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deparse.c
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1 /*-------------------------------------------------------------------------
2  *
3  * deparse.c
4  * Query deparser for postgres_fdw
5  *
6  * This file includes functions that examine query WHERE clauses to see
7  * whether they're safe to send to the remote server for execution, as
8  * well as functions to construct the query text to be sent. The latter
9  * functionality is annoyingly duplicative of ruleutils.c, but there are
10  * enough special considerations that it seems best to keep this separate.
11  * One saving grace is that we only need deparse logic for node types that
12  * we consider safe to send.
13  *
14  * We assume that the remote session's search_path is exactly "pg_catalog",
15  * and thus we need schema-qualify all and only names outside pg_catalog.
16  *
17  * We do not consider that it is ever safe to send COLLATE expressions to
18  * the remote server: it might not have the same collation names we do.
19  * (Later we might consider it safe to send COLLATE "C", but even that would
20  * fail on old remote servers.) An expression is considered safe to send
21  * only if all operator/function input collations used in it are traceable to
22  * Var(s) of the foreign table. That implies that if the remote server gets
23  * a different answer than we do, the foreign table's columns are not marked
24  * with collations that match the remote table's columns, which we can
25  * consider to be user error.
26  *
27  * Portions Copyright (c) 2012-2019, PostgreSQL Global Development Group
28  *
29  * IDENTIFICATION
30  * contrib/postgres_fdw/deparse.c
31  *
32  *-------------------------------------------------------------------------
33  */
34 #include "postgres.h"
35 
36 #include "postgres_fdw.h"
37 
38 #include "access/htup_details.h"
39 #include "access/sysattr.h"
40 #include "access/table.h"
41 #include "catalog/pg_aggregate.h"
42 #include "catalog/pg_collation.h"
43 #include "catalog/pg_namespace.h"
44 #include "catalog/pg_operator.h"
45 #include "catalog/pg_proc.h"
46 #include "catalog/pg_type.h"
47 #include "commands/defrem.h"
48 #include "nodes/makefuncs.h"
49 #include "nodes/nodeFuncs.h"
50 #include "nodes/plannodes.h"
51 #include "optimizer/optimizer.h"
52 #include "optimizer/prep.h"
53 #include "optimizer/tlist.h"
54 #include "parser/parsetree.h"
55 #include "utils/builtins.h"
56 #include "utils/lsyscache.h"
57 #include "utils/rel.h"
58 #include "utils/syscache.h"
59 #include "utils/typcache.h"
60 
61 
62 /*
63  * Global context for foreign_expr_walker's search of an expression tree.
64  */
65 typedef struct foreign_glob_cxt
66 {
67  PlannerInfo *root; /* global planner state */
68  RelOptInfo *foreignrel; /* the foreign relation we are planning for */
69  Relids relids; /* relids of base relations in the underlying
70  * scan */
71 } foreign_glob_cxt;
72 
73 /*
74  * Local (per-tree-level) context for foreign_expr_walker's search.
75  * This is concerned with identifying collations used in the expression.
76  */
77 typedef enum
78 {
79  FDW_COLLATE_NONE, /* expression is of a noncollatable type, or
80  * it has default collation that is not
81  * traceable to a foreign Var */
82  FDW_COLLATE_SAFE, /* collation derives from a foreign Var */
83  FDW_COLLATE_UNSAFE /* collation is non-default and derives from
84  * something other than a foreign Var */
85 } FDWCollateState;
86 
87 typedef struct foreign_loc_cxt
88 {
89  Oid collation; /* OID of current collation, if any */
90  FDWCollateState state; /* state of current collation choice */
91 } foreign_loc_cxt;
92 
93 /*
94  * Context for deparseExpr
95  */
96 typedef struct deparse_expr_cxt
97 {
98  PlannerInfo *root; /* global planner state */
99  RelOptInfo *foreignrel; /* the foreign relation we are planning for */
100  RelOptInfo *scanrel; /* the underlying scan relation. Same as
101  * foreignrel, when that represents a join or
102  * a base relation. */
103  StringInfo buf; /* output buffer to append to */
104  List **params_list; /* exprs that will become remote Params */
105 } deparse_expr_cxt;
106 
107 #define REL_ALIAS_PREFIX "r"
108 /* Handy macro to add relation name qualification */
109 #define ADD_REL_QUALIFIER(buf, varno) \
110  appendStringInfo((buf), "%s%d.", REL_ALIAS_PREFIX, (varno))
111 #define SUBQUERY_REL_ALIAS_PREFIX "s"
112 #define SUBQUERY_COL_ALIAS_PREFIX "c"
113 
114 /*
115  * Functions to determine whether an expression can be evaluated safely on
116  * remote server.
117  */
118 static bool foreign_expr_walker(Node *node,
119  foreign_glob_cxt *glob_cxt,
120  foreign_loc_cxt *outer_cxt);
121 static char *deparse_type_name(Oid type_oid, int32 typemod);
122 
123 /*
124  * Functions to construct string representation of a node tree.
125  */
126 static void deparseTargetList(StringInfo buf,
127  RangeTblEntry *rte,
128  Index rtindex,
129  Relation rel,
130  bool is_returning,
131  Bitmapset *attrs_used,
132  bool qualify_col,
133  List **retrieved_attrs);
134 static void deparseExplicitTargetList(List *tlist,
135  bool is_returning,
136  List **retrieved_attrs,
137  deparse_expr_cxt *context);
138 static void deparseSubqueryTargetList(deparse_expr_cxt *context);
139 static void deparseReturningList(StringInfo buf, RangeTblEntry *rte,
140  Index rtindex, Relation rel,
141  bool trig_after_row,
142  List *withCheckOptionList,
143  List *returningList,
144  List **retrieved_attrs);
145 static void deparseColumnRef(StringInfo buf, int varno, int varattno,
146  RangeTblEntry *rte, bool qualify_col);
147 static void deparseRelation(StringInfo buf, Relation rel);
148 static void deparseExpr(Expr *expr, deparse_expr_cxt *context);
149 static void deparseVar(Var *node, deparse_expr_cxt *context);
150 static void deparseConst(Const *node, deparse_expr_cxt *context, int showtype);
151 static void deparseParam(Param *node, deparse_expr_cxt *context);
152 static void deparseSubscriptingRef(SubscriptingRef *node, deparse_expr_cxt *context);
153 static void deparseFuncExpr(FuncExpr *node, deparse_expr_cxt *context);
154 static void deparseOpExpr(OpExpr *node, deparse_expr_cxt *context);
155 static void deparseOperatorName(StringInfo buf, Form_pg_operator opform);
156 static void deparseDistinctExpr(DistinctExpr *node, deparse_expr_cxt *context);
157 static void deparseScalarArrayOpExpr(ScalarArrayOpExpr *node,
158  deparse_expr_cxt *context);
159 static void deparseRelabelType(RelabelType *node, deparse_expr_cxt *context);
160 static void deparseBoolExpr(BoolExpr *node, deparse_expr_cxt *context);
161 static void deparseNullTest(NullTest *node, deparse_expr_cxt *context);
162 static void deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context);
163 static void printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod,
164  deparse_expr_cxt *context);
165 static void printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
166  deparse_expr_cxt *context);
167 static void deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs,
168  deparse_expr_cxt *context);
169 static void deparseLockingClause(deparse_expr_cxt *context);
170 static void appendOrderByClause(List *pathkeys, bool has_final_sort,
171  deparse_expr_cxt *context);
172 static void appendLimitClause(deparse_expr_cxt *context);
173 static void appendConditions(List *exprs, deparse_expr_cxt *context);
174 static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root,
175  RelOptInfo *foreignrel, bool use_alias,
176  Index ignore_rel, List **ignore_conds,
177  List **params_list);
178 static void deparseFromExpr(List *quals, deparse_expr_cxt *context);
179 static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root,
180  RelOptInfo *foreignrel, bool make_subquery,
181  Index ignore_rel, List **ignore_conds, List **params_list);
182 static void deparseAggref(Aggref *node, deparse_expr_cxt *context);
183 static void appendGroupByClause(List *tlist, deparse_expr_cxt *context);
184 static void appendAggOrderBy(List *orderList, List *targetList,
185  deparse_expr_cxt *context);
186 static void appendFunctionName(Oid funcid, deparse_expr_cxt *context);
187 static Node *deparseSortGroupClause(Index ref, List *tlist, bool force_colno,
188  deparse_expr_cxt *context);
189 
190 /*
191  * Helper functions
192  */
193 static bool is_subquery_var(Var *node, RelOptInfo *foreignrel,
194  int *relno, int *colno);
195 static void get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
196  int *relno, int *colno);
197 
198 
199 /*
200  * Examine each qual clause in input_conds, and classify them into two groups,
201  * which are returned as two lists:
202  * - remote_conds contains expressions that can be evaluated remotely
203  * - local_conds contains expressions that can't be evaluated remotely
204  */
205 void
206 classifyConditions(PlannerInfo *root,
207  RelOptInfo *baserel,
208  List *input_conds,
209  List **remote_conds,
210  List **local_conds)
211 {
212  ListCell *lc;
213 
214  *remote_conds = NIL;
215  *local_conds = NIL;
216 
217  foreach(lc, input_conds)
218  {
219  RestrictInfo *ri = lfirst_node(RestrictInfo, lc);
220 
221  if (is_foreign_expr(root, baserel, ri->clause))
222  *remote_conds = lappend(*remote_conds, ri);
223  else
224  *local_conds = lappend(*local_conds, ri);
225  }
226 }
227 
228 /*
229  * Returns true if given expr is safe to evaluate on the foreign server.
230  */
231 bool
232 is_foreign_expr(PlannerInfo *root,
233  RelOptInfo *baserel,
234  Expr *expr)
235 {
236  foreign_glob_cxt glob_cxt;
237  foreign_loc_cxt loc_cxt;
238  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) (baserel->fdw_private);
239 
240  /*
241  * Check that the expression consists of nodes that are safe to execute
242  * remotely.
243  */
244  glob_cxt.root = root;
245  glob_cxt.foreignrel = baserel;
246 
247  /*
248  * For an upper relation, use relids from its underneath scan relation,
249  * because the upperrel's own relids currently aren't set to anything
250  * meaningful by the core code. For other relation, use their own relids.
251  */
252  if (IS_UPPER_REL(baserel))
253  glob_cxt.relids = fpinfo->outerrel->relids;
254  else
255  glob_cxt.relids = baserel->relids;
256  loc_cxt.collation = InvalidOid;
257  loc_cxt.state = FDW_COLLATE_NONE;
258  if (!foreign_expr_walker((Node *) expr, &glob_cxt, &loc_cxt))
259  return false;
260 
261  /*
262  * If the expression has a valid collation that does not arise from a
263  * foreign var, the expression can not be sent over.
264  */
265  if (loc_cxt.state == FDW_COLLATE_UNSAFE)
266  return false;
267 
268  /*
269  * An expression which includes any mutable functions can't be sent over
270  * because its result is not stable. For example, sending now() remote
271  * side could cause confusion from clock offsets. Future versions might
272  * be able to make this choice with more granularity. (We check this last
273  * because it requires a lot of expensive catalog lookups.)
274  */
275  if (contain_mutable_functions((Node *) expr))
276  return false;
277 
278  /* OK to evaluate on the remote server */
279  return true;
280 }
281 
282 /*
283  * Check if expression is safe to execute remotely, and return true if so.
284  *
285  * In addition, *outer_cxt is updated with collation information.
286  *
287  * We must check that the expression contains only node types we can deparse,
288  * that all types/functions/operators are safe to send (they are "shippable"),
289  * and that all collations used in the expression derive from Vars of the
290  * foreign table. Because of the latter, the logic is pretty close to
291  * assign_collations_walker() in parse_collate.c, though we can assume here
292  * that the given expression is valid. Note function mutability is not
293  * currently considered here.
294  */
295 static bool
296 foreign_expr_walker(Node *node,
297  foreign_glob_cxt *glob_cxt,
298  foreign_loc_cxt *outer_cxt)
299 {
300  bool check_type = true;
301  PgFdwRelationInfo *fpinfo;
302  foreign_loc_cxt inner_cxt;
303  Oid collation;
304  FDWCollateState state;
305 
306  /* Need do nothing for empty subexpressions */
307  if (node == NULL)
308  return true;
309 
310  /* May need server info from baserel's fdw_private struct */
311  fpinfo = (PgFdwRelationInfo *) (glob_cxt->foreignrel->fdw_private);
312 
313  /* Set up inner_cxt for possible recursion to child nodes */
314  inner_cxt.collation = InvalidOid;
315  inner_cxt.state = FDW_COLLATE_NONE;
316 
317  switch (nodeTag(node))
318  {
319  case T_Var:
320  {
321  Var *var = (Var *) node;
322 
323  /*
324  * If the Var is from the foreign table, we consider its
325  * collation (if any) safe to use. If it is from another
326  * table, we treat its collation the same way as we would a
327  * Param's collation, ie it's not safe for it to have a
328  * non-default collation.
329  */
330  if (bms_is_member(var->varno, glob_cxt->relids) &&
331  var->varlevelsup == 0)
332  {
333  /* Var belongs to foreign table */
334 
335  /*
336  * System columns other than ctid should not be sent to
337  * the remote, since we don't make any effort to ensure
338  * that local and remote values match (tableoid, in
339  * particular, almost certainly doesn't match).
340  */
341  if (var->varattno < 0 &&
342  var->varattno != SelfItemPointerAttributeNumber)
343  return false;
344 
345  /* Else check the collation */
346  collation = var->varcollid;
347  state = OidIsValid(collation) ? FDW_COLLATE_SAFE : FDW_COLLATE_NONE;
348  }
349  else
350  {
351  /* Var belongs to some other table */
352  collation = var->varcollid;
353  if (collation == InvalidOid ||
354  collation == DEFAULT_COLLATION_OID)
355  {
356  /*
357  * It's noncollatable, or it's safe to combine with a
358  * collatable foreign Var, so set state to NONE.
359  */
360  state = FDW_COLLATE_NONE;
361  }
362  else
363  {
364  /*
365  * Do not fail right away, since the Var might appear
366  * in a collation-insensitive context.
367  */
368  state = FDW_COLLATE_UNSAFE;
369  }
370  }
371  }
372  break;
373  case T_Const:
374  {
375  Const *c = (Const *) node;
376 
377  /*
378  * If the constant has nondefault collation, either it's of a
379  * non-builtin type, or it reflects folding of a CollateExpr.
380  * It's unsafe to send to the remote unless it's used in a
381  * non-collation-sensitive context.
382  */
383  collation = c->constcollid;
384  if (collation == InvalidOid ||
385  collation == DEFAULT_COLLATION_OID)
386  state = FDW_COLLATE_NONE;
387  else
388  state = FDW_COLLATE_UNSAFE;
389  }
390  break;
391  case T_Param:
392  {
393  Param *p = (Param *) node;
394 
395  /*
396  * Collation rule is same as for Consts and non-foreign Vars.
397  */
398  collation = p->paramcollid;
399  if (collation == InvalidOid ||
400  collation == DEFAULT_COLLATION_OID)
401  state = FDW_COLLATE_NONE;
402  else
403  state = FDW_COLLATE_UNSAFE;
404  }
405  break;
406  case T_SubscriptingRef:
407  {
408  SubscriptingRef *sr = (SubscriptingRef *) node;
409 
410  /* Assignment should not be in restrictions. */
411  if (sr->refassgnexpr != NULL)
412  return false;
413 
414  /*
415  * Recurse to remaining subexpressions. Since the container
416  * subscripts must yield (noncollatable) integers, they won't
417  * affect the inner_cxt state.
418  */
419  if (!foreign_expr_walker((Node *) sr->refupperindexpr,
420  glob_cxt, &inner_cxt))
421  return false;
422  if (!foreign_expr_walker((Node *) sr->reflowerindexpr,
423  glob_cxt, &inner_cxt))
424  return false;
425  if (!foreign_expr_walker((Node *) sr->refexpr,
426  glob_cxt, &inner_cxt))
427  return false;
428 
429  /*
430  * Container subscripting should yield same collation as
431  * input, but for safety use same logic as for function nodes.
432  */
433  collation = sr->refcollid;
434  if (collation == InvalidOid)
435  state = FDW_COLLATE_NONE;
436  else if (inner_cxt.state == FDW_COLLATE_SAFE &&
437  collation == inner_cxt.collation)
438  state = FDW_COLLATE_SAFE;
439  else if (collation == DEFAULT_COLLATION_OID)
440  state = FDW_COLLATE_NONE;
441  else
442  state = FDW_COLLATE_UNSAFE;
443  }
444  break;
445  case T_FuncExpr:
446  {
447  FuncExpr *fe = (FuncExpr *) node;
448 
449  /*
450  * If function used by the expression is not shippable, it
451  * can't be sent to remote because it might have incompatible
452  * semantics on remote side.
453  */
454  if (!is_shippable(fe->funcid, ProcedureRelationId, fpinfo))
455  return false;
456 
457  /*
458  * Recurse to input subexpressions.
459  */
460  if (!foreign_expr_walker((Node *) fe->args,
461  glob_cxt, &inner_cxt))
462  return false;
463 
464  /*
465  * If function's input collation is not derived from a foreign
466  * Var, it can't be sent to remote.
467  */
468  if (fe->inputcollid == InvalidOid)
469  /* OK, inputs are all noncollatable */ ;
470  else if (inner_cxt.state != FDW_COLLATE_SAFE ||
471  fe->inputcollid != inner_cxt.collation)
472  return false;
473 
474  /*
475  * Detect whether node is introducing a collation not derived
476  * from a foreign Var. (If so, we just mark it unsafe for now
477  * rather than immediately returning false, since the parent
478  * node might not care.)
479  */
480  collation = fe->funccollid;
481  if (collation == InvalidOid)
482  state = FDW_COLLATE_NONE;
483  else if (inner_cxt.state == FDW_COLLATE_SAFE &&
484  collation == inner_cxt.collation)
485  state = FDW_COLLATE_SAFE;
486  else if (collation == DEFAULT_COLLATION_OID)
487  state = FDW_COLLATE_NONE;
488  else
489  state = FDW_COLLATE_UNSAFE;
490  }
491  break;
492  case T_OpExpr:
493  case T_DistinctExpr: /* struct-equivalent to OpExpr */
494  {
495  OpExpr *oe = (OpExpr *) node;
496 
497  /*
498  * Similarly, only shippable operators can be sent to remote.
499  * (If the operator is shippable, we assume its underlying
500  * function is too.)
501  */
502  if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
503  return false;
504 
505  /*
506  * Recurse to input subexpressions.
507  */
508  if (!foreign_expr_walker((Node *) oe->args,
509  glob_cxt, &inner_cxt))
510  return false;
511 
512  /*
513  * If operator's input collation is not derived from a foreign
514  * Var, it can't be sent to remote.
515  */
516  if (oe->inputcollid == InvalidOid)
517  /* OK, inputs are all noncollatable */ ;
518  else if (inner_cxt.state != FDW_COLLATE_SAFE ||
519  oe->inputcollid != inner_cxt.collation)
520  return false;
521 
522  /* Result-collation handling is same as for functions */
523  collation = oe->opcollid;
524  if (collation == InvalidOid)
525  state = FDW_COLLATE_NONE;
526  else if (inner_cxt.state == FDW_COLLATE_SAFE &&
527  collation == inner_cxt.collation)
528  state = FDW_COLLATE_SAFE;
529  else if (collation == DEFAULT_COLLATION_OID)
530  state = FDW_COLLATE_NONE;
531  else
532  state = FDW_COLLATE_UNSAFE;
533  }
534  break;
535  case T_ScalarArrayOpExpr:
536  {
537  ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node;
538 
539  /*
540  * Again, only shippable operators can be sent to remote.
541  */
542  if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
543  return false;
544 
545  /*
546  * Recurse to input subexpressions.
547  */
548  if (!foreign_expr_walker((Node *) oe->args,
549  glob_cxt, &inner_cxt))
550  return false;
551 
552  /*
553  * If operator's input collation is not derived from a foreign
554  * Var, it can't be sent to remote.
555  */
556  if (oe->inputcollid == InvalidOid)
557  /* OK, inputs are all noncollatable */ ;
558  else if (inner_cxt.state != FDW_COLLATE_SAFE ||
559  oe->inputcollid != inner_cxt.collation)
560  return false;
561 
562  /* Output is always boolean and so noncollatable. */
563  collation = InvalidOid;
564  state = FDW_COLLATE_NONE;
565  }
566  break;
567  case T_RelabelType:
568  {
569  RelabelType *r = (RelabelType *) node;
570 
571  /*
572  * Recurse to input subexpression.
573  */
574  if (!foreign_expr_walker((Node *) r->arg,
575  glob_cxt, &inner_cxt))
576  return false;
577 
578  /*
579  * RelabelType must not introduce a collation not derived from
580  * an input foreign Var (same logic as for a real function).
581  */
582  collation = r->resultcollid;
583  if (collation == InvalidOid)
584  state = FDW_COLLATE_NONE;
585  else if (inner_cxt.state == FDW_COLLATE_SAFE &&
586  collation == inner_cxt.collation)
587  state = FDW_COLLATE_SAFE;
588  else if (collation == DEFAULT_COLLATION_OID)
589  state = FDW_COLLATE_NONE;
590  else
591  state = FDW_COLLATE_UNSAFE;
592  }
593  break;
594  case T_BoolExpr:
595  {
596  BoolExpr *b = (BoolExpr *) node;
597 
598  /*
599  * Recurse to input subexpressions.
600  */
601  if (!foreign_expr_walker((Node *) b->args,
602  glob_cxt, &inner_cxt))
603  return false;
604 
605  /* Output is always boolean and so noncollatable. */
606  collation = InvalidOid;
607  state = FDW_COLLATE_NONE;
608  }
609  break;
610  case T_NullTest:
611  {
612  NullTest *nt = (NullTest *) node;
613 
614  /*
615  * Recurse to input subexpressions.
616  */
617  if (!foreign_expr_walker((Node *) nt->arg,
618  glob_cxt, &inner_cxt))
619  return false;
620 
621  /* Output is always boolean and so noncollatable. */
622  collation = InvalidOid;
623  state = FDW_COLLATE_NONE;
624  }
625  break;
626  case T_ArrayExpr:
627  {
628  ArrayExpr *a = (ArrayExpr *) node;
629 
630  /*
631  * Recurse to input subexpressions.
632  */
633  if (!foreign_expr_walker((Node *) a->elements,
634  glob_cxt, &inner_cxt))
635  return false;
636 
637  /*
638  * ArrayExpr must not introduce a collation not derived from
639  * an input foreign Var (same logic as for a function).
640  */
641  collation = a->array_collid;
642  if (collation == InvalidOid)
643  state = FDW_COLLATE_NONE;
644  else if (inner_cxt.state == FDW_COLLATE_SAFE &&
645  collation == inner_cxt.collation)
646  state = FDW_COLLATE_SAFE;
647  else if (collation == DEFAULT_COLLATION_OID)
648  state = FDW_COLLATE_NONE;
649  else
650  state = FDW_COLLATE_UNSAFE;
651  }
652  break;
653  case T_List:
654  {
655  List *l = (List *) node;
656  ListCell *lc;
657 
658  /*
659  * Recurse to component subexpressions.
660  */
661  foreach(lc, l)
662  {
663  if (!foreign_expr_walker((Node *) lfirst(lc),
664  glob_cxt, &inner_cxt))
665  return false;
666  }
667 
668  /*
669  * When processing a list, collation state just bubbles up
670  * from the list elements.
671  */
672  collation = inner_cxt.collation;
673  state = inner_cxt.state;
674 
675  /* Don't apply exprType() to the list. */
676  check_type = false;
677  }
678  break;
679  case T_Aggref:
680  {
681  Aggref *agg = (Aggref *) node;
682  ListCell *lc;
683 
684  /* Not safe to pushdown when not in grouping context */
685  if (!IS_UPPER_REL(glob_cxt->foreignrel))
686  return false;
687 
688  /* Only non-split aggregates are pushable. */
689  if (agg->aggsplit != AGGSPLIT_SIMPLE)
690  return false;
691 
692  /* As usual, it must be shippable. */
693  if (!is_shippable(agg->aggfnoid, ProcedureRelationId, fpinfo))
694  return false;
695 
696  /*
697  * Recurse to input args. aggdirectargs, aggorder and
698  * aggdistinct are all present in args, so no need to check
699  * their shippability explicitly.
700  */
701  foreach(lc, agg->args)
702  {
703  Node *n = (Node *) lfirst(lc);
704 
705  /* If TargetEntry, extract the expression from it */
706  if (IsA(n, TargetEntry))
707  {
708  TargetEntry *tle = (TargetEntry *) n;
709 
710  n = (Node *) tle->expr;
711  }
712 
713  if (!foreign_expr_walker(n, glob_cxt, &inner_cxt))
714  return false;
715  }
716 
717  /*
718  * For aggorder elements, check whether the sort operator, if
719  * specified, is shippable or not.
720  */
721  if (agg->aggorder)
722  {
723  ListCell *lc;
724 
725  foreach(lc, agg->aggorder)
726  {
727  SortGroupClause *srt = (SortGroupClause *) lfirst(lc);
728  Oid sortcoltype;
729  TypeCacheEntry *typentry;
730  TargetEntry *tle;
731 
732  tle = get_sortgroupref_tle(srt->tleSortGroupRef,
733  agg->args);
734  sortcoltype = exprType((Node *) tle->expr);
735  typentry = lookup_type_cache(sortcoltype,
736  TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
737  /* Check shippability of non-default sort operator. */
738  if (srt->sortop != typentry->lt_opr &&
739  srt->sortop != typentry->gt_opr &&
740  !is_shippable(srt->sortop, OperatorRelationId,
741  fpinfo))
742  return false;
743  }
744  }
745 
746  /* Check aggregate filter */
747  if (!foreign_expr_walker((Node *) agg->aggfilter,
748  glob_cxt, &inner_cxt))
749  return false;
750 
751  /*
752  * If aggregate's input collation is not derived from a
753  * foreign Var, it can't be sent to remote.
754  */
755  if (agg->inputcollid == InvalidOid)
756  /* OK, inputs are all noncollatable */ ;
757  else if (inner_cxt.state != FDW_COLLATE_SAFE ||
758  agg->inputcollid != inner_cxt.collation)
759  return false;
760 
761  /*
762  * Detect whether node is introducing a collation not derived
763  * from a foreign Var. (If so, we just mark it unsafe for now
764  * rather than immediately returning false, since the parent
765  * node might not care.)
766  */
767  collation = agg->aggcollid;
768  if (collation == InvalidOid)
769  state = FDW_COLLATE_NONE;
770  else if (inner_cxt.state == FDW_COLLATE_SAFE &&
771  collation == inner_cxt.collation)
772  state = FDW_COLLATE_SAFE;
773  else if (collation == DEFAULT_COLLATION_OID)
774  state = FDW_COLLATE_NONE;
775  else
776  state = FDW_COLLATE_UNSAFE;
777  }
778  break;
779  default:
780 
781  /*
782  * If it's anything else, assume it's unsafe. This list can be
783  * expanded later, but don't forget to add deparse support below.
784  */
785  return false;
786  }
787 
788  /*
789  * If result type of given expression is not shippable, it can't be sent
790  * to remote because it might have incompatible semantics on remote side.
791  */
792  if (check_type && !is_shippable(exprType(node), TypeRelationId, fpinfo))
793  return false;
794 
795  /*
796  * Now, merge my collation information into my parent's state.
797  */
798  if (state > outer_cxt->state)
799  {
800  /* Override previous parent state */
801  outer_cxt->collation = collation;
802  outer_cxt->state = state;
803  }
804  else if (state == outer_cxt->state)
805  {
806  /* Merge, or detect error if there's a collation conflict */
807  switch (state)
808  {
809  case FDW_COLLATE_NONE:
810  /* Nothing + nothing is still nothing */
811  break;
812  case FDW_COLLATE_SAFE:
813  if (collation != outer_cxt->collation)
814  {
815  /*
816  * Non-default collation always beats default.
817  */
818  if (outer_cxt->collation == DEFAULT_COLLATION_OID)
819  {
820  /* Override previous parent state */
821  outer_cxt->collation = collation;
822  }
823  else if (collation != DEFAULT_COLLATION_OID)
824  {
825  /*
826  * Conflict; show state as indeterminate. We don't
827  * want to "return false" right away, since parent
828  * node might not care about collation.
829  */
830  outer_cxt->state = FDW_COLLATE_UNSAFE;
831  }
832  }
833  break;
834  case FDW_COLLATE_UNSAFE:
835  /* We're still conflicted ... */
836  break;
837  }
838  }
839 
840  /* It looks OK */
841  return true;
842 }
843 
844 /*
845  * Returns true if given expr is something we'd have to send the value of
846  * to the foreign server.
847  *
848  * This should return true when the expression is a shippable node that
849  * deparseExpr would add to context->params_list. Note that we don't care
850  * if the expression *contains* such a node, only whether one appears at top
851  * level. We need this to detect cases where setrefs.c would recognize a
852  * false match between an fdw_exprs item (which came from the params_list)
853  * and an entry in fdw_scan_tlist (which we're considering putting the given
854  * expression into).
855  */
856 bool
857 is_foreign_param(PlannerInfo *root,
858  RelOptInfo *baserel,
859  Expr *expr)
860 {
861  if (expr == NULL)
862  return false;
863 
864  switch (nodeTag(expr))
865  {
866  case T_Var:
867  {
868  /* It would have to be sent unless it's a foreign Var */
869  Var *var = (Var *) expr;
870  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) (baserel->fdw_private);
871  Relids relids;
872 
873  if (IS_UPPER_REL(baserel))
874  relids = fpinfo->outerrel->relids;
875  else
876  relids = baserel->relids;
877 
878  if (bms_is_member(var->varno, relids) && var->varlevelsup == 0)
879  return false; /* foreign Var, so not a param */
880  else
881  return true; /* it'd have to be a param */
882  break;
883  }
884  case T_Param:
885  /* Params always have to be sent to the foreign server */
886  return true;
887  default:
888  break;
889  }
890  return false;
891 }
892 
893 /*
894  * Convert type OID + typmod info into a type name we can ship to the remote
895  * server. Someplace else had better have verified that this type name is
896  * expected to be known on the remote end.
897  *
898  * This is almost just format_type_with_typemod(), except that if left to its
899  * own devices, that function will make schema-qualification decisions based
900  * on the local search_path, which is wrong. We must schema-qualify all
901  * type names that are not in pg_catalog. We assume here that built-in types
902  * are all in pg_catalog and need not be qualified; otherwise, qualify.
903  */
904 static char *
905 deparse_type_name(Oid type_oid, int32 typemod)
906 {
907  bits16 flags = FORMAT_TYPE_TYPEMOD_GIVEN;
908 
909  if (!is_builtin(type_oid))
910  flags |= FORMAT_TYPE_FORCE_QUALIFY;
911 
912  return format_type_extended(type_oid, typemod, flags);
913 }
914 
915 /*
916  * Build the targetlist for given relation to be deparsed as SELECT clause.
917  *
918  * The output targetlist contains the columns that need to be fetched from the
919  * foreign server for the given relation. If foreignrel is an upper relation,
920  * then the output targetlist can also contain expressions to be evaluated on
921  * foreign server.
922  */
923 List *
924 build_tlist_to_deparse(RelOptInfo *foreignrel)
925 {
926  List *tlist = NIL;
927  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
928  ListCell *lc;
929 
930  /*
931  * For an upper relation, we have already built the target list while
932  * checking shippability, so just return that.
933  */
934  if (IS_UPPER_REL(foreignrel))
935  return fpinfo->grouped_tlist;
936 
937  /*
938  * We require columns specified in foreignrel->reltarget->exprs and those
939  * required for evaluating the local conditions.
940  */
941  tlist = add_to_flat_tlist(tlist,
942  pull_var_clause((Node *) foreignrel->reltarget->exprs,
943  PVC_RECURSE_PLACEHOLDERS));
944  foreach(lc, fpinfo->local_conds)
945  {
946  RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
947 
948  tlist = add_to_flat_tlist(tlist,
949  pull_var_clause((Node *) rinfo->clause,
950  PVC_RECURSE_PLACEHOLDERS));
951  }
952 
953  return tlist;
954 }
955 
956 /*
957  * Deparse SELECT statement for given relation into buf.
958  *
959  * tlist contains the list of desired columns to be fetched from foreign server.
960  * For a base relation fpinfo->attrs_used is used to construct SELECT clause,
961  * hence the tlist is ignored for a base relation.
962  *
963  * remote_conds is the list of conditions to be deparsed into the WHERE clause
964  * (or, in the case of upper relations, into the HAVING clause).
965  *
966  * If params_list is not NULL, it receives a list of Params and other-relation
967  * Vars used in the clauses; these values must be transmitted to the remote
968  * server as parameter values.
969  *
970  * If params_list is NULL, we're generating the query for EXPLAIN purposes,
971  * so Params and other-relation Vars should be replaced by dummy values.
972  *
973  * pathkeys is the list of pathkeys to order the result by.
974  *
975  * is_subquery is the flag to indicate whether to deparse the specified
976  * relation as a subquery.
977  *
978  * List of columns selected is returned in retrieved_attrs.
979  */
980 void
981 deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *rel,
982  List *tlist, List *remote_conds, List *pathkeys,
983  bool has_final_sort, bool has_limit, bool is_subquery,
984  List **retrieved_attrs, List **params_list)
985 {
986  deparse_expr_cxt context;
987  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
988  List *quals;
989 
990  /*
991  * We handle relations for foreign tables, joins between those and upper
992  * relations.
993  */
994  Assert(IS_JOIN_REL(rel) || IS_SIMPLE_REL(rel) || IS_UPPER_REL(rel));
995 
996  /* Fill portions of context common to upper, join and base relation */
997  context.buf = buf;
998  context.root = root;
999  context.foreignrel = rel;
1000  context.scanrel = IS_UPPER_REL(rel) ? fpinfo->outerrel : rel;
1001  context.params_list = params_list;
1002 
1003  /* Construct SELECT clause */
1004  deparseSelectSql(tlist, is_subquery, retrieved_attrs, &context);
1005 
1006  /*
1007  * For upper relations, the WHERE clause is built from the remote
1008  * conditions of the underlying scan relation; otherwise, we can use the
1009  * supplied list of remote conditions directly.
1010  */
1011  if (IS_UPPER_REL(rel))
1012  {
1013  PgFdwRelationInfo *ofpinfo;
1014 
1015  ofpinfo = (PgFdwRelationInfo *) fpinfo->outerrel->fdw_private;
1016  quals = ofpinfo->remote_conds;
1017  }
1018  else
1019  quals = remote_conds;
1020 
1021  /* Construct FROM and WHERE clauses */
1022  deparseFromExpr(quals, &context);
1023 
1024  if (IS_UPPER_REL(rel))
1025  {
1026  /* Append GROUP BY clause */
1027  appendGroupByClause(tlist, &context);
1028 
1029  /* Append HAVING clause */
1030  if (remote_conds)
1031  {
1032  appendStringInfoString(buf, " HAVING ");
1033  appendConditions(remote_conds, &context);
1034  }
1035  }
1036 
1037  /* Add ORDER BY clause if we found any useful pathkeys */
1038  if (pathkeys)
1039  appendOrderByClause(pathkeys, has_final_sort, &context);
1040 
1041  /* Add LIMIT clause if necessary */
1042  if (has_limit)
1043  appendLimitClause(&context);
1044 
1045  /* Add any necessary FOR UPDATE/SHARE. */
1046  deparseLockingClause(&context);
1047 }
1048 
1049 /*
1050  * Construct a simple SELECT statement that retrieves desired columns
1051  * of the specified foreign table, and append it to "buf". The output
1052  * contains just "SELECT ... ".
1053  *
1054  * We also create an integer List of the columns being retrieved, which is
1055  * returned to *retrieved_attrs, unless we deparse the specified relation
1056  * as a subquery.
1057  *
1058  * tlist is the list of desired columns. is_subquery is the flag to
1059  * indicate whether to deparse the specified relation as a subquery.
1060  * Read prologue of deparseSelectStmtForRel() for details.
1061  */
1062 static void
1063 deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs,
1064  deparse_expr_cxt *context)
1065 {
1066  StringInfo buf = context->buf;
1067  RelOptInfo *foreignrel = context->foreignrel;
1068  PlannerInfo *root = context->root;
1069  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
1070 
1071  /*
1072  * Construct SELECT list
1073  */
1074  appendStringInfoString(buf, "SELECT ");
1075 
1076  if (is_subquery)
1077  {
1078  /*
1079  * For a relation that is deparsed as a subquery, emit expressions
1080  * specified in the relation's reltarget. Note that since this is for
1081  * the subquery, no need to care about *retrieved_attrs.
1082  */
1083  deparseSubqueryTargetList(context);
1084  }
1085  else if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel))
1086  {
1087  /*
1088  * For a join or upper relation the input tlist gives the list of
1089  * columns required to be fetched from the foreign server.
1090  */
1091  deparseExplicitTargetList(tlist, false, retrieved_attrs, context);
1092  }
1093  else
1094  {
1095  /*
1096  * For a base relation fpinfo->attrs_used gives the list of columns
1097  * required to be fetched from the foreign server.
1098  */
1099  RangeTblEntry *rte = planner_rt_fetch(foreignrel->relid, root);
1100 
1101  /*
1102  * Core code already has some lock on each rel being planned, so we
1103  * can use NoLock here.
1104  */
1105  Relation rel = table_open(rte->relid, NoLock);
1106 
1107  deparseTargetList(buf, rte, foreignrel->relid, rel, false,
1108  fpinfo->attrs_used, false, retrieved_attrs);
1109  table_close(rel, NoLock);
1110  }
1111 }
1112 
1113 /*
1114  * Construct a FROM clause and, if needed, a WHERE clause, and append those to
1115  * "buf".
1116  *
1117  * quals is the list of clauses to be included in the WHERE clause.
1118  * (These may or may not include RestrictInfo decoration.)
1119  */
1120 static void
1121 deparseFromExpr(List *quals, deparse_expr_cxt *context)
1122 {
1123  StringInfo buf = context->buf;
1124  RelOptInfo *scanrel = context->scanrel;
1125 
1126  /* For upper relations, scanrel must be either a joinrel or a baserel */
1127  Assert(!IS_UPPER_REL(context->foreignrel) ||
1128  IS_JOIN_REL(scanrel) || IS_SIMPLE_REL(scanrel));
1129 
1130  /* Construct FROM clause */
1131  appendStringInfoString(buf, " FROM ");
1132  deparseFromExprForRel(buf, context->root, scanrel,
1133  (bms_membership(scanrel->relids) == BMS_MULTIPLE),
1134  (Index) 0, NULL, context->params_list);
1135 
1136  /* Construct WHERE clause */
1137  if (quals != NIL)
1138  {
1139  appendStringInfoString(buf, " WHERE ");
1140  appendConditions(quals, context);
1141  }
1142 }
1143 
1144 /*
1145  * Emit a target list that retrieves the columns specified in attrs_used.
1146  * This is used for both SELECT and RETURNING targetlists; the is_returning
1147  * parameter is true only for a RETURNING targetlist.
1148  *
1149  * The tlist text is appended to buf, and we also create an integer List
1150  * of the columns being retrieved, which is returned to *retrieved_attrs.
1151  *
1152  * If qualify_col is true, add relation alias before the column name.
1153  */
1154 static void
1155 deparseTargetList(StringInfo buf,
1156  RangeTblEntry *rte,
1157  Index rtindex,
1158  Relation rel,
1159  bool is_returning,
1160  Bitmapset *attrs_used,
1161  bool qualify_col,
1162  List **retrieved_attrs)
1163 {
1164  TupleDesc tupdesc = RelationGetDescr(rel);
1165  bool have_wholerow;
1166  bool first;
1167  int i;
1168 
1169  *retrieved_attrs = NIL;
1170 
1171  /* If there's a whole-row reference, we'll need all the columns. */
1172  have_wholerow = bms_is_member(0 - FirstLowInvalidHeapAttributeNumber,
1173  attrs_used);
1174 
1175  first = true;
1176  for (i = 1; i <= tupdesc->natts; i++)
1177  {
1178  Form_pg_attribute attr = TupleDescAttr(tupdesc, i - 1);
1179 
1180  /* Ignore dropped attributes. */
1181  if (attr->attisdropped)
1182  continue;
1183 
1184  if (have_wholerow ||
1185  bms_is_member(i - FirstLowInvalidHeapAttributeNumber,
1186  attrs_used))
1187  {
1188  if (!first)
1189  appendStringInfoString(buf, ", ");
1190  else if (is_returning)
1191  appendStringInfoString(buf, " RETURNING ");
1192  first = false;
1193 
1194  deparseColumnRef(buf, rtindex, i, rte, qualify_col);
1195 
1196  *retrieved_attrs = lappend_int(*retrieved_attrs, i);
1197  }
1198  }
1199 
1200  /*
1201  * Add ctid if needed. We currently don't support retrieving any other
1202  * system columns.
1203  */
1204  if (bms_is_member(SelfItemPointerAttributeNumber - FirstLowInvalidHeapAttributeNumber,
1205  attrs_used))
1206  {
1207  if (!first)
1208  appendStringInfoString(buf, ", ");
1209  else if (is_returning)
1210  appendStringInfoString(buf, " RETURNING ");
1211  first = false;
1212 
1213  if (qualify_col)
1214  ADD_REL_QUALIFIER(buf, rtindex);
1215  appendStringInfoString(buf, "ctid");
1216 
1217  *retrieved_attrs = lappend_int(*retrieved_attrs,
1218  SelfItemPointerAttributeNumber);
1219  }
1220 
1221  /* Don't generate bad syntax if no undropped columns */
1222  if (first && !is_returning)
1223  appendStringInfoString(buf, "NULL");
1224 }
1225 
1226 /*
1227  * Deparse the appropriate locking clause (FOR UPDATE or FOR SHARE) for a
1228  * given relation (context->scanrel).
1229  */
1230 static void
1231 deparseLockingClause(deparse_expr_cxt *context)
1232 {
1233  StringInfo buf = context->buf;
1234  PlannerInfo *root = context->root;
1235  RelOptInfo *rel = context->scanrel;
1236  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
1237  int relid = -1;
1238 
1239  while ((relid = bms_next_member(rel->relids, relid)) >= 0)
1240  {
1241  /*
1242  * Ignore relation if it appears in a lower subquery. Locking clause
1243  * for such a relation is included in the subquery if necessary.
1244  */
1245  if (bms_is_member(relid, fpinfo->lower_subquery_rels))
1246  continue;
1247 
1248  /*
1249  * Add FOR UPDATE/SHARE if appropriate. We apply locking during the
1250  * initial row fetch, rather than later on as is done for local
1251  * tables. The extra roundtrips involved in trying to duplicate the
1252  * local semantics exactly don't seem worthwhile (see also comments
1253  * for RowMarkType).
1254  *
1255  * Note: because we actually run the query as a cursor, this assumes
1256  * that DECLARE CURSOR ... FOR UPDATE is supported, which it isn't
1257  * before 8.3.
1258  */
1259  if (relid == root->parse->resultRelation &&
1260  (root->parse->commandType == CMD_UPDATE ||
1261  root->parse->commandType == CMD_DELETE))
1262  {
1263  /* Relation is UPDATE/DELETE target, so use FOR UPDATE */
1264  appendStringInfoString(buf, " FOR UPDATE");
1265 
1266  /* Add the relation alias if we are here for a join relation */
1267  if (IS_JOIN_REL(rel))
1268  appendStringInfo(buf, " OF %s%d", REL_ALIAS_PREFIX, relid);
1269  }
1270  else
1271  {
1272  PlanRowMark *rc = get_plan_rowmark(root->rowMarks, relid);
1273 
1274  if (rc)
1275  {
1276  /*
1277  * Relation is specified as a FOR UPDATE/SHARE target, so
1278  * handle that. (But we could also see LCS_NONE, meaning this
1279  * isn't a target relation after all.)
1280  *
1281  * For now, just ignore any [NO] KEY specification, since (a)
1282  * it's not clear what that means for a remote table that we
1283  * don't have complete information about, and (b) it wouldn't
1284  * work anyway on older remote servers. Likewise, we don't
1285  * worry about NOWAIT.
1286  */
1287  switch (rc->strength)
1288  {
1289  case LCS_NONE:
1290  /* No locking needed */
1291  break;
1292  case LCS_FORKEYSHARE:
1293  case LCS_FORSHARE:
1294  appendStringInfoString(buf, " FOR SHARE");
1295  break;
1296  case LCS_FORNOKEYUPDATE:
1297  case LCS_FORUPDATE:
1298  appendStringInfoString(buf, " FOR UPDATE");
1299  break;
1300  }
1301 
1302  /* Add the relation alias if we are here for a join relation */
1303  if (bms_membership(rel->relids) == BMS_MULTIPLE &&
1304  rc->strength != LCS_NONE)
1305  appendStringInfo(buf, " OF %s%d", REL_ALIAS_PREFIX, relid);
1306  }
1307  }
1308  }
1309 }
1310 
1311 /*
1312  * Deparse conditions from the provided list and append them to buf.
1313  *
1314  * The conditions in the list are assumed to be ANDed. This function is used to
1315  * deparse WHERE clauses, JOIN .. ON clauses and HAVING clauses.
1316  *
1317  * Depending on the caller, the list elements might be either RestrictInfos
1318  * or bare clauses.
1319  */
1320 static void
1321 appendConditions(List *exprs, deparse_expr_cxt *context)
1322 {
1323  int nestlevel;
1324  ListCell *lc;
1325  bool is_first = true;
1326  StringInfo buf = context->buf;
1327 
1328  /* Make sure any constants in the exprs are printed portably */
1329  nestlevel = set_transmission_modes();
1330 
1331  foreach(lc, exprs)
1332  {
1333  Expr *expr = (Expr *) lfirst(lc);
1334 
1335  /* Extract clause from RestrictInfo, if required */
1336  if (IsA(expr, RestrictInfo))
1337  expr = ((RestrictInfo *) expr)->clause;
1338 
1339  /* Connect expressions with "AND" and parenthesize each condition. */
1340  if (!is_first)
1341  appendStringInfoString(buf, " AND ");
1342 
1343  appendStringInfoChar(buf, '(');
1344  deparseExpr(expr, context);
1345  appendStringInfoChar(buf, ')');
1346 
1347  is_first = false;
1348  }
1349 
1350  reset_transmission_modes(nestlevel);
1351 }
1352 
1353 /* Output join name for given join type */
1354 const char *
1355 get_jointype_name(JoinType jointype)
1356 {
1357  switch (jointype)
1358  {
1359  case JOIN_INNER:
1360  return "INNER";
1361 
1362  case JOIN_LEFT:
1363  return "LEFT";
1364 
1365  case JOIN_RIGHT:
1366  return "RIGHT";
1367 
1368  case JOIN_FULL:
1369  return "FULL";
1370 
1371  default:
1372  /* Shouldn't come here, but protect from buggy code. */
1373  elog(ERROR, "unsupported join type %d", jointype);
1374  }
1375 
1376  /* Keep compiler happy */
1377  return NULL;
1378 }
1379 
1380 /*
1381  * Deparse given targetlist and append it to context->buf.
1382  *
1383  * tlist is list of TargetEntry's which in turn contain Var nodes.
1384  *
1385  * retrieved_attrs is the list of continuously increasing integers starting
1386  * from 1. It has same number of entries as tlist.
1387  *
1388  * This is used for both SELECT and RETURNING targetlists; the is_returning
1389  * parameter is true only for a RETURNING targetlist.
1390  */
1391 static void
1392 deparseExplicitTargetList(List *tlist,
1393  bool is_returning,
1394  List **retrieved_attrs,
1395  deparse_expr_cxt *context)
1396 {
1397  ListCell *lc;
1398  StringInfo buf = context->buf;
1399  int i = 0;
1400 
1401  *retrieved_attrs = NIL;
1402 
1403  foreach(lc, tlist)
1404  {
1405  TargetEntry *tle = lfirst_node(TargetEntry, lc);
1406 
1407  if (i > 0)
1408  appendStringInfoString(buf, ", ");
1409  else if (is_returning)
1410  appendStringInfoString(buf, " RETURNING ");
1411 
1412  deparseExpr((Expr *) tle->expr, context);
1413 
1414  *retrieved_attrs = lappend_int(*retrieved_attrs, i + 1);
1415  i++;
1416  }
1417 
1418  if (i == 0 && !is_returning)
1419  appendStringInfoString(buf, "NULL");
1420 }
1421 
1422 /*
1423  * Emit expressions specified in the given relation's reltarget.
1424  *
1425  * This is used for deparsing the given relation as a subquery.
1426  */
1427 static void
1428 deparseSubqueryTargetList(deparse_expr_cxt *context)
1429 {
1430  StringInfo buf = context->buf;
1431  RelOptInfo *foreignrel = context->foreignrel;
1432  bool first;
1433  ListCell *lc;
1434 
1435  /* Should only be called in these cases. */
1436  Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
1437 
1438  first = true;
1439  foreach(lc, foreignrel->reltarget->exprs)
1440  {
1441  Node *node = (Node *) lfirst(lc);
1442 
1443  if (!first)
1444  appendStringInfoString(buf, ", ");
1445  first = false;
1446 
1447  deparseExpr((Expr *) node, context);
1448  }
1449 
1450  /* Don't generate bad syntax if no expressions */
1451  if (first)
1452  appendStringInfoString(buf, "NULL");
1453 }
1454 
1455 /*
1456  * Construct FROM clause for given relation
1457  *
1458  * The function constructs ... JOIN ... ON ... for join relation. For a base
1459  * relation it just returns schema-qualified tablename, with the appropriate
1460  * alias if so requested.
1461  *
1462  * 'ignore_rel' is either zero or the RT index of a target relation. In the
1463  * latter case the function constructs FROM clause of UPDATE or USING clause
1464  * of DELETE; it deparses the join relation as if the relation never contained
1465  * the target relation, and creates a List of conditions to be deparsed into
1466  * the top-level WHERE clause, which is returned to *ignore_conds.
1467  */
1468 static void
1469 deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
1470  bool use_alias, Index ignore_rel, List **ignore_conds,
1471  List **params_list)
1472 {
1473  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
1474 
1475  if (IS_JOIN_REL(foreignrel))
1476  {
1477  StringInfoData join_sql_o;
1478  StringInfoData join_sql_i;
1479  RelOptInfo *outerrel = fpinfo->outerrel;
1480  RelOptInfo *innerrel = fpinfo->innerrel;
1481  bool outerrel_is_target = false;
1482  bool innerrel_is_target = false;
1483 
1484  if (ignore_rel > 0 && bms_is_member(ignore_rel, foreignrel->relids))
1485  {
1486  /*
1487  * If this is an inner join, add joinclauses to *ignore_conds and
1488  * set it to empty so that those can be deparsed into the WHERE
1489  * clause. Note that since the target relation can never be
1490  * within the nullable side of an outer join, those could safely
1491  * be pulled up into the WHERE clause (see foreign_join_ok()).
1492  * Note also that since the target relation is only inner-joined
1493  * to any other relation in the query, all conditions in the join
1494  * tree mentioning the target relation could be deparsed into the
1495  * WHERE clause by doing this recursively.
1496  */
1497  if (fpinfo->jointype == JOIN_INNER)
1498  {
1499  *ignore_conds = list_concat(*ignore_conds,
1500  fpinfo->joinclauses);
1501  fpinfo->joinclauses = NIL;
1502  }
1503 
1504  /*
1505  * Check if either of the input relations is the target relation.
1506  */
1507  if (outerrel->relid == ignore_rel)
1508  outerrel_is_target = true;
1509  else if (innerrel->relid == ignore_rel)
1510  innerrel_is_target = true;
1511  }
1512 
1513  /* Deparse outer relation if not the target relation. */
1514  if (!outerrel_is_target)
1515  {
1516  initStringInfo(&join_sql_o);
1517  deparseRangeTblRef(&join_sql_o, root, outerrel,
1518  fpinfo->make_outerrel_subquery,
1519  ignore_rel, ignore_conds, params_list);
1520 
1521  /*
1522  * If inner relation is the target relation, skip deparsing it.
1523  * Note that since the join of the target relation with any other
1524  * relation in the query is an inner join and can never be within
1525  * the nullable side of an outer join, the join could be
1526  * interchanged with higher-level joins (cf. identity 1 on outer
1527  * join reordering shown in src/backend/optimizer/README), which
1528  * means it's safe to skip the target-relation deparsing here.
1529  */
1530  if (innerrel_is_target)
1531  {
1532  Assert(fpinfo->jointype == JOIN_INNER);
1533  Assert(fpinfo->joinclauses == NIL);
1534  appendBinaryStringInfo(buf, join_sql_o.data, join_sql_o.len);
1535  return;
1536  }
1537  }
1538 
1539  /* Deparse inner relation if not the target relation. */
1540  if (!innerrel_is_target)
1541  {
1542  initStringInfo(&join_sql_i);
1543  deparseRangeTblRef(&join_sql_i, root, innerrel,
1544  fpinfo->make_innerrel_subquery,
1545  ignore_rel, ignore_conds, params_list);
1546 
1547  /*
1548  * If outer relation is the target relation, skip deparsing it.
1549  * See the above note about safety.
1550  */
1551  if (outerrel_is_target)
1552  {
1553  Assert(fpinfo->jointype == JOIN_INNER);
1554  Assert(fpinfo->joinclauses == NIL);
1555  appendBinaryStringInfo(buf, join_sql_i.data, join_sql_i.len);
1556  return;
1557  }
1558  }
1559 
1560  /* Neither of the relations is the target relation. */
1561  Assert(!outerrel_is_target && !innerrel_is_target);
1562 
1563  /*
1564  * For a join relation FROM clause entry is deparsed as
1565  *
1566  * ((outer relation) <join type> (inner relation) ON (joinclauses))
1567  */
1568  appendStringInfo(buf, "(%s %s JOIN %s ON ", join_sql_o.data,
1569  get_jointype_name(fpinfo->jointype), join_sql_i.data);
1570 
1571  /* Append join clause; (TRUE) if no join clause */
1572  if (fpinfo->joinclauses)
1573  {
1574  deparse_expr_cxt context;
1575 
1576  context.buf = buf;
1577  context.foreignrel = foreignrel;
1578  context.scanrel = foreignrel;
1579  context.root = root;
1580  context.params_list = params_list;
1581 
1582  appendStringInfoChar(buf, '(');
1583  appendConditions(fpinfo->joinclauses, &context);
1584  appendStringInfoChar(buf, ')');
1585  }
1586  else
1587  appendStringInfoString(buf, "(TRUE)");
1588 
1589  /* End the FROM clause entry. */
1590  appendStringInfoChar(buf, ')');
1591  }
1592  else
1593  {
1594  RangeTblEntry *rte = planner_rt_fetch(foreignrel->relid, root);
1595 
1596  /*
1597  * Core code already has some lock on each rel being planned, so we
1598  * can use NoLock here.
1599  */
1600  Relation rel = table_open(rte->relid, NoLock);
1601 
1602  deparseRelation(buf, rel);
1603 
1604  /*
1605  * Add a unique alias to avoid any conflict in relation names due to
1606  * pulled up subqueries in the query being built for a pushed down
1607  * join.
1608  */
1609  if (use_alias)
1610  appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, foreignrel->relid);
1611 
1612  table_close(rel, NoLock);
1613  }
1614 }
1615 
1616 /*
1617  * Append FROM clause entry for the given relation into buf.
1618  */
1619 static void
1620 deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
1621  bool make_subquery, Index ignore_rel, List **ignore_conds,
1622  List **params_list)
1623 {
1624  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
1625 
1626  /* Should only be called in these cases. */
1627  Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
1628 
1629  Assert(fpinfo->local_conds == NIL);
1630 
1631  /* If make_subquery is true, deparse the relation as a subquery. */
1632  if (make_subquery)
1633  {
1634  List *retrieved_attrs;
1635  int ncols;
1636 
1637  /*
1638  * The given relation shouldn't contain the target relation, because
1639  * this should only happen for input relations for a full join, and
1640  * such relations can never contain an UPDATE/DELETE target.
1641  */
1642  Assert(ignore_rel == 0 ||
1643  !bms_is_member(ignore_rel, foreignrel->relids));
1644 
1645  /* Deparse the subquery representing the relation. */
1646  appendStringInfoChar(buf, '(');
1647  deparseSelectStmtForRel(buf, root, foreignrel, NIL,
1648  fpinfo->remote_conds, NIL,
1649  false, false, true,
1650  &retrieved_attrs, params_list);
1651  appendStringInfoChar(buf, ')');
1652 
1653  /* Append the relation alias. */
1654  appendStringInfo(buf, " %s%d", SUBQUERY_REL_ALIAS_PREFIX,
1655  fpinfo->relation_index);
1656 
1657  /*
1658  * Append the column aliases if needed. Note that the subquery emits
1659  * expressions specified in the relation's reltarget (see
1660  * deparseSubqueryTargetList).
1661  */
1662  ncols = list_length(foreignrel->reltarget->exprs);
1663  if (ncols > 0)
1664  {
1665  int i;
1666 
1667  appendStringInfoChar(buf, '(');
1668  for (i = 1; i <= ncols; i++)
1669  {
1670  if (i > 1)
1671  appendStringInfoString(buf, ", ");
1672 
1673  appendStringInfo(buf, "%s%d", SUBQUERY_COL_ALIAS_PREFIX, i);
1674  }
1675  appendStringInfoChar(buf, ')');
1676  }
1677  }
1678  else
1679  deparseFromExprForRel(buf, root, foreignrel, true, ignore_rel,
1680  ignore_conds, params_list);
1681 }
1682 
1683 /*
1684  * deparse remote INSERT statement
1685  *
1686  * The statement text is appended to buf, and we also create an integer List
1687  * of the columns being retrieved by WITH CHECK OPTION or RETURNING (if any),
1688  * which is returned to *retrieved_attrs.
1689  */
1690 void
1691 deparseInsertSql(StringInfo buf, RangeTblEntry *rte,
1692  Index rtindex, Relation rel,
1693  List *targetAttrs, bool doNothing,
1694  List *withCheckOptionList, List *returningList,
1695  List **retrieved_attrs)
1696 {
1697  AttrNumber pindex;
1698  bool first;
1699  ListCell *lc;
1700 
1701  appendStringInfoString(buf, "INSERT INTO ");
1702  deparseRelation(buf, rel);
1703 
1704  if (targetAttrs)
1705  {
1706  appendStringInfoChar(buf, '(');
1707 
1708  first = true;
1709  foreach(lc, targetAttrs)
1710  {
1711  int attnum = lfirst_int(lc);
1712 
1713  if (!first)
1714  appendStringInfoString(buf, ", ");
1715  first = false;
1716 
1717  deparseColumnRef(buf, rtindex, attnum, rte, false);
1718  }
1719 
1720  appendStringInfoString(buf, ") VALUES (");
1721 
1722  pindex = 1;
1723  first = true;
1724  foreach(lc, targetAttrs)
1725  {
1726  if (!first)
1727  appendStringInfoString(buf, ", ");
1728  first = false;
1729 
1730  appendStringInfo(buf, "$%d", pindex);
1731  pindex++;
1732  }
1733 
1734  appendStringInfoChar(buf, ')');
1735  }
1736  else
1737  appendStringInfoString(buf, " DEFAULT VALUES");
1738 
1739  if (doNothing)
1740  appendStringInfoString(buf, " ON CONFLICT DO NOTHING");
1741 
1742  deparseReturningList(buf, rte, rtindex, rel,
1743  rel->trigdesc && rel->trigdesc->trig_insert_after_row,
1744  withCheckOptionList, returningList, retrieved_attrs);
1745 }
1746 
1747 /*
1748  * deparse remote UPDATE statement
1749  *
1750  * The statement text is appended to buf, and we also create an integer List
1751  * of the columns being retrieved by WITH CHECK OPTION or RETURNING (if any),
1752  * which is returned to *retrieved_attrs.
1753  */
1754 void
1755 deparseUpdateSql(StringInfo buf, RangeTblEntry *rte,
1756  Index rtindex, Relation rel,
1757  List *targetAttrs,
1758  List *withCheckOptionList, List *returningList,
1759  List **retrieved_attrs)
1760 {
1761  AttrNumber pindex;
1762  bool first;
1763  ListCell *lc;
1764 
1765  appendStringInfoString(buf, "UPDATE ");
1766  deparseRelation(buf, rel);
1767  appendStringInfoString(buf, " SET ");
1768 
1769  pindex = 2; /* ctid is always the first param */
1770  first = true;
1771  foreach(lc, targetAttrs)
1772  {
1773  int attnum = lfirst_int(lc);
1774 
1775  if (!first)
1776  appendStringInfoString(buf, ", ");
1777  first = false;
1778 
1779  deparseColumnRef(buf, rtindex, attnum, rte, false);
1780  appendStringInfo(buf, " = $%d", pindex);
1781  pindex++;
1782  }
1783  appendStringInfoString(buf, " WHERE ctid = $1");
1784 
1785  deparseReturningList(buf, rte, rtindex, rel,
1786  rel->trigdesc && rel->trigdesc->trig_update_after_row,
1787  withCheckOptionList, returningList, retrieved_attrs);
1788 }
1789 
1790 /*
1791  * deparse remote UPDATE statement
1792  *
1793  * 'buf' is the output buffer to append the statement to
1794  * 'rtindex' is the RT index of the associated target relation
1795  * 'rel' is the relation descriptor for the target relation
1796  * 'foreignrel' is the RelOptInfo for the target relation or the join relation
1797  * containing all base relations in the query
1798  * 'targetlist' is the tlist of the underlying foreign-scan plan node
1799  * 'targetAttrs' is the target columns of the UPDATE
1800  * 'remote_conds' is the qual clauses that must be evaluated remotely
1801  * '*params_list' is an output list of exprs that will become remote Params
1802  * 'returningList' is the RETURNING targetlist
1803  * '*retrieved_attrs' is an output list of integers of columns being retrieved
1804  * by RETURNING (if any)
1805  */
1806 void
1807 deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
1808  Index rtindex, Relation rel,
1809  RelOptInfo *foreignrel,
1810  List *targetlist,
1811  List *targetAttrs,
1812  List *remote_conds,
1813  List **params_list,
1814  List *returningList,
1815  List **retrieved_attrs)
1816 {
1817  deparse_expr_cxt context;
1818  int nestlevel;
1819  bool first;
1820  ListCell *lc;
1821  RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
1822 
1823  /* Set up context struct for recursion */
1824  context.root = root;
1825  context.foreignrel = foreignrel;
1826  context.scanrel = foreignrel;
1827  context.buf = buf;
1828  context.params_list = params_list;
1829 
1830  appendStringInfoString(buf, "UPDATE ");
1831  deparseRelation(buf, rel);
1832  if (foreignrel->reloptkind == RELOPT_JOINREL)
1833  appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, rtindex);
1834  appendStringInfoString(buf, " SET ");
1835 
1836  /* Make sure any constants in the exprs are printed portably */
1837  nestlevel = set_transmission_modes();
1838 
1839  first = true;
1840  foreach(lc, targetAttrs)
1841  {
1842  int attnum = lfirst_int(lc);
1843  TargetEntry *tle = get_tle_by_resno(targetlist, attnum);
1844 
1845  if (!tle)
1846  elog(ERROR, "attribute number %d not found in UPDATE targetlist",
1847  attnum);
1848 
1849  if (!first)
1850  appendStringInfoString(buf, ", ");
1851  first = false;
1852 
1853  deparseColumnRef(buf, rtindex, attnum, rte, false);
1854  appendStringInfoString(buf, " = ");
1855  deparseExpr((Expr *) tle->expr, &context);
1856  }
1857 
1858  reset_transmission_modes(nestlevel);
1859 
1860  if (foreignrel->reloptkind == RELOPT_JOINREL)
1861  {
1862  List *ignore_conds = NIL;
1863 
1864  appendStringInfoString(buf, " FROM ");
1865  deparseFromExprForRel(buf, root, foreignrel, true, rtindex,
1866  &ignore_conds, params_list);
1867  remote_conds = list_concat(remote_conds, ignore_conds);
1868  }
1869 
1870  if (remote_conds)
1871  {
1872  appendStringInfoString(buf, " WHERE ");
1873  appendConditions(remote_conds, &context);
1874  }
1875 
1876  if (foreignrel->reloptkind == RELOPT_JOINREL)
1877  deparseExplicitTargetList(returningList, true, retrieved_attrs,
1878  &context);
1879  else
1880  deparseReturningList(buf, rte, rtindex, rel, false,
1881  NIL, returningList, retrieved_attrs);
1882 }
1883 
1884 /*
1885  * deparse remote DELETE statement
1886  *
1887  * The statement text is appended to buf, and we also create an integer List
1888  * of the columns being retrieved by RETURNING (if any), which is returned
1889  * to *retrieved_attrs.
1890  */
1891 void
1892 deparseDeleteSql(StringInfo buf, RangeTblEntry *rte,
1893  Index rtindex, Relation rel,
1894  List *returningList,
1895  List **retrieved_attrs)
1896 {
1897  appendStringInfoString(buf, "DELETE FROM ");
1898  deparseRelation(buf, rel);
1899  appendStringInfoString(buf, " WHERE ctid = $1");
1900 
1901  deparseReturningList(buf, rte, rtindex, rel,
1902  rel->trigdesc && rel->trigdesc->trig_delete_after_row,
1903  NIL, returningList, retrieved_attrs);
1904 }
1905 
1906 /*
1907  * deparse remote DELETE statement
1908  *
1909  * 'buf' is the output buffer to append the statement to
1910  * 'rtindex' is the RT index of the associated target relation
1911  * 'rel' is the relation descriptor for the target relation
1912  * 'foreignrel' is the RelOptInfo for the target relation or the join relation
1913  * containing all base relations in the query
1914  * 'remote_conds' is the qual clauses that must be evaluated remotely
1915  * '*params_list' is an output list of exprs that will become remote Params
1916  * 'returningList' is the RETURNING targetlist
1917  * '*retrieved_attrs' is an output list of integers of columns being retrieved
1918  * by RETURNING (if any)
1919  */
1920 void
1921 deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
1922  Index rtindex, Relation rel,
1923  RelOptInfo *foreignrel,
1924  List *remote_conds,
1925  List **params_list,
1926  List *returningList,
1927  List **retrieved_attrs)
1928 {
1929  deparse_expr_cxt context;
1930 
1931  /* Set up context struct for recursion */
1932  context.root = root;
1933  context.foreignrel = foreignrel;
1934  context.scanrel = foreignrel;
1935  context.buf = buf;
1936  context.params_list = params_list;
1937 
1938  appendStringInfoString(buf, "DELETE FROM ");
1939  deparseRelation(buf, rel);
1940  if (foreignrel->reloptkind == RELOPT_JOINREL)
1941  appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, rtindex);
1942 
1943  if (foreignrel->reloptkind == RELOPT_JOINREL)
1944  {
1945  List *ignore_conds = NIL;
1946 
1947  appendStringInfoString(buf, " USING ");
1948  deparseFromExprForRel(buf, root, foreignrel, true, rtindex,
1949  &ignore_conds, params_list);
1950  remote_conds = list_concat(remote_conds, ignore_conds);
1951  }
1952 
1953  if (remote_conds)
1954  {
1955  appendStringInfoString(buf, " WHERE ");
1956  appendConditions(remote_conds, &context);
1957  }
1958 
1959  if (foreignrel->reloptkind == RELOPT_JOINREL)
1960  deparseExplicitTargetList(returningList, true, retrieved_attrs,
1961  &context);
1962  else
1963  deparseReturningList(buf, planner_rt_fetch(rtindex, root),
1964  rtindex, rel, false,
1965  NIL, returningList, retrieved_attrs);
1966 }
1967 
1968 /*
1969  * Add a RETURNING clause, if needed, to an INSERT/UPDATE/DELETE.
1970  */
1971 static void
1972 deparseReturningList(StringInfo buf, RangeTblEntry *rte,
1973  Index rtindex, Relation rel,
1974  bool trig_after_row,
1975  List *withCheckOptionList,
1976  List *returningList,
1977  List **retrieved_attrs)
1978 {
1979  Bitmapset *attrs_used = NULL;
1980 
1981  if (trig_after_row)
1982  {
1983  /* whole-row reference acquires all non-system columns */
1984  attrs_used =
1985  bms_make_singleton(0 - FirstLowInvalidHeapAttributeNumber);
1986  }
1987 
1988  if (withCheckOptionList != NIL)
1989  {
1990  /*
1991  * We need the attrs, non-system and system, mentioned in the local
1992  * query's WITH CHECK OPTION list.
1993  *
1994  * Note: we do this to ensure that WCO constraints will be evaluated
1995  * on the data actually inserted/updated on the remote side, which
1996  * might differ from the data supplied by the core code, for example
1997  * as a result of remote triggers.
1998  */
1999  pull_varattnos((Node *) withCheckOptionList, rtindex,
2000  &attrs_used);
2001  }
2002 
2003  if (returningList != NIL)
2004  {
2005  /*
2006  * We need the attrs, non-system and system, mentioned in the local
2007  * query's RETURNING list.
2008  */
2009  pull_varattnos((Node *) returningList, rtindex,
2010  &attrs_used);
2011  }
2012 
2013  if (attrs_used != NULL)
2014  deparseTargetList(buf, rte, rtindex, rel, true, attrs_used, false,
2015  retrieved_attrs);
2016  else
2017  *retrieved_attrs = NIL;
2018 }
2019 
2020 /*
2021  * Construct SELECT statement to acquire size in blocks of given relation.
2022  *
2023  * Note: we use local definition of block size, not remote definition.
2024  * This is perhaps debatable.
2025  *
2026  * Note: pg_relation_size() exists in 8.1 and later.
2027  */
2028 void
2029 deparseAnalyzeSizeSql(StringInfo buf, Relation rel)
2030 {
2031  StringInfoData relname;
2032 
2033  /* We'll need the remote relation name as a literal. */
2034  initStringInfo(&relname);
2035  deparseRelation(&relname, rel);
2036 
2037  appendStringInfoString(buf, "SELECT pg_catalog.pg_relation_size(");
2038  deparseStringLiteral(buf, relname.data);
2039  appendStringInfo(buf, "::pg_catalog.regclass) / %d", BLCKSZ);
2040 }
2041 
2042 /*
2043  * Construct SELECT statement to acquire sample rows of given relation.
2044  *
2045  * SELECT command is appended to buf, and list of columns retrieved
2046  * is returned to *retrieved_attrs.
2047  */
2048 void
2049 deparseAnalyzeSql(StringInfo buf, Relation rel, List **retrieved_attrs)
2050 {
2051  Oid relid = RelationGetRelid(rel);
2052  TupleDesc tupdesc = RelationGetDescr(rel);
2053  int i;
2054  char *colname;
2055  List *options;
2056  ListCell *lc;
2057  bool first = true;
2058 
2059  *retrieved_attrs = NIL;
2060 
2061  appendStringInfoString(buf, "SELECT ");
2062  for (i = 0; i < tupdesc->natts; i++)
2063  {
2064  /* Ignore dropped columns. */
2065  if (TupleDescAttr(tupdesc, i)->attisdropped)
2066  continue;
2067 
2068  if (!first)
2069  appendStringInfoString(buf, ", ");
2070  first = false;
2071 
2072  /* Use attribute name or column_name option. */
2073  colname = NameStr(TupleDescAttr(tupdesc, i)->attname);
2074  options = GetForeignColumnOptions(relid, i + 1);
2075 
2076  foreach(lc, options)
2077  {
2078  DefElem *def = (DefElem *) lfirst(lc);
2079 
2080  if (strcmp(def->defname, "column_name") == 0)
2081  {
2082  colname = defGetString(def);
2083  break;
2084  }
2085  }
2086 
2087  appendStringInfoString(buf, quote_identifier(colname));
2088 
2089  *retrieved_attrs = lappend_int(*retrieved_attrs, i + 1);
2090  }
2091 
2092  /* Don't generate bad syntax for zero-column relation. */
2093  if (first)
2094  appendStringInfoString(buf, "NULL");
2095 
2096  /*
2097  * Construct FROM clause
2098  */
2099  appendStringInfoString(buf, " FROM ");
2100  deparseRelation(buf, rel);
2101 }
2102 
2103 /*
2104  * Construct name to use for given column, and emit it into buf.
2105  * If it has a column_name FDW option, use that instead of attribute name.
2106  *
2107  * If qualify_col is true, qualify column name with the alias of relation.
2108  */
2109 static void
2110 deparseColumnRef(StringInfo buf, int varno, int varattno, RangeTblEntry *rte,
2111  bool qualify_col)
2112 {
2113  /* We support fetching the remote side's CTID and OID. */
2114  if (varattno == SelfItemPointerAttributeNumber)
2115  {
2116  if (qualify_col)
2117  ADD_REL_QUALIFIER(buf, varno);
2118  appendStringInfoString(buf, "ctid");
2119  }
2120  else if (varattno < 0)
2121  {
2122  /*
2123  * All other system attributes are fetched as 0, except for table OID,
2124  * which is fetched as the local table OID. However, we must be
2125  * careful; the table could be beneath an outer join, in which case it
2126  * must go to NULL whenever the rest of the row does.
2127  */
2128  Oid fetchval = 0;
2129 
2130  if (varattno == TableOidAttributeNumber)
2131  fetchval = rte->relid;
2132 
2133  if (qualify_col)
2134  {
2135  appendStringInfoString(buf, "CASE WHEN (");
2136  ADD_REL_QUALIFIER(buf, varno);
2137  appendStringInfo(buf, "*)::text IS NOT NULL THEN %u END", fetchval);
2138  }
2139  else
2140  appendStringInfo(buf, "%u", fetchval);
2141  }
2142  else if (varattno == 0)
2143  {
2144  /* Whole row reference */
2145  Relation rel;
2146  Bitmapset *attrs_used;
2147 
2148  /* Required only to be passed down to deparseTargetList(). */
2149  List *retrieved_attrs;
2150 
2151  /*
2152  * The lock on the relation will be held by upper callers, so it's
2153  * fine to open it with no lock here.
2154  */
2155  rel = table_open(rte->relid, NoLock);
2156 
2157  /*
2158  * The local name of the foreign table can not be recognized by the
2159  * foreign server and the table it references on foreign server might
2160  * have different column ordering or different columns than those
2161  * declared locally. Hence we have to deparse whole-row reference as
2162  * ROW(columns referenced locally). Construct this by deparsing a
2163  * "whole row" attribute.
2164  */
2165  attrs_used = bms_add_member(NULL,
2166  0 - FirstLowInvalidHeapAttributeNumber);
2167 
2168  /*
2169  * In case the whole-row reference is under an outer join then it has
2170  * to go NULL whenever the rest of the row goes NULL. Deparsing a join
2171  * query would always involve multiple relations, thus qualify_col
2172  * would be true.
2173  */
2174  if (qualify_col)
2175  {
2176  appendStringInfoString(buf, "CASE WHEN (");
2177  ADD_REL_QUALIFIER(buf, varno);
2178  appendStringInfoString(buf, "*)::text IS NOT NULL THEN ");
2179  }
2180 
2181  appendStringInfoString(buf, "ROW(");
2182  deparseTargetList(buf, rte, varno, rel, false, attrs_used, qualify_col,
2183  &retrieved_attrs);
2184  appendStringInfoChar(buf, ')');
2185 
2186  /* Complete the CASE WHEN statement started above. */
2187  if (qualify_col)
2188  appendStringInfoString(buf, " END");
2189 
2190  table_close(rel, NoLock);
2191  bms_free(attrs_used);
2192  }
2193  else
2194  {
2195  char *colname = NULL;
2196  List *options;
2197  ListCell *lc;
2198 
2199  /* varno must not be any of OUTER_VAR, INNER_VAR and INDEX_VAR. */
2200  Assert(!IS_SPECIAL_VARNO(varno));
2201 
2202  /*
2203  * If it's a column of a foreign table, and it has the column_name FDW
2204  * option, use that value.
2205  */
2206  options = GetForeignColumnOptions(rte->relid, varattno);
2207  foreach(lc, options)
2208  {
2209  DefElem *def = (DefElem *) lfirst(lc);
2210 
2211  if (strcmp(def->defname, "column_name") == 0)
2212  {
2213  colname = defGetString(def);
2214  break;
2215  }
2216  }
2217 
2218  /*
2219  * If it's a column of a regular table or it doesn't have column_name
2220  * FDW option, use attribute name.
2221  */
2222  if (colname == NULL)
2223  colname = get_attname(rte->relid, varattno, false);
2224 
2225  if (qualify_col)
2226  ADD_REL_QUALIFIER(buf, varno);
2227 
2228  appendStringInfoString(buf, quote_identifier(colname));
2229  }
2230 }
2231 
2232 /*
2233  * Append remote name of specified foreign table to buf.
2234  * Use value of table_name FDW option (if any) instead of relation's name.
2235  * Similarly, schema_name FDW option overrides schema name.
2236  */
2237 static void
2238 deparseRelation(StringInfo buf, Relation rel)
2239 {
2240  ForeignTable *table;
2241  const char *nspname = NULL;
2242  const char *relname = NULL;
2243  ListCell *lc;
2244 
2245  /* obtain additional catalog information. */
2246  table = GetForeignTable(RelationGetRelid(rel));
2247 
2248  /*
2249  * Use value of FDW options if any, instead of the name of object itself.
2250  */
2251  foreach(lc, table->options)
2252  {
2253  DefElem *def = (DefElem *) lfirst(lc);
2254 
2255  if (strcmp(def->defname, "schema_name") == 0)
2256  nspname = defGetString(def);
2257  else if (strcmp(def->defname, "table_name") == 0)
2258  relname = defGetString(def);
2259  }
2260 
2261  /*
2262  * Note: we could skip printing the schema name if it's pg_catalog, but
2263  * that doesn't seem worth the trouble.
2264  */
2265  if (nspname == NULL)
2266  nspname = get_namespace_name(RelationGetNamespace(rel));
2267  if (relname == NULL)
2268  relname = RelationGetRelationName(rel);
2269 
2270  appendStringInfo(buf, "%s.%s",
2271  quote_identifier(nspname), quote_identifier(relname));
2272 }
2273 
2274 /*
2275  * Append a SQL string literal representing "val" to buf.
2276  */
2277 void
2278 deparseStringLiteral(StringInfo buf, const char *val)
2279 {
2280  const char *valptr;
2281 
2282  /*
2283  * Rather than making assumptions about the remote server's value of
2284  * standard_conforming_strings, always use E'foo' syntax if there are any
2285  * backslashes. This will fail on remote servers before 8.1, but those
2286  * are long out of support.
2287  */
2288  if (strchr(val, '\\') != NULL)
2289  appendStringInfoChar(buf, ESCAPE_STRING_SYNTAX);
2290  appendStringInfoChar(buf, '\'');
2291  for (valptr = val; *valptr; valptr++)
2292  {
2293  char ch = *valptr;
2294 
2295  if (SQL_STR_DOUBLE(ch, true))
2296  appendStringInfoChar(buf, ch);
2297  appendStringInfoChar(buf, ch);
2298  }
2299  appendStringInfoChar(buf, '\'');
2300 }
2301 
2302 /*
2303  * Deparse given expression into context->buf.
2304  *
2305  * This function must support all the same node types that foreign_expr_walker
2306  * accepts.
2307  *
2308  * Note: unlike ruleutils.c, we just use a simple hard-wired parenthesization
2309  * scheme: anything more complex than a Var, Const, function call or cast
2310  * should be self-parenthesized.
2311  */
2312 static void
2313 deparseExpr(Expr *node, deparse_expr_cxt *context)
2314 {
2315  if (node == NULL)
2316  return;
2317 
2318  switch (nodeTag(node))
2319  {
2320  case T_Var:
2321  deparseVar((Var *) node, context);
2322  break;
2323  case T_Const:
2324  deparseConst((Const *) node, context, 0);
2325  break;
2326  case T_Param:
2327  deparseParam((Param *) node, context);
2328  break;
2329  case T_SubscriptingRef:
2330  deparseSubscriptingRef((SubscriptingRef *) node, context);
2331  break;
2332  case T_FuncExpr:
2333  deparseFuncExpr((FuncExpr *) node, context);
2334  break;
2335  case T_OpExpr:
2336  deparseOpExpr((OpExpr *) node, context);
2337  break;
2338  case T_DistinctExpr:
2339  deparseDistinctExpr((DistinctExpr *) node, context);
2340  break;
2341  case T_ScalarArrayOpExpr:
2342  deparseScalarArrayOpExpr((ScalarArrayOpExpr *) node, context);
2343  break;
2344  case T_RelabelType:
2345  deparseRelabelType((RelabelType *) node, context);
2346  break;
2347  case T_BoolExpr:
2348  deparseBoolExpr((BoolExpr *) node, context);
2349  break;
2350  case T_NullTest:
2351  deparseNullTest((NullTest *) node, context);
2352  break;
2353  case T_ArrayExpr:
2354  deparseArrayExpr((ArrayExpr *) node, context);
2355  break;
2356  case T_Aggref:
2357  deparseAggref((Aggref *) node, context);
2358  break;
2359  default:
2360  elog(ERROR, "unsupported expression type for deparse: %d",
2361  (int) nodeTag(node));
2362  break;
2363  }
2364 }
2365 
2366 /*
2367  * Deparse given Var node into context->buf.
2368  *
2369  * If the Var belongs to the foreign relation, just print its remote name.
2370  * Otherwise, it's effectively a Param (and will in fact be a Param at
2371  * run time). Handle it the same way we handle plain Params --- see
2372  * deparseParam for comments.
2373  */
2374 static void
2375 deparseVar(Var *node, deparse_expr_cxt *context)
2376 {
2377  Relids relids = context->scanrel->relids;
2378  int relno;
2379  int colno;
2380 
2381  /* Qualify columns when multiple relations are involved. */
2382  bool qualify_col = (bms_membership(relids) == BMS_MULTIPLE);
2383 
2384  /*
2385  * If the Var belongs to the foreign relation that is deparsed as a
2386  * subquery, use the relation and column alias to the Var provided by the
2387  * subquery, instead of the remote name.
2388  */
2389  if (is_subquery_var(node, context->scanrel, &relno, &colno))
2390  {
2391  appendStringInfo(context->buf, "%s%d.%s%d",
2392  SUBQUERY_REL_ALIAS_PREFIX, relno,
2393  SUBQUERY_COL_ALIAS_PREFIX, colno);
2394  return;
2395  }
2396 
2397  if (bms_is_member(node->varno, relids) && node->varlevelsup == 0)
2398  deparseColumnRef(context->buf, node->varno, node->varattno,
2399  planner_rt_fetch(node->varno, context->root),
2400  qualify_col);
2401  else
2402  {
2403  /* Treat like a Param */
2404  if (context->params_list)
2405  {
2406  int pindex = 0;
2407  ListCell *lc;
2408 
2409  /* find its index in params_list */
2410  foreach(lc, *context->params_list)
2411  {
2412  pindex++;
2413  if (equal(node, (Node *) lfirst(lc)))
2414  break;
2415  }
2416  if (lc == NULL)
2417  {
2418  /* not in list, so add it */
2419  pindex++;
2420  *context->params_list = lappend(*context->params_list, node);
2421  }
2422 
2423  printRemoteParam(pindex, node->vartype, node->vartypmod, context);
2424  }
2425  else
2426  {
2427  printRemotePlaceholder(node->vartype, node->vartypmod, context);
2428  }
2429  }
2430 }
2431 
2432 /*
2433  * Deparse given constant value into context->buf.
2434  *
2435  * This function has to be kept in sync with ruleutils.c's get_const_expr.
2436  * As for that function, showtype can be -1 to never show "::typename" decoration,
2437  * or +1 to always show it, or 0 to show it only if the constant wouldn't be assumed
2438  * to be the right type by default.
2439  */
2440 static void
2441 deparseConst(Const *node, deparse_expr_cxt *context, int showtype)
2442 {
2443  StringInfo buf = context->buf;
2444  Oid typoutput;
2445  bool typIsVarlena;
2446  char *extval;
2447  bool isfloat = false;
2448  bool needlabel;
2449 
2450  if (node->constisnull)
2451  {
2452  appendStringInfoString(buf, "NULL");
2453  if (showtype >= 0)
2454  appendStringInfo(buf, "::%s",
2455  deparse_type_name(node->consttype,
2456  node->consttypmod));
2457  return;
2458  }
2459 
2460  getTypeOutputInfo(node->consttype,
2461  &typoutput, &typIsVarlena);
2462  extval = OidOutputFunctionCall(typoutput, node->constvalue);
2463 
2464  switch (node->consttype)
2465  {
2466  case INT2OID:
2467  case INT4OID:
2468  case INT8OID:
2469  case OIDOID:
2470  case FLOAT4OID:
2471  case FLOAT8OID:
2472  case NUMERICOID:
2473  {
2474  /*
2475  * No need to quote unless it's a special value such as 'NaN'.
2476  * See comments in get_const_expr().
2477  */
2478  if (strspn(extval, "0123456789+-eE.") == strlen(extval))
2479  {
2480  if (extval[0] == '+' || extval[0] == '-')
2481  appendStringInfo(buf, "(%s)", extval);
2482  else
2483  appendStringInfoString(buf, extval);
2484  if (strcspn(extval, "eE.") != strlen(extval))
2485  isfloat = true; /* it looks like a float */
2486  }
2487  else
2488  appendStringInfo(buf, "'%s'", extval);
2489  }
2490  break;
2491  case BITOID:
2492  case VARBITOID:
2493  appendStringInfo(buf, "B'%s'", extval);
2494  break;
2495  case BOOLOID:
2496  if (strcmp(extval, "t") == 0)
2497  appendStringInfoString(buf, "true");
2498  else
2499  appendStringInfoString(buf, "false");
2500  break;
2501  default:
2502  deparseStringLiteral(buf, extval);
2503  break;
2504  }
2505 
2506  pfree(extval);
2507 
2508  if (showtype < 0)
2509  return;
2510 
2511  /*
2512  * For showtype == 0, append ::typename unless the constant will be
2513  * implicitly typed as the right type when it is read in.
2514  *
2515  * XXX this code has to be kept in sync with the behavior of the parser,
2516  * especially make_const.
2517  */
2518  switch (node->consttype)
2519  {
2520  case BOOLOID:
2521  case INT4OID:
2522  case UNKNOWNOID:
2523  needlabel = false;
2524  break;
2525  case NUMERICOID:
2526  needlabel = !isfloat || (node->consttypmod >= 0);
2527  break;
2528  default:
2529  needlabel = true;
2530  break;
2531  }
2532  if (needlabel || showtype > 0)
2533  appendStringInfo(buf, "::%s",
2534  deparse_type_name(node->consttype,
2535  node->consttypmod));
2536 }
2537 
2538 /*
2539  * Deparse given Param node.
2540  *
2541  * If we're generating the query "for real", add the Param to
2542  * context->params_list if it's not already present, and then use its index
2543  * in that list as the remote parameter number. During EXPLAIN, there's
2544  * no need to identify a parameter number.
2545  */
2546 static void
2547 deparseParam(Param *node, deparse_expr_cxt *context)
2548 {
2549  if (context->params_list)
2550  {
2551  int pindex = 0;
2552  ListCell *lc;
2553 
2554  /* find its index in params_list */
2555  foreach(lc, *context->params_list)
2556  {
2557  pindex++;
2558  if (equal(node, (Node *) lfirst(lc)))
2559  break;
2560  }
2561  if (lc == NULL)
2562  {
2563  /* not in list, so add it */
2564  pindex++;
2565  *context->params_list = lappend(*context->params_list, node);
2566  }
2567 
2568  printRemoteParam(pindex, node->paramtype, node->paramtypmod, context);
2569  }
2570  else
2571  {
2572  printRemotePlaceholder(node->paramtype, node->paramtypmod, context);
2573  }
2574 }
2575 
2576 /*
2577  * Deparse a container subscript expression.
2578  */
2579 static void
2580 deparseSubscriptingRef(SubscriptingRef *node, deparse_expr_cxt *context)
2581 {
2582  StringInfo buf = context->buf;
2583  ListCell *lowlist_item;
2584  ListCell *uplist_item;
2585 
2586  /* Always parenthesize the expression. */
2587  appendStringInfoChar(buf, '(');
2588 
2589  /*
2590  * Deparse referenced array expression first. If that expression includes
2591  * a cast, we have to parenthesize to prevent the array subscript from
2592  * being taken as typename decoration. We can avoid that in the typical
2593  * case of subscripting a Var, but otherwise do it.
2594  */
2595  if (IsA(node->refexpr, Var))
2596  deparseExpr(node->refexpr, context);
2597  else
2598  {
2599  appendStringInfoChar(buf, '(');
2600  deparseExpr(node->refexpr, context);
2601  appendStringInfoChar(buf, ')');
2602  }
2603 
2604  /* Deparse subscript expressions. */
2605  lowlist_item = list_head(node->reflowerindexpr); /* could be NULL */
2606  foreach(uplist_item, node->refupperindexpr)
2607  {
2608  appendStringInfoChar(buf, '[');
2609  if (lowlist_item)
2610  {
2611  deparseExpr(lfirst(lowlist_item), context);
2612  appendStringInfoChar(buf, ':');
2613  lowlist_item = lnext(node->reflowerindexpr, lowlist_item);
2614  }
2615  deparseExpr(lfirst(uplist_item), context);
2616  appendStringInfoChar(buf, ']');
2617  }
2618 
2619  appendStringInfoChar(buf, ')');
2620 }
2621 
2622 /*
2623  * Deparse a function call.
2624  */
2625 static void
2626 deparseFuncExpr(FuncExpr *node, deparse_expr_cxt *context)
2627 {
2628  StringInfo buf = context->buf;
2629  bool use_variadic;
2630  bool first;
2631  ListCell *arg;
2632 
2633  /*
2634  * If the function call came from an implicit coercion, then just show the
2635  * first argument.
2636  */
2637  if (node->funcformat == COERCE_IMPLICIT_CAST)
2638  {
2639  deparseExpr((Expr *) linitial(node->args), context);
2640  return;
2641  }
2642 
2643  /*
2644  * If the function call came from a cast, then show the first argument
2645  * plus an explicit cast operation.
2646  */
2647  if (node->funcformat == COERCE_EXPLICIT_CAST)
2648  {
2649  Oid rettype = node->funcresulttype;
2650  int32 coercedTypmod;
2651 
2652  /* Get the typmod if this is a length-coercion function */
2653  (void) exprIsLengthCoercion((Node *) node, &coercedTypmod);
2654 
2655  deparseExpr((Expr *) linitial(node->args), context);
2656  appendStringInfo(buf, "::%s",
2657  deparse_type_name(rettype, coercedTypmod));
2658  return;
2659  }
2660 
2661  /* Check if need to print VARIADIC (cf. ruleutils.c) */
2662  use_variadic = node->funcvariadic;
2663 
2664  /*
2665  * Normal function: display as proname(args).
2666  */
2667  appendFunctionName(node->funcid, context);
2668  appendStringInfoChar(buf, '(');
2669 
2670  /* ... and all the arguments */
2671  first = true;
2672  foreach(arg, node->args)
2673  {
2674  if (!first)
2675  appendStringInfoString(buf, ", ");
2676  if (use_variadic && lnext(node->args, arg) == NULL)
2677  appendStringInfoString(buf, "VARIADIC ");
2678  deparseExpr((Expr *) lfirst(arg), context);
2679  first = false;
2680  }
2681  appendStringInfoChar(buf, ')');
2682 }
2683 
2684 /*
2685  * Deparse given operator expression. To avoid problems around
2686  * priority of operations, we always parenthesize the arguments.
2687  */
2688 static void
2689 deparseOpExpr(OpExpr *node, deparse_expr_cxt *context)
2690 {
2691  StringInfo buf = context->buf;
2692  HeapTuple tuple;
2693  Form_pg_operator form;
2694  char oprkind;
2695  ListCell *arg;
2696 
2697  /* Retrieve information about the operator from system catalog. */
2698  tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno));
2699  if (!HeapTupleIsValid(tuple))
2700  elog(ERROR, "cache lookup failed for operator %u", node->opno);
2701  form = (Form_pg_operator) GETSTRUCT(tuple);
2702  oprkind = form->oprkind;
2703 
2704  /* Sanity check. */
2705  Assert((oprkind == 'r' && list_length(node->args) == 1) ||
2706  (oprkind == 'l' && list_length(node->args) == 1) ||
2707  (oprkind == 'b' && list_length(node->args) == 2));
2708 
2709  /* Always parenthesize the expression. */
2710  appendStringInfoChar(buf, '(');
2711 
2712  /* Deparse left operand. */
2713  if (oprkind == 'r' || oprkind == 'b')
2714  {
2715  arg = list_head(node->args);
2716  deparseExpr(lfirst(arg), context);
2717  appendStringInfoChar(buf, ' ');
2718  }
2719 
2720  /* Deparse operator name. */
2721  deparseOperatorName(buf, form);
2722 
2723  /* Deparse right operand. */
2724  if (oprkind == 'l' || oprkind == 'b')
2725  {
2726  arg = list_tail(node->args);
2727  appendStringInfoChar(buf, ' ');
2728  deparseExpr(lfirst(arg), context);
2729  }
2730 
2731  appendStringInfoChar(buf, ')');
2732 
2733  ReleaseSysCache(tuple);
2734 }
2735 
2736 /*
2737  * Print the name of an operator.
2738  */
2739 static void
2740 deparseOperatorName(StringInfo buf, Form_pg_operator opform)
2741 {
2742  char *opname;
2743 
2744  /* opname is not a SQL identifier, so we should not quote it. */
2745  opname = NameStr(opform->oprname);
2746 
2747  /* Print schema name only if it's not pg_catalog */
2748  if (opform->oprnamespace != PG_CATALOG_NAMESPACE)
2749  {
2750  const char *opnspname;
2751 
2752  opnspname = get_namespace_name(opform->oprnamespace);
2753  /* Print fully qualified operator name. */
2754  appendStringInfo(buf, "OPERATOR(%s.%s)",
2755  quote_identifier(opnspname), opname);
2756  }
2757  else
2758  {
2759  /* Just print operator name. */
2760  appendStringInfoString(buf, opname);
2761  }
2762 }
2763 
2764 /*
2765  * Deparse IS DISTINCT FROM.
2766  */
2767 static void
2768 deparseDistinctExpr(DistinctExpr *node, deparse_expr_cxt *context)
2769 {
2770  StringInfo buf = context->buf;
2771 
2772  Assert(list_length(node->args) == 2);
2773 
2774  appendStringInfoChar(buf, '(');
2775  deparseExpr(linitial(node->args), context);
2776  appendStringInfoString(buf, " IS DISTINCT FROM ");
2777  deparseExpr(lsecond(node->args), context);
2778  appendStringInfoChar(buf, ')');
2779 }
2780 
2781 /*
2782  * Deparse given ScalarArrayOpExpr expression. To avoid problems
2783  * around priority of operations, we always parenthesize the arguments.
2784  */
2785 static void
2786 deparseScalarArrayOpExpr(ScalarArrayOpExpr *node, deparse_expr_cxt *context)
2787 {
2788  StringInfo buf = context->buf;
2789  HeapTuple tuple;
2790  Form_pg_operator form;
2791  Expr *arg1;
2792  Expr *arg2;
2793 
2794  /* Retrieve information about the operator from system catalog. */
2795  tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno));
2796  if (!HeapTupleIsValid(tuple))
2797  elog(ERROR, "cache lookup failed for operator %u", node->opno);
2798  form = (Form_pg_operator) GETSTRUCT(tuple);
2799 
2800  /* Sanity check. */
2801  Assert(list_length(node->args) == 2);
2802 
2803  /* Always parenthesize the expression. */
2804  appendStringInfoChar(buf, '(');
2805 
2806  /* Deparse left operand. */
2807  arg1 = linitial(node->args);
2808  deparseExpr(arg1, context);
2809  appendStringInfoChar(buf, ' ');
2810 
2811  /* Deparse operator name plus decoration. */
2812  deparseOperatorName(buf, form);
2813  appendStringInfo(buf, " %s (", node->useOr ? "ANY" : "ALL");
2814 
2815  /* Deparse right operand. */
2816  arg2 = lsecond(node->args);
2817  deparseExpr(arg2, context);
2818 
2819  appendStringInfoChar(buf, ')');
2820 
2821  /* Always parenthesize the expression. */
2822  appendStringInfoChar(buf, ')');
2823 
2824  ReleaseSysCache(tuple);
2825 }
2826 
2827 /*
2828  * Deparse a RelabelType (binary-compatible cast) node.
2829  */
2830 static void
2831 deparseRelabelType(RelabelType *node, deparse_expr_cxt *context)
2832 {
2833  deparseExpr(node->arg, context);
2834  if (node->relabelformat != COERCE_IMPLICIT_CAST)
2835  appendStringInfo(context->buf, "::%s",
2836  deparse_type_name(node->resulttype,
2837  node->resulttypmod));
2838 }
2839 
2840 /*
2841  * Deparse a BoolExpr node.
2842  */
2843 static void
2844 deparseBoolExpr(BoolExpr *node, deparse_expr_cxt *context)
2845 {
2846  StringInfo buf = context->buf;
2847  const char *op = NULL; /* keep compiler quiet */
2848  bool first;
2849  ListCell *lc;
2850 
2851  switch (node->boolop)
2852  {
2853  case AND_EXPR:
2854  op = "AND";
2855  break;
2856  case OR_EXPR:
2857  op = "OR";
2858  break;
2859  case NOT_EXPR:
2860  appendStringInfoString(buf, "(NOT ");
2861  deparseExpr(linitial(node->args), context);
2862  appendStringInfoChar(buf, ')');
2863  return;
2864  }
2865 
2866  appendStringInfoChar(buf, '(');
2867  first = true;
2868  foreach(lc, node->args)
2869  {
2870  if (!first)
2871  appendStringInfo(buf, " %s ", op);
2872  deparseExpr((Expr *) lfirst(lc), context);
2873  first = false;
2874  }
2875  appendStringInfoChar(buf, ')');
2876 }
2877 
2878 /*
2879  * Deparse IS [NOT] NULL expression.
2880  */
2881 static void
2882 deparseNullTest(NullTest *node, deparse_expr_cxt *context)
2883 {
2884  StringInfo buf = context->buf;
2885 
2886  appendStringInfoChar(buf, '(');
2887  deparseExpr(node->arg, context);
2888 
2889  /*
2890  * For scalar inputs, we prefer to print as IS [NOT] NULL, which is
2891  * shorter and traditional. If it's a rowtype input but we're applying a
2892  * scalar test, must print IS [NOT] DISTINCT FROM NULL to be semantically
2893  * correct.
2894  */
2895  if (node->argisrow || !type_is_rowtype(exprType((Node *) node->arg)))
2896  {
2897  if (node->nulltesttype == IS_NULL)
2898  appendStringInfoString(buf, " IS NULL)");
2899  else
2900  appendStringInfoString(buf, " IS NOT NULL)");
2901  }
2902  else
2903  {
2904  if (node->nulltesttype == IS_NULL)
2905  appendStringInfoString(buf, " IS NOT DISTINCT FROM NULL)");
2906  else
2907  appendStringInfoString(buf, " IS DISTINCT FROM NULL)");
2908  }
2909 }
2910 
2911 /*
2912  * Deparse ARRAY[...] construct.
2913  */
2914 static void
2915 deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context)
2916 {
2917  StringInfo buf = context->buf;
2918  bool first = true;
2919  ListCell *lc;
2920 
2921  appendStringInfoString(buf, "ARRAY[");
2922  foreach(lc, node->elements)
2923  {
2924  if (!first)
2925  appendStringInfoString(buf, ", ");
2926  deparseExpr(lfirst(lc), context);
2927  first = false;
2928  }
2929  appendStringInfoChar(buf, ']');
2930 
2931  /* If the array is empty, we need an explicit cast to the array type. */
2932  if (node->elements == NIL)
2933  appendStringInfo(buf, "::%s",
2934  deparse_type_name(node->array_typeid, -1));
2935 }
2936 
2937 /*
2938  * Deparse an Aggref node.
2939  */
2940 static void
2941 deparseAggref(Aggref *node, deparse_expr_cxt *context)
2942 {
2943  StringInfo buf = context->buf;
2944  bool use_variadic;
2945 
2946  /* Only basic, non-split aggregation accepted. */
2947  Assert(node->aggsplit == AGGSPLIT_SIMPLE);
2948 
2949  /* Check if need to print VARIADIC (cf. ruleutils.c) */
2950  use_variadic = node->aggvariadic;
2951 
2952  /* Find aggregate name from aggfnoid which is a pg_proc entry */
2953  appendFunctionName(node->aggfnoid, context);
2954  appendStringInfoChar(buf, '(');
2955 
2956  /* Add DISTINCT */
2957  appendStringInfoString(buf, (node->aggdistinct != NIL) ? "DISTINCT " : "");
2958 
2959  if (AGGKIND_IS_ORDERED_SET(node->aggkind))
2960  {
2961  /* Add WITHIN GROUP (ORDER BY ..) */
2962  ListCell *arg;
2963  bool first = true;
2964 
2965  Assert(!node->aggvariadic);
2966  Assert(node->aggorder != NIL);
2967 
2968  foreach(arg, node->aggdirectargs)
2969  {
2970  if (!first)
2971  appendStringInfoString(buf, ", ");
2972  first = false;
2973 
2974  deparseExpr((Expr *) lfirst(arg), context);
2975  }
2976 
2977  appendStringInfoString(buf, ") WITHIN GROUP (ORDER BY ");
2978  appendAggOrderBy(node->aggorder, node->args, context);
2979  }
2980  else
2981  {
2982  /* aggstar can be set only in zero-argument aggregates */
2983  if (node->aggstar)
2984  appendStringInfoChar(buf, '*');
2985  else
2986  {
2987  ListCell *arg;
2988  bool first = true;
2989 
2990  /* Add all the arguments */
2991  foreach(arg, node->args)
2992  {
2993  TargetEntry *tle = (TargetEntry *) lfirst(arg);
2994  Node *n = (Node *) tle->expr;
2995 
2996  if (tle->resjunk)
2997  continue;
2998 
2999  if (!first)
3000  appendStringInfoString(buf, ", ");
3001  first = false;
3002 
3003  /* Add VARIADIC */
3004  if (use_variadic && lnext(node->args, arg) == NULL)
3005  appendStringInfoString(buf, "VARIADIC ");
3006 
3007  deparseExpr((Expr *) n, context);
3008  }
3009  }
3010 
3011  /* Add ORDER BY */
3012  if (node->aggorder != NIL)
3013  {
3014  appendStringInfoString(buf, " ORDER BY ");
3015  appendAggOrderBy(node->aggorder, node->args, context);
3016  }
3017  }
3018 
3019  /* Add FILTER (WHERE ..) */
3020  if (node->aggfilter != NULL)
3021  {
3022  appendStringInfoString(buf, ") FILTER (WHERE ");
3023  deparseExpr((Expr *) node->aggfilter, context);
3024  }
3025 
3026  appendStringInfoChar(buf, ')');
3027 }
3028 
3029 /*
3030  * Append ORDER BY within aggregate function.
3031  */
3032 static void
3033 appendAggOrderBy(List *orderList, List *targetList, deparse_expr_cxt *context)
3034 {
3035  StringInfo buf = context->buf;
3036  ListCell *lc;
3037  bool first = true;
3038 
3039  foreach(lc, orderList)
3040  {
3041  SortGroupClause *srt = (SortGroupClause *) lfirst(lc);
3042  Node *sortexpr;
3043  Oid sortcoltype;
3044  TypeCacheEntry *typentry;
3045 
3046  if (!first)
3047  appendStringInfoString(buf, ", ");
3048  first = false;
3049 
3050  sortexpr = deparseSortGroupClause(srt->tleSortGroupRef, targetList,
3051  false, context);
3052  sortcoltype = exprType(sortexpr);
3053  /* See whether operator is default < or > for datatype */
3054  typentry = lookup_type_cache(sortcoltype,
3055  TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
3056  if (srt->sortop == typentry->lt_opr)
3057  appendStringInfoString(buf, " ASC");
3058  else if (srt->sortop == typentry->gt_opr)
3059  appendStringInfoString(buf, " DESC");
3060  else
3061  {
3062  HeapTuple opertup;
3063  Form_pg_operator operform;
3064 
3065  appendStringInfoString(buf, " USING ");
3066 
3067  /* Append operator name. */
3068  opertup = SearchSysCache1(OPEROID, ObjectIdGetDatum(srt->sortop));
3069  if (!HeapTupleIsValid(opertup))
3070  elog(ERROR, "cache lookup failed for operator %u", srt->sortop);
3071  operform = (Form_pg_operator) GETSTRUCT(opertup);
3072  deparseOperatorName(buf, operform);
3073  ReleaseSysCache(opertup);
3074  }
3075 
3076  if (srt->nulls_first)
3077  appendStringInfoString(buf, " NULLS FIRST");
3078  else
3079  appendStringInfoString(buf, " NULLS LAST");
3080  }
3081 }
3082 
3083 /*
3084  * Print the representation of a parameter to be sent to the remote side.
3085  *
3086  * Note: we always label the Param's type explicitly rather than relying on
3087  * transmitting a numeric type OID in PQexecParams(). This allows us to
3088  * avoid assuming that types have the same OIDs on the remote side as they
3089  * do locally --- they need only have the same names.
3090  */
3091 static void
3092 printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod,
3093  deparse_expr_cxt *context)
3094 {
3095  StringInfo buf = context->buf;
3096  char *ptypename = deparse_type_name(paramtype, paramtypmod);
3097 
3098  appendStringInfo(buf, "$%d::%s", paramindex, ptypename);
3099 }
3100 
3101 /*
3102  * Print the representation of a placeholder for a parameter that will be
3103  * sent to the remote side at execution time.
3104  *
3105  * This is used when we're just trying to EXPLAIN the remote query.
3106  * We don't have the actual value of the runtime parameter yet, and we don't
3107  * want the remote planner to generate a plan that depends on such a value
3108  * anyway. Thus, we can't do something simple like "$1::paramtype".
3109  * Instead, we emit "((SELECT null::paramtype)::paramtype)".
3110  * In all extant versions of Postgres, the planner will see that as an unknown
3111  * constant value, which is what we want. This might need adjustment if we
3112  * ever make the planner flatten scalar subqueries. Note: the reason for the
3113  * apparently useless outer cast is to ensure that the representation as a
3114  * whole will be parsed as an a_expr and not a select_with_parens; the latter
3115  * would do the wrong thing in the context "x = ANY(...)".
3116  */
3117 static void
3118 printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
3119  deparse_expr_cxt *context)
3120 {
3121  StringInfo buf = context->buf;
3122  char *ptypename = deparse_type_name(paramtype, paramtypmod);
3123 
3124  appendStringInfo(buf, "((SELECT null::%s)::%s)", ptypename, ptypename);
3125 }
3126 
3127 /*
3128  * Deparse GROUP BY clause.
3129  */
3130 static void
3131 appendGroupByClause(List *tlist, deparse_expr_cxt *context)
3132 {
3133  StringInfo buf = context->buf;
3134  Query *query = context->root->parse;
3135  ListCell *lc;
3136  bool first = true;
3137 
3138  /* Nothing to be done, if there's no GROUP BY clause in the query. */
3139  if (!query->groupClause)
3140  return;
3141 
3142  appendStringInfoString(buf, " GROUP BY ");
3143 
3144  /*
3145  * Queries with grouping sets are not pushed down, so we don't expect
3146  * grouping sets here.
3147  */
3148  Assert(!query->groupingSets);
3149 
3150  foreach(lc, query->groupClause)
3151  {
3152  SortGroupClause *grp = (SortGroupClause *) lfirst(lc);
3153 
3154  if (!first)
3155  appendStringInfoString(buf, ", ");
3156  first = false;
3157 
3158  deparseSortGroupClause(grp->tleSortGroupRef, tlist, true, context);
3159  }
3160 }
3161 
3162 /*
3163  * Deparse ORDER BY clause according to the given pathkeys for given base
3164  * relation. From given pathkeys expressions belonging entirely to the given
3165  * base relation are obtained and deparsed.
3166  */
3167 static void
3168 appendOrderByClause(List *pathkeys, bool has_final_sort,
3169  deparse_expr_cxt *context)
3170 {
3171  ListCell *lcell;
3172  int nestlevel;
3173  char *delim = " ";
3174  RelOptInfo *baserel = context->scanrel;
3175  StringInfo buf = context->buf;
3176 
3177  /* Make sure any constants in the exprs are printed portably */
3178  nestlevel = set_transmission_modes();
3179 
3180  appendStringInfoString(buf, " ORDER BY");
3181  foreach(lcell, pathkeys)
3182  {
3183  PathKey *pathkey = lfirst(lcell);
3184  Expr *em_expr;
3185 
3186  if (has_final_sort)
3187  {
3188  /*
3189  * By construction, context->foreignrel is the input relation to
3190  * the final sort.
3191  */
3192  em_expr = find_em_expr_for_input_target(context->root,
3193  pathkey->pk_eclass,
3194  context->foreignrel->reltarget);
3195  }
3196  else
3197  em_expr = find_em_expr_for_rel(pathkey->pk_eclass, baserel);
3198 
3199  Assert(em_expr != NULL);
3200 
3201  appendStringInfoString(buf, delim);
3202  deparseExpr(em_expr, context);
3203  if (pathkey->pk_strategy == BTLessStrategyNumber)
3204  appendStringInfoString(buf, " ASC");
3205  else
3206  appendStringInfoString(buf, " DESC");
3207 
3208  if (pathkey->pk_nulls_first)
3209  appendStringInfoString(buf, " NULLS FIRST");
3210  else
3211  appendStringInfoString(buf, " NULLS LAST");
3212 
3213  delim = ", ";
3214  }
3215  reset_transmission_modes(nestlevel);
3216 }
3217 
3218 /*
3219  * Deparse LIMIT/OFFSET clause.
3220  */
3221 static void
3222 appendLimitClause(deparse_expr_cxt *context)
3223 {
3224  PlannerInfo *root = context->root;
3225  StringInfo buf = context->buf;
3226  int nestlevel;
3227 
3228  /* Make sure any constants in the exprs are printed portably */
3229  nestlevel = set_transmission_modes();
3230 
3231  if (root->parse->limitCount)
3232  {
3233  appendStringInfoString(buf, " LIMIT ");
3234  deparseExpr((Expr *) root->parse->limitCount, context);
3235  }
3236  if (root->parse->limitOffset)
3237  {
3238  appendStringInfoString(buf, " OFFSET ");
3239  deparseExpr((Expr *) root->parse->limitOffset, context);
3240  }
3241 
3242  reset_transmission_modes(nestlevel);
3243 }
3244 
3245 /*
3246  * appendFunctionName
3247  * Deparses function name from given function oid.
3248  */
3249 static void
3250 appendFunctionName(Oid funcid, deparse_expr_cxt *context)
3251 {
3252  StringInfo buf = context->buf;
3253  HeapTuple proctup;
3254  Form_pg_proc procform;
3255  const char *proname;
3256 
3257  proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
3258  if (!HeapTupleIsValid(proctup))
3259  elog(ERROR, "cache lookup failed for function %u", funcid);
3260  procform = (Form_pg_proc) GETSTRUCT(proctup);
3261 
3262  /* Print schema name only if it's not pg_catalog */
3263  if (procform->pronamespace != PG_CATALOG_NAMESPACE)
3264  {
3265  const char *schemaname;
3266 
3267  schemaname = get_namespace_name(procform->pronamespace);
3268  appendStringInfo(buf, "%s.", quote_identifier(schemaname));
3269  }
3270 
3271  /* Always print the function name */
3272  proname = NameStr(procform->proname);
3273  appendStringInfoString(buf, quote_identifier(proname));
3274 
3275  ReleaseSysCache(proctup);
3276 }
3277 
3278 /*
3279  * Appends a sort or group clause.
3280  *
3281  * Like get_rule_sortgroupclause(), returns the expression tree, so caller
3282  * need not find it again.
3283  */
3284 static Node *
3285 deparseSortGroupClause(Index ref, List *tlist, bool force_colno,
3286  deparse_expr_cxt *context)
3287 {
3288  StringInfo buf = context->buf;
3289  TargetEntry *tle;
3290  Expr *expr;
3291 
3292  tle = get_sortgroupref_tle(ref, tlist);
3293  expr = tle->expr;
3294 
3295  if (force_colno)
3296  {
3297  /* Use column-number form when requested by caller. */
3298  Assert(!tle->resjunk);
3299  appendStringInfo(buf, "%d", tle->resno);
3300  }
3301  else if (expr && IsA(expr, Const))
3302  {
3303  /*
3304  * Force a typecast here so that we don't emit something like "GROUP
3305  * BY 2", which will be misconstrued as a column position rather than
3306  * a constant.
3307  */
3308  deparseConst((Const *) expr, context, 1);
3309  }
3310  else if (!expr || IsA(expr, Var))
3311  deparseExpr(expr, context);
3312  else
3313  {
3314  /* Always parenthesize the expression. */
3315  appendStringInfoChar(buf, '(');
3316  deparseExpr(expr, context);
3317  appendStringInfoChar(buf, ')');
3318  }
3319 
3320  return (Node *) expr;
3321 }
3322 
3323 
3324 /*
3325  * Returns true if given Var is deparsed as a subquery output column, in
3326  * which case, *relno and *colno are set to the IDs for the relation and
3327  * column alias to the Var provided by the subquery.
3328  */
3329 static bool
3330 is_subquery_var(Var *node, RelOptInfo *foreignrel, int *relno, int *colno)
3331 {
3332  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
3333  RelOptInfo *outerrel = fpinfo->outerrel;
3334  RelOptInfo *innerrel = fpinfo->innerrel;
3335 
3336  /* Should only be called in these cases. */
3337  Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
3338 
3339  /*
3340  * If the given relation isn't a join relation, it doesn't have any lower
3341  * subqueries, so the Var isn't a subquery output column.
3342  */
3343  if (!IS_JOIN_REL(foreignrel))
3344  return false;
3345 
3346  /*
3347  * If the Var doesn't belong to any lower subqueries, it isn't a subquery
3348  * output column.
3349  */
3350  if (!bms_is_member(node->varno, fpinfo->lower_subquery_rels))
3351  return false;
3352 
3353  if (bms_is_member(node->varno, outerrel->relids))
3354  {
3355  /*
3356  * If outer relation is deparsed as a subquery, the Var is an output
3357  * column of the subquery; get the IDs for the relation/column alias.
3358  */
3359  if (fpinfo->make_outerrel_subquery)
3360  {
3361  get_relation_column_alias_ids(node, outerrel, relno, colno);
3362  return true;
3363  }
3364 
3365  /* Otherwise, recurse into the outer relation. */
3366  return is_subquery_var(node, outerrel, relno, colno);
3367  }
3368  else
3369  {
3370  Assert(bms_is_member(node->varno, innerrel->relids));
3371 
3372  /*
3373  * If inner relation is deparsed as a subquery, the Var is an output
3374  * column of the subquery; get the IDs for the relation/column alias.
3375  */
3376  if (fpinfo->make_innerrel_subquery)
3377  {
3378  get_relation_column_alias_ids(node, innerrel, relno, colno);
3379  return true;
3380  }
3381 
3382  /* Otherwise, recurse into the inner relation. */
3383  return is_subquery_var(node, innerrel, relno, colno);
3384  }
3385 }
3386 
3387 /*
3388  * Get the IDs for the relation and column alias to given Var belonging to
3389  * given relation, which are returned into *relno and *colno.
3390  */
3391 static void
3392 get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
3393  int *relno, int *colno)
3394 {
3395  PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
3396  int i;
3397  ListCell *lc;
3398 
3399  /* Get the relation alias ID */
3400  *relno = fpinfo->relation_index;
3401 
3402  /* Get the column alias ID */
3403  i = 1;
3404  foreach(lc, foreignrel->reltarget->exprs)
3405  {
3406  if (equal(lfirst(lc), (Node *) node))
3407  {
3408  *colno = i;
3409  return;
3410  }
3411  i++;
3412  }
3413 
3414  /* Shouldn't get here */
3415  elog(ERROR, "unexpected expression in subquery output");
3416 }
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