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plancache.c
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1 /*-------------------------------------------------------------------------
2  *
3  * plancache.c
4  * Plan cache management.
5  *
6  * The plan cache manager has two principal responsibilities: deciding when
7  * to use a generic plan versus a custom (parameter-value-specific) plan,
8  * and tracking whether cached plans need to be invalidated because of schema
9  * changes in the objects they depend on.
10  *
11  * The logic for choosing generic or custom plans is in choose_custom_plan,
12  * which see for comments.
13  *
14  * Cache invalidation is driven off sinval events. Any CachedPlanSource
15  * that matches the event is marked invalid, as is its generic CachedPlan
16  * if it has one. When (and if) the next demand for a cached plan occurs,
17  * parse analysis and rewrite is repeated to build a new valid query tree,
18  * and then planning is performed as normal. We also force re-analysis and
19  * re-planning if the active search_path is different from the previous time
20  * or, if RLS is involved, if the user changes or the RLS environment changes.
21  *
22  * Note that if the sinval was a result of user DDL actions, parse analysis
23  * could throw an error, for example if a column referenced by the query is
24  * no longer present. Another possibility is for the query's output tupdesc
25  * to change (for instance "SELECT *" might expand differently than before).
26  * The creator of a cached plan can specify whether it is allowable for the
27  * query to change output tupdesc on replan --- if so, it's up to the
28  * caller to notice changes and cope with them.
29  *
30  * Currently, we track exactly the dependencies of plans on relations,
31  * user-defined functions, and domains. On relcache invalidation events or
32  * pg_proc or pg_type syscache invalidation events, we invalidate just those
33  * plans that depend on the particular object being modified. (Note: this
34  * scheme assumes that any table modification that requires replanning will
35  * generate a relcache inval event.) We also watch for inval events on
36  * certain other system catalogs, such as pg_namespace; but for them, our
37  * response is just to invalidate all plans. We expect updates on those
38  * catalogs to be infrequent enough that more-detailed tracking is not worth
39  * the effort.
40  *
41  * In addition to full-fledged query plans, we provide a facility for
42  * detecting invalidations of simple scalar expressions. This is fairly
43  * bare-bones; it's the caller's responsibility to build a new expression
44  * if the old one gets invalidated.
45  *
46  *
47  * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
48  * Portions Copyright (c) 1994, Regents of the University of California
49  *
50  * IDENTIFICATION
51  * src/backend/utils/cache/plancache.c
52  *
53  *-------------------------------------------------------------------------
54  */
55 #include "postgres.h"
56 
57 #include <limits.h>
58 
59 #include "access/transam.h"
60 #include "catalog/namespace.h"
61 #include "executor/executor.h"
62 #include "miscadmin.h"
63 #include "nodes/nodeFuncs.h"
64 #include "optimizer/optimizer.h"
65 #include "parser/analyze.h"
66 #include "parser/parsetree.h"
67 #include "storage/lmgr.h"
68 #include "tcop/pquery.h"
69 #include "tcop/utility.h"
70 #include "utils/inval.h"
71 #include "utils/memutils.h"
72 #include "utils/resowner_private.h"
73 #include "utils/rls.h"
74 #include "utils/snapmgr.h"
75 #include "utils/syscache.h"
76 
77 
78 /*
79  * We must skip "overhead" operations that involve database access when the
80  * cached plan's subject statement is a transaction control command.
81  */
82 #define IsTransactionStmtPlan(plansource) \
83  ((plansource)->raw_parse_tree && \
84  IsA((plansource)->raw_parse_tree->stmt, TransactionStmt))
85 
86 /*
87  * This is the head of the backend's list of "saved" CachedPlanSources (i.e.,
88  * those that are in long-lived storage and are examined for sinval events).
89  * We use a dlist instead of separate List cells so that we can guarantee
90  * to save a CachedPlanSource without error.
91  */
92 static dlist_head saved_plan_list = DLIST_STATIC_INIT(saved_plan_list);
93 
94 /*
95  * This is the head of the backend's list of CachedExpressions.
96  */
97 static dlist_head cached_expression_list = DLIST_STATIC_INIT(cached_expression_list);
98 
99 static void ReleaseGenericPlan(CachedPlanSource *plansource);
100 static List *RevalidateCachedQuery(CachedPlanSource *plansource,
101  QueryEnvironment *queryEnv);
102 static bool CheckCachedPlan(CachedPlanSource *plansource);
103 static CachedPlan *BuildCachedPlan(CachedPlanSource *plansource, List *qlist,
104  ParamListInfo boundParams, QueryEnvironment *queryEnv);
105 static bool choose_custom_plan(CachedPlanSource *plansource,
106  ParamListInfo boundParams);
107 static double cached_plan_cost(CachedPlan *plan, bool include_planner);
108 static Query *QueryListGetPrimaryStmt(List *stmts);
109 static void AcquireExecutorLocks(List *stmt_list, bool acquire);
110 static void AcquirePlannerLocks(List *stmt_list, bool acquire);
111 static void ScanQueryForLocks(Query *parsetree, bool acquire);
112 static bool ScanQueryWalker(Node *node, bool *acquire);
113 static TupleDesc PlanCacheComputeResultDesc(List *stmt_list);
114 static void PlanCacheRelCallback(Datum arg, Oid relid);
115 static void PlanCacheObjectCallback(Datum arg, int cacheid, uint32 hashvalue);
116 static void PlanCacheSysCallback(Datum arg, int cacheid, uint32 hashvalue);
117 
118 /* GUC parameter */
120 
121 /*
122  * InitPlanCache: initialize module during InitPostgres.
123  *
124  * All we need to do is hook into inval.c's callback lists.
125  */
126 void
128 {
137 }
138 
139 /*
140  * CreateCachedPlan: initially create a plan cache entry.
141  *
142  * Creation of a cached plan is divided into two steps, CreateCachedPlan and
143  * CompleteCachedPlan. CreateCachedPlan should be called after running the
144  * query through raw_parser, but before doing parse analysis and rewrite;
145  * CompleteCachedPlan is called after that. The reason for this arrangement
146  * is that it can save one round of copying of the raw parse tree, since
147  * the parser will normally scribble on the raw parse tree. Callers would
148  * otherwise need to make an extra copy of the parse tree to ensure they
149  * still had a clean copy to present at plan cache creation time.
150  *
151  * All arguments presented to CreateCachedPlan are copied into a memory
152  * context created as a child of the call-time CurrentMemoryContext, which
153  * should be a reasonably short-lived working context that will go away in
154  * event of an error. This ensures that the cached plan data structure will
155  * likewise disappear if an error occurs before we have fully constructed it.
156  * Once constructed, the cached plan can be made longer-lived, if needed,
157  * by calling SaveCachedPlan.
158  *
159  * raw_parse_tree: output of raw_parser(), or NULL if empty query
160  * query_string: original query text
161  * commandTag: command tag for query, or UNKNOWN if empty query
162  */
164 CreateCachedPlan(RawStmt *raw_parse_tree,
165  const char *query_string,
166  CommandTag commandTag)
167 {
168  CachedPlanSource *plansource;
169  MemoryContext source_context;
170  MemoryContext oldcxt;
171 
172  Assert(query_string != NULL); /* required as of 8.4 */
173 
174  /*
175  * Make a dedicated memory context for the CachedPlanSource and its
176  * permanent subsidiary data. It's probably not going to be large, but
177  * just in case, allow it to grow large. Initially it's a child of the
178  * caller's context (which we assume to be transient), so that it will be
179  * cleaned up on error.
180  */
182  "CachedPlanSource",
184 
185  /*
186  * Create and fill the CachedPlanSource struct within the new context.
187  * Most fields are just left empty for the moment.
188  */
189  oldcxt = MemoryContextSwitchTo(source_context);
190 
191  plansource = (CachedPlanSource *) palloc0(sizeof(CachedPlanSource));
192  plansource->magic = CACHEDPLANSOURCE_MAGIC;
193  plansource->raw_parse_tree = copyObject(raw_parse_tree);
194  plansource->query_string = pstrdup(query_string);
195  MemoryContextSetIdentifier(source_context, plansource->query_string);
196  plansource->commandTag = commandTag;
197  plansource->param_types = NULL;
198  plansource->num_params = 0;
199  plansource->parserSetup = NULL;
200  plansource->parserSetupArg = NULL;
201  plansource->cursor_options = 0;
202  plansource->fixed_result = false;
203  plansource->resultDesc = NULL;
204  plansource->context = source_context;
205  plansource->query_list = NIL;
206  plansource->relationOids = NIL;
207  plansource->invalItems = NIL;
208  plansource->search_path = NULL;
209  plansource->query_context = NULL;
210  plansource->rewriteRoleId = InvalidOid;
211  plansource->rewriteRowSecurity = false;
212  plansource->dependsOnRLS = false;
213  plansource->gplan = NULL;
214  plansource->is_oneshot = false;
215  plansource->is_complete = false;
216  plansource->is_saved = false;
217  plansource->is_valid = false;
218  plansource->generation = 0;
219  plansource->generic_cost = -1;
220  plansource->total_custom_cost = 0;
221  plansource->num_generic_plans = 0;
222  plansource->num_custom_plans = 0;
223 
224  MemoryContextSwitchTo(oldcxt);
225 
226  return plansource;
227 }
228 
229 /*
230  * CreateOneShotCachedPlan: initially create a one-shot plan cache entry.
231  *
232  * This variant of CreateCachedPlan creates a plan cache entry that is meant
233  * to be used only once. No data copying occurs: all data structures remain
234  * in the caller's memory context (which typically should get cleared after
235  * completing execution). The CachedPlanSource struct itself is also created
236  * in that context.
237  *
238  * A one-shot plan cannot be saved or copied, since we make no effort to
239  * preserve the raw parse tree unmodified. There is also no support for
240  * invalidation, so plan use must be completed in the current transaction,
241  * and DDL that might invalidate the querytree_list must be avoided as well.
242  *
243  * raw_parse_tree: output of raw_parser(), or NULL if empty query
244  * query_string: original query text
245  * commandTag: command tag for query, or NULL if empty query
246  */
249  const char *query_string,
250  CommandTag commandTag)
251 {
252  CachedPlanSource *plansource;
253 
254  Assert(query_string != NULL); /* required as of 8.4 */
255 
256  /*
257  * Create and fill the CachedPlanSource struct within the caller's memory
258  * context. Most fields are just left empty for the moment.
259  */
260  plansource = (CachedPlanSource *) palloc0(sizeof(CachedPlanSource));
261  plansource->magic = CACHEDPLANSOURCE_MAGIC;
262  plansource->raw_parse_tree = raw_parse_tree;
263  plansource->query_string = query_string;
264  plansource->commandTag = commandTag;
265  plansource->param_types = NULL;
266  plansource->num_params = 0;
267  plansource->parserSetup = NULL;
268  plansource->parserSetupArg = NULL;
269  plansource->cursor_options = 0;
270  plansource->fixed_result = false;
271  plansource->resultDesc = NULL;
272  plansource->context = CurrentMemoryContext;
273  plansource->query_list = NIL;
274  plansource->relationOids = NIL;
275  plansource->invalItems = NIL;
276  plansource->search_path = NULL;
277  plansource->query_context = NULL;
278  plansource->rewriteRoleId = InvalidOid;
279  plansource->rewriteRowSecurity = false;
280  plansource->dependsOnRLS = false;
281  plansource->gplan = NULL;
282  plansource->is_oneshot = true;
283  plansource->is_complete = false;
284  plansource->is_saved = false;
285  plansource->is_valid = false;
286  plansource->generation = 0;
287  plansource->generic_cost = -1;
288  plansource->total_custom_cost = 0;
289  plansource->num_generic_plans = 0;
290  plansource->num_custom_plans = 0;
291 
292  return plansource;
293 }
294 
295 /*
296  * CompleteCachedPlan: second step of creating a plan cache entry.
297  *
298  * Pass in the analyzed-and-rewritten form of the query, as well as the
299  * required subsidiary data about parameters and such. All passed values will
300  * be copied into the CachedPlanSource's memory, except as specified below.
301  * After this is called, GetCachedPlan can be called to obtain a plan, and
302  * optionally the CachedPlanSource can be saved using SaveCachedPlan.
303  *
304  * If querytree_context is not NULL, the querytree_list must be stored in that
305  * context (but the other parameters need not be). The querytree_list is not
306  * copied, rather the given context is kept as the initial query_context of
307  * the CachedPlanSource. (It should have been created as a child of the
308  * caller's working memory context, but it will now be reparented to belong
309  * to the CachedPlanSource.) The querytree_context is normally the context in
310  * which the caller did raw parsing and parse analysis. This approach saves
311  * one tree copying step compared to passing NULL, but leaves lots of extra
312  * cruft in the query_context, namely whatever extraneous stuff parse analysis
313  * created, as well as whatever went unused from the raw parse tree. Using
314  * this option is a space-for-time tradeoff that is appropriate if the
315  * CachedPlanSource is not expected to survive long.
316  *
317  * plancache.c cannot know how to copy the data referenced by parserSetupArg,
318  * and it would often be inappropriate to do so anyway. When using that
319  * option, it is caller's responsibility that the referenced data remains
320  * valid for as long as the CachedPlanSource exists.
321  *
322  * If the CachedPlanSource is a "oneshot" plan, then no querytree copying
323  * occurs at all, and querytree_context is ignored; it is caller's
324  * responsibility that the passed querytree_list is sufficiently long-lived.
325  *
326  * plansource: structure returned by CreateCachedPlan
327  * querytree_list: analyzed-and-rewritten form of query (list of Query nodes)
328  * querytree_context: memory context containing querytree_list,
329  * or NULL to copy querytree_list into a fresh context
330  * param_types: array of fixed parameter type OIDs, or NULL if none
331  * num_params: number of fixed parameters
332  * parserSetup: alternate method for handling query parameters
333  * parserSetupArg: data to pass to parserSetup
334  * cursor_options: options bitmask to pass to planner
335  * fixed_result: true to disallow future changes in query's result tupdesc
336  */
337 void
339  List *querytree_list,
340  MemoryContext querytree_context,
341  Oid *param_types,
342  int num_params,
343  ParserSetupHook parserSetup,
344  void *parserSetupArg,
345  int cursor_options,
346  bool fixed_result)
347 {
348  MemoryContext source_context = plansource->context;
350 
351  /* Assert caller is doing things in a sane order */
352  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
353  Assert(!plansource->is_complete);
354 
355  /*
356  * If caller supplied a querytree_context, reparent it underneath the
357  * CachedPlanSource's context; otherwise, create a suitable context and
358  * copy the querytree_list into it. But no data copying should be done
359  * for one-shot plans; for those, assume the passed querytree_list is
360  * sufficiently long-lived.
361  */
362  if (plansource->is_oneshot)
363  {
364  querytree_context = CurrentMemoryContext;
365  }
366  else if (querytree_context != NULL)
367  {
368  MemoryContextSetParent(querytree_context, source_context);
369  MemoryContextSwitchTo(querytree_context);
370  }
371  else
372  {
373  /* Again, it's a good bet the querytree_context can be small */
374  querytree_context = AllocSetContextCreate(source_context,
375  "CachedPlanQuery",
377  MemoryContextSwitchTo(querytree_context);
378  querytree_list = copyObject(querytree_list);
379  }
380 
381  plansource->query_context = querytree_context;
382  plansource->query_list = querytree_list;
383 
384  if (!plansource->is_oneshot && !IsTransactionStmtPlan(plansource))
385  {
386  /*
387  * Use the planner machinery to extract dependencies. Data is saved
388  * in query_context. (We assume that not a lot of extra cruft is
389  * created by this call.) We can skip this for one-shot plans, and
390  * transaction control commands have no such dependencies anyway.
391  */
392  extract_query_dependencies((Node *) querytree_list,
393  &plansource->relationOids,
394  &plansource->invalItems,
395  &plansource->dependsOnRLS);
396 
397  /* Update RLS info as well. */
398  plansource->rewriteRoleId = GetUserId();
399  plansource->rewriteRowSecurity = row_security;
400 
401  /*
402  * Also save the current search_path in the query_context. (This
403  * should not generate much extra cruft either, since almost certainly
404  * the path is already valid.) Again, we don't really need this for
405  * one-shot plans; and we *must* skip this for transaction control
406  * commands, because this could result in catalog accesses.
407  */
408  plansource->search_path = GetOverrideSearchPath(querytree_context);
409  }
410 
411  /*
412  * Save the final parameter types (or other parameter specification data)
413  * into the source_context, as well as our other parameters. Also save
414  * the result tuple descriptor.
415  */
416  MemoryContextSwitchTo(source_context);
417 
418  if (num_params > 0)
419  {
420  plansource->param_types = (Oid *) palloc(num_params * sizeof(Oid));
421  memcpy(plansource->param_types, param_types, num_params * sizeof(Oid));
422  }
423  else
424  plansource->param_types = NULL;
425  plansource->num_params = num_params;
426  plansource->parserSetup = parserSetup;
427  plansource->parserSetupArg = parserSetupArg;
428  plansource->cursor_options = cursor_options;
429  plansource->fixed_result = fixed_result;
430  plansource->resultDesc = PlanCacheComputeResultDesc(querytree_list);
431 
432  MemoryContextSwitchTo(oldcxt);
433 
434  plansource->is_complete = true;
435  plansource->is_valid = true;
436 }
437 
438 /*
439  * SaveCachedPlan: save a cached plan permanently
440  *
441  * This function moves the cached plan underneath CacheMemoryContext (making
442  * it live for the life of the backend, unless explicitly dropped), and adds
443  * it to the list of cached plans that are checked for invalidation when an
444  * sinval event occurs.
445  *
446  * This is guaranteed not to throw error, except for the caller-error case
447  * of trying to save a one-shot plan. Callers typically depend on that
448  * since this is called just before or just after adding a pointer to the
449  * CachedPlanSource to some permanent data structure of their own. Up until
450  * this is done, a CachedPlanSource is just transient data that will go away
451  * automatically on transaction abort.
452  */
453 void
455 {
456  /* Assert caller is doing things in a sane order */
457  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
458  Assert(plansource->is_complete);
459  Assert(!plansource->is_saved);
460 
461  /* This seems worth a real test, though */
462  if (plansource->is_oneshot)
463  elog(ERROR, "cannot save one-shot cached plan");
464 
465  /*
466  * In typical use, this function would be called before generating any
467  * plans from the CachedPlanSource. If there is a generic plan, moving it
468  * into CacheMemoryContext would be pretty risky since it's unclear
469  * whether the caller has taken suitable care with making references
470  * long-lived. Best thing to do seems to be to discard the plan.
471  */
472  ReleaseGenericPlan(plansource);
473 
474  /*
475  * Reparent the source memory context under CacheMemoryContext so that it
476  * will live indefinitely. The query_context follows along since it's
477  * already a child of the other one.
478  */
480 
481  /*
482  * Add the entry to the global list of cached plans.
483  */
484  dlist_push_tail(&saved_plan_list, &plansource->node);
485 
486  plansource->is_saved = true;
487 }
488 
489 /*
490  * DropCachedPlan: destroy a cached plan.
491  *
492  * Actually this only destroys the CachedPlanSource: any referenced CachedPlan
493  * is released, but not destroyed until its refcount goes to zero. That
494  * handles the situation where DropCachedPlan is called while the plan is
495  * still in use.
496  */
497 void
499 {
500  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
501 
502  /* If it's been saved, remove it from the list */
503  if (plansource->is_saved)
504  {
505  dlist_delete(&plansource->node);
506  plansource->is_saved = false;
507  }
508 
509  /* Decrement generic CachedPlan's refcount and drop if no longer needed */
510  ReleaseGenericPlan(plansource);
511 
512  /* Mark it no longer valid */
513  plansource->magic = 0;
514 
515  /*
516  * Remove the CachedPlanSource and all subsidiary data (including the
517  * query_context if any). But if it's a one-shot we can't free anything.
518  */
519  if (!plansource->is_oneshot)
520  MemoryContextDelete(plansource->context);
521 }
522 
523 /*
524  * ReleaseGenericPlan: release a CachedPlanSource's generic plan, if any.
525  */
526 static void
528 {
529  /* Be paranoid about the possibility that ReleaseCachedPlan fails */
530  if (plansource->gplan)
531  {
532  CachedPlan *plan = plansource->gplan;
533 
534  Assert(plan->magic == CACHEDPLAN_MAGIC);
535  plansource->gplan = NULL;
536  ReleaseCachedPlan(plan, false);
537  }
538 }
539 
540 /*
541  * RevalidateCachedQuery: ensure validity of analyzed-and-rewritten query tree.
542  *
543  * What we do here is re-acquire locks and redo parse analysis if necessary.
544  * On return, the query_list is valid and we have sufficient locks to begin
545  * planning.
546  *
547  * If any parse analysis activity is required, the caller's memory context is
548  * used for that work.
549  *
550  * The result value is the transient analyzed-and-rewritten query tree if we
551  * had to do re-analysis, and NIL otherwise. (This is returned just to save
552  * a tree copying step in a subsequent BuildCachedPlan call.)
553  */
554 static List *
556  QueryEnvironment *queryEnv)
557 {
558  bool snapshot_set;
559  RawStmt *rawtree;
560  List *tlist; /* transient query-tree list */
561  List *qlist; /* permanent query-tree list */
562  TupleDesc resultDesc;
563  MemoryContext querytree_context;
564  MemoryContext oldcxt;
565 
566  /*
567  * For one-shot plans, we do not support revalidation checking; it's
568  * assumed the query is parsed, planned, and executed in one transaction,
569  * so that no lock re-acquisition is necessary. Also, there is never any
570  * need to revalidate plans for transaction control commands (and we
571  * mustn't risk any catalog accesses when handling those).
572  */
573  if (plansource->is_oneshot || IsTransactionStmtPlan(plansource))
574  {
575  Assert(plansource->is_valid);
576  return NIL;
577  }
578 
579  /*
580  * If the query is currently valid, we should have a saved search_path ---
581  * check to see if that matches the current environment. If not, we want
582  * to force replan.
583  */
584  if (plansource->is_valid)
585  {
586  Assert(plansource->search_path != NULL);
588  {
589  /* Invalidate the querytree and generic plan */
590  plansource->is_valid = false;
591  if (plansource->gplan)
592  plansource->gplan->is_valid = false;
593  }
594  }
595 
596  /*
597  * If the query rewrite phase had a possible RLS dependency, we must redo
598  * it if either the role or the row_security setting has changed.
599  */
600  if (plansource->is_valid && plansource->dependsOnRLS &&
601  (plansource->rewriteRoleId != GetUserId() ||
602  plansource->rewriteRowSecurity != row_security))
603  plansource->is_valid = false;
604 
605  /*
606  * If the query is currently valid, acquire locks on the referenced
607  * objects; then check again. We need to do it this way to cover the race
608  * condition that an invalidation message arrives before we get the locks.
609  */
610  if (plansource->is_valid)
611  {
612  AcquirePlannerLocks(plansource->query_list, true);
613 
614  /*
615  * By now, if any invalidation has happened, the inval callback
616  * functions will have marked the query invalid.
617  */
618  if (plansource->is_valid)
619  {
620  /* Successfully revalidated and locked the query. */
621  return NIL;
622  }
623 
624  /* Oops, the race case happened. Release useless locks. */
625  AcquirePlannerLocks(plansource->query_list, false);
626  }
627 
628  /*
629  * Discard the no-longer-useful query tree. (Note: we don't want to do
630  * this any earlier, else we'd not have been able to release locks
631  * correctly in the race condition case.)
632  */
633  plansource->is_valid = false;
634  plansource->query_list = NIL;
635  plansource->relationOids = NIL;
636  plansource->invalItems = NIL;
637  plansource->search_path = NULL;
638 
639  /*
640  * Free the query_context. We don't really expect MemoryContextDelete to
641  * fail, but just in case, make sure the CachedPlanSource is left in a
642  * reasonably sane state. (The generic plan won't get unlinked yet, but
643  * that's acceptable.)
644  */
645  if (plansource->query_context)
646  {
647  MemoryContext qcxt = plansource->query_context;
648 
649  plansource->query_context = NULL;
650  MemoryContextDelete(qcxt);
651  }
652 
653  /* Drop the generic plan reference if any */
654  ReleaseGenericPlan(plansource);
655 
656  /*
657  * Now re-do parse analysis and rewrite. This not incidentally acquires
658  * the locks we need to do planning safely.
659  */
660  Assert(plansource->is_complete);
661 
662  /*
663  * If a snapshot is already set (the normal case), we can just use that
664  * for parsing/planning. But if it isn't, install one. Note: no point in
665  * checking whether parse analysis requires a snapshot; utility commands
666  * don't have invalidatable plans, so we'd not get here for such a
667  * command.
668  */
669  snapshot_set = false;
670  if (!ActiveSnapshotSet())
671  {
673  snapshot_set = true;
674  }
675 
676  /*
677  * Run parse analysis and rule rewriting. The parser tends to scribble on
678  * its input, so we must copy the raw parse tree to prevent corruption of
679  * the cache.
680  */
681  rawtree = copyObject(plansource->raw_parse_tree);
682  if (rawtree == NULL)
683  tlist = NIL;
684  else if (plansource->parserSetup != NULL)
685  tlist = pg_analyze_and_rewrite_params(rawtree,
686  plansource->query_string,
687  plansource->parserSetup,
688  plansource->parserSetupArg,
689  queryEnv);
690  else
691  tlist = pg_analyze_and_rewrite(rawtree,
692  plansource->query_string,
693  plansource->param_types,
694  plansource->num_params,
695  queryEnv);
696 
697  /* Release snapshot if we got one */
698  if (snapshot_set)
700 
701  /*
702  * Check or update the result tupdesc. XXX should we use a weaker
703  * condition than equalTupleDescs() here?
704  *
705  * We assume the parameter types didn't change from the first time, so no
706  * need to update that.
707  */
708  resultDesc = PlanCacheComputeResultDesc(tlist);
709  if (resultDesc == NULL && plansource->resultDesc == NULL)
710  {
711  /* OK, doesn't return tuples */
712  }
713  else if (resultDesc == NULL || plansource->resultDesc == NULL ||
714  !equalTupleDescs(resultDesc, plansource->resultDesc))
715  {
716  /* can we give a better error message? */
717  if (plansource->fixed_result)
718  ereport(ERROR,
719  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
720  errmsg("cached plan must not change result type")));
721  oldcxt = MemoryContextSwitchTo(plansource->context);
722  if (resultDesc)
723  resultDesc = CreateTupleDescCopy(resultDesc);
724  if (plansource->resultDesc)
725  FreeTupleDesc(plansource->resultDesc);
726  plansource->resultDesc = resultDesc;
727  MemoryContextSwitchTo(oldcxt);
728  }
729 
730  /*
731  * Allocate new query_context and copy the completed querytree into it.
732  * It's transient until we complete the copying and dependency extraction.
733  */
734  querytree_context = AllocSetContextCreate(CurrentMemoryContext,
735  "CachedPlanQuery",
737  oldcxt = MemoryContextSwitchTo(querytree_context);
738 
739  qlist = copyObject(tlist);
740 
741  /*
742  * Use the planner machinery to extract dependencies. Data is saved in
743  * query_context. (We assume that not a lot of extra cruft is created by
744  * this call.)
745  */
747  &plansource->relationOids,
748  &plansource->invalItems,
749  &plansource->dependsOnRLS);
750 
751  /* Update RLS info as well. */
752  plansource->rewriteRoleId = GetUserId();
753  plansource->rewriteRowSecurity = row_security;
754 
755  /*
756  * Also save the current search_path in the query_context. (This should
757  * not generate much extra cruft either, since almost certainly the path
758  * is already valid.)
759  */
760  plansource->search_path = GetOverrideSearchPath(querytree_context);
761 
762  MemoryContextSwitchTo(oldcxt);
763 
764  /* Now reparent the finished query_context and save the links */
765  MemoryContextSetParent(querytree_context, plansource->context);
766 
767  plansource->query_context = querytree_context;
768  plansource->query_list = qlist;
769 
770  /*
771  * Note: we do not reset generic_cost or total_custom_cost, although we
772  * could choose to do so. If the DDL or statistics change that prompted
773  * the invalidation meant a significant change in the cost estimates, it
774  * would be better to reset those variables and start fresh; but often it
775  * doesn't, and we're better retaining our hard-won knowledge about the
776  * relative costs.
777  */
778 
779  plansource->is_valid = true;
780 
781  /* Return transient copy of querytrees for possible use in planning */
782  return tlist;
783 }
784 
785 /*
786  * CheckCachedPlan: see if the CachedPlanSource's generic plan is valid.
787  *
788  * Caller must have already called RevalidateCachedQuery to verify that the
789  * querytree is up to date.
790  *
791  * On a "true" return, we have acquired the locks needed to run the plan.
792  * (We must do this for the "true" result to be race-condition-free.)
793  */
794 static bool
796 {
797  CachedPlan *plan = plansource->gplan;
798 
799  /* Assert that caller checked the querytree */
800  Assert(plansource->is_valid);
801 
802  /* If there's no generic plan, just say "false" */
803  if (!plan)
804  return false;
805 
806  Assert(plan->magic == CACHEDPLAN_MAGIC);
807  /* Generic plans are never one-shot */
808  Assert(!plan->is_oneshot);
809 
810  /*
811  * If plan isn't valid for current role, we can't use it.
812  */
813  if (plan->is_valid && plan->dependsOnRole &&
814  plan->planRoleId != GetUserId())
815  plan->is_valid = false;
816 
817  /*
818  * If it appears valid, acquire locks and recheck; this is much the same
819  * logic as in RevalidateCachedQuery, but for a plan.
820  */
821  if (plan->is_valid)
822  {
823  /*
824  * Plan must have positive refcount because it is referenced by
825  * plansource; so no need to fear it disappears under us here.
826  */
827  Assert(plan->refcount > 0);
828 
829  AcquireExecutorLocks(plan->stmt_list, true);
830 
831  /*
832  * If plan was transient, check to see if TransactionXmin has
833  * advanced, and if so invalidate it.
834  */
835  if (plan->is_valid &&
838  plan->is_valid = false;
839 
840  /*
841  * By now, if any invalidation has happened, the inval callback
842  * functions will have marked the plan invalid.
843  */
844  if (plan->is_valid)
845  {
846  /* Successfully revalidated and locked the query. */
847  return true;
848  }
849 
850  /* Oops, the race case happened. Release useless locks. */
851  AcquireExecutorLocks(plan->stmt_list, false);
852  }
853 
854  /*
855  * Plan has been invalidated, so unlink it from the parent and release it.
856  */
857  ReleaseGenericPlan(plansource);
858 
859  return false;
860 }
861 
862 /*
863  * BuildCachedPlan: construct a new CachedPlan from a CachedPlanSource.
864  *
865  * qlist should be the result value from a previous RevalidateCachedQuery,
866  * or it can be set to NIL if we need to re-copy the plansource's query_list.
867  *
868  * To build a generic, parameter-value-independent plan, pass NULL for
869  * boundParams. To build a custom plan, pass the actual parameter values via
870  * boundParams. For best effect, the PARAM_FLAG_CONST flag should be set on
871  * each parameter value; otherwise the planner will treat the value as a
872  * hint rather than a hard constant.
873  *
874  * Planning work is done in the caller's memory context. The finished plan
875  * is in a child memory context, which typically should get reparented
876  * (unless this is a one-shot plan, in which case we don't copy the plan).
877  */
878 static CachedPlan *
880  ParamListInfo boundParams, QueryEnvironment *queryEnv)
881 {
882  CachedPlan *plan;
883  List *plist;
884  bool snapshot_set;
885  bool is_transient;
886  MemoryContext plan_context;
888  ListCell *lc;
889 
890  /*
891  * Normally the querytree should be valid already, but if it's not,
892  * rebuild it.
893  *
894  * NOTE: GetCachedPlan should have called RevalidateCachedQuery first, so
895  * we ought to be holding sufficient locks to prevent any invalidation.
896  * However, if we're building a custom plan after having built and
897  * rejected a generic plan, it's possible to reach here with is_valid
898  * false due to an invalidation while making the generic plan. In theory
899  * the invalidation must be a false positive, perhaps a consequence of an
900  * sinval reset event or the CLOBBER_CACHE_ALWAYS debug code. But for
901  * safety, let's treat it as real and redo the RevalidateCachedQuery call.
902  */
903  if (!plansource->is_valid)
904  qlist = RevalidateCachedQuery(plansource, queryEnv);
905 
906  /*
907  * If we don't already have a copy of the querytree list that can be
908  * scribbled on by the planner, make one. For a one-shot plan, we assume
909  * it's okay to scribble on the original query_list.
910  */
911  if (qlist == NIL)
912  {
913  if (!plansource->is_oneshot)
914  qlist = copyObject(plansource->query_list);
915  else
916  qlist = plansource->query_list;
917  }
918 
919  /*
920  * If a snapshot is already set (the normal case), we can just use that
921  * for planning. But if it isn't, and we need one, install one.
922  */
923  snapshot_set = false;
924  if (!ActiveSnapshotSet() &&
925  plansource->raw_parse_tree &&
927  {
929  snapshot_set = true;
930  }
931 
932  /*
933  * Generate the plan.
934  */
935  plist = pg_plan_queries(qlist, plansource->query_string,
936  plansource->cursor_options, boundParams);
937 
938  /* Release snapshot if we got one */
939  if (snapshot_set)
941 
942  /*
943  * Normally we make a dedicated memory context for the CachedPlan and its
944  * subsidiary data. (It's probably not going to be large, but just in
945  * case, allow it to grow large. It's transient for the moment.) But for
946  * a one-shot plan, we just leave it in the caller's memory context.
947  */
948  if (!plansource->is_oneshot)
949  {
951  "CachedPlan",
953  MemoryContextCopyAndSetIdentifier(plan_context, plansource->query_string);
954 
955  /*
956  * Copy plan into the new context.
957  */
958  MemoryContextSwitchTo(plan_context);
959 
960  plist = copyObject(plist);
961  }
962  else
963  plan_context = CurrentMemoryContext;
964 
965  /*
966  * Create and fill the CachedPlan struct within the new context.
967  */
968  plan = (CachedPlan *) palloc(sizeof(CachedPlan));
969  plan->magic = CACHEDPLAN_MAGIC;
970  plan->stmt_list = plist;
971 
972  /*
973  * CachedPlan is dependent on role either if RLS affected the rewrite
974  * phase or if a role dependency was injected during planning. And it's
975  * transient if any plan is marked so.
976  */
977  plan->planRoleId = GetUserId();
978  plan->dependsOnRole = plansource->dependsOnRLS;
979  is_transient = false;
980  foreach(lc, plist)
981  {
982  PlannedStmt *plannedstmt = lfirst_node(PlannedStmt, lc);
983 
984  if (plannedstmt->commandType == CMD_UTILITY)
985  continue; /* Ignore utility statements */
986 
987  if (plannedstmt->transientPlan)
988  is_transient = true;
989  if (plannedstmt->dependsOnRole)
990  plan->dependsOnRole = true;
991  }
992  if (is_transient)
993  {
995  plan->saved_xmin = TransactionXmin;
996  }
997  else
999  plan->refcount = 0;
1000  plan->context = plan_context;
1001  plan->is_oneshot = plansource->is_oneshot;
1002  plan->is_saved = false;
1003  plan->is_valid = true;
1004 
1005  /* assign generation number to new plan */
1006  plan->generation = ++(plansource->generation);
1007 
1008  MemoryContextSwitchTo(oldcxt);
1009 
1010  return plan;
1011 }
1012 
1013 /*
1014  * choose_custom_plan: choose whether to use custom or generic plan
1015  *
1016  * This defines the policy followed by GetCachedPlan.
1017  */
1018 static bool
1020 {
1021  double avg_custom_cost;
1022 
1023  /* One-shot plans will always be considered custom */
1024  if (plansource->is_oneshot)
1025  return true;
1026 
1027  /* Otherwise, never any point in a custom plan if there's no parameters */
1028  if (boundParams == NULL)
1029  return false;
1030  /* ... nor for transaction control statements */
1031  if (IsTransactionStmtPlan(plansource))
1032  return false;
1033 
1034  /* Let settings force the decision */
1036  return false;
1038  return true;
1039 
1040  /* See if caller wants to force the decision */
1041  if (plansource->cursor_options & CURSOR_OPT_GENERIC_PLAN)
1042  return false;
1043  if (plansource->cursor_options & CURSOR_OPT_CUSTOM_PLAN)
1044  return true;
1045 
1046  /* Generate custom plans until we have done at least 5 (arbitrary) */
1047  if (plansource->num_custom_plans < 5)
1048  return true;
1049 
1050  avg_custom_cost = plansource->total_custom_cost / plansource->num_custom_plans;
1051 
1052  /*
1053  * Prefer generic plan if it's less expensive than the average custom
1054  * plan. (Because we include a charge for cost of planning in the
1055  * custom-plan costs, this means the generic plan only has to be less
1056  * expensive than the execution cost plus replan cost of the custom
1057  * plans.)
1058  *
1059  * Note that if generic_cost is -1 (indicating we've not yet determined
1060  * the generic plan cost), we'll always prefer generic at this point.
1061  */
1062  if (plansource->generic_cost < avg_custom_cost)
1063  return false;
1064 
1065  return true;
1066 }
1067 
1068 /*
1069  * cached_plan_cost: calculate estimated cost of a plan
1070  *
1071  * If include_planner is true, also include the estimated cost of constructing
1072  * the plan. (We must factor that into the cost of using a custom plan, but
1073  * we don't count it for a generic plan.)
1074  */
1075 static double
1076 cached_plan_cost(CachedPlan *plan, bool include_planner)
1077 {
1078  double result = 0;
1079  ListCell *lc;
1080 
1081  foreach(lc, plan->stmt_list)
1082  {
1083  PlannedStmt *plannedstmt = lfirst_node(PlannedStmt, lc);
1084 
1085  if (plannedstmt->commandType == CMD_UTILITY)
1086  continue; /* Ignore utility statements */
1087 
1088  result += plannedstmt->planTree->total_cost;
1089 
1090  if (include_planner)
1091  {
1092  /*
1093  * Currently we use a very crude estimate of planning effort based
1094  * on the number of relations in the finished plan's rangetable.
1095  * Join planning effort actually scales much worse than linearly
1096  * in the number of relations --- but only until the join collapse
1097  * limits kick in. Also, while inheritance child relations surely
1098  * add to planning effort, they don't make the join situation
1099  * worse. So the actual shape of the planning cost curve versus
1100  * number of relations isn't all that obvious. It will take
1101  * considerable work to arrive at a less crude estimate, and for
1102  * now it's not clear that's worth doing.
1103  *
1104  * The other big difficulty here is that we don't have any very
1105  * good model of how planning cost compares to execution costs.
1106  * The current multiplier of 1000 * cpu_operator_cost is probably
1107  * on the low side, but we'll try this for awhile before making a
1108  * more aggressive correction.
1109  *
1110  * If we ever do write a more complicated estimator, it should
1111  * probably live in src/backend/optimizer/ not here.
1112  */
1113  int nrelations = list_length(plannedstmt->rtable);
1114 
1115  result += 1000.0 * cpu_operator_cost * (nrelations + 1);
1116  }
1117  }
1118 
1119  return result;
1120 }
1121 
1122 /*
1123  * GetCachedPlan: get a cached plan from a CachedPlanSource.
1124  *
1125  * This function hides the logic that decides whether to use a generic
1126  * plan or a custom plan for the given parameters: the caller does not know
1127  * which it will get.
1128  *
1129  * On return, the plan is valid and we have sufficient locks to begin
1130  * execution.
1131  *
1132  * On return, the refcount of the plan has been incremented; a later
1133  * ReleaseCachedPlan() call is expected. The refcount has been reported
1134  * to the CurrentResourceOwner if useResOwner is true (note that that must
1135  * only be true if it's a "saved" CachedPlanSource).
1136  *
1137  * Note: if any replanning activity is required, the caller's memory context
1138  * is used for that work.
1139  */
1140 CachedPlan *
1142  bool useResOwner, QueryEnvironment *queryEnv)
1143 {
1144  CachedPlan *plan = NULL;
1145  List *qlist;
1146  bool customplan;
1147 
1148  /* Assert caller is doing things in a sane order */
1149  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
1150  Assert(plansource->is_complete);
1151  /* This seems worth a real test, though */
1152  if (useResOwner && !plansource->is_saved)
1153  elog(ERROR, "cannot apply ResourceOwner to non-saved cached plan");
1154 
1155  /* Make sure the querytree list is valid and we have parse-time locks */
1156  qlist = RevalidateCachedQuery(plansource, queryEnv);
1157 
1158  /* Decide whether to use a custom plan */
1159  customplan = choose_custom_plan(plansource, boundParams);
1160 
1161  if (!customplan)
1162  {
1163  if (CheckCachedPlan(plansource))
1164  {
1165  /* We want a generic plan, and we already have a valid one */
1166  plan = plansource->gplan;
1167  Assert(plan->magic == CACHEDPLAN_MAGIC);
1168  }
1169  else
1170  {
1171  /* Build a new generic plan */
1172  plan = BuildCachedPlan(plansource, qlist, NULL, queryEnv);
1173  /* Just make real sure plansource->gplan is clear */
1174  ReleaseGenericPlan(plansource);
1175  /* Link the new generic plan into the plansource */
1176  plansource->gplan = plan;
1177  plan->refcount++;
1178  /* Immediately reparent into appropriate context */
1179  if (plansource->is_saved)
1180  {
1181  /* saved plans all live under CacheMemoryContext */
1183  plan->is_saved = true;
1184  }
1185  else
1186  {
1187  /* otherwise, it should be a sibling of the plansource */
1189  MemoryContextGetParent(plansource->context));
1190  }
1191  /* Update generic_cost whenever we make a new generic plan */
1192  plansource->generic_cost = cached_plan_cost(plan, false);
1193 
1194  /*
1195  * If, based on the now-known value of generic_cost, we'd not have
1196  * chosen to use a generic plan, then forget it and make a custom
1197  * plan. This is a bit of a wart but is necessary to avoid a
1198  * glitch in behavior when the custom plans are consistently big
1199  * winners; at some point we'll experiment with a generic plan and
1200  * find it's a loser, but we don't want to actually execute that
1201  * plan.
1202  */
1203  customplan = choose_custom_plan(plansource, boundParams);
1204 
1205  /*
1206  * If we choose to plan again, we need to re-copy the query_list,
1207  * since the planner probably scribbled on it. We can force
1208  * BuildCachedPlan to do that by passing NIL.
1209  */
1210  qlist = NIL;
1211  }
1212  }
1213 
1214  if (customplan)
1215  {
1216  /* Build a custom plan */
1217  plan = BuildCachedPlan(plansource, qlist, boundParams, queryEnv);
1218  /* Accumulate total costs of custom plans */
1219  plansource->total_custom_cost += cached_plan_cost(plan, true);
1220 
1221  plansource->num_custom_plans++;
1222  }
1223  else
1224  {
1225  plansource->num_generic_plans++;
1226  }
1227 
1228  Assert(plan != NULL);
1229 
1230  /* Flag the plan as in use by caller */
1231  if (useResOwner)
1233  plan->refcount++;
1234  if (useResOwner)
1236 
1237  /*
1238  * Saved plans should be under CacheMemoryContext so they will not go away
1239  * until their reference count goes to zero. In the generic-plan cases we
1240  * already took care of that, but for a custom plan, do it as soon as we
1241  * have created a reference-counted link.
1242  */
1243  if (customplan && plansource->is_saved)
1244  {
1246  plan->is_saved = true;
1247  }
1248 
1249  return plan;
1250 }
1251 
1252 /*
1253  * ReleaseCachedPlan: release active use of a cached plan.
1254  *
1255  * This decrements the reference count, and frees the plan if the count
1256  * has thereby gone to zero. If useResOwner is true, it is assumed that
1257  * the reference count is managed by the CurrentResourceOwner.
1258  *
1259  * Note: useResOwner = false is used for releasing references that are in
1260  * persistent data structures, such as the parent CachedPlanSource or a
1261  * Portal. Transient references should be protected by a resource owner.
1262  */
1263 void
1264 ReleaseCachedPlan(CachedPlan *plan, bool useResOwner)
1265 {
1266  Assert(plan->magic == CACHEDPLAN_MAGIC);
1267  if (useResOwner)
1268  {
1269  Assert(plan->is_saved);
1271  }
1272  Assert(plan->refcount > 0);
1273  plan->refcount--;
1274  if (plan->refcount == 0)
1275  {
1276  /* Mark it no longer valid */
1277  plan->magic = 0;
1278 
1279  /* One-shot plans do not own their context, so we can't free them */
1280  if (!plan->is_oneshot)
1282  }
1283 }
1284 
1285 /*
1286  * CachedPlanAllowsSimpleValidityCheck: can we use CachedPlanIsSimplyValid?
1287  *
1288  * This function, together with CachedPlanIsSimplyValid, provides a fast path
1289  * for revalidating "simple" generic plans. The core requirement to be simple
1290  * is that the plan must not require taking any locks, which translates to
1291  * not touching any tables; this happens to match up well with an important
1292  * use-case in PL/pgSQL. This function tests whether that's true, along
1293  * with checking some other corner cases that we'd rather not bother with
1294  * handling in the fast path. (Note that it's still possible for such a plan
1295  * to be invalidated, for example due to a change in a function that was
1296  * inlined into the plan.)
1297  *
1298  * If the plan is simply valid, and "owner" is not NULL, record a refcount on
1299  * the plan in that resowner before returning. It is caller's responsibility
1300  * to be sure that a refcount is held on any plan that's being actively used.
1301  *
1302  * This must only be called on known-valid generic plans (eg, ones just
1303  * returned by GetCachedPlan). If it returns true, the caller may re-use
1304  * the cached plan as long as CachedPlanIsSimplyValid returns true; that
1305  * check is much cheaper than the full revalidation done by GetCachedPlan.
1306  * Nonetheless, no required checks are omitted.
1307  */
1308 bool
1310  CachedPlan *plan, ResourceOwner owner)
1311 {
1312  ListCell *lc;
1313 
1314  /*
1315  * Sanity-check that the caller gave us a validated generic plan. Notice
1316  * that we *don't* assert plansource->is_valid as you might expect; that's
1317  * because it's possible that that's already false when GetCachedPlan
1318  * returns, e.g. because ResetPlanCache happened partway through. We
1319  * should accept the plan as long as plan->is_valid is true, and expect to
1320  * replan after the next CachedPlanIsSimplyValid call.
1321  */
1322  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
1323  Assert(plan->magic == CACHEDPLAN_MAGIC);
1324  Assert(plan->is_valid);
1325  Assert(plan == plansource->gplan);
1326  Assert(plansource->search_path != NULL);
1328 
1329  /* We don't support oneshot plans here. */
1330  if (plansource->is_oneshot)
1331  return false;
1332  Assert(!plan->is_oneshot);
1333 
1334  /*
1335  * If the plan is dependent on RLS considerations, or it's transient,
1336  * reject. These things probably can't ever happen for table-free
1337  * queries, but for safety's sake let's check.
1338  */
1339  if (plansource->dependsOnRLS)
1340  return false;
1341  if (plan->dependsOnRole)
1342  return false;
1343  if (TransactionIdIsValid(plan->saved_xmin))
1344  return false;
1345 
1346  /*
1347  * Reject if AcquirePlannerLocks would have anything to do. This is
1348  * simplistic, but there's no need to inquire any more carefully; indeed,
1349  * for current callers it shouldn't even be possible to hit any of these
1350  * checks.
1351  */
1352  foreach(lc, plansource->query_list)
1353  {
1354  Query *query = lfirst_node(Query, lc);
1355 
1356  if (query->commandType == CMD_UTILITY)
1357  return false;
1358  if (query->rtable || query->cteList || query->hasSubLinks)
1359  return false;
1360  }
1361 
1362  /*
1363  * Reject if AcquireExecutorLocks would have anything to do. This is
1364  * probably unnecessary given the previous check, but let's be safe.
1365  */
1366  foreach(lc, plan->stmt_list)
1367  {
1368  PlannedStmt *plannedstmt = lfirst_node(PlannedStmt, lc);
1369  ListCell *lc2;
1370 
1371  if (plannedstmt->commandType == CMD_UTILITY)
1372  return false;
1373 
1374  /*
1375  * We have to grovel through the rtable because it's likely to contain
1376  * an RTE_RESULT relation, rather than being totally empty.
1377  */
1378  foreach(lc2, plannedstmt->rtable)
1379  {
1380  RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc2);
1381 
1382  if (rte->rtekind == RTE_RELATION)
1383  return false;
1384  }
1385  }
1386 
1387  /*
1388  * Okay, it's simple. Note that what we've primarily established here is
1389  * that no locks need be taken before checking the plan's is_valid flag.
1390  */
1391 
1392  /* Bump refcount if requested. */
1393  if (owner)
1394  {
1396  plan->refcount++;
1397  ResourceOwnerRememberPlanCacheRef(owner, plan);
1398  }
1399 
1400  return true;
1401 }
1402 
1403 /*
1404  * CachedPlanIsSimplyValid: quick check for plan still being valid
1405  *
1406  * This function must not be used unless CachedPlanAllowsSimpleValidityCheck
1407  * previously said it was OK.
1408  *
1409  * If the plan is valid, and "owner" is not NULL, record a refcount on
1410  * the plan in that resowner before returning. It is caller's responsibility
1411  * to be sure that a refcount is held on any plan that's being actively used.
1412  *
1413  * The code here is unconditionally safe as long as the only use of this
1414  * CachedPlanSource is in connection with the particular CachedPlan pointer
1415  * that's passed in. If the plansource were being used for other purposes,
1416  * it's possible that its generic plan could be invalidated and regenerated
1417  * while the current caller wasn't looking, and then there could be a chance
1418  * collision of address between this caller's now-stale plan pointer and the
1419  * actual address of the new generic plan. For current uses, that scenario
1420  * can't happen; but with a plansource shared across multiple uses, it'd be
1421  * advisable to also save plan->generation and verify that that still matches.
1422  */
1423 bool
1425  ResourceOwner owner)
1426 {
1427  /*
1428  * Careful here: since the caller doesn't necessarily hold a refcount on
1429  * the plan to start with, it's possible that "plan" is a dangling
1430  * pointer. Don't dereference it until we've verified that it still
1431  * matches the plansource's gplan (which is either valid or NULL).
1432  */
1433  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
1434 
1435  /*
1436  * Has cache invalidation fired on this plan? We can check this right
1437  * away since there are no locks that we'd need to acquire first. Note
1438  * that here we *do* check plansource->is_valid, so as to force plan
1439  * rebuild if that's become false.
1440  */
1441  if (!plansource->is_valid || plan != plansource->gplan || !plan->is_valid)
1442  return false;
1443 
1444  Assert(plan->magic == CACHEDPLAN_MAGIC);
1445 
1446  /* Is the search_path still the same as when we made it? */
1447  Assert(plansource->search_path != NULL);
1449  return false;
1450 
1451  /* It's still good. Bump refcount if requested. */
1452  if (owner)
1453  {
1455  plan->refcount++;
1456  ResourceOwnerRememberPlanCacheRef(owner, plan);
1457  }
1458 
1459  return true;
1460 }
1461 
1462 /*
1463  * CachedPlanSetParentContext: move a CachedPlanSource to a new memory context
1464  *
1465  * This can only be applied to unsaved plans; once saved, a plan always
1466  * lives underneath CacheMemoryContext.
1467  */
1468 void
1470  MemoryContext newcontext)
1471 {
1472  /* Assert caller is doing things in a sane order */
1473  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
1474  Assert(plansource->is_complete);
1475 
1476  /* These seem worth real tests, though */
1477  if (plansource->is_saved)
1478  elog(ERROR, "cannot move a saved cached plan to another context");
1479  if (plansource->is_oneshot)
1480  elog(ERROR, "cannot move a one-shot cached plan to another context");
1481 
1482  /* OK, let the caller keep the plan where he wishes */
1483  MemoryContextSetParent(plansource->context, newcontext);
1484 
1485  /*
1486  * The query_context needs no special handling, since it's a child of
1487  * plansource->context. But if there's a generic plan, it should be
1488  * maintained as a sibling of plansource->context.
1489  */
1490  if (plansource->gplan)
1491  {
1492  Assert(plansource->gplan->magic == CACHEDPLAN_MAGIC);
1493  MemoryContextSetParent(plansource->gplan->context, newcontext);
1494  }
1495 }
1496 
1497 /*
1498  * CopyCachedPlan: make a copy of a CachedPlanSource
1499  *
1500  * This is a convenience routine that does the equivalent of
1501  * CreateCachedPlan + CompleteCachedPlan, using the data stored in the
1502  * input CachedPlanSource. The result is therefore "unsaved" (regardless
1503  * of the state of the source), and we don't copy any generic plan either.
1504  * The result will be currently valid, or not, the same as the source.
1505  */
1508 {
1509  CachedPlanSource *newsource;
1510  MemoryContext source_context;
1511  MemoryContext querytree_context;
1512  MemoryContext oldcxt;
1513 
1514  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
1515  Assert(plansource->is_complete);
1516 
1517  /*
1518  * One-shot plans can't be copied, because we haven't taken care that
1519  * parsing/planning didn't scribble on the raw parse tree or querytrees.
1520  */
1521  if (plansource->is_oneshot)
1522  elog(ERROR, "cannot copy a one-shot cached plan");
1523 
1525  "CachedPlanSource",
1527 
1528  oldcxt = MemoryContextSwitchTo(source_context);
1529 
1530  newsource = (CachedPlanSource *) palloc0(sizeof(CachedPlanSource));
1531  newsource->magic = CACHEDPLANSOURCE_MAGIC;
1532  newsource->raw_parse_tree = copyObject(plansource->raw_parse_tree);
1533  newsource->query_string = pstrdup(plansource->query_string);
1534  MemoryContextSetIdentifier(source_context, newsource->query_string);
1535  newsource->commandTag = plansource->commandTag;
1536  if (plansource->num_params > 0)
1537  {
1538  newsource->param_types = (Oid *)
1539  palloc(plansource->num_params * sizeof(Oid));
1540  memcpy(newsource->param_types, plansource->param_types,
1541  plansource->num_params * sizeof(Oid));
1542  }
1543  else
1544  newsource->param_types = NULL;
1545  newsource->num_params = plansource->num_params;
1546  newsource->parserSetup = plansource->parserSetup;
1547  newsource->parserSetupArg = plansource->parserSetupArg;
1548  newsource->cursor_options = plansource->cursor_options;
1549  newsource->fixed_result = plansource->fixed_result;
1550  if (plansource->resultDesc)
1551  newsource->resultDesc = CreateTupleDescCopy(plansource->resultDesc);
1552  else
1553  newsource->resultDesc = NULL;
1554  newsource->context = source_context;
1555 
1556  querytree_context = AllocSetContextCreate(source_context,
1557  "CachedPlanQuery",
1559  MemoryContextSwitchTo(querytree_context);
1560  newsource->query_list = copyObject(plansource->query_list);
1561  newsource->relationOids = copyObject(plansource->relationOids);
1562  newsource->invalItems = copyObject(plansource->invalItems);
1563  if (plansource->search_path)
1564  newsource->search_path = CopyOverrideSearchPath(plansource->search_path);
1565  newsource->query_context = querytree_context;
1566  newsource->rewriteRoleId = plansource->rewriteRoleId;
1567  newsource->rewriteRowSecurity = plansource->rewriteRowSecurity;
1568  newsource->dependsOnRLS = plansource->dependsOnRLS;
1569 
1570  newsource->gplan = NULL;
1571 
1572  newsource->is_oneshot = false;
1573  newsource->is_complete = true;
1574  newsource->is_saved = false;
1575  newsource->is_valid = plansource->is_valid;
1576  newsource->generation = plansource->generation;
1577 
1578  /* We may as well copy any acquired cost knowledge */
1579  newsource->generic_cost = plansource->generic_cost;
1580  newsource->total_custom_cost = plansource->total_custom_cost;
1581  newsource->num_generic_plans = plansource->num_generic_plans;
1582  newsource->num_custom_plans = plansource->num_custom_plans;
1583 
1584  MemoryContextSwitchTo(oldcxt);
1585 
1586  return newsource;
1587 }
1588 
1589 /*
1590  * CachedPlanIsValid: test whether the rewritten querytree within a
1591  * CachedPlanSource is currently valid (that is, not marked as being in need
1592  * of revalidation).
1593  *
1594  * This result is only trustworthy (ie, free from race conditions) if
1595  * the caller has acquired locks on all the relations used in the plan.
1596  */
1597 bool
1599 {
1600  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
1601  return plansource->is_valid;
1602 }
1603 
1604 /*
1605  * CachedPlanGetTargetList: return tlist, if any, describing plan's output
1606  *
1607  * The result is guaranteed up-to-date. However, it is local storage
1608  * within the cached plan, and may disappear next time the plan is updated.
1609  */
1610 List *
1612  QueryEnvironment *queryEnv)
1613 {
1614  Query *pstmt;
1615 
1616  /* Assert caller is doing things in a sane order */
1617  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
1618  Assert(plansource->is_complete);
1619 
1620  /*
1621  * No work needed if statement doesn't return tuples (we assume this
1622  * feature cannot be changed by an invalidation)
1623  */
1624  if (plansource->resultDesc == NULL)
1625  return NIL;
1626 
1627  /* Make sure the querytree list is valid and we have parse-time locks */
1628  RevalidateCachedQuery(plansource, queryEnv);
1629 
1630  /* Get the primary statement and find out what it returns */
1631  pstmt = QueryListGetPrimaryStmt(plansource->query_list);
1632 
1633  return FetchStatementTargetList((Node *) pstmt);
1634 }
1635 
1636 /*
1637  * GetCachedExpression: construct a CachedExpression for an expression.
1638  *
1639  * This performs the same transformations on the expression as
1640  * expression_planner(), ie, convert an expression as emitted by parse
1641  * analysis to be ready to pass to the executor.
1642  *
1643  * The result is stashed in a private, long-lived memory context.
1644  * (Note that this might leak a good deal of memory in the caller's
1645  * context before that.) The passed-in expr tree is not modified.
1646  */
1649 {
1650  CachedExpression *cexpr;
1651  List *relationOids;
1652  List *invalItems;
1653  MemoryContext cexpr_context;
1654  MemoryContext oldcxt;
1655 
1656  /*
1657  * Pass the expression through the planner, and collect dependencies.
1658  * Everything built here is leaked in the caller's context; that's
1659  * intentional to minimize the size of the permanent data structure.
1660  */
1661  expr = (Node *) expression_planner_with_deps((Expr *) expr,
1662  &relationOids,
1663  &invalItems);
1664 
1665  /*
1666  * Make a private memory context, and copy what we need into that. To
1667  * avoid leaking a long-lived context if we fail while copying data, we
1668  * initially make the context under the caller's context.
1669  */
1671  "CachedExpression",
1673 
1674  oldcxt = MemoryContextSwitchTo(cexpr_context);
1675 
1676  cexpr = (CachedExpression *) palloc(sizeof(CachedExpression));
1677  cexpr->magic = CACHEDEXPR_MAGIC;
1678  cexpr->expr = copyObject(expr);
1679  cexpr->is_valid = true;
1680  cexpr->relationOids = copyObject(relationOids);
1681  cexpr->invalItems = copyObject(invalItems);
1682  cexpr->context = cexpr_context;
1683 
1684  MemoryContextSwitchTo(oldcxt);
1685 
1686  /*
1687  * Reparent the expr's memory context under CacheMemoryContext so that it
1688  * will live indefinitely.
1689  */
1691 
1692  /*
1693  * Add the entry to the global list of cached expressions.
1694  */
1695  dlist_push_tail(&cached_expression_list, &cexpr->node);
1696 
1697  return cexpr;
1698 }
1699 
1700 /*
1701  * FreeCachedExpression
1702  * Delete a CachedExpression.
1703  */
1704 void
1706 {
1707  /* Sanity check */
1708  Assert(cexpr->magic == CACHEDEXPR_MAGIC);
1709  /* Unlink from global list */
1710  dlist_delete(&cexpr->node);
1711  /* Free all storage associated with CachedExpression */
1712  MemoryContextDelete(cexpr->context);
1713 }
1714 
1715 /*
1716  * QueryListGetPrimaryStmt
1717  * Get the "primary" stmt within a list, ie, the one marked canSetTag.
1718  *
1719  * Returns NULL if no such stmt. If multiple queries within the list are
1720  * marked canSetTag, returns the first one. Neither of these cases should
1721  * occur in present usages of this function.
1722  */
1723 static Query *
1725 {
1726  ListCell *lc;
1727 
1728  foreach(lc, stmts)
1729  {
1730  Query *stmt = lfirst_node(Query, lc);
1731 
1732  if (stmt->canSetTag)
1733  return stmt;
1734  }
1735  return NULL;
1736 }
1737 
1738 /*
1739  * AcquireExecutorLocks: acquire locks needed for execution of a cached plan;
1740  * or release them if acquire is false.
1741  */
1742 static void
1743 AcquireExecutorLocks(List *stmt_list, bool acquire)
1744 {
1745  ListCell *lc1;
1746 
1747  foreach(lc1, stmt_list)
1748  {
1749  PlannedStmt *plannedstmt = lfirst_node(PlannedStmt, lc1);
1750  ListCell *lc2;
1751 
1752  if (plannedstmt->commandType == CMD_UTILITY)
1753  {
1754  /*
1755  * Ignore utility statements, except those (such as EXPLAIN) that
1756  * contain a parsed-but-not-planned query. Note: it's okay to use
1757  * ScanQueryForLocks, even though the query hasn't been through
1758  * rule rewriting, because rewriting doesn't change the query
1759  * representation.
1760  */
1761  Query *query = UtilityContainsQuery(plannedstmt->utilityStmt);
1762 
1763  if (query)
1764  ScanQueryForLocks(query, acquire);
1765  continue;
1766  }
1767 
1768  foreach(lc2, plannedstmt->rtable)
1769  {
1770  RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc2);
1771 
1772  if (rte->rtekind != RTE_RELATION)
1773  continue;
1774 
1775  /*
1776  * Acquire the appropriate type of lock on each relation OID. Note
1777  * that we don't actually try to open the rel, and hence will not
1778  * fail if it's been dropped entirely --- we'll just transiently
1779  * acquire a non-conflicting lock.
1780  */
1781  if (acquire)
1782  LockRelationOid(rte->relid, rte->rellockmode);
1783  else
1784  UnlockRelationOid(rte->relid, rte->rellockmode);
1785  }
1786  }
1787 }
1788 
1789 /*
1790  * AcquirePlannerLocks: acquire locks needed for planning of a querytree list;
1791  * or release them if acquire is false.
1792  *
1793  * Note that we don't actually try to open the relations, and hence will not
1794  * fail if one has been dropped entirely --- we'll just transiently acquire
1795  * a non-conflicting lock.
1796  */
1797 static void
1798 AcquirePlannerLocks(List *stmt_list, bool acquire)
1799 {
1800  ListCell *lc;
1801 
1802  foreach(lc, stmt_list)
1803  {
1804  Query *query = lfirst_node(Query, lc);
1805 
1806  if (query->commandType == CMD_UTILITY)
1807  {
1808  /* Ignore utility statements, unless they contain a Query */
1809  query = UtilityContainsQuery(query->utilityStmt);
1810  if (query)
1811  ScanQueryForLocks(query, acquire);
1812  continue;
1813  }
1814 
1815  ScanQueryForLocks(query, acquire);
1816  }
1817 }
1818 
1819 /*
1820  * ScanQueryForLocks: recursively scan one Query for AcquirePlannerLocks.
1821  */
1822 static void
1823 ScanQueryForLocks(Query *parsetree, bool acquire)
1824 {
1825  ListCell *lc;
1826 
1827  /* Shouldn't get called on utility commands */
1828  Assert(parsetree->commandType != CMD_UTILITY);
1829 
1830  /*
1831  * First, process RTEs of the current query level.
1832  */
1833  foreach(lc, parsetree->rtable)
1834  {
1835  RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
1836 
1837  switch (rte->rtekind)
1838  {
1839  case RTE_RELATION:
1840  /* Acquire or release the appropriate type of lock */
1841  if (acquire)
1842  LockRelationOid(rte->relid, rte->rellockmode);
1843  else
1844  UnlockRelationOid(rte->relid, rte->rellockmode);
1845  break;
1846 
1847  case RTE_SUBQUERY:
1848  /* Recurse into subquery-in-FROM */
1849  ScanQueryForLocks(rte->subquery, acquire);
1850  break;
1851 
1852  default:
1853  /* ignore other types of RTEs */
1854  break;
1855  }
1856  }
1857 
1858  /* Recurse into subquery-in-WITH */
1859  foreach(lc, parsetree->cteList)
1860  {
1862 
1863  ScanQueryForLocks(castNode(Query, cte->ctequery), acquire);
1864  }
1865 
1866  /*
1867  * Recurse into sublink subqueries, too. But we already did the ones in
1868  * the rtable and cteList.
1869  */
1870  if (parsetree->hasSubLinks)
1871  {
1873  (void *) &acquire,
1875  }
1876 }
1877 
1878 /*
1879  * Walker to find sublink subqueries for ScanQueryForLocks
1880  */
1881 static bool
1882 ScanQueryWalker(Node *node, bool *acquire)
1883 {
1884  if (node == NULL)
1885  return false;
1886  if (IsA(node, SubLink))
1887  {
1888  SubLink *sub = (SubLink *) node;
1889 
1890  /* Do what we came for */
1891  ScanQueryForLocks(castNode(Query, sub->subselect), *acquire);
1892  /* Fall through to process lefthand args of SubLink */
1893  }
1894 
1895  /*
1896  * Do NOT recurse into Query nodes, because ScanQueryForLocks already
1897  * processed subselects of subselects for us.
1898  */
1900  (void *) acquire);
1901 }
1902 
1903 /*
1904  * PlanCacheComputeResultDesc: given a list of analyzed-and-rewritten Queries,
1905  * determine the result tupledesc it will produce. Returns NULL if the
1906  * execution will not return tuples.
1907  *
1908  * Note: the result is created or copied into current memory context.
1909  */
1910 static TupleDesc
1912 {
1913  Query *query;
1914 
1915  switch (ChoosePortalStrategy(stmt_list))
1916  {
1917  case PORTAL_ONE_SELECT:
1918  case PORTAL_ONE_MOD_WITH:
1919  query = linitial_node(Query, stmt_list);
1920  return ExecCleanTypeFromTL(query->targetList);
1921 
1922  case PORTAL_ONE_RETURNING:
1923  query = QueryListGetPrimaryStmt(stmt_list);
1924  Assert(query->returningList);
1925  return ExecCleanTypeFromTL(query->returningList);
1926 
1927  case PORTAL_UTIL_SELECT:
1928  query = linitial_node(Query, stmt_list);
1929  Assert(query->utilityStmt);
1930  return UtilityTupleDescriptor(query->utilityStmt);
1931 
1932  case PORTAL_MULTI_QUERY:
1933  /* will not return tuples */
1934  break;
1935  }
1936  return NULL;
1937 }
1938 
1939 /*
1940  * PlanCacheRelCallback
1941  * Relcache inval callback function
1942  *
1943  * Invalidate all plans mentioning the given rel, or all plans mentioning
1944  * any rel at all if relid == InvalidOid.
1945  */
1946 static void
1948 {
1949  dlist_iter iter;
1950 
1951  dlist_foreach(iter, &saved_plan_list)
1952  {
1954  node, iter.cur);
1955 
1956  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
1957 
1958  /* No work if it's already invalidated */
1959  if (!plansource->is_valid)
1960  continue;
1961 
1962  /* Never invalidate transaction control commands */
1963  if (IsTransactionStmtPlan(plansource))
1964  continue;
1965 
1966  /*
1967  * Check the dependency list for the rewritten querytree.
1968  */
1969  if ((relid == InvalidOid) ? plansource->relationOids != NIL :
1970  list_member_oid(plansource->relationOids, relid))
1971  {
1972  /* Invalidate the querytree and generic plan */
1973  plansource->is_valid = false;
1974  if (plansource->gplan)
1975  plansource->gplan->is_valid = false;
1976  }
1977 
1978  /*
1979  * The generic plan, if any, could have more dependencies than the
1980  * querytree does, so we have to check it too.
1981  */
1982  if (plansource->gplan && plansource->gplan->is_valid)
1983  {
1984  ListCell *lc;
1985 
1986  foreach(lc, plansource->gplan->stmt_list)
1987  {
1988  PlannedStmt *plannedstmt = lfirst_node(PlannedStmt, lc);
1989 
1990  if (plannedstmt->commandType == CMD_UTILITY)
1991  continue; /* Ignore utility statements */
1992  if ((relid == InvalidOid) ? plannedstmt->relationOids != NIL :
1993  list_member_oid(plannedstmt->relationOids, relid))
1994  {
1995  /* Invalidate the generic plan only */
1996  plansource->gplan->is_valid = false;
1997  break; /* out of stmt_list scan */
1998  }
1999  }
2000  }
2001  }
2002 
2003  /* Likewise check cached expressions */
2004  dlist_foreach(iter, &cached_expression_list)
2005  {
2007  node, iter.cur);
2008 
2009  Assert(cexpr->magic == CACHEDEXPR_MAGIC);
2010 
2011  /* No work if it's already invalidated */
2012  if (!cexpr->is_valid)
2013  continue;
2014 
2015  if ((relid == InvalidOid) ? cexpr->relationOids != NIL :
2016  list_member_oid(cexpr->relationOids, relid))
2017  {
2018  cexpr->is_valid = false;
2019  }
2020  }
2021 }
2022 
2023 /*
2024  * PlanCacheObjectCallback
2025  * Syscache inval callback function for PROCOID and TYPEOID caches
2026  *
2027  * Invalidate all plans mentioning the object with the specified hash value,
2028  * or all plans mentioning any member of this cache if hashvalue == 0.
2029  */
2030 static void
2031 PlanCacheObjectCallback(Datum arg, int cacheid, uint32 hashvalue)
2032 {
2033  dlist_iter iter;
2034 
2035  dlist_foreach(iter, &saved_plan_list)
2036  {
2038  node, iter.cur);
2039  ListCell *lc;
2040 
2041  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
2042 
2043  /* No work if it's already invalidated */
2044  if (!plansource->is_valid)
2045  continue;
2046 
2047  /* Never invalidate transaction control commands */
2048  if (IsTransactionStmtPlan(plansource))
2049  continue;
2050 
2051  /*
2052  * Check the dependency list for the rewritten querytree.
2053  */
2054  foreach(lc, plansource->invalItems)
2055  {
2056  PlanInvalItem *item = (PlanInvalItem *) lfirst(lc);
2057 
2058  if (item->cacheId != cacheid)
2059  continue;
2060  if (hashvalue == 0 ||
2061  item->hashValue == hashvalue)
2062  {
2063  /* Invalidate the querytree and generic plan */
2064  plansource->is_valid = false;
2065  if (plansource->gplan)
2066  plansource->gplan->is_valid = false;
2067  break;
2068  }
2069  }
2070 
2071  /*
2072  * The generic plan, if any, could have more dependencies than the
2073  * querytree does, so we have to check it too.
2074  */
2075  if (plansource->gplan && plansource->gplan->is_valid)
2076  {
2077  foreach(lc, plansource->gplan->stmt_list)
2078  {
2079  PlannedStmt *plannedstmt = lfirst_node(PlannedStmt, lc);
2080  ListCell *lc3;
2081 
2082  if (plannedstmt->commandType == CMD_UTILITY)
2083  continue; /* Ignore utility statements */
2084  foreach(lc3, plannedstmt->invalItems)
2085  {
2086  PlanInvalItem *item = (PlanInvalItem *) lfirst(lc3);
2087 
2088  if (item->cacheId != cacheid)
2089  continue;
2090  if (hashvalue == 0 ||
2091  item->hashValue == hashvalue)
2092  {
2093  /* Invalidate the generic plan only */
2094  plansource->gplan->is_valid = false;
2095  break; /* out of invalItems scan */
2096  }
2097  }
2098  if (!plansource->gplan->is_valid)
2099  break; /* out of stmt_list scan */
2100  }
2101  }
2102  }
2103 
2104  /* Likewise check cached expressions */
2105  dlist_foreach(iter, &cached_expression_list)
2106  {
2108  node, iter.cur);
2109  ListCell *lc;
2110 
2111  Assert(cexpr->magic == CACHEDEXPR_MAGIC);
2112 
2113  /* No work if it's already invalidated */
2114  if (!cexpr->is_valid)
2115  continue;
2116 
2117  foreach(lc, cexpr->invalItems)
2118  {
2119  PlanInvalItem *item = (PlanInvalItem *) lfirst(lc);
2120 
2121  if (item->cacheId != cacheid)
2122  continue;
2123  if (hashvalue == 0 ||
2124  item->hashValue == hashvalue)
2125  {
2126  cexpr->is_valid = false;
2127  break;
2128  }
2129  }
2130  }
2131 }
2132 
2133 /*
2134  * PlanCacheSysCallback
2135  * Syscache inval callback function for other caches
2136  *
2137  * Just invalidate everything...
2138  */
2139 static void
2140 PlanCacheSysCallback(Datum arg, int cacheid, uint32 hashvalue)
2141 {
2142  ResetPlanCache();
2143 }
2144 
2145 /*
2146  * ResetPlanCache: invalidate all cached plans.
2147  */
2148 void
2150 {
2151  dlist_iter iter;
2152 
2153  dlist_foreach(iter, &saved_plan_list)
2154  {
2156  node, iter.cur);
2157  ListCell *lc;
2158 
2159  Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
2160 
2161  /* No work if it's already invalidated */
2162  if (!plansource->is_valid)
2163  continue;
2164 
2165  /*
2166  * We *must not* mark transaction control statements as invalid,
2167  * particularly not ROLLBACK, because they may need to be executed in
2168  * aborted transactions when we can't revalidate them (cf bug #5269).
2169  */
2170  if (IsTransactionStmtPlan(plansource))
2171  continue;
2172 
2173  /*
2174  * In general there is no point in invalidating utility statements
2175  * since they have no plans anyway. So invalidate it only if it
2176  * contains at least one non-utility statement, or contains a utility
2177  * statement that contains a pre-analyzed query (which could have
2178  * dependencies.)
2179  */
2180  foreach(lc, plansource->query_list)
2181  {
2182  Query *query = lfirst_node(Query, lc);
2183 
2184  if (query->commandType != CMD_UTILITY ||
2186  {
2187  /* non-utility statement, so invalidate */
2188  plansource->is_valid = false;
2189  if (plansource->gplan)
2190  plansource->gplan->is_valid = false;
2191  /* no need to look further */
2192  break;
2193  }
2194  }
2195  }
2196 
2197  /* Likewise invalidate cached expressions */
2198  dlist_foreach(iter, &cached_expression_list)
2199  {
2201  node, iter.cur);
2202 
2203  Assert(cexpr->magic == CACHEDEXPR_MAGIC);
2204 
2205  cexpr->is_valid = false;
2206  }
2207 }
Oid planRoleId
Definition: plancache.h:154
#define CACHEDPLAN_MAGIC
Definition: plancache.h:41
bool dependsOnRole
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MemoryContext context
Definition: plancache.h:109
static CachedPlan * BuildCachedPlan(CachedPlanSource *plansource, List *qlist, ParamListInfo boundParams, QueryEnvironment *queryEnv)
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#define NIL
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CommandTag
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bool query_tree_walker(Query *query, bool(*walker)(), void *context, int flags)
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Definition: analyze.c:357
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Definition: plancache.c:527
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CachedPlanSource * CreateOneShotCachedPlan(RawStmt *raw_parse_tree, const char *query_string, CommandTag commandTag)
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MemoryContext context
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Definition: nodes.h:528
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Definition: plancache.h:155
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Definition: resowner.c:1121
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Definition: parsenodes.h:120
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Snapshot GetTransactionSnapshot(void)
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Definition: plancache.h:121
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