmhandler)->repeatable_across_scans))
896  {
897  path = (Path *) create_material_path(rel, path);
898  }
899 
900  add_path(rel, path);
901 
902  /* For the moment, at least, there are no other paths to consider */
903 }
904 
905 /*
906  * set_foreign_size
907  * Set size estimates for a foreign table RTE
908  */
909 static void
910 set_foreign_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
911 {
912  /* Mark rel with estimated output rows, width, etc */
913  set_foreign_size_estimates(root, rel);
914 
915  /* Let FDW adjust the size estimates, if it can */
916  rel->fdwroutine->GetForeignRelSize(root, rel, rte->relid);
917 
918  /* ... but do not let it set the rows estimate to zero */
919  rel->rows = clamp_row_est(rel->rows);
920 
921  /*
922  * Also, make sure rel->tuples is not insane relative to rel->rows.
923  * Notably, this ensures sanity if pg_class.reltuples contains -1 and the
924  * FDW doesn't do anything to replace that.
925  */
926  rel->tuples = Max(rel->tuples, rel->rows);
927 }
928 
929 /*
930  * set_foreign_pathlist
931  * Build access paths for a foreign table RTE
932  */
933 static void
934 set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
935 {
936  /* Call the FDW's GetForeignPaths function to generate path(s) */
937  rel->fdwroutine->GetForeignPaths(root, rel, rte->relid);
938 }
939 
940 /*
941  * set_append_rel_size
942  * Set size estimates for a simple "append relation"
943  *
944  * The passed-in rel and RTE represent the entire append relation. The
945  * relation's contents are computed by appending together the output of the
946  * individual member relations. Note that in the non-partitioned inheritance
947  * case, the first member relation is actually the same table as is mentioned
948  * in the parent RTE ... but it has a different RTE and RelOptInfo. This is
949  * a good thing because their outputs are not the same size.
950  */
951 static void
952 set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
953  Index rti, RangeTblEntry *rte)
954 {
955  int parentRTindex = rti;
956  bool has_live_children;
957  double parent_rows;
958  double parent_size;
959  double *parent_attrsizes;
960  int nattrs;
961  ListCell *l;
962 
963  /* Guard against stack overflow due to overly deep inheritance tree. */
964  check_stack_depth();
965 
966  Assert(IS_SIMPLE_REL(rel));
967 
968  /*
969  * If this is a partitioned baserel, set the consider_partitionwise_join
970  * flag; currently, we only consider partitionwise joins with the baserel
971  * if its targetlist doesn't contain a whole-row Var.
972  */
973  if (enable_partitionwise_join &&
974  rel->reloptkind == RELOPT_BASEREL &&
975  rte->relkind == RELKIND_PARTITIONED_TABLE &&
976  bms_is_empty(rel->attr_needed[InvalidAttrNumber - rel->min_attr]))
977  rel->consider_partitionwise_join = true;
978 
979  /*
980  * Initialize to compute size estimates for whole append relation.
981  *
982  * We handle width estimates by weighting the widths of different child
983  * rels proportionally to their number of rows. This is sensible because
984  * the use of width estimates is mainly to compute the total relation
985  * "footprint" if we have to sort or hash it. To do this, we sum the
986  * total equivalent size (in "double" arithmetic) and then divide by the
987  * total rowcount estimate. This is done separately for the total rel
988  * width and each attribute.
989  *
990  * Note: if you consider changing this logic, beware that child rels could
991  * have zero rows and/or width, if they were excluded by constraints.
992  */
993  has_live_children = false;
994  parent_rows = 0;
995  parent_size = 0;
996  nattrs = rel->max_attr - rel->min_attr + 1;
997  parent_attrsizes = (double *) palloc0(nattrs * sizeof(double));
998 
999  foreach(l, root->append_rel_list)
1000  {
1001  AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
1002  int childRTindex;
1003  RangeTblEntry *childRTE;
1004  RelOptInfo *childrel;
1005  List *childrinfos;
1006  ListCell *parentvars;
1007  ListCell *childvars;
1008  ListCell *lc;
1009 
1010  /* append_rel_list contains all append rels; ignore others */
1011  if (appinfo->parent_relid != parentRTindex)
1012  continue;
1013 
1014  childRTindex = appinfo->child_relid;
1015  childRTE = root->simple_rte_array[childRTindex];
1016 
1017  /*
1018  * The child rel's RelOptInfo was already created during
1019  * add_other_rels_to_query.
1020  */
1021  childrel = find_base_rel(root, childRTindex);
1022  Assert(childrel->reloptkind == RELOPT_OTHER_MEMBER_REL);
1023 
1024  /* We may have already proven the child to be dummy. */
1025  if (IS_DUMMY_REL(childrel))
1026  continue;
1027 
1028  /*
1029  * We have to copy the parent's targetlist and quals to the child,
1030  * with appropriate substitution of variables. However, the
1031  * baserestrictinfo quals were already copied/substituted when the
1032  * child RelOptInfo was built. So we don't need any additional setup
1033  * before applying constraint exclusion.
1034  */
1035  if (relation_excluded_by_constraints(root, childrel, childRTE))
1036  {
1037  /*
1038  * This child need not be scanned, so we can omit it from the
1039  * appendrel.
1040  */
1041  set_dummy_rel_pathlist(childrel);
1042  continue;
1043  }
1044 
1045  /*
1046  * Constraint exclusion failed, so copy the parent's join quals and
1047  * targetlist to the child, with appropriate variable substitutions.
1048  *
1049  * We skip join quals that came from above outer joins that can null
1050  * this rel, since they would be of no value while generating paths
1051  * for the child. This saves some effort while processing the child
1052  * rel, and it also avoids an implementation restriction in
1053  * adjust_appendrel_attrs (it can't apply nullingrels to a non-Var).
1054  */
1055  childrinfos = NIL;
1056  foreach(lc, rel->joininfo)
1057  {
1058  RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
1059 
1060  if (!bms_overlap(rinfo->clause_relids, rel->nulling_relids))
1061  childrinfos = lappend(childrinfos,
1062  adjust_appendrel_attrs(root,
1063  (Node *) rinfo,
1064  1, &appinfo));
1065  }
1066  childrel->joininfo = childrinfos;
1067 
1068  /*
1069  * Now for the child's targetlist.
1070  *
1071  * NB: the resulting childrel->reltarget->exprs may contain arbitrary
1072  * expressions, which otherwise would not occur in a rel's targetlist.
1073  * Code that might be looking at an appendrel child must cope with
1074  * such. (Normally, a rel's targetlist would only include Vars and
1075  * PlaceHolderVars.) XXX we do not bother to update the cost or width
1076  * fields of childrel->reltarget; not clear if that would be useful.
1077  */
1078  childrel->reltarget->exprs = (List *)
1079  adjust_appendrel_attrs(root,
1080  (Node *) rel->reltarget->exprs,
1081  1, &appinfo);
1082 
1083  /*
1084  * We have to make child entries in the EquivalenceClass data
1085  * structures as well. This is needed either if the parent
1086  * participates in some eclass joins (because we will want to consider
1087  * inner-indexscan joins on the individual children) or if the parent
1088  * has useful pathkeys (because we should try to build MergeAppend
1089  * paths that produce those sort orderings).
1090  */
1091  if (rel->has_eclass_joins || has_useful_pathkeys(root, rel))
1092  add_child_rel_equivalences(root, appinfo, rel, childrel);
1093  childrel->has_eclass_joins = rel->has_eclass_joins;
1094 
1095  /*
1096  * Note: we could compute appropriate attr_needed data for the child's
1097  * variables, by transforming the parent's attr_needed through the
1098  * translated_vars mapping. However, currently there's no need
1099  * because attr_needed is only examined for base relations not
1100  * otherrels. So we just leave the child's attr_needed empty.
1101  */
1102 
1103  /*
1104  * If we consider partitionwise joins with the parent rel, do the same
1105  * for partitioned child rels.
1106  *
1107  * Note: here we abuse the consider_partitionwise_join flag by setting
1108  * it for child rels that are not themselves partitioned. We do so to
1109  * tell try_partitionwise_join() that the child rel is sufficiently
1110  * valid to be used as a per-partition input, even if it later gets
1111  * proven to be dummy. (It's not usable until we've set up the
1112  * reltarget and EC entries, which we just did.)
1113  */
1114  if (rel->consider_partitionwise_join)
1115  childrel->consider_partitionwise_join = true;
1116 
1117  /*
1118  * If parallelism is allowable for this query in general, see whether
1119  * it's allowable for this childrel in particular. But if we've
1120  * already decided the appendrel is not parallel-safe as a whole,
1121  * there's no point in considering parallelism for this child. For
1122  * consistency, do this before calling set_rel_size() for the child.
1123  */
1124  if (root->glob->parallelModeOK && rel->consider_parallel)
1125  set_rel_consider_parallel(root, childrel, childRTE);
1126 
1127  /*
1128  * Compute the child's size.
1129  */
1130  set_rel_size(root, childrel, childRTindex, childRTE);
1131 
1132  /*
1133  * It is possible that constraint exclusion detected a contradiction
1134  * within a child subquery, even though we didn't prove one above. If
1135  * so, we can skip this child.
1136  */
1137  if (IS_DUMMY_REL(childrel))
1138  continue;
1139 
1140  /* We have at least one live child. */
1141  has_live_children = true;
1142 
1143  /*
1144  * If any live child is not parallel-safe, treat the whole appendrel
1145  * as not parallel-safe. In future we might be able to generate plans
1146  * in which some children are farmed out to workers while others are
1147  * not; but we don't have that today, so it's a waste to consider
1148  * partial paths anywhere in the appendrel unless it's all safe.
1149  * (Child rels visited before this one will be unmarked in
1150  * set_append_rel_pathlist().)
1151  */
1152  if (!childrel->consider_parallel)
1153  rel->consider_parallel = false;
1154 
1155  /*
1156  * Accumulate size information from each live child.
1157  */
1158  Assert(childrel->rows > 0);
1159 
1160  parent_rows += childrel->rows;
1161  parent_size += childrel->reltarget->width * childrel->rows;
1162 
1163  /*
1164  * Accumulate per-column estimates too. We need not do anything for
1165  * PlaceHolderVars in the parent list. If child expression isn't a
1166  * Var, or we didn't record a width estimate for it, we have to fall
1167  * back on a datatype-based estimate.
1168  *
1169  * By construction, child's targetlist is 1-to-1 with parent's.
1170  */
1171  forboth(parentvars, rel->reltarget->exprs,
1172  childvars, childrel->reltarget->exprs)
1173  {
1174  Var *parentvar = (Var *) lfirst(parentvars);
1175  Node *childvar = (Node *) lfirst(childvars);
1176 
1177  if (IsA(parentvar, Var) && parentvar->varno == parentRTindex)
1178  {
1179  int pndx = parentvar->varattno - rel->min_attr;
1180  int32 child_width = 0;
1181 
1182  if (IsA(childvar, Var) &&
1183  ((Var *) childvar)->varno == childrel->relid)
1184  {
1185  int cndx = ((Var *) childvar)->varattno - childrel->min_attr;
1186 
1187  child_width = childrel->attr_widths[cndx];
1188  }
1189  if (child_width <= 0)
1190  child_width = get_typavgwidth(exprType(childvar),
1191  exprTypmod(childvar));
1192  Assert(child_width > 0);
1193  parent_attrsizes[pndx] += child_width * childrel->rows;
1194  }
1195  }
1196  }
1197 
1198  if (has_live_children)
1199  {
1200  /*
1201  * Save the finished size estimates.
1202  */
1203  int i;
1204 
1205  Assert(parent_rows > 0);
1206  rel->rows = parent_rows;
1207  rel->reltarget->width = rint(parent_size / parent_rows);
1208  for (i = 0; i < nattrs; i++)
1209  rel->attr_widths[i] = rint(parent_attrsizes[i] / parent_rows);
1210 
1211  /*
1212  * Set "raw tuples" count equal to "rows" for the appendrel; needed
1213  * because some places assume rel->tuples is valid for any baserel.
1214  */
1215  rel->tuples = parent_rows;
1216 
1217  /*
1218  * Note that we leave rel->pages as zero; this is important to avoid
1219  * double-counting the appendrel tree in total_table_pages.
1220  */
1221  }
1222  else
1223  {
1224  /*
1225  * All children were excluded by constraints, so mark the whole
1226  * appendrel dummy. We must do this in this phase so that the rel's
1227  * dummy-ness is visible when we generate paths for other rels.
1228  */
1229  set_dummy_rel_pathlist(rel);
1230  }
1231 
1232  pfree(parent_attrsizes);
1233 }
1234 
1235 /*
1236  * set_append_rel_pathlist
1237  * Build access paths for an "append relation"
1238  */
1239 static void
1240 set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
1241  Index rti, RangeTblEntry *rte)
1242 {
1243  int parentRTindex = rti;
1244  List *live_childrels = NIL;
1245  ListCell *l;
1246 
1247  /*
1248  * Generate access paths for each member relation, and remember the
1249  * non-dummy children.
1250  */
1251  foreach(l, root->append_rel_list)
1252  {
1253  AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
1254  int childRTindex;
1255  RangeTblEntry *childRTE;
1256  RelOptInfo *childrel;
1257 
1258  /* append_rel_list contains all append rels; ignore others */
1259  if (appinfo->parent_relid != parentRTindex)
1260  continue;
1261 
1262  /* Re-locate the child RTE and RelOptInfo */
1263  childRTindex = appinfo->child_relid;
1264  childRTE = root->simple_rte_array[childRTindex];
1265  childrel = root->simple_rel_array[childRTindex];
1266 
1267  /*
1268  * If set_append_rel_size() decided the parent appendrel was
1269  * parallel-unsafe at some point after visiting this child rel, we
1270  * need to propagate the unsafety marking down to the child, so that
1271  * we don't generate useless partial paths for it.
1272  */
1273  if (!rel->consider_parallel)
1274  childrel->consider_parallel = false;
1275 
1276  /*
1277  * Compute the child's access paths.
1278  */
1279  set_rel_pathlist(root, childrel, childRTindex, childRTE);
1280 
1281  /*
1282  * If child is dummy, ignore it.
1283  */
1284  if (IS_DUMMY_REL(childrel))
1285  continue;
1286 
1287  /*
1288  * Child is live, so add it to the live_childrels list for use below.
1289  */
1290  live_childrels = lappend(live_childrels, childrel);
1291  }
1292 
1293  /* Add paths to the append relation. */
1294  add_paths_to_append_rel(root, rel, live_childrels);
1295 }
1296 
1297 
1298 /*
1299  * add_paths_to_append_rel
1300  * Generate paths for the given append relation given the set of non-dummy
1301  * child rels.
1302  *
1303  * The function collects all parameterizations and orderings supported by the
1304  * non-dummy children. For every such parameterization or ordering, it creates
1305  * an append path collecting one path from each non-dummy child with given
1306  * parameterization or ordering. Similarly it collects partial paths from
1307  * non-dummy children to create partial append paths.
1308  */
1309 void
1310 add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
1311  List *live_childrels)
1312 {
1313  List *subpaths = NIL;
1314  bool subpaths_valid = true;
1315  List *startup_subpaths = NIL;
1316  bool startup_subpaths_valid = true;
1317  List *partial_subpaths = NIL;
1318  List *pa_partial_subpaths = NIL;
1319  List *pa_nonpartial_subpaths = NIL;
1320  bool partial_subpaths_valid = true;
1321  bool pa_subpaths_valid;
1322  List *all_child_pathkeys = NIL;
1323  List *all_child_outers = NIL;
1324  ListCell *l;
1325  double partial_rows = -1;
1326 
1327  /* If appropriate, consider parallel append */
1328  pa_subpaths_valid = enable_parallel_append && rel->consider_parallel;
1329 
1330  /*
1331  * For every non-dummy child, remember the cheapest path. Also, identify
1332  * all pathkeys (orderings) and parameterizations (required_outer sets)
1333  * available for the non-dummy member relations.
1334  */
1335  foreach(l, live_childrels)
1336  {
1337  RelOptInfo *childrel = lfirst(l);
1338  ListCell *lcp;
1339  Path *cheapest_partial_path = NULL;
1340 
1341  /*
1342  * If child has an unparameterized cheapest-total path, add that to
1343  * the unparameterized Append path we are constructing for the parent.
1344  * If not, there's no workable unparameterized path.
1345  *
1346  * With partitionwise aggregates, the child rel's pathlist may be
1347  * empty, so don't assume that a path exists here.
1348  */
1349  if (childrel->pathlist != NIL &&
1350  childrel->cheapest_total_path->param_info == NULL)
1351  accumulate_append_subpath(childrel->cheapest_total_path,
1352  &subpaths, NULL);
1353  else
1354  subpaths_valid = false;
1355 
1356  /*
1357  * When the planner is considering cheap startup plans, we'll also
1358  * collect all the cheapest_startup_paths (if set) and build an
1359  * AppendPath containing those as subpaths.
1360  */
1361  if (rel->consider_startup && childrel->cheapest_startup_path != NULL)
1362  {
1363  /* cheapest_startup_path must not be a parameterized path. */
1364  Assert(childrel->cheapest_startup_path->param_info == NULL);
1365  accumulate_append_subpath(childrel->cheapest_startup_path,
1366  &startup_subpaths,
1367  NULL);
1368  }
1369  else
1370  startup_subpaths_valid = false;
1371 
1372 
1373  /* Same idea, but for a partial plan. */
1374  if (childrel->partial_pathlist != NIL)
1375  {
1376  cheapest_partial_path = linitial(childrel->partial_pathlist);
1377  accumulate_append_subpath(cheapest_partial_path,
1378  &partial_subpaths, NULL);
1379  }
1380  else
1381  partial_subpaths_valid = false;
1382 
1383  /*
1384  * Same idea, but for a parallel append mixing partial and non-partial
1385  * paths.
1386  */
1387  if (pa_subpaths_valid)
1388  {
1389  Path *nppath = NULL;
1390 
1391  nppath =
1392  get_cheapest_parallel_safe_total_inner(childrel->pathlist);
1393 
1394  if (cheapest_partial_path == NULL && nppath == NULL)
1395  {
1396  /* Neither a partial nor a parallel-safe path? Forget it. */
1397  pa_subpaths_valid = false;
1398  }
1399  else if (nppath == NULL ||
1400  (cheapest_partial_path != NULL &&
1401  cheapest_partial_path->total_cost < nppath->total_cost))
1402  {
1403  /* Partial path is cheaper or the only option. */
1404  Assert(cheapest_partial_path != NULL);
1405  accumulate_append_subpath(cheapest_partial_path,
1406  &pa_partial_subpaths,
1407  &pa_nonpartial_subpaths);
1408  }
1409  else
1410  {
1411  /*
1412  * Either we've got only a non-partial path, or we think that
1413  * a single backend can execute the best non-partial path
1414  * faster than all the parallel backends working together can
1415  * execute the best partial path.
1416  *
1417  * It might make sense to be more aggressive here. Even if
1418  * the best non-partial path is more expensive than the best
1419  * partial path, it could still be better to choose the
1420  * non-partial path if there are several such paths that can
1421  * be given to different workers. For now, we don't try to
1422  * figure that out.
1423  */
1424  accumulate_append_subpath(nppath,
1425  &pa_nonpartial_subpaths,
1426  NULL);
1427  }
1428  }
1429 
1430  /*
1431  * Collect lists of all the available path orderings and
1432  * parameterizations for all the children. We use these as a
1433  * heuristic to indicate which sort orderings and parameterizations we
1434  * should build Append and MergeAppend paths for.
1435  */
1436  foreach(lcp, childrel->pathlist)
1437  {
1438  Path *childpath = (Path *) lfirst(lcp);
1439  List *childkeys = childpath->pathkeys;
1440  Relids childouter = PATH_REQ_OUTER(childpath);
1441 
1442  /* Unsorted paths don't contribute to pathkey list */
1443  if (childkeys != NIL)
1444  {
1445  ListCell *lpk;
1446  bool found = false;
1447 
1448  /* Have we already seen this ordering? */
1449  foreach(lpk, all_child_pathkeys)
1450  {
1451  List *existing_pathkeys = (List *) lfirst(lpk);
1452 
1453  if (compare_pathkeys(existing_pathkeys,
1454  childkeys) == PATHKEYS_EQUAL)
1455  {
1456  found = true;
1457  break;
1458  }
1459  }
1460  if (!found)
1461  {
1462  /* No, so add it to all_child_pathkeys */
1463  all_child_pathkeys = lappend(all_child_pathkeys,
1464  childkeys);
1465  }
1466  }
1467 
1468  /* Unparameterized paths don't contribute to param-set list */
1469  if (childouter)
1470  {
1471  ListCell *lco;
1472  bool found = false;
1473 
1474  /* Have we already seen this param set? */
1475  foreach(lco, all_child_outers)
1476  {
1477  Relids existing_outers = (Relids) lfirst(lco);
1478 
1479  if (bms_equal(existing_outers, childouter))
1480  {
1481  found = true;
1482  break;
1483  }
1484  }
1485  if (!found)
1486  {
1487  /* No, so add it to all_child_outers */
1488  all_child_outers = lappend(all_child_outers,
1489  childouter);
1490  }
1491  }
1492  }
1493  }
1494 
1495  /*
1496  * If we found unparameterized paths for all children, build an unordered,
1497  * unparameterized Append path for the rel. (Note: this is correct even
1498  * if we have zero or one live subpath due to constraint exclusion.)
1499  */
1500  if (subpaths_valid)
1501  add_path(rel, (Path *) create_append_path(root, rel, subpaths, NIL,
1502  NIL, NULL, 0, false,
1503  -1));
1504 
1505  /* build an AppendPath for the cheap startup paths, if valid */
1506  if (startup_subpaths_valid)
1507  add_path(rel, (Path *) create_append_path(root, rel, startup_subpaths,
1508  NIL, NIL, NULL, 0, false, -1));
1509 
1510  /*
1511  * Consider an append of unordered, unparameterized partial paths. Make
1512  * it parallel-aware if possible.
1513  */
1514  if (partial_subpaths_valid && partial_subpaths != NIL)
1515  {
1516  AppendPath *appendpath;
1517  ListCell *lc;
1518  int parallel_workers = 0;
1519 
1520  /* Find the highest number of workers requested for any subpath. */
1521  foreach(lc, partial_subpaths)
1522  {
1523  Path *path = lfirst(lc);
1524 
1525  parallel_workers = Max(parallel_workers, path->parallel_workers);
1526  }
1527  Assert(parallel_workers > 0);
1528 
1529  /*
1530  * If the use of parallel append is permitted, always request at least
1531  * log2(# of children) workers. We assume it can be useful to have
1532  * extra workers in this case because they will be spread out across
1533  * the children. The precise formula is just a guess, but we don't
1534  * want to end up with a radically different answer for a table with N
1535  * partitions vs. an unpartitioned table with the same data, so the
1536  * use of some kind of log-scaling here seems to make some sense.
1537  */
1538  if (enable_parallel_append)
1539  {
1540  parallel_workers = Max(parallel_workers,
1541  pg_leftmost_one_pos32(list_length(live_childrels)) + 1);
1542  parallel_workers = Min(parallel_workers,
1543  max_parallel_workers_per_gather);
1544  }
1545  Assert(parallel_workers > 0);
1546 
1547  /* Generate a partial append path. */
1548  appendpath = create_append_path(root, rel, NIL, partial_subpaths,
1549  NIL, NULL, parallel_workers,
1550  enable_parallel_append,
1551  -1);
1552 
1553  /*
1554  * Make sure any subsequent partial paths use the same row count
1555  * estimate.
1556  */
1557  partial_rows = appendpath->path.rows;
1558 
1559  /* Add the path. */
1560  add_partial_path(rel, (Path *) appendpath);
1561  }
1562 
1563  /*
1564  * Consider a parallel-aware append using a mix of partial and non-partial
1565  * paths. (This only makes sense if there's at least one child which has
1566  * a non-partial path that is substantially cheaper than any partial path;
1567  * otherwise, we should use the append path added in the previous step.)
1568  */
1569  if (pa_subpaths_valid && pa_nonpartial_subpaths != NIL)
1570  {
1571  AppendPath *appendpath;
1572  ListCell *lc;
1573  int parallel_workers = 0;
1574 
1575  /*
1576  * Find the highest number of workers requested for any partial
1577  * subpath.
1578  */
1579  foreach(lc, pa_partial_subpaths)
1580  {
1581  Path *path = lfirst(lc);
1582 
1583  parallel_workers = Max(parallel_workers, path->parallel_workers);
1584  }
1585 
1586  /*
1587  * Same formula here as above. It's even more important in this
1588  * instance because the non-partial paths won't contribute anything to
1589  * the planned number of parallel workers.
1590  */
1591  parallel_workers = Max(parallel_workers,
1592  pg_leftmost_one_pos32(list_length(live_childrels)) + 1);
1593  parallel_workers = Min(parallel_workers,
1594  max_parallel_workers_per_gather);
1595  Assert(parallel_workers > 0);
1596 
1597  appendpath = create_append_path(root, rel, pa_nonpartial_subpaths,
1598  pa_partial_subpaths,
1599  NIL, NULL, parallel_workers, true,
1600  partial_rows);
1601  add_partial_path(rel, (Path *) appendpath);
1602  }
1603 
1604  /*
1605  * Also build unparameterized ordered append paths based on the collected
1606  * list of child pathkeys.
1607  */
1608  if (subpaths_valid)
1609  generate_orderedappend_paths(root, rel, live_childrels,
1610  all_child_pathkeys);
1611 
1612  /*
1613  * Build Append paths for each parameterization seen among the child rels.
1614  * (This may look pretty expensive, but in most cases of practical
1615  * interest, the child rels will expose mostly the same parameterizations,
1616  * so that not that many cases actually get considered here.)
1617  *
1618  * The Append node itself cannot enforce quals, so all qual checking must
1619  * be done in the child paths. This means that to have a parameterized
1620  * Append path, we must have the exact same parameterization for each
1621  * child path; otherwise some children might be failing to check the
1622  * moved-down quals. To make them match up, we can try to increase the
1623  * parameterization of lesser-parameterized paths.
1624  */
1625  foreach(l, all_child_outers)
1626  {
1627  Relids required_outer = (Relids) lfirst(l);
1628  ListCell *lcr;
1629 
1630  /* Select the child paths for an Append with this parameterization */
1631  subpaths = NIL;
1632  subpaths_valid = true;
1633  foreach(lcr, live_childrels)
1634  {
1635  RelOptInfo *childrel = (RelOptInfo *) lfirst(lcr);
1636  Path *subpath;
1637 
1638  if (childrel->pathlist == NIL)
1639  {
1640  /* failed to make a suitable path for this child */
1641  subpaths_valid = false;
1642  break;
1643  }
1644 
1645  subpath = get_cheapest_parameterized_child_path(root,
1646  childrel,
1647  required_outer);
1648  if (subpath == NULL)
1649  {
1650  /* failed to make a suitable path for this child */
1651  subpaths_valid = false;
1652  break;
1653  }
1654  accumulate_append_subpath(subpath, &subpaths, NULL);
1655  }
1656 
1657  if (subpaths_valid)
1658  add_path(rel, (Path *)
1659  create_append_path(root, rel, subpaths, NIL,
1660  NIL, required_outer, 0, false,
1661  -1));
1662  }
1663 
1664  /*
1665  * When there is only a single child relation, the Append path can inherit
1666  * any ordering available for the child rel's path, so that it's useful to
1667  * consider ordered partial paths. Above we only considered the cheapest
1668  * partial path for each child, but let's also make paths using any
1669  * partial paths that have pathkeys.
1670  */
1671  if (list_length(live_childrels) == 1)
1672  {
1673  RelOptInfo *childrel = (RelOptInfo *) linitial(live_childrels);
1674 
1675  /* skip the cheapest partial path, since we already used that above */
1676  for_each_from(l, childrel->partial_pathlist, 1)
1677  {
1678  Path *path = (Path *) lfirst(l);
1679  AppendPath *appendpath;
1680 
1681  /* skip paths with no pathkeys. */
1682  if (path->pathkeys == NIL)
1683  continue;
1684 
1685  appendpath = create_append_path(root, rel, NIL, list_make1(path),
1686  NIL, NULL,
1687  path->parallel_workers, true,
1688  partial_rows);
1689  add_partial_path(rel, (Path *) appendpath);
1690  }
1691  }
1692 }
1693 
1694 /*
1695  * generate_orderedappend_paths
1696  * Generate ordered append paths for an append relation
1697  *
1698  * Usually we generate MergeAppend paths here, but there are some special
1699  * cases where we can generate simple Append paths, because the subpaths
1700  * can provide tuples in the required order already.
1701  *
1702  * We generate a path for each ordering (pathkey list) appearing in
1703  * all_child_pathkeys.
1704  *
1705  * We consider both cheapest-startup and cheapest-total cases, ie, for each
1706  * interesting ordering, collect all the cheapest startup subpaths and all the
1707  * cheapest total paths, and build a suitable path for each case.
1708  *
1709  * We don't currently generate any parameterized ordered paths here. While
1710  * it would not take much more code here to do so, it's very unclear that it
1711  * is worth the planning cycles to investigate such paths: there's little
1712  * use for an ordered path on the inside of a nestloop. In fact, it's likely
1713  * that the current coding of add_path would reject such paths out of hand,
1714  * because add_path gives no credit for sort ordering of parameterized paths,
1715  * and a parameterized MergeAppend is going to be more expensive than the
1716  * corresponding parameterized Append path. If we ever try harder to support
1717  * parameterized mergejoin plans, it might be worth adding support for
1718  * parameterized paths here to feed such joins. (See notes in
1719  * optimizer/README for why that might not ever happen, though.)
1720  */
1721 static void
1722 generate_orderedappend_paths(PlannerInfo *root, RelOptInfo *rel,
1723  List *live_childrels,
1724  List *all_child_pathkeys)
1725 {
1726  ListCell *lcp;
1727  List *partition_pathkeys = NIL;
1728  List *partition_pathkeys_desc = NIL;
1729  bool partition_pathkeys_partial = true;
1730  bool partition_pathkeys_desc_partial = true;
1731 
1732  /*
1733  * Some partitioned table setups may allow us to use an Append node
1734  * instead of a MergeAppend. This is possible in cases such as RANGE
1735  * partitioned tables where it's guaranteed that an earlier partition must
1736  * contain rows which come earlier in the sort order. To detect whether
1737  * this is relevant, build pathkey descriptions of the partition ordering,
1738  * for both forward and reverse scans.
1739  */
1740  if (rel->part_scheme != NULL && IS_SIMPLE_REL(rel) &&
1741  partitions_are_ordered(rel->boundinfo, rel->live_parts))
1742  {
1743  partition_pathkeys = build_partition_pathkeys(root, rel,
1744  ForwardScanDirection,
1745  &partition_pathkeys_partial);
1746 
1747  partition_pathkeys_desc = build_partition_pathkeys(root, rel,
1748  BackwardScanDirection,
1749  &partition_pathkeys_desc_partial);
1750 
1751  /*
1752  * You might think we should truncate_useless_pathkeys here, but
1753  * allowing partition keys which are a subset of the query's pathkeys
1754  * can often be useful. For example, consider a table partitioned by
1755  * RANGE (a, b), and a query with ORDER BY a, b, c. If we have child
1756  * paths that can produce the a, b, c ordering (perhaps via indexes on
1757  * (a, b, c)) then it works to consider the appendrel output as
1758  * ordered by a, b, c.
1759  */
1760  }
1761 
1762  /* Now consider each interesting sort ordering */
1763  foreach(lcp, all_child_pathkeys)
1764  {
1765  List *pathkeys = (List *) lfirst(lcp);
1766  List *startup_subpaths = NIL;
1767  List *total_subpaths = NIL;
1768  List *fractional_subpaths = NIL;
1769  bool startup_neq_total = false;
1770  bool match_partition_order;
1771  bool match_partition_order_desc;
1772  int end_index;
1773  int first_index;
1774  int direction;
1775 
1776  /*
1777  * Determine if this sort ordering matches any partition pathkeys we
1778  * have, for both ascending and descending partition order. If the
1779  * partition pathkeys happen to be contained in pathkeys then it still
1780  * works, as described above, providing that the partition pathkeys
1781  * are complete and not just a prefix of the partition keys. (In such
1782  * cases we'll be relying on the child paths to have sorted the
1783  * lower-order columns of the required pathkeys.)
1784  */
1785  match_partition_order =
1786  pathkeys_contained_in(pathkeys, partition_pathkeys) ||
1787  (!partition_pathkeys_partial &&
1788  pathkeys_contained_in(partition_pathkeys, pathkeys));
1789 
1790  match_partition_order_desc = !match_partition_order &&
1791  (pathkeys_contained_in(pathkeys, partition_pathkeys_desc) ||
1792  (!partition_pathkeys_desc_partial &&
1793  pathkeys_contained_in(partition_pathkeys_desc, pathkeys)));
1794 
1795  /*
1796  * When the required pathkeys match the reverse of the partition
1797  * order, we must build the list of paths in reverse starting with the
1798  * last matching partition first. We can get away without making any
1799  * special cases for this in the loop below by just looping backward
1800  * over the child relations in this case.
1801  */
1802  if (match_partition_order_desc)
1803  {
1804  /* loop backward */
1805  first_index = list_length(live_childrels) - 1;
1806  end_index = -1;
1807  direction = -1;
1808 
1809  /*
1810  * Set this to true to save us having to check for
1811  * match_partition_order_desc in the loop below.
1812  */
1813  match_partition_order = true;
1814  }
1815  else
1816  {
1817  /* for all other case, loop forward */
1818  first_index = 0;
1819  end_index = list_length(live_childrels);
1820  direction = 1;
1821  }
1822 
1823  /* Select the child paths for this ordering... */
1824  for (int i = first_index; i != end_index; i += direction)
1825  {
1826  RelOptInfo *childrel = list_nth_node(RelOptInfo, live_childrels, i);
1827  Path *cheapest_startup,
1828  *cheapest_total,
1829  *cheapest_fractional = NULL;
1830 
1831  /* Locate the right paths, if they are available. */
1832  cheapest_startup =
1833  get_cheapest_path_for_pathkeys(childrel->pathlist,
1834  pathkeys,
1835  NULL,
1836  STARTUP_COST,
1837  false);
1838  cheapest_total =
1839  get_cheapest_path_for_pathkeys(childrel->pathlist,
1840  pathkeys,
1841  NULL,
1842  TOTAL_COST,
1843  false);
1844 
1845  /*
1846  * If we can't find any paths with the right order just use the
1847  * cheapest-total path; we'll have to sort it later.
1848  */
1849  if (cheapest_startup == NULL || cheapest_total == NULL)
1850  {
1851  cheapest_startup = cheapest_total =
1852  childrel->cheapest_total_path;
1853  /* Assert we do have an unparameterized path for this child */
1854  Assert(cheapest_total->param_info == NULL);
1855  }
1856 
1857  /*
1858  * When building a fractional path, determine a cheapest
1859  * fractional path for each child relation too. Looking at startup
1860  * and total costs is not enough, because the cheapest fractional
1861  * path may be dominated by two separate paths (one for startup,
1862  * one for total).
1863  *
1864  * When needed (building fractional path), determine the cheapest
1865  * fractional path too.
1866  */
1867  if (root->tuple_fraction > 0)
1868  {
1869  double path_fraction = (1.0 / root->tuple_fraction);
1870 
1871  cheapest_fractional =
1872  get_cheapest_fractional_path_for_pathkeys(childrel->pathlist,
1873  pathkeys,
1874  NULL,
1875  path_fraction);
1876 
1877  /*
1878  * If we found no path with matching pathkeys, use the
1879  * cheapest total path instead.
1880  *
1881  * XXX We might consider partially sorted paths too (with an
1882  * incremental sort on top). But we'd have to build all the
1883  * incremental paths, do the costing etc.
1884  */
1885  if (!cheapest_fractional)
1886  cheapest_fractional = cheapest_total;
1887  }
1888 
1889  /*
1890  * Notice whether we actually have different paths for the
1891  * "cheapest" and "total" cases; frequently there will be no point
1892  * in two create_merge_append_path() calls.
1893  */
1894  if (cheapest_startup != cheapest_total)
1895  startup_neq_total = true;
1896 
1897  /*
1898  * Collect the appropriate child paths. The required logic varies
1899  * for the Append and MergeAppend cases.
1900  */
1901  if (match_partition_order)
1902  {
1903  /*
1904  * We're going to make a plain Append path. We don't need
1905  * most of what accumulate_append_subpath would do, but we do
1906  * want to cut out child Appends or MergeAppends if they have
1907  * just a single subpath (and hence aren't doing anything
1908  * useful).
1909  */
1910  cheapest_startup = get_singleton_append_subpath(cheapest_startup);
1911  cheapest_total = get_singleton_append_subpath(cheapest_total);
1912 
1913  startup_subpaths = lappend(startup_subpaths, cheapest_startup);
1914  total_subpaths = lappend(total_subpaths, cheapest_total);
1915 
1916  if (cheapest_fractional)
1917  {
1918  cheapest_fractional = get_singleton_append_subpath(cheapest_fractional);
1919  fractional_subpaths = lappend(fractional_subpaths, cheapest_fractional);
1920  }
1921  }
1922  else
1923  {
1924  /*
1925  * Otherwise, rely on accumulate_append_subpath to collect the
1926  * child paths for the MergeAppend.
1927  */
1928  accumulate_append_subpath(cheapest_startup,
1929  &startup_subpaths, NULL);
1930  accumulate_append_subpath(cheapest_total,
1931  &total_subpaths, NULL);
1932 
1933  if (cheapest_fractional)
1934  accumulate_append_subpath(cheapest_fractional,
1935  &fractional_subpaths, NULL);
1936  }
1937  }
1938 
1939  /* ... and build the Append or MergeAppend paths */
1940  if (match_partition_order)
1941  {
1942  /* We only need Append */
1943  add_path(rel, (Path *) create_append_path(root,
1944  rel,
1945  startup_subpaths,
1946  NIL,
1947  pathkeys,
1948  NULL,
1949  0,
1950  false,
1951  -1));
1952  if (startup_neq_total)
1953  add_path(rel, (Path *) create_append_path(root,
1954  rel,
1955  total_subpaths,
1956  NIL,
1957  pathkeys,
1958  NULL,
1959  0,
1960  false,
1961  -1));
1962 
1963  if (fractional_subpaths)
1964  add_path(rel, (Path *) create_append_path(root,
1965  rel,
1966  fractional_subpaths,
1967  NIL,
1968  pathkeys,
1969  NULL,
1970  0,
1971  false,
1972  -1));
1973  }
1974  else
1975  {
1976  /* We need MergeAppend */
1977  add_path(rel, (Path *) create_merge_append_path(root,
1978  rel,
1979  startup_subpaths,
1980  pathkeys,
1981  NULL));
1982  if (startup_neq_total)
1983  add_path(rel, (Path *) create_merge_append_path(root,
1984  rel,
1985  total_subpaths,
1986  pathkeys,
1987  NULL));
1988 
1989  if (fractional_subpaths)
1990  add_path(rel, (Path *) create_merge_append_path(root,
1991  rel,
1992  fractional_subpaths,
1993  pathkeys,
1994  NULL));
1995  }
1996  }
1997 }
1998 
1999 /*
2000  * get_cheapest_parameterized_child_path
2001  * Get cheapest path for this relation that has exactly the requested
2002  * parameterization.
2003  *
2004  * Returns NULL if unable to create such a path.
2005  */
2006 static Path *
2007 get_cheapest_parameterized_child_path(PlannerInfo *root, RelOptInfo *rel,
2008  Relids required_outer)
2009 {
2010  Path *cheapest;
2011  ListCell *lc;
2012 
2013  /*
2014  * Look up the cheapest existing path with no more than the needed
2015  * parameterization. If it has exactly the needed parameterization, we're
2016  * done.
2017  */
2018  cheapest = get_cheapest_path_for_pathkeys(rel->pathlist,
2019  NIL,
2020  required_outer,
2021  TOTAL_COST,
2022  false);
2023  Assert(cheapest != NULL);
2024  if (bms_equal(PATH_REQ_OUTER(cheapest), required_outer))
2025  return cheapest;
2026 
2027  /*
2028  * Otherwise, we can "reparameterize" an existing path to match the given
2029  * parameterization, which effectively means pushing down additional
2030  * joinquals to be checked within the path's scan. However, some existing
2031  * paths might check the available joinquals already while others don't;
2032  * therefore, it's not clear which existing path will be cheapest after
2033  * reparameterization. We have to go through them all and find out.
2034  */
2035  cheapest = NULL;
2036  foreach(lc, rel->pathlist)
2037  {
2038  Path *path = (Path *) lfirst(lc);
2039 
2040  /* Can't use it if it needs more than requested parameterization */
2041  if (!bms_is_subset(PATH_REQ_OUTER(path), required_outer))
2042  continue;
2043 
2044  /*
2045  * Reparameterization can only increase the path's cost, so if it's
2046  * already more expensive than the current cheapest, forget it.
2047  */
2048  if (cheapest != NULL &&
2049  compare_path_costs(cheapest, path, TOTAL_COST) <= 0)
2050  continue;
2051 
2052  /* Reparameterize if needed, then recheck cost */
2053  if (!bms_equal(PATH_REQ_OUTER(path), required_outer))
2054  {
2055  path = reparameterize_path(root, path, required_outer, 1.0);
2056  if (path == NULL)
2057  continue; /* failed to reparameterize this one */
2058  Assert(bms_equal(PATH_REQ_OUTER(path), required_outer));
2059 
2060  if (cheapest != NULL &&
2061  compare_path_costs(cheapest, path, TOTAL_COST) <= 0)
2062  continue;
2063  }
2064 
2065  /* We have a new best path */
2066  cheapest = path;
2067  }
2068 
2069  /* Return the best path, or NULL if we found no suitable candidate */
2070  return cheapest;
2071 }
2072 
2073 /*
2074  * accumulate_append_subpath
2075  * Add a subpath to the list being built for an Append or MergeAppend.
2076  *
2077  * It's possible that the child is itself an Append or MergeAppend path, in
2078  * which case we can "cut out the middleman" and just add its child paths to
2079  * our own list. (We don't try to do this earlier because we need to apply
2080  * both levels of transformation to the quals.)
2081  *
2082  * Note that if we omit a child MergeAppend in this way, we are effectively
2083  * omitting a sort step, which seems fine: if the parent is to be an Append,
2084  * its result would be unsorted anyway, while if the parent is to be a
2085  * MergeAppend, there's no point in a separate sort on a child.
2086  *
2087  * Normally, either path is a partial path and subpaths is a list of partial
2088  * paths, or else path is a non-partial plan and subpaths is a list of those.
2089  * However, if path is a parallel-aware Append, then we add its partial path
2090  * children to subpaths and the rest to special_subpaths. If the latter is
2091  * NULL, we don't flatten the path at all (unless it contains only partial
2092  * paths).
2093  */
2094 static void
2095 accumulate_append_subpath(Path *path, List **subpaths, List **special_subpaths)
2096 {
2097  if (IsA(path, AppendPath))
2098  {
2099  AppendPath *apath = (AppendPath *) path;
2100 
2101  if (!apath->path.parallel_aware || apath->first_partial_path == 0)
2102  {
2103  *subpaths = list_concat(*subpaths, apath->subpaths);
2104  return;
2105  }
2106  else if (special_subpaths != NULL)
2107  {
2108  List *new_special_subpaths;
2109 
2110  /* Split Parallel Append into partial and non-partial subpaths */
2111  *subpaths = list_concat(*subpaths,
2112  list_copy_tail(apath->subpaths,
2113  apath->first_partial_path));
2114  new_special_subpaths = list_copy_head(apath->subpaths,
2115  apath->first_partial_path);
2116  *special_subpaths = list_concat(*special_subpaths,
2117  new_special_subpaths);
2118  return;
2119  }
2120  }
2121  else if (IsA(path, MergeAppendPath))
2122  {
2123  MergeAppendPath *mpath = (MergeAppendPath *) path;
2124 
2125  *subpaths = list_concat(*subpaths, mpath->subpaths);
2126  return;
2127  }
2128 
2129  *subpaths = lappend(*subpaths, path);
2130 }
2131 
2132 /*
2133  * get_singleton_append_subpath
2134  * Returns the single subpath of an Append/MergeAppend, or just
2135  * return 'path' if it's not a single sub-path Append/MergeAppend.
2136  *
2137  * Note: 'path' must not be a parallel-aware path.
2138  */
2139 static Path *
2140 get_singleton_append_subpath(Path *path)
2141 {
2142  Assert(!path->parallel_aware);
2143 
2144  if (IsA(path, AppendPath))
2145  {
2146  AppendPath *apath = (AppendPath *) path;
2147 
2148  if (list_length(apath->subpaths) == 1)
2149  return (Path *) linitial(apath->subpaths);
2150  }
2151  else if (IsA(path, MergeAppendPath))
2152  {
2153  MergeAppendPath *mpath = (MergeAppendPath *) path;
2154 
2155  if (list_length(mpath->subpaths) == 1)
2156  return (Path *) linitial(mpath->subpaths);
2157  }
2158 
2159  return path;
2160 }
2161 
2162 /*
2163  * set_dummy_rel_pathlist
2164  * Build a dummy path for a relation that's been excluded by constraints
2165  *
2166  * Rather than inventing a special "dummy" path type, we represent this as an
2167  * AppendPath with no members (see also IS_DUMMY_APPEND/IS_DUMMY_REL macros).
2168  *
2169  * (See also mark_dummy_rel, which does basically the same thing, but is
2170  * typically used to change a rel into dummy state after we already made
2171  * paths for it.)
2172  */
2173 static void
2174 set_dummy_rel_pathlist(RelOptInfo *rel)
2175 {
2176  /* Set dummy size estimates --- we leave attr_widths[] as zeroes */
2177  rel->rows = 0;
2178  rel->reltarget->width = 0;
2179 
2180  /* Discard any pre-existing paths; no further need for them */
2181  rel->pathlist = NIL;
2182  rel->partial_pathlist = NIL;
2183 
2184  /* Set up the dummy path */
2185  add_path(rel, (Path *) create_append_path(NULL, rel, NIL, NIL,
2186  NIL, rel->lateral_relids,
2187  0, false, -1));
2188 
2189  /*
2190  * We set the cheapest-path fields immediately, just in case they were
2191  * pointing at some discarded path. This is redundant in current usage
2192  * because set_rel_pathlist will do it later, but it's cheap so we keep it
2193  * for safety and consistency with mark_dummy_rel.
2194  */
2195  set_cheapest(rel);
2196 }
2197 
2198 /*
2199  * find_window_run_conditions
2200  * Determine if 'wfunc' is really a WindowFunc and call its prosupport
2201  * function to determine the function's monotonic properties. We then
2202  * see if 'opexpr' can be used to short-circuit execution.
2203  *
2204  * For example row_number() over (order by ...) always produces a value one
2205  * higher than the previous. If someone has a window function in a subquery
2206  * and has a WHERE clause in the outer query to filter rows <= 10, then we may
2207  * as well stop processing the windowagg once the row number reaches 11. Here
2208  * we check if 'opexpr' might help us to stop doing needless extra processing
2209  * in WindowAgg nodes.
2210  *
2211  * '*keep_original' is set to true if the caller should also use 'opexpr' for
2212  * its original purpose. This is set to false if the caller can assume that
2213  * the run condition will handle all of the required filtering.
2214  *
2215  * Returns true if 'opexpr' was found to be useful and was added to the
2216  * WindowFunc's runCondition. We also set *keep_original accordingly and add
2217  * 'attno' to *run_cond_attrs offset by FirstLowInvalidHeapAttributeNumber.
2218  * If the 'opexpr' cannot be used then we set *keep_original to true and
2219  * return false.
2220  */
2221 static bool
2222 find_window_run_conditions(Query *subquery, RangeTblEntry *rte, Index rti,
2223  AttrNumber attno, WindowFunc *wfunc, OpExpr *opexpr,
2224  bool wfunc_left, bool *keep_original,
2225  Bitmapset **run_cond_attrs)
2226 {
2227  Oid prosupport;
2228  Expr *otherexpr;
2229  SupportRequestWFuncMonotonic req;
2230  SupportRequestWFuncMonotonic *res;
2231  WindowClause *wclause;
2232  List *opinfos;
2233  OpExpr *runopexpr;
2234  Oid runoperator;
2235  ListCell *lc;
2236 
2237  *keep_original = true;
2238 
2239  while (IsA(wfunc, RelabelType))
2240  wfunc = (WindowFunc *) ((RelabelType *) wfunc)->arg;
2241 
2242  /* we can only work with window functions */
2243  if (!IsA(wfunc, WindowFunc))
2244  return false;
2245 
2246  /* can't use it if there are subplans in the WindowFunc */
2247  if (contain_subplans((Node *) wfunc))
2248  return false;
2249 
2250  prosupport = get_func_support(wfunc->winfnoid);
2251 
2252  /* Check if there's a support function for 'wfunc' */
2253  if (!OidIsValid(prosupport))
2254  return false;
2255 
2256  /* get the Expr from the other side of the OpExpr */
2257  if (wfunc_left)
2258  otherexpr = lsecond(opexpr->args);
2259  else
2260  otherexpr = linitial(opexpr->args);
2261 
2262  /*
2263  * The value being compared must not change during the evaluation of the
2264  * window partition.
2265  */
2266  if (!is_pseudo_constant_clause((Node *) otherexpr))
2267  return false;
2268 
2269  /* find the window clause belonging to the window function */
2270  wclause = (WindowClause *) list_nth(subquery->windowClause,
2271  wfunc->winref - 1);
2272 
2273  req.type = T_SupportRequestWFuncMonotonic;
2274  req.window_func = wfunc;
2275  req.window_clause = wclause;
2276 
2277  /* call the support function */
2278  res = (SupportRequestWFuncMonotonic *)
2279  DatumGetPointer(OidFunctionCall1(prosupport,
2280  PointerGetDatum(&req)));
2281 
2282  /*
2283  * Nothing to do if the function is neither monotonically increasing nor
2284  * monotonically decreasing.
2285  */
2286  if (res == NULL || res->monotonic == MONOTONICFUNC_NONE)
2287  return false;
2288 
2289  runopexpr = NULL;
2290  runoperator = InvalidOid;
2291  opinfos = get_op_btree_interpretation(opexpr->opno);
2292 
2293  foreach(lc, opinfos)
2294  {
2295  OpBtreeInterpretation *opinfo = (OpBtreeInterpretation *) lfirst(lc);
2296  int strategy = opinfo->strategy;
2297 
2298  /* handle < / <= */
2299  if (strategy == BTLessStrategyNumber ||
2300  strategy == BTLessEqualStrategyNumber)
2301  {
2302  /*
2303  * < / <= is supported for monotonically increasing functions in
2304  * the form <wfunc> op <pseudoconst> and <pseudoconst> op <wfunc>
2305  * for monotonically decreasing functions.
2306  */
2307  if ((wfunc_left && (res->monotonic & MONOTONICFUNC_INCREASING)) ||
2308  (!wfunc_left && (res->monotonic & MONOTONICFUNC_DECREASING)))
2309  {
2310  *keep_original = false;
2311  runopexpr = opexpr;
2312  runoperator = opexpr->opno;
2313  }
2314  break;
2315  }
2316  /* handle > / >= */
2317  else if (strategy == BTGreaterStrategyNumber ||
2318  strategy == BTGreaterEqualStrategyNumber)
2319  {
2320  /*
2321  * > / >= is supported for monotonically decreasing functions in
2322  * the form <wfunc> op <pseudoconst> and <pseudoconst> op <wfunc>
2323  * for monotonically increasing functions.
2324  */
2325  if ((wfunc_left && (res->monotonic & MONOTONICFUNC_DECREASING)) ||
2326  (!wfunc_left && (res->monotonic & MONOTONICFUNC_INCREASING)))
2327  {
2328  *keep_original = false;
2329  runopexpr = opexpr;
2330  runoperator = opexpr->opno;
2331  }
2332  break;
2333  }
2334  /* handle = */
2335  else if (strategy == BTEqualStrategyNumber)
2336  {
2337  int16 newstrategy;
2338 
2339  /*
2340  * When both monotonically increasing and decreasing then the
2341  * return value of the window function will be the same each time.
2342  * We can simply use 'opexpr' as the run condition without
2343  * modifying it.
2344  */
2345  if ((res->monotonic & MONOTONICFUNC_BOTH) == MONOTONICFUNC_BOTH)
2346  {
2347  *keep_original = false;
2348  runopexpr = opexpr;
2349  runoperator = opexpr->opno;
2350  break;
2351  }
2352 
2353  /*
2354  * When monotonically increasing we make a qual with <wfunc> <=
2355  * <value> or <value> >= <wfunc> in order to filter out values
2356  * which are above the value in the equality condition. For
2357  * monotonically decreasing functions we want to filter values
2358  * below the value in the equality condition.
2359  */
2360  if (res->monotonic & MONOTONICFUNC_INCREASING)
2361  newstrategy = wfunc_left ? BTLessEqualStrategyNumber : BTGreaterEqualStrategyNumber;
2362  else
2363  newstrategy = wfunc_left ? BTGreaterEqualStrategyNumber : BTLessEqualStrategyNumber;
2364 
2365  /* We must keep the original equality qual */
2366  *keep_original = true;
2367  runopexpr = opexpr;
2368 
2369  /* determine the operator to use for the WindowFuncRunCondition */
2370  runoperator = get_opfamily_member(opinfo->opfamily_id,
2371  opinfo->oplefttype,
2372  opinfo->oprighttype,
2373  newstrategy);
2374  break;
2375  }
2376  }
2377 
2378  if (runopexpr != NULL)
2379  {
2380  WindowFuncRunCondition *wfuncrc;
2381 
2382  wfuncrc = makeNode(WindowFuncRunCondition);
2383  wfuncrc->opno = runoperator;
2384  wfuncrc->inputcollid = runopexpr->inputcollid;
2385  wfuncrc->wfunc_left = wfunc_left;
2386  wfuncrc->arg = copyObject(otherexpr);
2387 
2388  wfunc->runCondition = lappend(wfunc->runCondition, wfuncrc);
2389 
2390  /* record that this attno was used in a run condition */
2391  *run_cond_attrs = bms_add_member(*run_cond_attrs,
2392  attno - FirstLowInvalidHeapAttributeNumber);
2393  return true;
2394  }
2395 
2396  /* unsupported OpExpr */
2397  return false;
2398 }
2399 
2400 /*
2401  * check_and_push_window_quals
2402  * Check if 'clause' is a qual that can be pushed into a WindowFunc
2403  * as a 'runCondition' qual. These, when present, allow some unnecessary
2404  * work to be skipped during execution.
2405  *
2406  * 'run_cond_attrs' will be populated with all targetlist resnos of subquery
2407  * targets (offset by FirstLowInvalidHeapAttributeNumber) that we pushed
2408  * window quals for.
2409  *
2410  * Returns true if the caller still must keep the original qual or false if
2411  * the caller can safely ignore the original qual because the WindowAgg node
2412  * will use the runCondition to stop returning tuples.
2413  */
2414 static bool
2415 check_and_push_window_quals(Query *subquery, RangeTblEntry *rte, Index rti,
2416  Node *clause, Bitmapset **run_cond_attrs)
2417 {
2418  OpExpr *opexpr = (OpExpr *) clause;
2419  bool keep_original = true;
2420  Var *var1;
2421  Var *var2;
2422 
2423  /* We're only able to use OpExprs with 2 operands */
2424  if (!IsA(opexpr, OpExpr))
2425  return true;
2426 
2427  if (list_length(opexpr->args) != 2)
2428  return true;
2429 
2430  /*
2431  * Currently, we restrict this optimization to strict OpExprs. The reason
2432  * for this is that during execution, once the runcondition becomes false,
2433  * we stop evaluating WindowFuncs. To avoid leaving around stale window
2434  * function result values, we set them to NULL. Having only strict
2435  * OpExprs here ensures that we properly filter out the tuples with NULLs
2436  * in the top-level WindowAgg.
2437  */
2438  set_opfuncid(opexpr);
2439  if (!func_strict(opexpr->opfuncid))
2440  return true;
2441 
2442  /*
2443  * Check for plain Vars that reference window functions in the subquery.
2444  * If we find any, we'll ask find_window_run_conditions() if 'opexpr' can
2445  * be used as part of the run condition.
2446  */
2447 
2448  /* Check the left side of the OpExpr */
2449  var1 = linitial(opexpr->args);
2450  if (IsA(var1, Var) && var1->varattno > 0)
2451  {
2452  TargetEntry *tle = list_nth(subquery->targetList, var1->varattno - 1);
2453  WindowFunc *wfunc = (WindowFunc *) tle->expr;
2454 
2455  if (find_window_run_conditions(subquery, rte, rti, tle->resno, wfunc,
2456  opexpr, true, &keep_original,
2457  run_cond_attrs))
2458  return keep_original;
2459  }
2460 
2461  /* and check the right side */
2462  var2 = lsecond(opexpr->args);
2463  if (IsA(var2, Var) && var2->varattno > 0)
2464  {
2465  TargetEntry *tle = list_nth(subquery->targetList, var2->varattno - 1);
2466  WindowFunc *wfunc = (WindowFunc *) tle->expr;
2467 
2468  if (find_window_run_conditions(subquery, rte, rti, tle->resno, wfunc,
2469  opexpr, false, &keep_original,
2470  run_cond_attrs))
2471  return keep_original;
2472  }
2473 
2474  return true;
2475 }
2476 
2477 /*
2478  * set_subquery_pathlist
2479  * Generate SubqueryScan access paths for a subquery RTE
2480  *
2481  * We don't currently support generating parameterized paths for subqueries
2482  * by pushing join clauses down into them; it seems too expensive to re-plan
2483  * the subquery multiple times to consider different alternatives.
2484  * (XXX that could stand to be reconsidered, now that we use Paths.)
2485  * So the paths made here will be parameterized if the subquery contains
2486  * LATERAL references, otherwise not. As long as that's true, there's no need
2487  * for a separate set_subquery_size phase: just make the paths right away.
2488  */
2489 static void
2490 set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
2491  Index rti, RangeTblEntry *rte)
2492 {
2493  Query *parse = root->parse;
2494  Query *subquery = rte->subquery;
2495  bool trivial_pathtarget;
2496  Relids required_outer;
2497  pushdown_safety_info safetyInfo;
2498  double tuple_fraction;
2499  RelOptInfo *sub_final_rel;
2500  Bitmapset *run_cond_attrs = NULL;
2501  ListCell *lc;
2502 
2503  /*
2504  * Must copy the Query so that planning doesn't mess up the RTE contents
2505  * (really really need to fix the planner to not scribble on its input,
2506  * someday ... but see remove_unused_subquery_outputs to start with).
2507  */
2508  subquery = copyObject(subquery);
2509 
2510  /*
2511  * If it's a LATERAL subquery, it might contain some Vars of the current
2512  * query level, requiring it to be treated as parameterized, even though
2513  * we don't support pushing down join quals into subqueries.
2514  */
2515  required_outer = rel->lateral_relids;
2516 
2517  /*
2518  * Zero out result area for subquery_is_pushdown_safe, so that it can set
2519  * flags as needed while recursing. In particular, we need a workspace
2520  * for keeping track of the reasons why columns are unsafe to reference.
2521  * These reasons are stored in the bits inside unsafeFlags[i] when we
2522  * discover reasons that column i of the subquery is unsafe to be used in
2523  * a pushed-down qual.
2524  */
2525  memset(&safetyInfo, 0, sizeof(safetyInfo));
2526  safetyInfo.unsafeFlags = (unsigned char *)
2527  palloc0((list_length(subquery->targetList) + 1) * sizeof(unsigned char));
2528 
2529  /*
2530  * If the subquery has the "security_barrier" flag, it means the subquery
2531  * originated from a view that must enforce row-level security. Then we
2532  * must not push down quals that contain leaky functions. (Ideally this
2533  * would be checked inside subquery_is_pushdown_safe, but since we don't
2534  * currently pass the RTE to that function, we must do it here.)
2535  */
2536  safetyInfo.unsafeLeaky = rte->security_barrier;
2537 
2538  /*
2539  * If there are any restriction clauses that have been attached to the
2540  * subquery relation, consider pushing them down to become WHERE or HAVING
2541  * quals of the subquery itself. This transformation is useful because it
2542  * may allow us to generate a better plan for the subquery than evaluating
2543  * all the subquery output rows and then filtering them.
2544  *
2545  * There are several cases where we cannot push down clauses. Restrictions
2546  * involving the subquery are checked by subquery_is_pushdown_safe().
2547  * Restrictions on individual clauses are checked by
2548  * qual_is_pushdown_safe(). Also, we don't want to push down
2549  * pseudoconstant clauses; better to have the gating node above the
2550  * subquery.
2551  *
2552  * Non-pushed-down clauses will get evaluated as qpquals of the
2553  * SubqueryScan node.
2554  *
2555  * XXX Are there any cases where we want to make a policy decision not to
2556  * push down a pushable qual, because it'd result in a worse plan?
2557  */
2558  if (rel->baserestrictinfo != NIL &&
2559  subquery_is_pushdown_safe(subquery, subquery, &safetyInfo))
2560  {
2561  /* OK to consider pushing down individual quals */
2562  List *upperrestrictlist = NIL;
2563  ListCell *l;
2564 
2565  foreach(l, rel->baserestrictinfo)
2566  {
2567  RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
2568  Node *clause = (Node *) rinfo->clause;
2569 
2570  if (rinfo->pseudoconstant)
2571  {
2572  upperrestrictlist = lappend(upperrestrictlist, rinfo);
2573  continue;
2574  }
2575 
2576  switch (qual_is_pushdown_safe(subquery, rti, rinfo, &safetyInfo))
2577  {
2578  case PUSHDOWN_SAFE:
2579  /* Push it down */
2580  subquery_push_qual(subquery, rte, rti, clause);
2581  break;
2582 
2583  case PUSHDOWN_WINDOWCLAUSE_RUNCOND:
2584 
2585  /*
2586  * Since we can't push the qual down into the subquery,
2587  * check if it happens to reference a window function. If
2588  * so then it might be useful to use for the WindowAgg's
2589  * runCondition.
2590  */
2591  if (!subquery->hasWindowFuncs ||
2592  check_and_push_window_quals(subquery, rte, rti, clause,
2593  &run_cond_attrs))
2594  {
2595  /*
2596  * subquery has no window funcs or the clause is not a
2597  * suitable window run condition qual or it is, but
2598  * the original must also be kept in the upper query.
2599  */
2600  upperrestrictlist = lappend(upperrestrictlist, rinfo);
2601  }
2602  break;
2603 
2604  case PUSHDOWN_UNSAFE:
2605  upperrestrictlist = lappend(upperrestrictlist, rinfo);
2606  break;
2607  }
2608  }
2609  rel->baserestrictinfo = upperrestrictlist;
2610  /* We don't bother recomputing baserestrict_min_security */
2611  }
2612 
2613  pfree(safetyInfo.unsafeFlags);
2614 
2615  /*
2616  * The upper query might not use all the subquery's output columns; if
2617  * not, we can simplify. Pass the attributes that were pushed down into
2618  * WindowAgg run conditions to ensure we don't accidentally think those
2619  * are unused.
2620  */
2621  remove_unused_subquery_outputs(subquery, rel, run_cond_attrs);
2622 
2623  /*
2624  * We can safely pass the outer tuple_fraction down to the subquery if the
2625  * outer level has no joining, aggregation, or sorting to do. Otherwise
2626  * we'd better tell the subquery to plan for full retrieval. (XXX This
2627  * could probably be made more intelligent ...)
2628  */
2629  if (parse->hasAggs ||
2630  parse->groupClause ||
2631  parse->groupingSets ||
2632  root->hasHavingQual ||
2633  parse->distinctClause ||
2634  parse->sortClause ||
2635  bms_membership(root->all_baserels) == BMS_MULTIPLE)
2636  tuple_fraction = 0.0; /* default case */
2637  else
2638  tuple_fraction = root->tuple_fraction;
2639 
2640  /* plan_params should not be in use in current query level */
2641  Assert(root->plan_params == NIL);
2642 
2643  /* Generate a subroot and Paths for the subquery */
2644  rel->subroot = subquery_planner(root->glob, subquery, root, false,
2645  tuple_fraction, NULL);
2646 
2647  /* Isolate the params needed by this specific subplan */
2648  rel->subplan_params = root->plan_params;
2649  root->plan_params = NIL;
2650 
2651  /*
2652  * It's possible that constraint exclusion proved the subquery empty. If
2653  * so, it's desirable to produce an unadorned dummy path so that we will
2654  * recognize appropriate optimizations at this query level.
2655  */
2656  sub_final_rel = fetch_upper_rel(rel->subroot, UPPERREL_FINAL, NULL);
2657 
2658  if (IS_DUMMY_REL(sub_final_rel))
2659  {
2660  set_dummy_rel_pathlist(rel);
2661  return;
2662  }
2663 
2664  /*
2665  * Mark rel with estimated output rows, width, etc. Note that we have to
2666  * do this before generating outer-query paths, else cost_subqueryscan is
2667  * not happy.
2668  */
2669  set_subquery_size_estimates(root, rel);
2670 
2671  /*
2672  * Also detect whether the reltarget is trivial, so that we can pass that
2673  * info to cost_subqueryscan (rather than re-deriving it multiple times).
2674  * It's trivial if it fetches all the subplan output columns in order.
2675  */
2676  if (list_length(rel->reltarget->exprs) != list_length(subquery->targetList))
2677  trivial_pathtarget = false;
2678  else
2679  {
2680  trivial_pathtarget = true;
2681  foreach(lc, rel->reltarget->exprs)
2682  {
2683  Node *node = (Node *) lfirst(lc);
2684  Var *var;
2685 
2686  if (!IsA(node, Var))
2687  {
2688  trivial_pathtarget = false;
2689  break;
2690  }
2691  var = (Var *) node;
2692  if (var->varno != rti ||
2693  var->varattno != foreach_current_index(lc) + 1)
2694  {
2695  trivial_pathtarget = false;
2696  break;
2697  }
2698  }
2699  }
2700 
2701  /*
2702  * For each Path that subquery_planner produced, make a SubqueryScanPath
2703  * in the outer query.
2704  */
2705  foreach(lc, sub_final_rel->pathlist)
2706  {
2707  Path *subpath = (Path *) lfirst(lc);
2708  List *pathkeys;
2709 
2710  /* Convert subpath's pathkeys to outer representation */
2711  pathkeys = convert_subquery_pathkeys(root,
2712  rel,
2713  subpath->pathkeys,
2714  make_tlist_from_pathtarget(subpath->pathtarget));
2715 
2716  /* Generate outer path using this subpath */
2717  add_path(rel, (Path *)
2718  create_subqueryscan_path(root, rel, subpath,
2719  trivial_pathtarget,
2720  pathkeys, required_outer));
2721  }
2722 
2723  /* If outer rel allows parallelism, do same for partial paths. */
2724  if (rel->consider_parallel && bms_is_empty(required_outer))
2725  {
2726  /* If consider_parallel is false, there should be no partial paths. */
2727  Assert(sub_final_rel->consider_parallel ||
2728  sub_final_rel->partial_pathlist == NIL);
2729 
2730  /* Same for partial paths. */
2731  foreach(lc, sub_final_rel->partial_pathlist)
2732  {
2733  Path *subpath = (Path *) lfirst(lc);
2734  List *pathkeys;
2735 
2736  /* Convert subpath's pathkeys to outer representation */
2737  pathkeys = convert_subquery_pathkeys(root,
2738  rel,
2739  subpath->pathkeys,
2740  make_tlist_from_pathtarget(subpath->pathtarget));
2741 
2742  /* Generate outer path using this subpath */
2743  add_partial_path(rel, (Path *)
2744  create_subqueryscan_path(root, rel, subpath,
2745  trivial_pathtarget,
2746  pathkeys,
2747  required_outer));
2748  }
2749  }
2750 }
2751 
2752 /*
2753  * set_function_pathlist
2754  * Build the (single) access path for a function RTE
2755  */
2756 static void
2757 set_function_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
2758 {
2759  Relids required_outer;
2760  List *pathkeys = NIL;
2761 
2762  /*
2763  * We don't support pushing join clauses into the quals of a function
2764  * scan, but it could still have required parameterization due to LATERAL
2765  * refs in the function expression.
2766  */
2767  required_outer = rel->lateral_relids;
2768 
2769  /*
2770  * The result is considered unordered unless ORDINALITY was used, in which
2771  * case it is ordered by the ordinal column (the last one). See if we
2772  * care, by checking for uses of that Var in equivalence classes.
2773  */
2774  if (rte->funcordinality)
2775  {
2776  AttrNumber ordattno = rel->max_attr;
2777  Var *var = NULL;
2778  ListCell *lc;
2779 
2780  /*
2781  * Is there a Var for it in rel's targetlist? If not, the query did
2782  * not reference the ordinality column, or at least not in any way
2783  * that would be interesting for sorting.
2784  */
2785  foreach(lc, rel->reltarget->exprs)
2786  {
2787  Var *node = (Var *) lfirst(lc);
2788 
2789  /* checking varno/varlevelsup is just paranoia */
2790  if (IsA(node, Var) &&
2791  node->varattno == ordattno &&
2792  node->varno == rel->relid &&
2793  node->varlevelsup == 0)
2794  {
2795  var = node;
2796  break;
2797  }
2798  }
2799 
2800  /*
2801  * Try to build pathkeys for this Var with int8 sorting. We tell
2802  * build_expression_pathkey not to build any new equivalence class; if
2803  * the Var isn't already mentioned in some EC, it means that nothing
2804  * cares about the ordering.
2805  */
2806  if (var)
2807  pathkeys = build_expression_pathkey(root,
2808  (Expr *) var,
2809  Int8LessOperator,
2810  rel->relids,
2811  false);
2812  }
2813 
2814  /* Generate appropriate path */
2815  add_path(rel, create_functionscan_path(root, rel,
2816  pathkeys, required_outer));
2817 }
2818 
2819 /*
2820  * set_values_pathlist
2821  * Build the (single) access path for a VALUES RTE
2822  */
2823 static void
2824 set_values_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
2825 {
2826  Relids required_outer;
2827 
2828  /*
2829  * We don't support pushing join clauses into the quals of a values scan,
2830  * but it could still have required parameterization due to LATERAL refs
2831  * in the values expressions.
2832  */
2833  required_outer = rel->lateral_relids;
2834 
2835  /* Generate appropriate path */
2836  add_path(rel, create_valuesscan_path(root, rel, required_outer));
2837 }
2838 
2839 /*
2840  * set_tablefunc_pathlist
2841  * Build the (single) access path for a table func RTE
2842  */
2843 static void
2844 set_tablefunc_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
2845 {
2846  Relids required_outer;
2847 
2848  /*
2849  * We don't support pushing join clauses into the quals of a tablefunc
2850  * scan, but it could still have required parameterization due to LATERAL
2851  * refs in the function expression.
2852  */
2853  required_outer = rel->lateral_relids;
2854 
2855  /* Generate appropriate path */
2856  add_path(rel, create_tablefuncscan_path(root, rel,
2857  required_outer));
2858 }
2859 
2860 /*
2861  * set_cte_pathlist
2862  * Build the (single) access path for a non-self-reference CTE RTE
2863  *
2864  * There's no need for a separate set_cte_size phase, since we don't
2865  * support join-qual-parameterized paths for CTEs.
2866  */
2867 static void
2868 set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
2869 {
2870  Path *ctepath;
2871  Plan *cteplan;
2872  PlannerInfo *cteroot;
2873  Index levelsup;
2874  List *pathkeys;
2875  int ndx;
2876  ListCell *lc;
2877  int plan_id;
2878  Relids required_outer;
2879 
2880  /*
2881  * Find the referenced CTE, and locate the path and plan previously made
2882  * for it.
2883  */
2884  levelsup = rte->ctelevelsup;
2885  cteroot = root;
2886  while (levelsup-- > 0)
2887  {
2888  cteroot = cteroot->parent_root;
2889  if (!cteroot) /* shouldn't happen */
2890  elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
2891  }
2892 
2893  /*
2894  * Note: cte_plan_ids can be shorter than cteList, if we are still working
2895  * on planning the CTEs (ie, this is a side-reference from another CTE).
2896  * So we mustn't use forboth here.
2897  */
2898  ndx = 0;
2899  foreach(lc, cteroot->parse->cteList)
2900  {
2901  CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
2902 
2903  if (strcmp(cte->ctename, rte->ctename) == 0)
2904  break;
2905  ndx++;
2906  }
2907  if (lc == NULL) /* shouldn't happen */
2908  elog(ERROR, "could not find CTE \"%s\"", rte->ctename);
2909  if (ndx >= list_length(cteroot->cte_plan_ids))
2910  elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
2911  plan_id = list_nth_int(cteroot->cte_plan_ids, ndx);
2912  if (plan_id <= 0)
2913  elog(ERROR, "no plan was made for CTE \"%s\"", rte->ctename);
2914 
2915  Assert(list_length(root->glob->subpaths) == list_length(root->glob->subplans));
2916  ctepath = (Path *) list_nth(root->glob->subpaths, plan_id - 1);
2917  cteplan = (Plan *) list_nth(root->glob->subplans, plan_id - 1);
2918 
2919  /* Mark rel with estimated output rows, width, etc */
2920  set_cte_size_estimates(root, rel, cteplan->plan_rows);
2921 
2922  /* Convert the ctepath's pathkeys to outer query's representation */
2923  pathkeys = convert_subquery_pathkeys(root,
2924  rel,
2925  ctepath->pathkeys,
2926  cteplan->targetlist);
2927 
2928  /*
2929  * We don't support pushing join clauses into the quals of a CTE scan, but
2930  * it could still have required parameterization due to LATERAL refs in
2931  * its tlist.
2932  */
2933  required_outer = rel->lateral_relids;
2934 
2935  /* Generate appropriate path */
2936  add_path(rel, create_ctescan_path(root, rel, pathkeys, required_outer));
2937 }
2938 
2939 /*
2940  * set_namedtuplestore_pathlist
2941  * Build the (single) access path for a named tuplestore RTE
2942  *
2943  * There's no need for a separate set_namedtuplestore_size phase, since we
2944  * don't support join-qual-parameterized paths for tuplestores.
2945  */
2946 static void
2947 set_namedtuplestore_pathlist(PlannerInfo *root, RelOptInfo *rel,
2948  RangeTblEntry *rte)
2949 {
2950  Relids required_outer;
2951 
2952  /* Mark rel with estimated output rows, width, etc */
2953  set_namedtuplestore_size_estimates(root, rel);
2954 
2955  /*
2956  * We don't support pushing join clauses into the quals of a tuplestore
2957  * scan, but it could still have required parameterization due to LATERAL
2958  * refs in its tlist.
2959  */
2960  required_outer = rel->lateral_relids;
2961 
2962  /* Generate appropriate path */
2963  add_path(rel, create_namedtuplestorescan_path(root, rel, required_outer));
2964 }
2965 
2966 /*
2967  * set_result_pathlist
2968  * Build the (single) access path for an RTE_RESULT RTE
2969  *
2970  * There's no need for a separate set_result_size phase, since we
2971  * don't support join-qual-parameterized paths for these RTEs.
2972  */
2973 static void
2974 set_result_pathlist(PlannerInfo *root, RelOptInfo *rel,
2975  RangeTblEntry *rte)
2976 {
2977  Relids required_outer;
2978 
2979  /* Mark rel with estimated output rows, width, etc */
2980  set_result_size_estimates(root, rel);
2981 
2982  /*
2983  * We don't support pushing join clauses into the quals of a Result scan,
2984  * but it could still have required parameterization due to LATERAL refs
2985  * in its tlist.
2986  */
2987  required_outer = rel->lateral_relids;
2988 
2989  /* Generate appropriate path */
2990  add_path(rel, create_resultscan_path(root, rel, required_outer));
2991 }
2992 
2993 /*
2994  * set_worktable_pathlist
2995  * Build the (single) access path for a self-reference CTE RTE
2996  *
2997  * There's no need for a separate set_worktable_size phase, since we don't
2998  * support join-qual-parameterized paths for CTEs.
2999  */
3000 static void
3001 set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
3002 {
3003  Path *ctepath;
3004  PlannerInfo *cteroot;
3005  Index levelsup;
3006  Relids required_outer;
3007 
3008  /*
3009  * We need to find the non-recursive term's path, which is in the plan
3010  * level that's processing the recursive UNION, which is one level *below*
3011  * where the CTE comes from.
3012  */
3013  levelsup = rte->ctelevelsup;
3014  if (levelsup == 0) /* shouldn't happen */
3015  elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
3016  levelsup--;
3017  cteroot = root;
3018  while (levelsup-- > 0)
3019  {
3020  cteroot = cteroot->parent_root;
3021  if (!cteroot) /* shouldn't happen */
3022  elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
3023  }
3024  ctepath = cteroot->non_recursive_path;
3025  if (!ctepath) /* shouldn't happen */
3026  elog(ERROR, "could not find path for CTE \"%s\"", rte->ctename);
3027 
3028  /* Mark rel with estimated output rows, width, etc */
3029  set_cte_size_estimates(root, rel, ctepath->rows);
3030 
3031  /*
3032  * We don't support pushing join clauses into the quals of a worktable
3033  * scan, but it could still have required parameterization due to LATERAL
3034  * refs in its tlist. (I'm not sure this is actually possible given the
3035  * restrictions on recursive references, but it's easy enough to support.)
3036  */
3037  required_outer = rel->lateral_relids;
3038 
3039  /* Generate appropriate path */
3040  add_path(rel, create_worktablescan_path(root, rel, required_outer));
3041 }
3042 
3043 /*
3044  * generate_gather_paths
3045  * Generate parallel access paths for a relation by pushing a Gather or
3046  * Gather Merge on top of a partial path.
3047  *
3048  * This must not be called until after we're done creating all partial paths
3049  * for the specified relation. (Otherwise, add_partial_path might delete a
3050  * path that some GatherPath or GatherMergePath has a reference to.)
3051  *
3052  * If we're generating paths for a scan or join relation, override_rows will
3053  * be false, and we'll just use the relation's size estimate. When we're
3054  * being called for a partially-grouped or partially-distinct path, though, we
3055  * need to override the rowcount estimate. (It's not clear that the
3056  * particular value we're using here is actually best, but the underlying rel
3057  * has no estimate so we must do something.)
3058  */
3059 void
3060 generate_gather_paths(PlannerInfo *root, RelOptInfo *rel, bool override_rows)
3061 {
3062  Path *cheapest_partial_path;
3063  Path *simple_gather_path;
3064  ListCell *lc;
3065  double rows;
3066  double *rowsp = NULL;
3067 
3068  /* If there are no partial paths, there's nothing to do here. */
3069  if (rel->partial_pathlist == NIL)
3070  return;
3071 
3072  /* Should we override the rel's rowcount estimate? */
3073  if (override_rows)
3074  rowsp = &rows;
3075 
3076  /*
3077  * The output of Gather is always unsorted, so there's only one partial
3078  * path of interest: the cheapest one. That will be the one at the front
3079  * of partial_pathlist because of the way add_partial_path works.
3080  */
3081  cheapest_partial_path = linitial(rel->partial_pathlist);
3082  rows = compute_gather_rows(cheapest_partial_path);
3083  simple_gather_path = (Path *)
3084  create_gather_path(root, rel, cheapest_partial_path, rel->reltarget,
3085  NULL, rowsp);
3086  add_path(rel, simple_gather_path);
3087 
3088  /*
3089  * For each useful ordering, we can consider an order-preserving Gather
3090  * Merge.
3091  */
3092  foreach(lc, rel->partial_pathlist)
3093  {
3094  Path *subpath = (Path *) lfirst(lc);
3095  GatherMergePath *path;
3096 
3097  if (subpath->pathkeys == NIL)
3098  continue;
3099 
3100  rows = compute_gather_rows(subpath);
3101  path = create_gather_merge_path(root, rel, subpath, rel->reltarget,
3102  subpath->pathkeys, NULL, rowsp);
3103  add_path(rel, &path->path);
3104  }
3105 }
3106 
3107 /*
3108  * get_useful_pathkeys_for_relation
3109  * Determine which orderings of a relation might be useful.
3110  *
3111  * Getting data in sorted order can be useful either because the requested
3112  * order matches the final output ordering for the overall query we're
3113  * planning, or because it enables an efficient merge join. Here, we try
3114  * to figure out which pathkeys to consider.
3115  *
3116  * This allows us to do incremental sort on top of an index scan under a gather
3117  * merge node, i.e. parallelized.
3118  *
3119  * If the require_parallel_safe is true, we also require the expressions to
3120  * be parallel safe (which allows pushing the sort below Gather Merge).
3121  *
3122  * XXX At the moment this can only ever return a list with a single element,
3123  * because it looks at query_pathkeys only. So we might return the pathkeys
3124  * directly, but it seems plausible we'll want to consider other orderings
3125  * in the future. For example, we might want to consider pathkeys useful for
3126  * merge joins.
3127  */
3128 static List *
3129 get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel,
3130  bool require_parallel_safe)
3131 {
3132  List *useful_pathkeys_list = NIL;
3133 
3134  /*
3135  * Considering query_pathkeys is always worth it, because it might allow
3136  * us to avoid a total sort when we have a partially presorted path
3137  * available or to push the total sort into the parallel portion of the
3138  * query.
3139  */
3140  if (root->query_pathkeys)
3141  {
3142  ListCell *lc;
3143  int npathkeys = 0; /* useful pathkeys */
3144 
3145  foreach(lc, root->query_pathkeys)
3146  {
3147  PathKey *pathkey = (PathKey *) lfirst(lc);
3148  EquivalenceClass *pathkey_ec = pathkey->pk_eclass;
3149 
3150  /*
3151  * We can only build a sort for pathkeys that contain a
3152  * safe-to-compute-early EC member computable from the current
3153  * relation's reltarget, so ignore the remainder of the list as
3154  * soon as we find a pathkey without such a member.
3155  *
3156  * It's still worthwhile to return any prefix of the pathkeys list
3157  * that meets this requirement, as we may be able to do an
3158  * incremental sort.
3159  *
3160  * If requested, ensure the sort expression is parallel-safe too.
3161  */
3162  if (!relation_can_be_sorted_early(root, rel, pathkey_ec,
3163  require_parallel_safe))
3164  break;
3165 
3166  npathkeys++;
3167  }
3168 
3169  /*
3170  * The whole query_pathkeys list matches, so append it directly, to
3171  * allow comparing pathkeys easily by comparing list pointer. If we
3172  * have to truncate the pathkeys, we gotta do a copy though.
3173  */
3174  if (npathkeys == list_length(root->query_pathkeys))
3175  useful_pathkeys_list = lappend(useful_pathkeys_list,
3176  root->query_pathkeys);
3177  else if (npathkeys > 0)
3178  useful_pathkeys_list = lappend(useful_pathkeys_list,
3179  list_copy_head(root->query_pathkeys,
3180  npathkeys));
3181  }
3182 
3183  return useful_pathkeys_list;
3184 }
3185 
3186 /*
3187  * generate_useful_gather_paths
3188  * Generate parallel access paths for a relation by pushing a Gather or
3189  * Gather Merge on top of a partial path.
3190  *
3191  * Unlike plain generate_gather_paths, this looks both at pathkeys of input
3192  * paths (aiming to preserve the ordering), but also considers ordering that
3193  * might be useful for nodes above the gather merge node, and tries to add
3194  * a sort (regular or incremental) to provide that.
3195  */
3196 void
3197 generate_useful_gather_paths(PlannerInfo *root, RelOptInfo *rel, bool override_rows)
3198 {
3199  ListCell *lc;
3200  double rows;
3201  double *rowsp = NULL;
3202  List *useful_pathkeys_list = NIL;
3203  Path *cheapest_partial_path = NULL;
3204 
3205  /* If there are no partial paths, there's nothing to do here. */
3206  if (rel->partial_pathlist == NIL)
3207  return;
3208 
3209  /* Should we override the rel's rowcount estimate? */
3210  if (override_rows)
3211  rowsp = &rows;
3212 
3213  /* generate the regular gather (merge) paths */
3214  generate_gather_paths(root, rel, override_rows);
3215 
3216  /* consider incremental sort for interesting orderings */
3217  useful_pathkeys_list = get_useful_pathkeys_for_relation(root, rel, true);
3218 
3219  /* used for explicit (full) sort paths */
3220  cheapest_partial_path = linitial(rel->partial_pathlist);
3221 
3222  /*
3223  * Consider sorted paths for each interesting ordering. We generate both
3224  * incremental and full sort.
3225  */
3226  foreach(lc, useful_pathkeys_list)
3227  {
3228  List *useful_pathkeys = lfirst(lc);
3229  ListCell *lc2;
3230  bool is_sorted;
3231  int presorted_keys;
3232 
3233  foreach(lc2, rel->partial_pathlist)
3234  {
3235  Path *subpath = (Path *) lfirst(lc2);
3236  GatherMergePath *path;
3237 
3238  is_sorted = pathkeys_count_contained_in(useful_pathkeys,
3239  subpath->pathkeys,
3240  &presorted_keys);
3241 
3242  /*
3243  * We don't need to consider the case where a subpath is already
3244  * fully sorted because generate_gather_paths already creates a
3245  * gather merge path for every subpath that has pathkeys present.
3246  *
3247  * But since the subpath is already sorted, we know we don't need
3248  * to consider adding a sort (full or incremental) on top of it,
3249  * so we can continue here.
3250  */
3251  if (is_sorted)
3252  continue;
3253 
3254  /*
3255  * Try at least sorting the cheapest path and also try
3256  * incrementally sorting any path which is partially sorted
3257  * already (no need to deal with paths which have presorted keys
3258  * when incremental sort is disabled unless it's the cheapest
3259  * input path).
3260  */
3261  if (subpath != cheapest_partial_path &&
3262  (presorted_keys == 0 || !enable_incremental_sort))
3263  continue;
3264 
3265  /*
3266  * Consider regular sort for any path that's not presorted or if
3267  * incremental sort is disabled. We've no need to consider both
3268  * sort and incremental sort on the same path. We assume that
3269  * incremental sort is always faster when there are presorted
3270  * keys.
3271  *
3272  * This is not redundant with the gather paths created in
3273  * generate_gather_paths, because that doesn't generate ordered
3274  * output. Here we add an explicit sort to match the useful
3275  * ordering.
3276  */
3277  if (presorted_keys == 0 || !enable_incremental_sort)
3278  {
3279  subpath = (Path *) create_sort_path(root,
3280  rel,
3281  subpath,
3282  useful_pathkeys,
3283  -1.0);
3284  }
3285  else
3286  subpath = (Path *) create_incremental_sort_path(root,
3287  rel,
3288  subpath,
3289  useful_pathkeys,
3290  presorted_keys,
3291  -1);
3292  rows = compute_gather_rows(subpath);
3293  path = create_gather_merge_path(root, rel,
3294  subpath,
3295  rel->reltarget,
3296  subpath->pathkeys,
3297  NULL,
3298  rowsp);
3299 
3300  add_path(rel, &path->path);
3301  }
3302  }
3303 }
3304 
3305 /*
3306  * make_rel_from_joinlist
3307  * Build access paths using a "joinlist" to guide the join path search.
3308  *
3309  * See comments for deconstruct_jointree() for definition of the joinlist
3310  * data structure.
3311  */
3312 static RelOptInfo *
3313 make_rel_from_joinlist(PlannerInfo *root, List *joinlist)
3314 {
3315  int levels_needed;
3316  List *initial_rels;
3317  ListCell *jl;
3318 
3319  /*
3320  * Count the number of child joinlist nodes. This is the depth of the
3321  * dynamic-programming algorithm we must employ to consider all ways of
3322  * joining the child nodes.
3323  */
3324  levels_needed = list_length(joinlist);
3325 
3326  if (levels_needed <= 0)
3327  return NULL; /* nothing to do? */
3328 
3329  /*
3330  * Construct a list of rels corresponding to the child joinlist nodes.
3331  * This may contain both base rels and rels constructed according to
3332  * sub-joinlists.
3333  */
3334  initial_rels = NIL;
3335  foreach(jl, joinlist)
3336  {
3337  Node *jlnode = (Node *) lfirst(jl);
3338  RelOptInfo *thisrel;
3339 
3340  if (IsA(jlnode, RangeTblRef))
3341  {
3342  int varno = ((RangeTblRef *) jlnode)->rtindex;
3343 
3344  thisrel = find_base_rel(root, varno);
3345  }
3346  else if (IsA(jlnode, List))
3347  {
3348  /* Recurse to handle subproblem */
3349  thisrel = make_rel_from_joinlist(root, (List *) jlnode);
3350  }
3351  else
3352  {
3353  elog(ERROR, "unrecognized joinlist node type: %d",
3354  (int) nodeTag(jlnode));
3355  thisrel = NULL; /* keep compiler quiet */
3356  }
3357 
3358  initial_rels = lappend(initial_rels, thisrel);
3359  }
3360 
3361  if (levels_needed == 1)
3362  {
3363  /*
3364  * Single joinlist node, so we're done.
3365  */
3366  return (RelOptInfo *) linitial(initial_rels);
3367  }
3368  else
3369  {
3370  /*
3371  * Consider the different orders in which we could join the rels,
3372  * using a plugin, GEQO, or the regular join search code.
3373  *
3374  * We put the initial_rels list into a PlannerInfo field because
3375  * has_legal_joinclause() needs to look at it (ugly :-().
3376  */
3377  root->initial_rels = initial_rels;
3378 
3379  if (join_search_hook)
3380  return (*join_search_hook) (root, levels_needed, initial_rels);
3381  else if (enable_geqo && levels_needed >= geqo_threshold)
3382  return geqo(root, levels_needed, initial_rels);
3383  else
3384  return standard_join_search(root, levels_needed, initial_rels);
3385  }
3386 }
3387 
3388 /*
3389  * standard_join_search
3390  * Find possible joinpaths for a query by successively finding ways
3391  * to join component relations into join relations.
3392  *
3393  * 'levels_needed' is the number of iterations needed, ie, the number of
3394  * independent jointree items in the query. This is > 1.
3395  *
3396  * 'initial_rels' is a list of RelOptInfo nodes for each independent
3397  * jointree item. These are the components to be joined together.
3398  * Note that levels_needed == list_length(initial_rels).
3399  *
3400  * Returns the final level of join relations, i.e., the relation that is
3401  * the result of joining all the original relations together.
3402  * At least one implementation path must be provided for this relation and
3403  * all required sub-relations.
3404  *
3405  * To support loadable plugins that modify planner behavior by changing the
3406  * join searching algorithm, we provide a hook variable that lets a plugin
3407  * replace or supplement this function. Any such hook must return the same
3408  * final join relation as the standard code would, but it might have a
3409  * different set of implementation paths attached, and only the sub-joinrels
3410  * needed for these paths need have been instantiated.
3411  *
3412  * Note to plugin authors: the functions invoked during standard_join_search()
3413  * modify root->join_rel_list and root->join_rel_hash. If you want to do more
3414  * than one join-order search, you'll probably need to save and restore the
3415  * original states of those data structures. See geqo_eval() for an example.
3416  */
3417 RelOptInfo *
3418 standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
3419 {
3420  int lev;
3421  RelOptInfo *rel;
3422 
3423  /*
3424  * This function cannot be invoked recursively within any one planning
3425  * problem, so join_rel_level[] can't be in use already.
3426  */
3427  Assert(root->join_rel_level == NULL);
3428 
3429  /*
3430  * We employ a simple "dynamic programming" algorithm: we first find all
3431  * ways to build joins of two jointree items, then all ways to build joins
3432  * of three items (from two-item joins and single items), then four-item
3433  * joins, and so on until we have considered all ways to join all the
3434  * items into one rel.
3435  *
3436  * root->join_rel_level[j] is a list of all the j-item rels. Initially we
3437  * set root->join_rel_level[1] to represent all the single-jointree-item
3438  * relations.
3439  */
3440  root->join_rel_level = (List **) palloc0((levels_needed + 1) * sizeof(List *));
3441 
3442  root->join_rel_level[1] = initial_rels;
3443 
3444  for (lev = 2; lev <= levels_needed; lev++)
3445  {
3446  ListCell *lc;
3447 
3448  /*
3449  * Determine all possible pairs of relations to be joined at this
3450  * level, and build paths for making each one from every available
3451  * pair of lower-level relations.
3452  */
3453  join_search_one_level(root, lev);
3454 
3455  /*
3456  * Run generate_partitionwise_join_paths() and
3457  * generate_useful_gather_paths() for each just-processed joinrel. We
3458  * could not do this earlier because both regular and partial paths
3459  * can get added to a particular joinrel at multiple times within
3460  * join_search_one_level.
3461  *
3462  * After that, we're done creating paths for the joinrel, so run
3463  * set_cheapest().
3464  */
3465  foreach(lc, root->join_rel_level[lev])
3466  {
3467  rel = (RelOptInfo *) lfirst(lc);
3468 
3469  /* Create paths for partitionwise joins. */
3470  generate_partitionwise_join_paths(root, rel);
3471 
3472  /*
3473  * Except for the topmost scan/join rel, consider gathering
3474  * partial paths. We'll do the same for the topmost scan/join rel
3475  * once we know the final targetlist (see grouping_planner's and
3476  * its call to apply_scanjoin_target_to_paths).
3477  */
3478  if (!bms_equal(rel->relids, root->all_query_rels))
3479  generate_useful_gather_paths(root, rel, false);
3480 
3481  /* Find and save the cheapest paths for this rel */
3482  set_cheapest(rel);
3483 
3484 #ifdef OPTIMIZER_DEBUG
3485  pprint(rel);
3486 #endif
3487  }
3488  }
3489 
3490  /*
3491  * We should have a single rel at the final level.
3492  */
3493  if (root->join_rel_level[levels_needed] == NIL)
3494  elog(ERROR, "failed to build any %d-way joins", levels_needed);
3495  Assert(list_length(root->join_rel_level[levels_needed]) == 1);
3496 
3497  rel = (RelOptInfo *) linitial(root->join_rel_level[levels_needed]);
3498 
3499  root->join_rel_level = NULL;
3500 
3501  return rel;
3502 }
3503 
3504 /*****************************************************************************
3505  * PUSHING QUALS DOWN INTO SUBQUERIES
3506  *****************************************************************************/
3507 
3508 /*
3509  * subquery_is_pushdown_safe - is a subquery safe for pushing down quals?
3510  *
3511  * subquery is the particular component query being checked. topquery
3512  * is the top component of a set-operations tree (the same Query if no
3513  * set-op is involved).
3514  *
3515  * Conditions checked here:
3516  *
3517  * 1. If the subquery has a LIMIT clause, we must not push down any quals,
3518  * since that could change the set of rows returned.
3519  *
3520  * 2. If the subquery contains EXCEPT or EXCEPT ALL set ops we cannot push
3521  * quals into it, because that could change the results.
3522  *
3523  * 3. If the subquery uses DISTINCT, we cannot push volatile quals into it.
3524  * This is because upper-level quals should semantically be evaluated only
3525  * once per distinct row, not once per original row, and if the qual is
3526  * volatile then extra evaluations could change the results. (This issue
3527  * does not apply to other forms of aggregation such as GROUP BY, because
3528  * when those are present we push into HAVING not WHERE, so that the quals
3529  * are still applied after aggregation.)
3530  *
3531  * 4. If the subquery contains window functions, we cannot push volatile quals
3532  * into it. The issue here is a bit different from DISTINCT: a volatile qual
3533  * might succeed for some rows of a window partition and fail for others,
3534  * thereby changing the partition contents and thus the window functions'
3535  * results for rows that remain.
3536  *
3537  * 5. If the subquery contains any set-returning functions in its targetlist,
3538  * we cannot push volatile quals into it. That would push them below the SRFs
3539  * and thereby change the number of times they are evaluated. Also, a
3540  * volatile qual could succeed for some SRF output rows and fail for others,
3541  * a behavior that cannot occur if it's evaluated before SRF expansion.
3542  *
3543  * 6. If the subquery has nonempty grouping sets, we cannot push down any
3544  * quals. The concern here is that a qual referencing a "constant" grouping
3545  * column could get constant-folded, which would be improper because the value
3546  * is potentially nullable by grouping-set expansion. This restriction could
3547  * be removed if we had a parsetree representation that shows that such
3548  * grouping columns are not really constant. (There are other ideas that
3549  * could be used to relax this restriction, but that's the approach most
3550  * likely to get taken in the future. Note that there's not much to be gained
3551  * so long as subquery_planner can't move HAVING clauses to WHERE within such
3552  * a subquery.)
3553  *
3554  * In addition, we make several checks on the subquery's output columns to see
3555  * if it is safe to reference them in pushed-down quals. If output column k
3556  * is found to be unsafe to reference, we set the reason for that inside
3557  * safetyInfo->unsafeFlags[k], but we don't reject the subquery overall since
3558  * column k might not be referenced by some/all quals. The unsafeFlags[]
3559  * array will be consulted later by qual_is_pushdown_safe(). It's better to
3560  * do it this way than to make the checks directly in qual_is_pushdown_safe(),
3561  * because when the subquery involves set operations we have to check the
3562  * output expressions in each arm of the set op.
3563  *
3564  * Note: pushing quals into a DISTINCT subquery is theoretically dubious:
3565  * we're effectively assuming that the quals cannot distinguish values that
3566  * the DISTINCT's equality operator sees as equal, yet there are many
3567  * counterexamples to that assumption. However use of such a qual with a
3568  * DISTINCT subquery would be unsafe anyway, since there's no guarantee which
3569  * "equal" value will be chosen as the output value by the DISTINCT operation.
3570  * So we don't worry too much about that. Another objection is that if the
3571  * qual is expensive to evaluate, running it for each original row might cost
3572  * more than we save by eliminating rows before the DISTINCT step. But it
3573  * would be very hard to estimate that at this stage, and in practice pushdown
3574  * seldom seems to make things worse, so we ignore that problem too.
3575  *
3576  * Note: likewise, pushing quals into a subquery with window functions is a
3577  * bit dubious: the quals might remove some rows of a window partition while
3578  * leaving others, causing changes in the window functions' results for the
3579  * surviving rows. We insist that such a qual reference only partitioning
3580  * columns, but again that only protects us if the qual does not distinguish
3581  * values that the partitioning equality operator sees as equal. The risks
3582  * here are perhaps larger than for DISTINCT, since no de-duplication of rows
3583  * occurs and thus there is no theoretical problem with such a qual. But
3584  * we'll do this anyway because the potential performance benefits are very
3585  * large, and we've seen no field complaints about the longstanding comparable
3586  * behavior with DISTINCT.
3587  */
3588 static bool
3589 subquery_is_pushdown_safe(Query *subquery, Query *topquery,
3590  pushdown_safety_info *safetyInfo)
3591 {
3592  SetOperationStmt *topop;
3593 
3594  /* Check point 1 */
3595  if (subquery->limitOffset != NULL || subquery->limitCount != NULL)
3596  return false;
3597 
3598  /* Check point 6 */
3599  if (subquery->groupClause && subquery->groupingSets)
3600  return false;
3601 
3602  /* Check points 3, 4, and 5 */
3603  if (subquery->distinctClause ||
3604  subquery->hasWindowFuncs ||
3605  subquery->hasTargetSRFs)
3606  safetyInfo->unsafeVolatile = true;
3607 
3608  /*
3609  * If we're at a leaf query, check for unsafe expressions in its target
3610  * list, and mark any reasons why they're unsafe in unsafeFlags[].
3611  * (Non-leaf nodes in setop trees have only simple Vars in their tlists,
3612  * so no need to check them.)
3613  */
3614  if (subquery->setOperations == NULL)
3615  check_output_expressions(subquery, safetyInfo);
3616 
3617  /* Are we at top level, or looking at a setop component? */
3618  if (subquery == topquery)
3619  {
3620  /* Top level, so check any component queries */
3621  if (subquery->setOperations != NULL)
3622  if (!recurse_pushdown_safe(subquery->setOperations, topquery,
3623  safetyInfo))
3624  return false;
3625  }
3626  else
3627  {
3628  /* Setop component must not have more components (too weird) */
3629  if (subquery->setOperations != NULL)
3630  return false;
3631  /* Check whether setop component output types match top level */
3632  topop = castNode(SetOperationStmt, topquery->setOperations);
3633  Assert(topop);
3634  compare_tlist_datatypes(subquery->targetList,
3635  topop->colTypes,
3636  safetyInfo);
3637  }
3638  return true;
3639 }
3640 
3641 /*
3642  * Helper routine to recurse through setOperations tree
3643  */
3644 static bool
3645 recurse_pushdown_safe(Node *setOp, Query *topquery,
3646  pushdown_safety_info *safetyInfo)
3647 {
3648  if (IsA(setOp, RangeTblRef))
3649  {
3650  RangeTblRef *rtr = (RangeTblRef *) setOp;
3651  RangeTblEntry *rte = rt_fetch(rtr->rtindex, topquery->rtable);
3652  Query *subquery = rte->subquery;
3653 
3654  Assert(subquery != NULL);
3655  return subquery_is_pushdown_safe(subquery, topquery, safetyInfo);
3656  }
3657  else if (IsA(setOp, SetOperationStmt))
3658  {
3659  SetOperationStmt *op = (SetOperationStmt *) setOp;
3660 
3661  /* EXCEPT is no good (point 2 for subquery_is_pushdown_safe) */
3662  if (op->op == SETOP_EXCEPT)
3663  return false;
3664  /* Else recurse */
3665  if (!recurse_pushdown_safe(op->larg, topquery, safetyInfo))
3666  return false;
3667  if (!recurse_pushdown_safe(op->rarg, topquery, safetyInfo))
3668  return false;
3669  }
3670  else
3671  {
3672  elog(ERROR, "unrecognized node type: %d",
3673  (int) nodeTag(setOp));
3674  }
3675  return true;
3676 }
3677 
3678 /*
3679  * check_output_expressions - check subquery's output expressions for safety
3680  *
3681  * There are several cases in which it's unsafe to push down an upper-level
3682  * qual if it references a particular output column of a subquery. We check
3683  * each output column of the subquery and set flags in unsafeFlags[k] when we
3684  * see that column is unsafe for a pushed-down qual to reference. The
3685  * conditions checked here are:
3686  *
3687  * 1. We must not push down any quals that refer to subselect outputs that
3688  * return sets, else we'd introduce functions-returning-sets into the
3689  * subquery's WHERE/HAVING quals.
3690  *
3691  * 2. We must not push down any quals that refer to subselect outputs that
3692  * contain volatile functions, for fear of introducing strange results due
3693  * to multiple evaluation of a volatile function.
3694  *
3695  * 3. If the subquery uses DISTINCT ON, we must not push down any quals that
3696  * refer to non-DISTINCT output columns, because that could change the set
3697  * of rows returned. (This condition is vacuous for DISTINCT, because then
3698  * there are no non-DISTINCT output columns, so we needn't check. Note that
3699  * subquery_is_pushdown_safe already reported that we can't use volatile
3700  * quals if there's DISTINCT or DISTINCT ON.)
3701  *
3702  * 4. If the subquery has any window functions, we must not push down quals
3703  * that reference any output columns that are not listed in all the subquery's
3704  * window PARTITION BY clauses. We can push down quals that use only
3705  * partitioning columns because they should succeed or fail identically for
3706  * every row of any one window partition, and totally excluding some
3707  * partitions will not change a window function's results for remaining
3708  * partitions. (Again, this also requires nonvolatile quals, but
3709  * subquery_is_pushdown_safe handles that.). Subquery columns marked as
3710  * unsafe for this reason can still have WindowClause run conditions pushed
3711  * down.
3712  */
3713 static void
3714 check_output_expressions(Query *subquery, pushdown_safety_info *safetyInfo)
3715 {
3716  ListCell *lc;
3717 
3718  foreach(lc, subquery->targetList)
3719  {
3720  TargetEntry *tle = (TargetEntry *) lfirst(lc);
3721 
3722  if (tle->resjunk)
3723  continue; /* ignore resjunk columns */
3724 
3725  /* Functions returning sets are unsafe (point 1) */
3726  if (subquery->hasTargetSRFs &&
3727  (safetyInfo->unsafeFlags[tle->resno] &
3728  UNSAFE_HAS_SET_FUNC) == 0 &&
3729  expression_returns_set((Node *) tle->expr))
3730  {
3731  safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_HAS_SET_FUNC;
3732  continue;
3733  }
3734 
3735  /* Volatile functions are unsafe (point 2) */
3736  if ((safetyInfo->unsafeFlags[tle->resno] &
3737  UNSAFE_HAS_VOLATILE_FUNC) == 0 &&
3738  contain_volatile_functions((Node *) tle->expr))
3739  {
3740  safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_HAS_VOLATILE_FUNC;
3741  continue;
3742  }
3743 
3744  /* If subquery uses DISTINCT ON, check point 3 */
3745  if (subquery->hasDistinctOn &&
3746  (safetyInfo->unsafeFlags[tle->resno] &
3747  UNSAFE_NOTIN_DISTINCTON_CLAUSE) == 0 &&
3748  !targetIsInSortList(tle, InvalidOid, subquery->distinctClause))
3749  {
3750  /* non-DISTINCT column, so mark it unsafe */
3751  safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_NOTIN_DISTINCTON_CLAUSE;
3752  continue;
3753  }
3754 
3755  /* If subquery uses window functions, check point 4 */
3756  if (subquery->hasWindowFuncs &&
3757  (safetyInfo->unsafeFlags[tle->resno] &
3758  UNSAFE_NOTIN_DISTINCTON_CLAUSE) == 0 &&
3759  !targetIsInAllPartitionLists(tle, subquery))
3760  {
3761  /* not present in all PARTITION BY clauses, so mark it unsafe */
3762  safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_NOTIN_PARTITIONBY_CLAUSE;
3763  continue;
3764  }
3765  }
3766 }
3767 
3768 /*
3769  * For subqueries using UNION/UNION ALL/INTERSECT/INTERSECT ALL, we can
3770  * push quals into each component query, but the quals can only reference
3771  * subquery columns that suffer no type coercions in the set operation.
3772  * Otherwise there are possible semantic gotchas. So, we check the
3773  * component queries to see if any of them have output types different from
3774  * the top-level setop outputs. We set the UNSAFE_TYPE_MISMATCH bit in
3775  * unsafeFlags[k] if column k has different type in any component.
3776  *
3777  * We don't have to care about typmods here: the only allowed difference
3778  * between set-op input and output typmods is input is a specific typmod
3779  * and output is -1, and that does not require a coercion.
3780  *
3781  * tlist is a subquery tlist.
3782  * colTypes is an OID list of the top-level setop's output column types.
3783  * safetyInfo is the pushdown_safety_info to set unsafeFlags[] for.
3784  */
3785 static void
3786 compare_tlist_datatypes(List *tlist, List *colTypes,
3787  pushdown_safety_info *safetyInfo)
3788 {
3789  ListCell *l;
3790  ListCell *colType = list_head(colTypes);
3791 
3792  foreach(l, tlist)
3793  {
3794  TargetEntry *tle = (TargetEntry *) lfirst(l);
3795 
3796  if (tle->resjunk)
3797  continue; /* ignore resjunk columns */
3798  if (colType == NULL)
3799  elog(ERROR, "wrong number of tlist entries");
3800  if (exprType((Node *) tle->expr) != lfirst_oid(colType))
3801  safetyInfo->unsafeFlags[tle->resno] |= UNSAFE_TYPE_MISMATCH;
3802  colType = lnext(colTypes, colType);
3803  }
3804  if (colType != NULL)
3805  elog(ERROR, "wrong number of tlist entries");
3806 }
3807 
3808 /*
3809  * targetIsInAllPartitionLists
3810  * True if the TargetEntry is listed in the PARTITION BY clause
3811  * of every window defined in the query.
3812  *
3813  * It would be safe to ignore windows not actually used by any window
3814  * function, but it's not easy to get that info at this stage; and it's
3815  * unlikely to be useful to spend any extra cycles getting it, since
3816  * unreferenced window definitions are probably infrequent in practice.
3817  */
3818 static bool
3819 targetIsInAllPartitionLists(TargetEntry *tle, Query *query)
3820 {
3821  ListCell *lc;
3822 
3823  foreach(lc, query->windowClause)
3824  {
3825  WindowClause *wc = (WindowClause *) lfirst(lc);
3826 
3827  if (!targetIsInSortList(tle, InvalidOid, wc->partitionClause))
3828  return false;
3829  }
3830  return true;
3831 }
3832 
3833 /*
3834  * qual_is_pushdown_safe - is a particular rinfo safe to push down?
3835  *
3836  * rinfo is a restriction clause applying to the given subquery (whose RTE
3837  * has index rti in the parent query).
3838  *
3839  * Conditions checked here:
3840  *
3841  * 1. rinfo's clause must not contain any SubPlans (mainly because it's
3842  * unclear that it will work correctly: SubLinks will already have been
3843  * transformed into SubPlans in the qual, but not in the subquery). Note that
3844  * SubLinks that transform to initplans are safe, and will be accepted here
3845  * because what we'll see in the qual is just a Param referencing the initplan
3846  * output.
3847  *
3848  * 2. If unsafeVolatile is set, rinfo's clause must not contain any volatile
3849  * functions.
3850  *
3851  * 3. If unsafeLeaky is set, rinfo's clause must not contain any leaky
3852  * functions that are passed Var nodes, and therefore might reveal values from
3853  * the subquery as side effects.
3854  *
3855  * 4. rinfo's clause must not refer to the whole-row output of the subquery
3856  * (since there is no easy way to name that within the subquery itself).
3857  *
3858  * 5. rinfo's clause must not refer to any subquery output columns that were
3859  * found to be unsafe to reference by subquery_is_pushdown_safe().
3860  */
3861 static pushdown_safe_type
3862 qual_is_pushdown_safe(Query *subquery, Index rti, RestrictInfo *rinfo,
3863  pushdown_safety_info *safetyInfo)
3864 {
3865  pushdown_safe_type safe = PUSHDOWN_SAFE;
3866  Node *qual = (Node *) rinfo->clause;
3867  List *vars;
3868  ListCell *vl;
3869 
3870  /* Refuse subselects (point 1) */
3871  if (contain_subplans(qual))
3872  return PUSHDOWN_UNSAFE;
3873 
3874  /* Refuse volatile quals if we found they'd be unsafe (point 2) */
3875  if (safetyInfo->unsafeVolatile &&
3876  contain_volatile_functions((Node *) rinfo))
3877  return PUSHDOWN_UNSAFE;
3878 
3879  /* Refuse leaky quals if told to (point 3) */
3880  if (safetyInfo->unsafeLeaky &&
3881  contain_leaked_vars(qual))
3882  return PUSHDOWN_UNSAFE;
3883 
3884  /*
3885  * Examine all Vars used in clause. Since it's a restriction clause, all
3886  * such Vars must refer to subselect output columns ... unless this is
3887  * part of a LATERAL subquery, in which case there could be lateral
3888  * references.
3889  *
3890  * By omitting the relevant flags, this also gives us a cheap sanity check
3891  * that no aggregates or window functions appear in the qual. Those would
3892  * be unsafe to push down, but at least for the moment we could never see
3893  * any in a qual anyhow.
3894  */
3895  vars = pull_var_clause(qual, PVC_INCLUDE_PLACEHOLDERS);
3896  foreach(vl, vars)
3897  {
3898  Var *var = (Var *) lfirst(vl);
3899 
3900  /*
3901  * XXX Punt if we find any PlaceHolderVars in the restriction clause.
3902  * It's not clear whether a PHV could safely be pushed down, and even
3903  * less clear whether such a situation could arise in any cases of
3904  * practical interest anyway. So for the moment, just refuse to push
3905  * down.
3906  */
3907  if (!IsA(var, Var))
3908  {
3909  safe = PUSHDOWN_UNSAFE;
3910  break;
3911  }
3912 
3913  /*
3914  * Punt if we find any lateral references. It would be safe to push
3915  * these down, but we'd have to convert them into outer references,
3916  * which subquery_push_qual lacks the infrastructure to do. The case
3917  * arises so seldom that it doesn't seem worth working hard on.
3918  */
3919  if (var->varno != rti)
3920  {
3921  safe = PUSHDOWN_UNSAFE;
3922  break;
3923  }
3924 
3925  /* Subqueries have no system columns */
3926  Assert(var->varattno >= 0);
3927 
3928  /* Check point 4 */
3929  if (var->varattno == 0)
3930  {
3931  safe = PUSHDOWN_UNSAFE;
3932  break;
3933  }
3934 
3935  /* Check point 5 */
3936  if (safetyInfo->unsafeFlags[var->varattno] != 0)
3937  {
3938  if (safetyInfo->unsafeFlags[var->varattno] &
3939  (UNSAFE_HAS_VOLATILE_FUNC | UNSAFE_HAS_SET_FUNC |
3940  UNSAFE_NOTIN_DISTINCTON_CLAUSE | UNSAFE_TYPE_MISMATCH))
3941  {
3942  safe = PUSHDOWN_UNSAFE;
3943  break;
3944  }
3945  else
3946  {
3947  /* UNSAFE_NOTIN_PARTITIONBY_CLAUSE is ok for run conditions */
3948  safe = PUSHDOWN_WINDOWCLAUSE_RUNCOND;
3949  /* don't break, we might find another Var that's unsafe */
3950  }
3951  }
3952  }
3953 
3954  list_free(vars);
3955 
3956  return safe;
3957 }
3958 
3959 /*
3960  * subquery_push_qual - push down a qual that we have determined is safe
3961  */
3962 static void
3963 subquery_push_qual(Query *subquery, RangeTblEntry *rte, Index rti, Node *qual)
3964 {
3965  if (subquery->setOperations != NULL)
3966  {
3967  /* Recurse to push it separately to each component query */
3968  recurse_push_qual(subquery->setOperations, subquery,
3969  rte, rti, qual);
3970  }
3971  else
3972  {
3973  /*
3974  * We need to replace Vars in the qual (which must refer to outputs of
3975  * the subquery) with copies of the subquery's targetlist expressions.
3976  * Note that at this point, any uplevel Vars in the qual should have
3977  * been replaced with Params, so they need no work.
3978  *
3979  * This step also ensures that when we are pushing into a setop tree,
3980  * each component query gets its own copy of the qual.
3981  */
3982  qual = ReplaceVarsFromTargetList(qual, rti, 0, rte,
3983  subquery->targetList,
3984  REPLACEVARS_REPORT_ERROR, 0,
3985  &subquery->hasSubLinks);
3986 
3987  /*
3988  * Now attach the qual to the proper place: normally WHERE, but if the
3989  * subquery uses grouping or aggregation, put it in HAVING (since the
3990  * qual really refers to the group-result rows).
3991  */
3992  if (subquery->hasAggs || subquery->groupClause || subquery->groupingSets || subquery->havingQual)
3993  subquery->havingQual = make_and_qual(subquery->havingQual, qual);
3994  else
3995  subquery->jointree->quals =
3996  make_and_qual(subquery->jointree->quals, qual);
3997 
3998  /*
3999  * We need not change the subquery's hasAggs or hasSubLinks flags,
4000  * since we can't be pushing down any aggregates that weren't there
4001  * before, and we don't push down subselects at all.
4002  */
4003  }
4004 }
4005 
4006 /*
4007  * Helper routine to recurse through setOperations tree
4008  */
4009 static void
4010 recurse_push_qual(Node *setOp, Query *topquery,
4011  RangeTblEntry *rte, Index rti, Node *qual)
4012 {
4013  if (IsA(setOp, RangeTblRef))
4014  {
4015  RangeTblRef *rtr = (RangeTblRef *) setOp;
4016  RangeTblEntry *subrte = rt_fetch(rtr->rtindex, topquery->rtable);
4017  Query *subquery = subrte->subquery;
4018 
4019  Assert(subquery != NULL);
4020  subquery_push_qual(subquery, rte, rti, qual);
4021  }
4022  else if (IsA(setOp, SetOperationStmt))
4023  {
4024  SetOperationStmt *op = (SetOperationStmt *) setOp;
4025 
4026  recurse_push_qual(op->larg, topquery, rte, rti, qual);
4027  recurse_push_qual(op->rarg, topquery, rte, rti, qual);
4028  }
4029  else
4030  {
4031  elog(ERROR, "unrecognized node type: %d",
4032  (int) nodeTag(setOp));
4033  }
4034 }
4035 
4036 /*****************************************************************************
4037  * SIMPLIFYING SUBQUERY TARGETLISTS
4038  *****************************************************************************/
4039 
4040 /*
4041  * remove_unused_subquery_outputs
4042  * Remove subquery targetlist items we don't need
4043  *
4044  * It's possible, even likely, that the upper query does not read all the
4045  * output columns of the subquery. We can remove any such outputs that are
4046  * not needed by the subquery itself (e.g., as sort/group columns) and do not
4047  * affect semantics otherwise (e.g., volatile functions can't be removed).
4048  * This is useful not only because we might be able to remove expensive-to-
4049  * compute expressions, but because deletion of output columns might allow
4050  * optimizations such as join removal to occur within the subquery.
4051  *
4052  * extra_used_attrs can be passed as non-NULL to mark any columns (offset by
4053  * FirstLowInvalidHeapAttributeNumber) that we should not remove. This
4054  * parameter is modified by the function, so callers must make a copy if they
4055  * need to use the passed in Bitmapset after calling this function.
4056  *
4057  * To avoid affecting column numbering in the targetlist, we don't physically
4058  * remove unused tlist entries, but rather replace their expressions with NULL
4059  * constants. This is implemented by modifying subquery->targetList.
4060  */
4061 static void
4062 remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel,
4063  Bitmapset *extra_used_attrs)
4064 {
4065  Bitmapset *attrs_used;
4066  ListCell *lc;
4067 
4068  /*
4069  * Just point directly to extra_used_attrs. No need to bms_copy as none of
4070  * the current callers use the Bitmapset after calling this function.
4071  */
4072  attrs_used = extra_used_attrs;
4073 
4074  /*
4075  * Do nothing if subquery has UNION/INTERSECT/EXCEPT: in principle we
4076  * could update all the child SELECTs' tlists, but it seems not worth the
4077  * trouble presently.
4078  */
4079  if (subquery->setOperations)
4080  return;
4081 
4082  /*
4083  * If subquery has regular DISTINCT (not DISTINCT ON), we're wasting our
4084  * time: all its output columns must be used in the distinctClause.
4085  */
4086  if (subquery->distinctClause && !subquery->hasDistinctOn)
4087  return;
4088 
4089  /*
4090  * Collect a bitmap of all the output column numbers used by the upper
4091  * query.
4092  *
4093  * Add all the attributes needed for joins or final output. Note: we must
4094  * look at rel's targetlist, not the attr_needed data, because attr_needed
4095  * isn't computed for inheritance child rels, cf set_append_rel_size().
4096  * (XXX might be worth changing that sometime.)
4097  */
4098  pull_varattnos((Node *) rel->reltarget->exprs, rel->relid, &attrs_used);
4099 
4100  /* Add all the attributes used by un-pushed-down restriction clauses. */
4101  foreach(lc, rel->baserestrictinfo)
4102  {
4103  RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
4104 
4105  pull_varattnos((Node *) rinfo->clause, rel->relid, &attrs_used);
4106  }
4107 
4108  /*
4109  * If there's a whole-row reference to the subquery, we can't remove
4110  * anything.
4111  */
4112  if (bms_is_member(0 - FirstLowInvalidHeapAttributeNumber, attrs_used))
4113  return;
4114 
4115  /*
4116  * Run through the tlist and zap entries we don't need. It's okay to
4117  * modify the tlist items in-place because set_subquery_pathlist made a
4118  * copy of the subquery.
4119  */
4120  foreach(lc, subquery->targetList)
4121  {
4122  TargetEntry *tle = (TargetEntry *) lfirst(lc);
4123  Node *texpr = (Node *) tle->expr;
4124 
4125  /*
4126  * If it has a sortgroupref number, it's used in some sort/group
4127  * clause so we'd better not remove it. Also, don't remove any
4128  * resjunk columns, since their reason for being has nothing to do
4129  * with anybody reading the subquery's output. (It's likely that
4130  * resjunk columns in a sub-SELECT would always have ressortgroupref
4131  * set, but even if they don't, it seems imprudent to remove them.)
4132  */
4133  if (tle->ressortgroupref || tle->resjunk)
4134  continue;
4135 
4136  /*
4137  * If it's used by the upper query, we can't remove it.
4138  */
4139  if (bms_is_member(tle->resno - FirstLowInvalidHeapAttributeNumber,
4140  attrs_used))
4141  continue;
4142 
4143  /*
4144  * If it contains a set-returning function, we can't remove it since
4145  * that could change the number of rows returned by the subquery.
4146  */
4147  if (subquery->hasTargetSRFs &&
4148  expression_returns_set(texpr))
4149  continue;
4150 
4151  /*
4152  * If it contains volatile functions, we daren't remove it for fear
4153  * that the user is expecting their side-effects to happen.
4154  */
4155  if (contain_volatile_functions(texpr))
4156  continue;
4157 
4158  /*
4159  * OK, we don't need it. Replace the expression with a NULL constant.
4160  * Preserve the exposed type of the expression, in case something
4161  * looks at the rowtype of the subquery's result.
4162  */
4163  tle->expr = (Expr *) makeNullConst(exprType(texpr),
4164  exprTypmod(texpr),
4165  exprCollation(texpr));
4166  }
4167 }
4168 
4169 /*
4170  * create_partial_bitmap_paths
4171  * Build partial bitmap heap path for the relation
4172  */
4173 void
4174 create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel,
4175  Path *bitmapqual)
4176 {
4177  int parallel_workers;
4178  double pages_fetched;
4179 
4180  /* Compute heap pages for bitmap heap scan */
4181  pages_fetched = compute_bitmap_pages(root, rel, bitmapqual, 1.0,
4182  NULL, NULL);
4183 
4184  parallel_workers = compute_parallel_worker(rel, pages_fetched, -1,
4185  max_parallel_workers_per_gather);
4186 
4187  if (parallel_workers <= 0)
4188  return;
4189 
4190  add_partial_path(rel, (Path *) create_bitmap_heap_path(root, rel,
4191  bitmapqual, rel->lateral_relids, 1.0, parallel_workers));
4192 }
4193 
4194 /*
4195  * Compute the number of parallel workers that should be used to scan a
4196  * relation. We compute the parallel workers based on the size of the heap to
4197  * be scanned and the size of the index to be scanned, then choose a minimum
4198  * of those.
4199  *
4200  * "heap_pages" is the number of pages from the table that we expect to scan, or
4201  * -1 if we don't expect to scan any.
4202  *
4203  * "index_pages" is the number of pages from the index that we expect to scan, or
4204  * -1 if we don't expect to scan any.
4205  *
4206  * "max_workers" is caller's limit on the number of workers. This typically
4207  * comes from a GUC.
4208  */
4209 int
4210 compute_parallel_worker(RelOptInfo *rel, double heap_pages, double index_pages,
4211  int max_workers)
4212 {
4213  int parallel_workers = 0;
4214 
4215  /*
4216  * If the user has set the parallel_workers reloption, use that; otherwise
4217  * select a default number of workers.
4218  */
4219  if (rel->rel_parallel_workers != -1)
4220  parallel_workers = rel->rel_parallel_workers;
4221  else
4222  {
4223  /*
4224  * If the number of pages being scanned is insufficient to justify a
4225  * parallel scan, just return zero ... unless it's an inheritance
4226  * child. In that case, we want to generate a parallel path here
4227  * anyway. It might not be worthwhile just for this relation, but
4228  * when combined with all of its inheritance siblings it may well pay
4229  * off.
4230  */
4231  if (rel->reloptkind == RELOPT_BASEREL &&
4232  ((heap_pages >= 0 && heap_pages < min_parallel_table_scan_size) ||
4233  (index_pages >= 0 && index_pages < min_parallel_index_scan_size)))
4234  return 0;
4235 
4236  if (heap_pages >= 0)
4237  {
4238  int heap_parallel_threshold;
4239  int heap_parallel_workers = 1;
4240 
4241  /*
4242  * Select the number of workers based on the log of the size of
4243  * the relation. This probably needs to be a good deal more
4244  * sophisticated, but we need something here for now. Note that
4245  * the upper limit of the min_parallel_table_scan_size GUC is
4246  * chosen to prevent overflow here.
4247  */
4248  heap_parallel_threshold = Max(min_parallel_table_scan_size, 1);
4249  while (heap_pages >= (BlockNumber) (heap_parallel_threshold * 3))
4250  {
4251  heap_parallel_workers++;
4252  heap_parallel_threshold *= 3;
4253  if (heap_parallel_threshold > INT_MAX / 3)
4254  break; /* avoid overflow */
4255  }
4256 
4257  parallel_workers = heap_parallel_workers;
4258  }
4259 
4260  if (index_pages >= 0)
4261  {
4262  int index_parallel_workers = 1;
4263  int index_parallel_threshold;
4264 
4265  /* same calculation as for heap_pages above */
4266  index_parallel_threshold = Max(min_parallel_index_scan_size, 1);
4267  while (index_pages >= (BlockNumber) (index_parallel_threshold * 3))
4268  {
4269  index_parallel_workers++;
4270  index_parallel_threshold *= 3;
4271  if (index_parallel_threshold > INT_MAX / 3)
4272  break; /* avoid overflow */
4273  }
4274 
4275  if (parallel_workers > 0)
4276  parallel_workers = Min(parallel_workers, index_parallel_workers);
4277  else
4278  parallel_workers = index_parallel_workers;
4279  }
4280  }
4281 
4282  /* In no case use more than caller supplied maximum number of workers */
4283  parallel_workers = Min(parallel_workers, max_workers);
4284 
4285  return parallel_workers;
4286 }
4287 
4288 /*
4289  * generate_partitionwise_join_paths
4290  * Create paths representing partitionwise join for given partitioned
4291  * join relation.
4292  *
4293  * This must not be called until after we are done adding paths for all
4294  * child-joins. Otherwise, add_path might delete a path to which some path
4295  * generated here has a reference.
4296  */
4297 void
4298 generate_partitionwise_join_paths(PlannerInfo *root, RelOptInfo *rel)
4299 {
4300  List *live_children = NIL;
4301  int cnt_parts;
4302  int num_parts;
4303  RelOptInfo **part_rels;
4304 
4305  /* Handle only join relations here. */
4306  if (!IS_JOIN_REL(rel))
4307  return;
4308 
4309  /* We've nothing to do if the relation is not partitioned. */
4310  if (!IS_PARTITIONED_REL(rel))
4311  return;
4312 
4313  /* The relation should have consider_partitionwise_join set. */
4314  Assert(rel->consider_partitionwise_join);
4315 
4316  /* Guard against stack overflow due to overly deep partition hierarchy. */
4317  check_stack_depth();
4318 
4319  num_parts = rel->nparts;
4320  part_rels = rel->part_rels;
4321 
4322  /* Collect non-dummy child-joins. */
4323  for (cnt_parts = 0; cnt_parts < num_parts; cnt_parts++)
4324  {
4325  RelOptInfo *child_rel = part_rels[cnt_parts];
4326 
4327  /* If it's been pruned entirely, it's certainly dummy. */
4328  if (child_rel == NULL)
4329  continue;
4330 
4331  /* Make partitionwise join paths for this partitioned child-join. */
4332  generate_partitionwise_join_paths(root, child_rel);
4333 
4334  /* If we failed to make any path for this child, we must give up. */
4335  if (child_rel->pathlist == NIL)
4336  {
4337  /*
4338  * Mark the parent joinrel as unpartitioned so that later
4339  * functions treat it correctly.
4340  */
4341  rel->nparts = 0;
4342  return;
4343  }
4344 
4345  /* Else, identify the cheapest path for it. */
4346  set_cheapest(child_rel);
4347 
4348  /* Dummy children need not be scanned, so ignore those. */
4349  if (IS_DUMMY_REL(child_rel))
4350  continue;
4351 
4352 #ifdef OPTIMIZER_DEBUG
4353  pprint(child_rel);
4354 #endif
4355 
4356  live_children = lappend(live_children, child_rel);
4357  }
4358 
4359  /* If all child-joins are dummy, parent join is also dummy. */
4360  if (!live_children)
4361  {
4362  mark_dummy_rel(rel);
4363  return;
4364  }
4365 
4366  /* Build additional paths for this rel from child-join paths. */
4367  add_paths_to_append_rel(root, rel, live_children);
4368  list_free(live_children);
4369 }
set_base_rel_sizes
static void set_base_rel_sizes(PlannerInfo *root)
Definition: allpaths.c:290
set_subquery_pathlist
static void set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry *rte)
Definition: allpaths.c:2490
find_window_run_conditions
static bool find_window_run_conditions(Query *subquery, RangeTblEntry *rte, Index rti, AttrNumber attno, WindowFunc *wfunc, OpExpr *opexpr, bool wfunc_left, bool *keep_original, Bitmapset **run_cond_attrs)
Definition: allpaths.c:2222
UNSAFE_TYPE_MISMATCH
#define UNSAFE_TYPE_MISMATCH
Definition: allpaths.c:57
get_cheapest_parameterized_child_path
static Path * get_cheapest_parameterized_child_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
Definition: allpaths.c:2007
set_namedtuplestore_pathlist
static void set_namedtuplestore_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:2947
subquery_push_qual
static void subquery_push_qual(Query *subquery, RangeTblEntry *rte, Index rti, Node *qual)
Definition: allpaths.c:3963
generate_partitionwise_join_paths
void generate_partitionwise_join_paths(PlannerInfo *root, RelOptInfo *rel)
Definition: allpaths.c:4298
standard_join_search
RelOptInfo * standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
Definition: allpaths.c:3418
set_base_rel_consider_startup
static void set_base_rel_consider_startup(PlannerInfo *root)
Definition: allpaths.c:247
UNSAFE_HAS_VOLATILE_FUNC
#define UNSAFE_HAS_VOLATILE_FUNC
Definition: allpaths.c:53
UNSAFE_NOTIN_DISTINCTON_CLAUSE
#define UNSAFE_NOTIN_DISTINCTON_CLAUSE
Definition: allpaths.c:55
set_rel_pathlist
static void set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry *rte)
Definition: allpaths.c:469
get_singleton_append_subpath
static Path * get_singleton_append_subpath(Path *path)
Definition: allpaths.c:2140
set_tablesample_rel_size
static void set_tablesample_rel_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:822
set_tablesample_rel_pathlist
static void set_tablesample_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:862
set_foreign_pathlist
static void set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:934
set_base_rel_pathlists
static void set_base_rel_pathlists(PlannerInfo *root)
Definition: allpaths.c:333
geqo_threshold
int geqo_threshold
Definition: allpaths.c:80
set_append_rel_pathlist
static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry *rte)
Definition: allpaths.c:1240
qual_is_pushdown_safe
static pushdown_safe_type qual_is_pushdown_safe(Query *subquery, Index rti, RestrictInfo *rinfo, pushdown_safety_info *safetyInfo)
Definition: allpaths.c:3862
set_result_pathlist
static void set_result_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:2974
compute_parallel_worker
int compute_parallel_worker(RelOptInfo *rel, double heap_pages, double index_pages, int max_workers)
Definition: allpaths.c:4210
generate_gather_paths
void generate_gather_paths(PlannerInfo *root, RelOptInfo *rel, bool override_rows)
Definition: allpaths.c:3060
set_dummy_rel_pathlist
static void set_dummy_rel_pathlist(RelOptInfo *rel)
Definition: allpaths.c:2174
compare_tlist_datatypes
static void compare_tlist_datatypes(List *tlist, List *colTypes, pushdown_safety_info *safetyInfo)
Definition: allpaths.c:3786
set_worktable_pathlist
static void set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:3001
targetIsInAllPartitionLists
static bool targetIsInAllPartitionLists(TargetEntry *tle, Query *query)
Definition: allpaths.c:3819
create_plain_partial_paths
static void create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
Definition: allpaths.c:802
subquery_is_pushdown_safe
static bool subquery_is_pushdown_safe(Query *subquery, Query *topquery, pushdown_safety_info *safetyInfo)
Definition: allpaths.c:3589
join_search_hook
join_search_hook_type join_search_hook
Definition: allpaths.c:88
enable_geqo
bool enable_geqo
Definition: allpaths.c:79
check_and_push_window_quals
static bool check_and_push_window_quals(Query *subquery, RangeTblEntry *rte, Index rti, Node *clause, Bitmapset **run_cond_attrs)
Definition: allpaths.c:2415
generate_useful_gather_paths
void generate_useful_gather_paths(PlannerInfo *root, RelOptInfo *rel, bool override_rows)
Definition: allpaths.c:3197
make_rel_from_joinlist
static RelOptInfo * make_rel_from_joinlist(PlannerInfo *root, List *joinlist)
Definition: allpaths.c:3313
set_function_pathlist
static void set_function_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:2757
recurse_push_qual
static void recurse_push_qual(Node *setOp, Query *topquery, RangeTblEntry *rte, Index rti, Node *qual)
Definition: allpaths.c:4010
set_plain_rel_pathlist
static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:764
get_useful_pathkeys_for_relation
static List * get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel, bool require_parallel_safe)
Definition: allpaths.c:3129
remove_unused_subquery_outputs
static void remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel, Bitmapset *extra_used_attrs)
Definition: allpaths.c:4062
check_output_expressions
static void check_output_expressions(Query *subquery, pushdown_safety_info *safetyInfo)
Definition: allpaths.c:3714
set_tablefunc_pathlist
static void set_tablefunc_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:2844
set_foreign_size
static void set_foreign_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:910
set_rel_pathlist_hook
set_rel_pathlist_hook_type set_rel_pathlist_hook
Definition: allpaths.c:85
set_values_pathlist
static void set_values_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:2824
pushdown_safety_info
struct pushdown_safety_info pushdown_safety_info
UNSAFE_HAS_SET_FUNC
#define UNSAFE_HAS_SET_FUNC
Definition: allpaths.c:54
set_cte_pathlist
static void set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:2868
set_rel_consider_parallel
static void set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:589
set_append_rel_size
static void set_append_rel_size(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry *rte)
Definition: allpaths.c:952
create_partial_bitmap_paths
void create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel, Path *bitmapqual)
Definition: allpaths.c:4174
set_plain_rel_size
static void set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: allpaths.c:572
add_paths_to_append_rel
void add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel, List *live_childrels)
Definition: allpaths.c:1310
set_rel_size
static void set_rel_size(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry *rte)
Definition: allpaths.c:360
generate_orderedappend_paths
static void generate_orderedappend_paths(PlannerInfo *root, RelOptInfo *rel, List *live_childrels, List *all_child_pathkeys)
Definition: allpaths.c:1722
UNSAFE_NOTIN_PARTITIONBY_CLAUSE
#define UNSAFE_NOTIN_PARTITIONBY_CLAUSE
Definition: allpaths.c:56
make_one_rel
RelOptInfo * make_one_rel(PlannerInfo *root, List *joinlist)
Definition: allpaths.c:171
recurse_pushdown_safe
static bool recurse_pushdown_safe(Node *setOp, Query *topquery, pushdown_safety_info *safetyInfo)
Definition: allpaths.c:3645
pushdown_safe_type
pushdown_safe_type
Definition: allpaths.c:71
PUSHDOWN_WINDOWCLAUSE_RUNCOND
@ PUSHDOWN_WINDOWCLAUSE_RUNCOND
Definition: allpaths.c:74
PUSHDOWN_UNSAFE
@ PUSHDOWN_UNSAFE
Definition: allpaths.c:72
PUSHDOWN_SAFE
@ PUSHDOWN_SAFE
Definition: allpaths.c:73
accumulate_append_subpath
static void accumulate_append_subpath(Path *path, List **subpaths, List **special_subpaths)
Definition: allpaths.c:2095
min_parallel_index_scan_size
int min_parallel_index_scan_size
Definition: allpaths.c:82
min_parallel_table_scan_size
int min_parallel_table_scan_size
Definition: allpaths.c:81
adjust_appendrel_attrs
Node * adjust_appendrel_attrs(PlannerInfo *root, Node *node, int nappinfos, AppendRelInfo **appinfos)
Definition: appendinfo.c:200
AttrNumber
int16 AttrNumber
Definition: attnum.h:21
InvalidAttrNumber
#define InvalidAttrNumber
Definition: attnum.h:23
pprint
void pprint(const void *obj)
Definition: print.c:54
bms_equal
bool bms_equal(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:142
bms_is_subset
bool bms_is_subset(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:412
bms_is_member
bool bms_is_member(int x, const Bitmapset *a)
Definition: bitmapset.c:510
bms_add_member
Bitmapset * bms_add_member(Bitmapset *a, int x)
Definition: bitmapset.c:815
bms_membership
BMS_Membership bms_membership(const Bitmapset *a)
Definition: bitmapset.c:781
bms_overlap
bool bms_overlap(const Bitmapset *a, const Bitmapset *b)
Definition: bitmapset.c:582
bms_get_singleton_member
bool bms_get_singleton_member(const Bitmapset *a, int *member)
Definition: bitmapset.c:715
bms_is_empty
#define bms_is_empty(a)
Definition: bitmapset.h:118
BMS_SINGLETON
@ BMS_SINGLETON
Definition: bitmapset.h:72
BMS_MULTIPLE
@ BMS_MULTIPLE
Definition: bitmapset.h:73
BlockNumber
uint32 BlockNumber
Definition: block.h:31
Min
#define Min(x, y)
Definition: c.h:1004
int16
signed short int16
Definition: c.h:493
int32
signed int int32
Definition: c.h:494
Max
#define Max(x, y)
Definition: c.h:998
Assert
#define Assert(condition)
Definition: c.h:858
Index
unsigned int Index
Definition: c.h:614
OidIsValid
#define OidIsValid(objectId)
Definition: c.h:775
is_pseudo_constant_clause
bool is_pseudo_constant_clause(Node *clause)
Definition: clauses.c:2088
contain_leaked_vars
bool contain_leaked_vars(Node *clause)
Definition: clauses.c:1263
is_parallel_safe
bool is_parallel_safe(PlannerInfo *root, Node *node)
Definition: clauses.c:753
contain_subplans
bool contain_subplans(Node *clause)
Definition: clauses.c:330
contain_volatile_functions
bool contain_volatile_functions(Node *clause)
Definition: clauses.c:538
set_namedtuplestore_size_estimates
void set_namedtuplestore_size_estimates(PlannerInfo *root, RelOptInfo *rel)
Definition: costsize.c:5976
max_parallel_workers_per_gather
int max_parallel_workers_per_gather
Definition: costsize.c:132
set_baserel_size_estimates
void set_baserel_size_estimates(PlannerInfo *root, RelOptInfo *rel)
Definition: costsize.c:5213
set_function_size_estimates
void set_function_size_estimates(PlannerInfo *root, RelOptInfo *rel)
Definition: costsize.c:5846
set_cte_size_estimates
void set_cte_size_estimates(PlannerInfo *root, RelOptInfo *rel, double cte_rows)
Definition: costsize.c:5938
compute_gather_rows
double compute_gather_rows(Path *path)
Definition: costsize.c:6488
set_result_size_estimates
void set_result_size_estimates(PlannerInfo *root, RelOptInfo *rel)
Definition: costsize.c:6009
enable_partitionwise_join
bool enable_partitionwise_join
Definition: costsize.c:148
compute_bitmap_pages
double compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel, Path *bitmapqual, double loop_count, Cost *cost_p, double *tuples_p)
Definition: costsize.c:6377
set_subquery_size_estimates
void set_subquery_size_estimates(PlannerInfo *root, RelOptInfo *rel)
Definition: costsize.c:5766
enable_parallel_append
bool enable_parallel_append
Definition: costsize.c:150
set_foreign_size_estimates
void set_foreign_size_estimates(PlannerInfo *root, RelOptInfo *rel)
Definition: costsize.c:6038
clamp_row_est
double clamp_row_est(double nrows)
Definition: costsize.c:202
set_tablefunc_size_estimates
void set_tablefunc_size_estimates(PlannerInfo *root, RelOptInfo *rel)
Definition: costsize.c:5884
set_values_size_estimates
void set_values_size_estimates(PlannerInfo *root, RelOptInfo *rel)
Definition: costsize.c:5906
enable_incremental_sort
bool enable_incremental_sort
Definition: costsize.c:140
ERROR
#define ERROR
Definition: elog.h:39
elog
#define elog(elevel,...)
Definition: elog.h:224
add_child_rel_equivalences
void add_child_rel_equivalences(PlannerInfo *root, AppendRelInfo *appinfo, RelOptInfo *parent_rel, RelOptInfo *child_rel)
Definition: equivclass.c:2636
relation_can_be_sorted_early
bool relation_can_be_sorted_early(PlannerInfo *root, RelOptInfo *rel, EquivalenceClass *ec, bool require_parallel_safe)
Definition: equivclass.c:922
OidFunctionCall1
#define OidFunctionCall1(functionId, arg1)
Definition: fmgr.h:680
geqo
RelOptInfo * geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
Definition: geqo_main.c:72
check_index_predicates
void check_index_predicates(PlannerInfo *root, RelOptInfo *rel)
Definition: indxpath.c:3244
create_index_paths
void create_index_paths(PlannerInfo *root, RelOptInfo *rel)
Definition: indxpath.c:234
i
int i
Definition: isn.c:73
if
if(TABLE==NULL||TABLE_index==NULL)
Definition: isn.c:77
join_search_one_level
void join_search_one_level(PlannerInfo *root, int level)
Definition: joinrels.c:72
mark_dummy_rel
void mark_dummy_rel(RelOptInfo *rel)
Definition: joinrels.c:1384
lappend
List * lappend(List *list, void *datum)
Definition: list.c:339
list_copy_head
List * list_copy_head(const List *oldlist, int len)
Definition: list.c:1593
list_free
void list_free(List *list)
Definition: list.c:1546
list_copy_tail
List * list_copy_tail(const List *oldlist, int nskip)
Definition: list.c:1613
list_concat
List * list_concat(List *list1, const List *list2)
Definition: list.c:561
get_rel_persistence
char get_rel_persistence(Oid relid)
Definition: lsyscache.c:2078
func_parallel
char func_parallel(Oid funcid)
Definition: lsyscache.c:1799
get_func_support
RegProcedure get_func_support(Oid funcid)
Definition: lsyscache.c:1858
get_opfamily_member
Oid get_opfamily_member(Oid opfamily, Oid lefttype, Oid righttype, int16 strategy)
Definition: lsyscache.c:166
func_strict
bool func_strict(Oid funcid)
Definition: lsyscache.c:1761
get_op_btree_interpretation
List * get_op_btree_interpretation(Oid opno)
Definition: lsyscache.c:601
get_typavgwidth
int32 get_typavgwidth(Oid typid, int32 typmod)
Definition: lsyscache.c:2578
subpath
Datum subpath(PG_FUNCTION_ARGS)
Definition: ltree_op.c:310
makeNullConst
Const * makeNullConst(Oid consttype, int32 consttypmod, Oid constcollid)
Definition: makefuncs.c:339
make_and_qual
Node * make_and_qual(Node *qual1, Node *qual2)
Definition: makefuncs.c:707
pfree
void pfree(void *pointer)
Definition: mcxt.c:1521
palloc0
void * palloc0(Size size)
Definition: mcxt.c:1347
exprType
Oid exprType(const Node *expr)
Definition: nodeFuncs.c:42
exprTypmod
int32 exprTypmod(const Node *expr)
Definition: nodeFuncs.c:298
exprCollation
Oid exprCollation(const Node *expr)
Definition: nodeFuncs.c:816
expression_returns_set
bool expression_returns_set(Node *clause)
Definition: nodeFuncs.c:758
set_opfuncid
void set_opfuncid(OpExpr *opexpr)
Definition: nodeFuncs.c:1862
IsA
#define IsA(nodeptr, _type_)
Definition: nodes.h:158
copyObject
#define copyObject(obj)
Definition: nodes.h:224
nodeTag
#define nodeTag(nodeptr)
Definition: nodes.h:133
makeNode
#define makeNode(_type_)
Definition: nodes.h:155
castNode
#define castNode(_type_, nodeptr)
Definition: nodes.h:176
JOIN_SEMI
@ JOIN_SEMI
Definition: nodes.h:307
JOIN_ANTI
@ JOIN_ANTI
Definition: nodes.h:308
PVC_INCLUDE_PLACEHOLDERS
#define PVC_INCLUDE_PLACEHOLDERS
Definition: optimizer.h:190
targetIsInSortList
bool targetIsInSortList(TargetEntry *tle, Oid sortop, List *sortList)
Definition: parse_clause.c:3632
parse_clause.h
SETOP_EXCEPT
@ SETOP_EXCEPT
Definition: parsenodes.h:2116
RTE_JOIN
@ RTE_JOIN
Definition: parsenodes.h:1030
RTE_CTE
@ RTE_CTE
Definition: parsenodes.h:1034
RTE_NAMEDTUPLESTORE
@ RTE_NAMEDTUPLESTORE
Definition: parsenodes.h:1035
RTE_VALUES
@ RTE_VALUES
Definition: parsenodes.h:1033
RTE_SUBQUERY
@ RTE_SUBQUERY
Definition: parsenodes.h:1029
RTE_RESULT
@ RTE_RESULT
Definition: parsenodes.h:1036
RTE_FUNCTION
@ RTE_FUNCTION
Definition: parsenodes.h:1031
RTE_TABLEFUNC
@ RTE_TABLEFUNC
Definition: parsenodes.h:1032
RTE_RELATION
@ RTE_RELATION
Definition: parsenodes.h:1028
rt_fetch
#define rt_fetch(rangetable_index, rangetable)
Definition: parsetree.h:31
partitions_are_ordered
bool partitions_are_ordered(PartitionBoundInfo boundinfo, Bitmapset *live_parts)
Definition: partbounds.c:2852
build_expression_pathkey
List * build_expression_pathkey(PlannerInfo *root, Expr *expr, Oid opno, Relids rel, bool create_it)
Definition: pathkeys.c:998
get_cheapest_path_for_pathkeys
Path * get_cheapest_path_for_pathkeys(List *paths, List *pathkeys, Relids required_outer, CostSelector cost_criterion, bool require_parallel_safe)
Definition: pathkeys.c:618
pathkeys_count_contained_in
bool pathkeys_count_contained_in(List *keys1, List *keys2, int *n_common)
Definition: pathkeys.c:556
has_useful_pathkeys
bool has_useful_pathkeys(PlannerInfo *root, RelOptInfo *rel)
Definition: pathkeys.c:2261
get_cheapest_parallel_safe_total_inner
Path * get_cheapest_parallel_safe_total_inner(List *paths)
Definition: pathkeys.c:697
convert_subquery_pathkeys
List * convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel, List *subquery_pathkeys, List *subquery_tlist)
Definition: pathkeys.c:1052
get_cheapest_fractional_path_for_pathkeys
Path * get_cheapest_fractional_path_for_pathkeys(List *paths, List *pathkeys, Relids required_outer, double fraction)
Definition: pathkeys.c:664
pathkeys_contained_in
bool pathkeys_contained_in(List *keys1, List *keys2)
Definition: pathkeys.c:341
compare_pathkeys
PathKeysComparison compare_pathkeys(List *keys1, List *keys2)
Definition: pathkeys.c:302
build_partition_pathkeys
List * build_partition_pathkeys(PlannerInfo *root, RelOptInfo *partrel, ScanDirection scandir, bool *partialkeys)
Definition: pathkeys.c:917
create_append_path
AppendPath * create_append_path(PlannerInfo *root, RelOptInfo *rel, List *subpaths, List *partial_subpaths, List *pathkeys, Relids required_outer, int parallel_workers, bool parallel_aware, double rows)
Definition: pathnode.c:1244
create_sort_path
SortPath * create_sort_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath, List *pathkeys, double limit_tuples)
Definition: pathnode.c:2988
create_gather_merge_path
GatherMergePath * create_gather_merge_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath, PathTarget *target, List *pathkeys, Relids required_outer, double *rows)
Definition: pathnode.c:1881
create_tablefuncscan_path
Path * create_tablefuncscan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
Definition: pathnode.c:2060
create_namedtuplestorescan_path
Path * create_namedtuplestorescan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
Definition: pathnode.c:2138
create_gather_path
GatherPath * create_gather_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath, PathTarget *target, Relids required_outer, double *rows)
Definition: pathnode.c:1960
create_resultscan_path
Path * create_resultscan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
Definition: pathnode.c:2164
create_samplescan_path
Path * create_samplescan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
Definition: pathnode.c:952
create_merge_append_path
MergeAppendPath * create_merge_append_path(PlannerInfo *root, RelOptInfo *rel, List *subpaths, List *pathkeys, Relids required_outer)
Definition: pathnode.c:1415
set_cheapest
void set_cheapest(RelOptInfo *parent_rel)
Definition: pathnode.c:242
reparameterize_path
Path * reparameterize_path(PlannerInfo *root, Path *path, Relids required_outer, double loop_count)
Definition: pathnode.c:3937
create_subqueryscan_path
SubqueryScanPath * create_subqueryscan_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath, bool trivial_pathtarget, List *pathkeys, Relids required_outer)
Definition: pathnode.c:2004
add_partial_path
void add_partial_path(RelOptInfo *parent_rel, Path *new_path)
Definition: pathnode.c:747
create_material_path
MaterialPath * create_material_path(RelOptInfo *rel, Path *subpath)
Definition: pathnode.c:1566
create_functionscan_path
Path * create_functionscan_path(PlannerInfo *root, RelOptInfo *rel, List *pathkeys, Relids required_outer)
Definition: pathnode.c:2034
create_incremental_sort_path
IncrementalSortPath * create_incremental_sort_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath, List *pathkeys, int presorted_keys, double limit_tuples)
Definition: pathnode.c:2939
create_worktablescan_path
Path * create_worktablescan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
Definition: pathnode.c:2190
add_path
void add_path(RelOptInfo *parent_rel, Path *new_path)
Definition: pathnode.c:420
create_valuesscan_path
Path * create_valuesscan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
Definition: pathnode.c:2086
compare_path_costs
int compare_path_costs(Path *path1, Path *path2, CostSelector criterion)
Definition: pathnode.c:69
create_seqscan_path
Path * create_seqscan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer, int parallel_workers)
Definition: pathnode.c:927
create_ctescan_path
Path * create_ctescan_path(PlannerInfo *root, RelOptInfo *rel, List *pathkeys, Relids required_outer)
Definition: pathnode.c:2112
create_bitmap_heap_path
BitmapHeapPath * create_bitmap_heap_path(PlannerInfo *root, RelOptInfo *rel, Path *bitmapqual, Relids required_outer, double loop_count, int parallel_degree)
Definition: pathnode.c:1042
IS_SIMPLE_REL
#define IS_SIMPLE_REL(rel)
Definition: pathnodes.h:833
IS_DUMMY_REL
#define IS_DUMMY_REL(r)
Definition: pathnodes.h:1946
IS_JOIN_REL
#define IS_JOIN_REL(rel)
Definition: pathnodes.h:838
TOTAL_COST
@ TOTAL_COST
Definition: pathnodes.h:38
STARTUP_COST
@ STARTUP_COST
Definition: pathnodes.h:38
IS_PARTITIONED_REL
#define IS_PARTITIONED_REL(rel)
Definition: pathnodes.h:1056
PATH_REQ_OUTER
#define PATH_REQ_OUTER(path)
Definition: pathnodes.h:1669
Relids
Bitmapset * Relids
Definition: pathnodes.h:30
UPPERREL_FINAL
@ UPPERREL_FINAL
Definition: pathnodes.h:79
RELOPT_BASEREL
@ RELOPT_BASEREL
Definition: pathnodes.h:821
RELOPT_OTHER_MEMBER_REL
@ RELOPT_OTHER_MEMBER_REL
Definition: pathnodes.h:823
join_search_hook_type
RelOptInfo *(* join_search_hook_type)(PlannerInfo *root, int levels_needed, List *initial_rels)
Definition: paths.h:46
set_rel_pathlist_hook_type
void(* set_rel_pathlist_hook_type)(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry *rte)
Definition: paths.h:30
PATHKEYS_EQUAL
@ PATHKEYS_EQUAL
Definition: paths.h:202
arg
void * arg
Definition: pg_backup_utils.c:27
pg_bitutils.h
pg_leftmost_one_pos32
static int pg_leftmost_one_pos32(uint32 word)
Definition: pg_bitutils.h:41
pg_class.h
lfirst
#define lfirst(lc)
Definition: pg_list.h:172
list_length
static int list_length(const List *l)
Definition: pg_list.h:152
NIL
#define NIL
Definition: pg_list.h:68
forboth
#define forboth(cell1, list1, cell2, list2)
Definition: pg_list.h:518
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#define foreach_current_index(var_or_cell)
Definition: pg_list.h:403
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#define list_make1(x1)
Definition: pg_list.h:212
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Definition: pg_list.h:128
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#define for_each_from(cell, lst, N)
Definition: pg_list.h:414
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#define linitial(l)
Definition: pg_list.h:178
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#define lsecond(l)
Definition: pg_list.h:183
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static void * list_nth(const List *list, int n)
Definition: pg_list.h:299
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#define list_nth_node(type, list, n)
Definition: pg_list.h:327
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Definition: pg_list.h:343
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#define lfirst_oid(lc)
Definition: pg_list.h:174
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Definition: pg_list.h:310
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pg_proc.h
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bool relation_excluded_by_constraints(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
Definition: plancat.c:1564
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Definition: planner.c:628
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Definition: planner.c:2625
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@ MONOTONICFUNC_NONE
Definition: plannodes.h:1587
MONOTONICFUNC_DECREASING
@ MONOTONICFUNC_DECREASING
Definition: plannodes.h:1589
MONOTONICFUNC_INCREASING
@ MONOTONICFUNC_INCREASING
Definition: plannodes.h:1588
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Definition: plannodes.h:1590
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Definition: postgres.h:322
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static Pointer DatumGetPointer(Datum X)
Definition: postgres.h:312
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#define InvalidOid
Definition: postgres_ext.h:36
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unsigned int Oid
Definition: postgres_ext.h:31
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tree ctl root
Definition: radixtree.h:1886
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Definition: regcomp.c:715
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Definition: relnode.c:414
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Definition: rewriteManip.c:1769
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@ REPLACEVARS_REPORT_ERROR
Definition: rewriteManip.h:38
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@ BackwardScanDirection
Definition: sdir.h:26
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@ ForwardScanDirection
Definition: sdir.h:28
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#define BTGreaterStrategyNumber
Definition: stratnum.h:33
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Definition: stratnum.h:29
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Definition: stratnum.h:31
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Definition: stratnum.h:32
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Definition: pathnodes.h:1932
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Definition: pathnodes.h:2970
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Definition: pathnodes.h:2969
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Definition: primnodes.h:2305
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Definition: pg_list.h:54
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Definition: primnodes.h:818
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Definition: pathnodes.h:1665
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Definition: pathnodes.h:1660
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Definition: pathnodes.h:1657
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Definition: pathnodes.h:1662
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Definition: pathnodes.h:1653
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Definition: plannodes.h:134
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Definition: plannodes.h:152
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Definition: pathnodes.h:305
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struct Path * non_recursive_path
Definition: pathnodes.h:532
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Definition: pathnodes.h:202
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Definition: parsenodes.h:214
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Definition: parsenodes.h:175
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Definition: parsenodes.h:219
Query::cteList
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Definition: parsenodes.h:166
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Definition: parsenodes.h:200
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Node * havingQual
Definition: parsenodes.h:205
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Definition: parsenodes.h:168
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Definition: parsenodes.h:213
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Definition: parsenodes.h:207
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Definition: parsenodes.h:191
Query::groupingSets
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Definition: parsenodes.h:203
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Definition: parsenodes.h:209
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char * ctename
Definition: parsenodes.h:1206
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Definition: parsenodes.h:1208
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Definition: parsenodes.h:1189
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Definition: parsenodes.h:1108
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Definition: parsenodes.h:1114
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Definition: parsenodes.h:1200
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Definition: parsenodes.h:1187
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Definition: parsenodes.h:1057
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Definition: pathnodes.h:979
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Definition: pathnodes.h:879
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Definition: pathnodes.h:948
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Definition: pathnodes.h:985
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Definition: pathnodes.h:865
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Definition: pathnodes.h:887
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Definition: pathnodes.h:912
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Definition: pathnodes.h:943
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bool consider_parallel
Definition: pathnodes.h:881
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Definition: pathnodes.h:942
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Definition: pathnodes.h:907
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Definition: pathnodes.h:892
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Definition: pathnodes.h:859
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Definition: pathnodes.h:895
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Definition: pathnodes.h:896
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Definition: pathnodes.h:987
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Definition: pathnodes.h:877
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Definition: pathnodes.h:1033
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int rel_parallel_workers
Definition: pathnodes.h:950
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Definition: pathnodes.h:993
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Definition: pathnodes.h:894
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Definition: pathnodes.h:947
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AttrNumber max_attr
Definition: pathnodes.h:920
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Definition: pathnodes.h:932
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Definition: pathnodes.h:871
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Definition: pathnodes.h:918
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Definition: pathnodes.h:916
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Definition: pathnodes.h:2564
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Definition: parsenodes.h:2191
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Definition: pathnodes.h:2898
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Definition: pathnodes.h:2897
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struct WindowClause * window_clause
Definition: supportnodes.h:296
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Definition: primnodes.h:2186
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Definition: primnodes.h:2188
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Definition: primnodes.h:2192
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bool repeatable_across_scans
Definition: tsmapi.h:65
TsmRoutine::SampleScanGetSampleSize
SampleScanGetSampleSize_function SampleScanGetSampleSize
Definition: tsmapi.h:68
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Definition: primnodes.h:248
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Definition: primnodes.h:260
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int varno
Definition: primnodes.h:255
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Definition: primnodes.h:280
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Definition: parsenodes.h:1546
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Definition: primnodes.h:581
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Definition: primnodes.h:567
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Definition: allpaths.c:61
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unsigned char * unsafeFlags
Definition: allpaths.c:62
pushdown_safety_info::unsafeVolatile
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Definition: allpaths.c:65
pushdown_safety_info::unsafeLeaky
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Definition: allpaths.c:66
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Definition: regcomp.c:281
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#define FirstLowInvalidHeapAttributeNumber
Definition: sysattr.h:27
GetTsmRoutine
TsmRoutine * GetTsmRoutine(Oid tsmhandler)
Definition: tablesample.c:27
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bool create_tidscan_paths(PlannerInfo *root, RelOptInfo *rel)
Definition: tidpath.c:498
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Definition: tlist.c:624
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Definition: var.c:607
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void pull_varattnos(Node *node, Index varno, Bitmapset **varattnos)
Definition: var.c:291