1 /*-------------------------------------------------------------------------
2 *
3 * subselect.c
4 * Planning routines for subselects.
5 *
6 * This module deals with SubLinks and CTEs, but not subquery RTEs (i.e.,
7 * not sub-SELECT-in-FROM cases).
8 *
9 * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
10 * Portions Copyright (c) 1994, Regents of the University of California
11 *
12 * IDENTIFICATION
13 * src/backend/optimizer/plan/subselect.c
14 *
15 *-------------------------------------------------------------------------
16 */
17 #include "postgres.h"
18
19 #include "access/htup_details.h"
20 #include "catalog/pg_operator.h"
21 #include "catalog/pg_type.h"
22 #include "executor/executor.h"
23 #include "miscadmin.h"
24 #include "nodes/makefuncs.h"
25 #include "nodes/nodeFuncs.h"
26 #include "optimizer/clauses.h"
27 #include "optimizer/cost.h"
28 #include "optimizer/paramassign.h"
29 #include "optimizer/pathnode.h"
30 #include "optimizer/planmain.h"
31 #include "optimizer/planner.h"
32 #include "optimizer/prep.h"
33 #include "optimizer/subselect.h"
34 #include "optimizer/var.h"
35 #include "parser/parse_relation.h"
36 #include "rewrite/rewriteManip.h"
37 #include "utils/builtins.h"
38 #include "utils/lsyscache.h"
39 #include "utils/syscache.h"
40
41
42 typedef struct convert_testexpr_context
43 {
44 PlannerInfo *root;
45 List *subst_nodes; /* Nodes to substitute for Params */
46 } convert_testexpr_context;
47
48 typedef struct process_sublinks_context
49 {
50 PlannerInfo *root;
51 bool isTopQual;
52 } process_sublinks_context;
53
54 typedef struct finalize_primnode_context
55 {
56 PlannerInfo *root;
57 Bitmapset *paramids; /* Non-local PARAM_EXEC paramids found */
58 } finalize_primnode_context;
59
60
61 static Node *build_subplan(PlannerInfo *root, Plan *plan, PlannerInfo *subroot,
62 List *plan_params,
63 SubLinkType subLinkType, int subLinkId,
64 Node *testexpr, List *testexpr_paramids,
65 bool unknownEqFalse);
66 static List *generate_subquery_params(PlannerInfo *root, List *tlist,
67 List **paramIds);
68 static List *generate_subquery_vars(PlannerInfo *root, List *tlist,
69 Index varno);
70 static Node *convert_testexpr(PlannerInfo *root,
71 Node *testexpr,
72 List *subst_nodes);
73 static Node *convert_testexpr_mutator(Node *node,
74 convert_testexpr_context *context);
75 static bool subplan_is_hashable(Plan *plan);
76 static bool testexpr_is_hashable(Node *testexpr, List *param_ids);
77 static bool test_opexpr_is_hashable(OpExpr *testexpr, List *param_ids);
78 static bool hash_ok_operator(OpExpr *expr);
79 static bool simplify_EXISTS_query(PlannerInfo *root, Query *query);
80 static Query *convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect,
81 Node **testexpr, List **paramIds);
82 static Node *replace_correlation_vars_mutator(Node *node, PlannerInfo *root);
83 static Node *process_sublinks_mutator(Node *node,
84 process_sublinks_context *context);
85 static Bitmapset *finalize_plan(PlannerInfo *root,
86 Plan *plan,
87 Bitmapset *valid_params,
88 Bitmapset *scan_params);
89 static bool finalize_primnode(Node *node, finalize_primnode_context *context);
90 static bool finalize_agg_primnode(Node *node, finalize_primnode_context *context);
91
92
93 /*
94 * Assign a (nonnegative) PARAM_EXEC ID for a special parameter (one that
95 * is not actually used to carry a value at runtime). Such parameters are
96 * used for special runtime signaling purposes, such as connecting a
97 * recursive union node to its worktable scan node or forcing plan
98 * re-evaluation within the EvalPlanQual mechanism. No actual Param node
99 * exists with this ID, however.
100 *
101 * XXX deprecated: use assign_special_exec_param directly, instead. We are
102 * keeping this in v11 and below only to avoid API breaks.
103 */
104 int
SS_assign_special_param(PlannerInfo * root)105 SS_assign_special_param(PlannerInfo *root)
106 {
107 return assign_special_exec_param(root);
108 }
109
110 /*
111 * Get the datatype/typmod/collation of the first column of the plan's output.
112 *
113 * This information is stored for ARRAY_SUBLINK execution and for
114 * exprType()/exprTypmod()/exprCollation(), which have no way to get at the
115 * plan associated with a SubPlan node. We really only need the info for
116 * EXPR_SUBLINK and ARRAY_SUBLINK subplans, but for consistency we save it
117 * always.
118 */
119 static void
get_first_col_type(Plan * plan,Oid * coltype,int32 * coltypmod,Oid * colcollation)120 get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod,
121 Oid *colcollation)
122 {
123 /* In cases such as EXISTS, tlist might be empty; arbitrarily use VOID */
124 if (plan->targetlist)
125 {
126 TargetEntry *tent = (TargetEntry *) linitial(plan->targetlist);
127
128 Assert(IsA(tent, TargetEntry));
129 if (!tent->resjunk)
130 {
131 *coltype = exprType((Node *) tent->expr);
132 *coltypmod = exprTypmod((Node *) tent->expr);
133 *colcollation = exprCollation((Node *) tent->expr);
134 return;
135 }
136 }
137 *coltype = VOIDOID;
138 *coltypmod = -1;
139 *colcollation = InvalidOid;
140 }
141
142 /*
143 * Convert a SubLink (as created by the parser) into a SubPlan.
144 *
145 * We are given the SubLink's contained query, type, ID, and testexpr. We are
146 * also told if this expression appears at top level of a WHERE/HAVING qual.
147 *
148 * Note: we assume that the testexpr has been AND/OR flattened (actually,
149 * it's been through eval_const_expressions), but not converted to
150 * implicit-AND form; and any SubLinks in it should already have been
151 * converted to SubPlans. The subquery is as yet untouched, however.
152 *
153 * The result is whatever we need to substitute in place of the SubLink node
154 * in the executable expression. If we're going to do the subplan as a
155 * regular subplan, this will be the constructed SubPlan node. If we're going
156 * to do the subplan as an InitPlan, the SubPlan node instead goes into
157 * root->init_plans, and what we return here is an expression tree
158 * representing the InitPlan's result: usually just a Param node representing
159 * a single scalar result, but possibly a row comparison tree containing
160 * multiple Param nodes, or for a MULTIEXPR subquery a simple NULL constant
161 * (since the real output Params are elsewhere in the tree, and the MULTIEXPR
162 * subquery itself is in a resjunk tlist entry whose value is uninteresting).
163 */
164 static Node *
make_subplan(PlannerInfo * root,Query * orig_subquery,SubLinkType subLinkType,int subLinkId,Node * testexpr,bool isTopQual)165 make_subplan(PlannerInfo *root, Query *orig_subquery,
166 SubLinkType subLinkType, int subLinkId,
167 Node *testexpr, bool isTopQual)
168 {
169 Query *subquery;
170 bool simple_exists = false;
171 double tuple_fraction;
172 PlannerInfo *subroot;
173 RelOptInfo *final_rel;
174 Path *best_path;
175 Plan *plan;
176 List *plan_params;
177 Node *result;
178
179 /*
180 * Copy the source Query node. This is a quick and dirty kluge to resolve
181 * the fact that the parser can generate trees with multiple links to the
182 * same sub-Query node, but the planner wants to scribble on the Query.
183 * Try to clean this up when we do querytree redesign...
184 */
185 subquery = (Query *) copyObject(orig_subquery);
186
187 /*
188 * If it's an EXISTS subplan, we might be able to simplify it.
189 */
190 if (subLinkType == EXISTS_SUBLINK)
191 simple_exists = simplify_EXISTS_query(root, subquery);
192
193 /*
194 * For an EXISTS subplan, tell lower-level planner to expect that only the
195 * first tuple will be retrieved. For ALL and ANY subplans, we will be
196 * able to stop evaluating if the test condition fails or matches, so very
197 * often not all the tuples will be retrieved; for lack of a better idea,
198 * specify 50% retrieval. For EXPR, MULTIEXPR, and ROWCOMPARE subplans,
199 * use default behavior (we're only expecting one row out, anyway).
200 *
201 * NOTE: if you change these numbers, also change cost_subplan() in
202 * path/costsize.c.
203 *
204 * XXX If an ANY subplan is uncorrelated, build_subplan may decide to hash
205 * its output. In that case it would've been better to specify full
206 * retrieval. At present, however, we can only check hashability after
207 * we've made the subplan :-(. (Determining whether it'll fit in work_mem
208 * is the really hard part.) Therefore, we don't want to be too
209 * optimistic about the percentage of tuples retrieved, for fear of
210 * selecting a plan that's bad for the materialization case.
211 */
212 if (subLinkType == EXISTS_SUBLINK)
213 tuple_fraction = 1.0; /* just like a LIMIT 1 */
214 else if (subLinkType == ALL_SUBLINK ||
215 subLinkType == ANY_SUBLINK)
216 tuple_fraction = 0.5; /* 50% */
217 else
218 tuple_fraction = 0.0; /* default behavior */
219
220 /* plan_params should not be in use in current query level */
221 Assert(root->plan_params == NIL);
222
223 /* Generate Paths for the subquery */
224 subroot = subquery_planner(root->glob, subquery,
225 root,
226 false, tuple_fraction);
227
228 /* Isolate the params needed by this specific subplan */
229 plan_params = root->plan_params;
230 root->plan_params = NIL;
231
232 /*
233 * Select best Path and turn it into a Plan. At least for now, there
234 * seems no reason to postpone doing that.
235 */
236 final_rel = fetch_upper_rel(subroot, UPPERREL_FINAL, NULL);
237 best_path = get_cheapest_fractional_path(final_rel, tuple_fraction);
238
239 plan = create_plan(subroot, best_path);
240
241 /* And convert to SubPlan or InitPlan format. */
242 result = build_subplan(root, plan, subroot, plan_params,
243 subLinkType, subLinkId,
244 testexpr, NIL, isTopQual);
245
246 /*
247 * If it's a correlated EXISTS with an unimportant targetlist, we might be
248 * able to transform it to the equivalent of an IN and then implement it
249 * by hashing. We don't have enough information yet to tell which way is
250 * likely to be better (it depends on the expected number of executions of
251 * the EXISTS qual, and we are much too early in planning the outer query
252 * to be able to guess that). So we generate both plans, if possible, and
253 * leave it to the executor to decide which to use.
254 */
255 if (simple_exists && IsA(result, SubPlan))
256 {
257 Node *newtestexpr;
258 List *paramIds;
259
260 /* Make a second copy of the original subquery */
261 subquery = (Query *) copyObject(orig_subquery);
262 /* and re-simplify */
263 simple_exists = simplify_EXISTS_query(root, subquery);
264 Assert(simple_exists);
265 /* See if it can be converted to an ANY query */
266 subquery = convert_EXISTS_to_ANY(root, subquery,
267 &newtestexpr, ¶mIds);
268 if (subquery)
269 {
270 /* Generate Paths for the ANY subquery; we'll need all rows */
271 subroot = subquery_planner(root->glob, subquery,
272 root,
273 false, 0.0);
274
275 /* Isolate the params needed by this specific subplan */
276 plan_params = root->plan_params;
277 root->plan_params = NIL;
278
279 /* Select best Path and turn it into a Plan */
280 final_rel = fetch_upper_rel(subroot, UPPERREL_FINAL, NULL);
281 best_path = final_rel->cheapest_total_path;
282
283 plan = create_plan(subroot, best_path);
284
285 /* Now we can check if it'll fit in work_mem */
286 /* XXX can we check this at the Path stage? */
287 if (subplan_is_hashable(plan))
288 {
289 SubPlan *hashplan;
290 AlternativeSubPlan *asplan;
291
292 /* OK, convert to SubPlan format. */
293 hashplan = (SubPlan *) build_subplan(root, plan, subroot,
294 plan_params,
295 ANY_SUBLINK, 0,
296 newtestexpr,
297 paramIds,
298 true);
299 /* Check we got what we expected */
300 Assert(IsA(hashplan, SubPlan));
301 Assert(hashplan->parParam == NIL);
302 Assert(hashplan->useHashTable);
303
304 /* Leave it to the executor to decide which plan to use */
305 asplan = makeNode(AlternativeSubPlan);
306 asplan->subplans = list_make2(result, hashplan);
307 result = (Node *) asplan;
308 }
309 }
310 }
311
312 return result;
313 }
314
315 /*
316 * Build a SubPlan node given the raw inputs --- subroutine for make_subplan
317 *
318 * Returns either the SubPlan, or a replacement expression if we decide to
319 * make it an InitPlan, as explained in the comments for make_subplan.
320 */
321 static Node *
build_subplan(PlannerInfo * root,Plan * plan,PlannerInfo * subroot,List * plan_params,SubLinkType subLinkType,int subLinkId,Node * testexpr,List * testexpr_paramids,bool unknownEqFalse)322 build_subplan(PlannerInfo *root, Plan *plan, PlannerInfo *subroot,
323 List *plan_params,
324 SubLinkType subLinkType, int subLinkId,
325 Node *testexpr, List *testexpr_paramids,
326 bool unknownEqFalse)
327 {
328 Node *result;
329 SubPlan *splan;
330 bool isInitPlan;
331 ListCell *lc;
332
333 /*
334 * Initialize the SubPlan node. Note plan_id, plan_name, and cost fields
335 * are set further down.
336 */
337 splan = makeNode(SubPlan);
338 splan->subLinkType = subLinkType;
339 splan->testexpr = NULL;
340 splan->paramIds = NIL;
341 get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod,
342 &splan->firstColCollation);
343 splan->useHashTable = false;
344 splan->unknownEqFalse = unknownEqFalse;
345 splan->setParam = NIL;
346 splan->parParam = NIL;
347 splan->args = NIL;
348
349 /*
350 * Make parParam and args lists of param IDs and expressions that current
351 * query level will pass to this child plan.
352 */
353 foreach(lc, plan_params)
354 {
355 PlannerParamItem *pitem = (PlannerParamItem *) lfirst(lc);
356 Node *arg = pitem->item;
357
358 /*
359 * The Var, PlaceHolderVar, or Aggref has already been adjusted to
360 * have the correct varlevelsup, phlevelsup, or agglevelsup.
361 *
362 * If it's a PlaceHolderVar or Aggref, its arguments might contain
363 * SubLinks, which have not yet been processed (see the comments for
364 * SS_replace_correlation_vars). Do that now.
365 */
366 if (IsA(arg, PlaceHolderVar) ||
367 IsA(arg, Aggref))
368 arg = SS_process_sublinks(root, arg, false);
369
370 splan->parParam = lappend_int(splan->parParam, pitem->paramId);
371 splan->args = lappend(splan->args, arg);
372 }
373
374 /*
375 * Un-correlated or undirect correlated plans of EXISTS, EXPR, ARRAY,
376 * ROWCOMPARE, or MULTIEXPR types can be used as initPlans. For EXISTS,
377 * EXPR, or ARRAY, we return a Param referring to the result of evaluating
378 * the initPlan. For ROWCOMPARE, we must modify the testexpr tree to
379 * contain PARAM_EXEC Params instead of the PARAM_SUBLINK Params emitted
380 * by the parser, and then return that tree. For MULTIEXPR, we return a
381 * null constant: the resjunk targetlist item containing the SubLink does
382 * not need to return anything useful, since the referencing Params are
383 * elsewhere.
384 */
385 if (splan->parParam == NIL && subLinkType == EXISTS_SUBLINK)
386 {
387 Param *prm;
388
389 Assert(testexpr == NULL);
390 prm = generate_new_exec_param(root, BOOLOID, -1, InvalidOid);
391 splan->setParam = list_make1_int(prm->paramid);
392 isInitPlan = true;
393 result = (Node *) prm;
394 }
395 else if (splan->parParam == NIL && subLinkType == EXPR_SUBLINK)
396 {
397 TargetEntry *te = linitial(plan->targetlist);
398 Param *prm;
399
400 Assert(!te->resjunk);
401 Assert(testexpr == NULL);
402 prm = generate_new_exec_param(root,
403 exprType((Node *) te->expr),
404 exprTypmod((Node *) te->expr),
405 exprCollation((Node *) te->expr));
406 splan->setParam = list_make1_int(prm->paramid);
407 isInitPlan = true;
408 result = (Node *) prm;
409 }
410 else if (splan->parParam == NIL && subLinkType == ARRAY_SUBLINK)
411 {
412 TargetEntry *te = linitial(plan->targetlist);
413 Oid arraytype;
414 Param *prm;
415
416 Assert(!te->resjunk);
417 Assert(testexpr == NULL);
418 arraytype = get_promoted_array_type(exprType((Node *) te->expr));
419 if (!OidIsValid(arraytype))
420 elog(ERROR, "could not find array type for datatype %s",
421 format_type_be(exprType((Node *) te->expr)));
422 prm = generate_new_exec_param(root,
423 arraytype,
424 exprTypmod((Node *) te->expr),
425 exprCollation((Node *) te->expr));
426 splan->setParam = list_make1_int(prm->paramid);
427 isInitPlan = true;
428 result = (Node *) prm;
429 }
430 else if (splan->parParam == NIL && subLinkType == ROWCOMPARE_SUBLINK)
431 {
432 /* Adjust the Params */
433 List *params;
434
435 Assert(testexpr != NULL);
436 params = generate_subquery_params(root,
437 plan->targetlist,
438 &splan->paramIds);
439 result = convert_testexpr(root,
440 testexpr,
441 params);
442 splan->setParam = list_copy(splan->paramIds);
443 isInitPlan = true;
444
445 /*
446 * The executable expression is returned to become part of the outer
447 * plan's expression tree; it is not kept in the initplan node.
448 */
449 }
450 else if (subLinkType == MULTIEXPR_SUBLINK)
451 {
452 /*
453 * Whether it's an initplan or not, it needs to set a PARAM_EXEC Param
454 * for each output column.
455 */
456 List *params;
457
458 Assert(testexpr == NULL);
459 params = generate_subquery_params(root,
460 plan->targetlist,
461 &splan->setParam);
462
463 /*
464 * Save the list of replacement Params in the n'th cell of
465 * root->multiexpr_params; setrefs.c will use it to replace
466 * PARAM_MULTIEXPR Params.
467 */
468 while (list_length(root->multiexpr_params) < subLinkId)
469 root->multiexpr_params = lappend(root->multiexpr_params, NIL);
470 lc = list_nth_cell(root->multiexpr_params, subLinkId - 1);
471 Assert(lfirst(lc) == NIL);
472 lfirst(lc) = params;
473
474 /* It can be an initplan if there are no parParams. */
475 if (splan->parParam == NIL)
476 {
477 isInitPlan = true;
478 result = (Node *) makeNullConst(RECORDOID, -1, InvalidOid);
479 }
480 else
481 {
482 isInitPlan = false;
483 result = (Node *) splan;
484 }
485 }
486 else
487 {
488 /*
489 * Adjust the Params in the testexpr, unless caller already took care
490 * of it (as indicated by passing a list of Param IDs).
491 */
492 if (testexpr && testexpr_paramids == NIL)
493 {
494 List *params;
495
496 params = generate_subquery_params(root,
497 plan->targetlist,
498 &splan->paramIds);
499 splan->testexpr = convert_testexpr(root,
500 testexpr,
501 params);
502 }
503 else
504 {
505 splan->testexpr = testexpr;
506 splan->paramIds = testexpr_paramids;
507 }
508
509 /*
510 * We can't convert subplans of ALL_SUBLINK or ANY_SUBLINK types to
511 * initPlans, even when they are uncorrelated or undirect correlated,
512 * because we need to scan the output of the subplan for each outer
513 * tuple. But if it's a not-direct-correlated IN (= ANY) test, we
514 * might be able to use a hashtable to avoid comparing all the tuples.
515 */
516 if (subLinkType == ANY_SUBLINK &&
517 splan->parParam == NIL &&
518 subplan_is_hashable(plan) &&
519 testexpr_is_hashable(splan->testexpr, splan->paramIds))
520 splan->useHashTable = true;
521
522 /*
523 * Otherwise, we have the option to tack a Material node onto the top
524 * of the subplan, to reduce the cost of reading it repeatedly. This
525 * is pointless for a direct-correlated subplan, since we'd have to
526 * recompute its results each time anyway. For uncorrelated/undirect
527 * correlated subplans, we add Material unless the subplan's top plan
528 * node would materialize its output anyway. Also, if enable_material
529 * is false, then the user does not want us to materialize anything
530 * unnecessarily, so we don't.
531 */
532 else if (splan->parParam == NIL && enable_material &&
533 !ExecMaterializesOutput(nodeTag(plan)))
534 plan = materialize_finished_plan(plan);
535
536 result = (Node *) splan;
537 isInitPlan = false;
538 }
539
540 /*
541 * Add the subplan and its PlannerInfo to the global lists.
542 */
543 root->glob->subplans = lappend(root->glob->subplans, plan);
544 root->glob->subroots = lappend(root->glob->subroots, subroot);
545 splan->plan_id = list_length(root->glob->subplans);
546
547 if (isInitPlan)
548 root->init_plans = lappend(root->init_plans, splan);
549
550 /*
551 * A parameterless subplan (not initplan) should be prepared to handle
552 * REWIND efficiently. If it has direct parameters then there's no point
553 * since it'll be reset on each scan anyway; and if it's an initplan then
554 * there's no point since it won't get re-run without parameter changes
555 * anyway. The input of a hashed subplan doesn't need REWIND either.
556 */
557 if (splan->parParam == NIL && !isInitPlan && !splan->useHashTable)
558 root->glob->rewindPlanIDs = bms_add_member(root->glob->rewindPlanIDs,
559 splan->plan_id);
560
561 /* Label the subplan for EXPLAIN purposes */
562 splan->plan_name = palloc(32 + 12 * list_length(splan->setParam));
563 sprintf(splan->plan_name, "%s %d",
564 isInitPlan ? "InitPlan" : "SubPlan",
565 splan->plan_id);
566 if (splan->setParam)
567 {
568 char *ptr = splan->plan_name + strlen(splan->plan_name);
569
570 ptr += sprintf(ptr, " (returns ");
571 foreach(lc, splan->setParam)
572 {
573 ptr += sprintf(ptr, "$%d%s",
574 lfirst_int(lc),
575 lnext(lc) ? "," : ")");
576 }
577 }
578
579 /* Lastly, fill in the cost estimates for use later */
580 cost_subplan(root, splan, plan);
581
582 return result;
583 }
584
585 /*
586 * generate_subquery_params: build a list of Params representing the output
587 * columns of a sublink's sub-select, given the sub-select's targetlist.
588 *
589 * We also return an integer list of the paramids of the Params.
590 */
591 static List *
generate_subquery_params(PlannerInfo * root,List * tlist,List ** paramIds)592 generate_subquery_params(PlannerInfo *root, List *tlist, List **paramIds)
593 {
594 List *result;
595 List *ids;
596 ListCell *lc;
597
598 result = ids = NIL;
599 foreach(lc, tlist)
600 {
601 TargetEntry *tent = (TargetEntry *) lfirst(lc);
602 Param *param;
603
604 if (tent->resjunk)
605 continue;
606
607 param = generate_new_exec_param(root,
608 exprType((Node *) tent->expr),
609 exprTypmod((Node *) tent->expr),
610 exprCollation((Node *) tent->expr));
611 result = lappend(result, param);
612 ids = lappend_int(ids, param->paramid);
613 }
614
615 *paramIds = ids;
616 return result;
617 }
618
619 /*
620 * generate_subquery_vars: build a list of Vars representing the output
621 * columns of a sublink's sub-select, given the sub-select's targetlist.
622 * The Vars have the specified varno (RTE index).
623 */
624 static List *
generate_subquery_vars(PlannerInfo * root,List * tlist,Index varno)625 generate_subquery_vars(PlannerInfo *root, List *tlist, Index varno)
626 {
627 List *result;
628 ListCell *lc;
629
630 result = NIL;
631 foreach(lc, tlist)
632 {
633 TargetEntry *tent = (TargetEntry *) lfirst(lc);
634 Var *var;
635
636 if (tent->resjunk)
637 continue;
638
639 var = makeVarFromTargetEntry(varno, tent);
640 result = lappend(result, var);
641 }
642
643 return result;
644 }
645
646 /*
647 * convert_testexpr: convert the testexpr given by the parser into
648 * actually executable form. This entails replacing PARAM_SUBLINK Params
649 * with Params or Vars representing the results of the sub-select. The
650 * nodes to be substituted are passed in as the List result from
651 * generate_subquery_params or generate_subquery_vars.
652 */
653 static Node *
convert_testexpr(PlannerInfo * root,Node * testexpr,List * subst_nodes)654 convert_testexpr(PlannerInfo *root,
655 Node *testexpr,
656 List *subst_nodes)
657 {
658 convert_testexpr_context context;
659
660 context.root = root;
661 context.subst_nodes = subst_nodes;
662 return convert_testexpr_mutator(testexpr, &context);
663 }
664
665 static Node *
convert_testexpr_mutator(Node * node,convert_testexpr_context * context)666 convert_testexpr_mutator(Node *node,
667 convert_testexpr_context *context)
668 {
669 if (node == NULL)
670 return NULL;
671 if (IsA(node, Param))
672 {
673 Param *param = (Param *) node;
674
675 if (param->paramkind == PARAM_SUBLINK)
676 {
677 if (param->paramid <= 0 ||
678 param->paramid > list_length(context->subst_nodes))
679 elog(ERROR, "unexpected PARAM_SUBLINK ID: %d", param->paramid);
680
681 /*
682 * We copy the list item to avoid having doubly-linked
683 * substructure in the modified parse tree. This is probably
684 * unnecessary when it's a Param, but be safe.
685 */
686 return (Node *) copyObject(list_nth(context->subst_nodes,
687 param->paramid - 1));
688 }
689 }
690 if (IsA(node, SubLink))
691 {
692 /*
693 * If we come across a nested SubLink, it is neither necessary nor
694 * correct to recurse into it: any PARAM_SUBLINKs we might find inside
695 * belong to the inner SubLink not the outer. So just return it as-is.
696 *
697 * This reasoning depends on the assumption that nothing will pull
698 * subexpressions into or out of the testexpr field of a SubLink, at
699 * least not without replacing PARAM_SUBLINKs first. If we did want
700 * to do that we'd need to rethink the parser-output representation
701 * altogether, since currently PARAM_SUBLINKs are only unique per
702 * SubLink not globally across the query. The whole point of
703 * replacing them with Vars or PARAM_EXEC nodes is to make them
704 * globally unique before they escape from the SubLink's testexpr.
705 *
706 * Note: this can't happen when called during SS_process_sublinks,
707 * because that recursively processes inner SubLinks first. It can
708 * happen when called from convert_ANY_sublink_to_join, though.
709 */
710 return node;
711 }
712 return expression_tree_mutator(node,
713 convert_testexpr_mutator,
714 (void *) context);
715 }
716
717 /*
718 * subplan_is_hashable: can we implement an ANY subplan by hashing?
719 */
720 static bool
subplan_is_hashable(Plan * plan)721 subplan_is_hashable(Plan *plan)
722 {
723 double subquery_size;
724
725 /*
726 * The estimated size of the subquery result must fit in work_mem. (Note:
727 * we use heap tuple overhead here even though the tuples will actually be
728 * stored as MinimalTuples; this provides some fudge factor for hashtable
729 * overhead.)
730 */
731 subquery_size = plan->plan_rows *
732 (MAXALIGN(plan->plan_width) + MAXALIGN(SizeofHeapTupleHeader));
733 if (subquery_size > work_mem * 1024L)
734 return false;
735
736 return true;
737 }
738
739 /*
740 * testexpr_is_hashable: is an ANY SubLink's test expression hashable?
741 *
742 * To identify LHS vs RHS of the hash expression, we must be given the
743 * list of output Param IDs of the SubLink's subquery.
744 */
745 static bool
testexpr_is_hashable(Node * testexpr,List * param_ids)746 testexpr_is_hashable(Node *testexpr, List *param_ids)
747 {
748 /*
749 * The testexpr must be a single OpExpr, or an AND-clause containing only
750 * OpExprs, each of which satisfy test_opexpr_is_hashable().
751 */
752 if (testexpr && IsA(testexpr, OpExpr))
753 {
754 if (test_opexpr_is_hashable((OpExpr *) testexpr, param_ids))
755 return true;
756 }
757 else if (and_clause(testexpr))
758 {
759 ListCell *l;
760
761 foreach(l, ((BoolExpr *) testexpr)->args)
762 {
763 Node *andarg = (Node *) lfirst(l);
764
765 if (!IsA(andarg, OpExpr))
766 return false;
767 if (!test_opexpr_is_hashable((OpExpr *) andarg, param_ids))
768 return false;
769 }
770 return true;
771 }
772
773 return false;
774 }
775
776 static bool
test_opexpr_is_hashable(OpExpr * testexpr,List * param_ids)777 test_opexpr_is_hashable(OpExpr *testexpr, List *param_ids)
778 {
779 /*
780 * The combining operator must be hashable and strict. The need for
781 * hashability is obvious, since we want to use hashing. Without
782 * strictness, behavior in the presence of nulls is too unpredictable. We
783 * actually must assume even more than plain strictness: it can't yield
784 * NULL for non-null inputs, either (see nodeSubplan.c). However, hash
785 * indexes and hash joins assume that too.
786 */
787 if (!hash_ok_operator(testexpr))
788 return false;
789
790 /*
791 * The left and right inputs must belong to the outer and inner queries
792 * respectively; hence Params that will be supplied by the subquery must
793 * not appear in the LHS, and Vars of the outer query must not appear in
794 * the RHS. (Ordinarily, this must be true because of the way that the
795 * parser builds an ANY SubLink's testexpr ... but inlining of functions
796 * could have changed the expression's structure, so we have to check.
797 * Such cases do not occur often enough to be worth trying to optimize, so
798 * we don't worry about trying to commute the clause or anything like
799 * that; we just need to be sure not to build an invalid plan.)
800 */
801 if (list_length(testexpr->args) != 2)
802 return false;
803 if (contain_exec_param((Node *) linitial(testexpr->args), param_ids))
804 return false;
805 if (contain_var_clause((Node *) lsecond(testexpr->args)))
806 return false;
807 return true;
808 }
809
810 /*
811 * Check expression is hashable + strict
812 *
813 * We could use op_hashjoinable() and op_strict(), but do it like this to
814 * avoid a redundant cache lookup.
815 */
816 static bool
hash_ok_operator(OpExpr * expr)817 hash_ok_operator(OpExpr *expr)
818 {
819 Oid opid = expr->opno;
820
821 /* quick out if not a binary operator */
822 if (list_length(expr->args) != 2)
823 return false;
824 if (opid == ARRAY_EQ_OP)
825 {
826 /* array_eq is strict, but must check input type to ensure hashable */
827 /* XXX record_eq will need same treatment when it becomes hashable */
828 Node *leftarg = linitial(expr->args);
829
830 return op_hashjoinable(opid, exprType(leftarg));
831 }
832 else
833 {
834 /* else must look up the operator properties */
835 HeapTuple tup;
836 Form_pg_operator optup;
837
838 tup = SearchSysCache1(OPEROID, ObjectIdGetDatum(opid));
839 if (!HeapTupleIsValid(tup))
840 elog(ERROR, "cache lookup failed for operator %u", opid);
841 optup = (Form_pg_operator) GETSTRUCT(tup);
842 if (!optup->oprcanhash || !func_strict(optup->oprcode))
843 {
844 ReleaseSysCache(tup);
845 return false;
846 }
847 ReleaseSysCache(tup);
848 return true;
849 }
850 }
851
852
853 /*
854 * SS_process_ctes: process a query's WITH list
855 *
856 * We plan each interesting WITH item and convert it to an initplan.
857 * A side effect is to fill in root->cte_plan_ids with a list that
858 * parallels root->parse->cteList and provides the subplan ID for
859 * each CTE's initplan.
860 */
861 void
SS_process_ctes(PlannerInfo * root)862 SS_process_ctes(PlannerInfo *root)
863 {
864 ListCell *lc;
865
866 Assert(root->cte_plan_ids == NIL);
867
868 foreach(lc, root->parse->cteList)
869 {
870 CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
871 CmdType cmdType = ((Query *) cte->ctequery)->commandType;
872 Query *subquery;
873 PlannerInfo *subroot;
874 RelOptInfo *final_rel;
875 Path *best_path;
876 Plan *plan;
877 SubPlan *splan;
878 int paramid;
879
880 /*
881 * Ignore SELECT CTEs that are not actually referenced anywhere.
882 */
883 if (cte->cterefcount == 0 && cmdType == CMD_SELECT)
884 {
885 /* Make a dummy entry in cte_plan_ids */
886 root->cte_plan_ids = lappend_int(root->cte_plan_ids, -1);
887 continue;
888 }
889
890 /*
891 * Copy the source Query node. Probably not necessary, but let's keep
892 * this similar to make_subplan.
893 */
894 subquery = (Query *) copyObject(cte->ctequery);
895
896 /* plan_params should not be in use in current query level */
897 Assert(root->plan_params == NIL);
898
899 /*
900 * Generate Paths for the CTE query. Always plan for full retrieval
901 * --- we don't have enough info to predict otherwise.
902 */
903 subroot = subquery_planner(root->glob, subquery,
904 root,
905 cte->cterecursive, 0.0);
906
907 /*
908 * Since the current query level doesn't yet contain any RTEs, it
909 * should not be possible for the CTE to have requested parameters of
910 * this level.
911 */
912 if (root->plan_params)
913 elog(ERROR, "unexpected outer reference in CTE query");
914
915 /*
916 * Select best Path and turn it into a Plan. At least for now, there
917 * seems no reason to postpone doing that.
918 */
919 final_rel = fetch_upper_rel(subroot, UPPERREL_FINAL, NULL);
920 best_path = final_rel->cheapest_total_path;
921
922 plan = create_plan(subroot, best_path);
923
924 /*
925 * Make a SubPlan node for it. This is just enough unlike
926 * build_subplan that we can't share code.
927 *
928 * Note plan_id, plan_name, and cost fields are set further down.
929 */
930 splan = makeNode(SubPlan);
931 splan->subLinkType = CTE_SUBLINK;
932 splan->testexpr = NULL;
933 splan->paramIds = NIL;
934 get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod,
935 &splan->firstColCollation);
936 splan->useHashTable = false;
937 splan->unknownEqFalse = false;
938 splan->setParam = NIL;
939 splan->parParam = NIL;
940 splan->args = NIL;
941
942 /*
943 * The node can't have any inputs (since it's an initplan), so the
944 * parParam and args lists remain empty. (It could contain references
945 * to earlier CTEs' output param IDs, but CTE outputs are not
946 * propagated via the args list.)
947 */
948
949 /*
950 * Assign a param ID to represent the CTE's output. No ordinary
951 * "evaluation" of this param slot ever happens, but we use the param
952 * ID for setParam/chgParam signaling just as if the CTE plan were
953 * returning a simple scalar output. (Also, the executor abuses the
954 * ParamExecData slot for this param ID for communication among
955 * multiple CteScan nodes that might be scanning this CTE.)
956 */
957 paramid = assign_special_exec_param(root);
958 splan->setParam = list_make1_int(paramid);
959
960 /*
961 * Add the subplan and its PlannerInfo to the global lists.
962 */
963 root->glob->subplans = lappend(root->glob->subplans, plan);
964 root->glob->subroots = lappend(root->glob->subroots, subroot);
965 splan->plan_id = list_length(root->glob->subplans);
966
967 root->init_plans = lappend(root->init_plans, splan);
968
969 root->cte_plan_ids = lappend_int(root->cte_plan_ids, splan->plan_id);
970
971 /* Label the subplan for EXPLAIN purposes */
972 splan->plan_name = psprintf("CTE %s", cte->ctename);
973
974 /* Lastly, fill in the cost estimates for use later */
975 cost_subplan(root, splan, plan);
976 }
977 }
978
979 /*
980 * convert_ANY_sublink_to_join: try to convert an ANY SubLink to a join
981 *
982 * The caller has found an ANY SubLink at the top level of one of the query's
983 * qual clauses, but has not checked the properties of the SubLink further.
984 * Decide whether it is appropriate to process this SubLink in join style.
985 * If so, form a JoinExpr and return it. Return NULL if the SubLink cannot
986 * be converted to a join.
987 *
988 * The only non-obvious input parameter is available_rels: this is the set
989 * of query rels that can safely be referenced in the sublink expression.
990 * (We must restrict this to avoid changing the semantics when a sublink
991 * is present in an outer join's ON qual.) The conversion must fail if
992 * the converted qual would reference any but these parent-query relids.
993 *
994 * On success, the returned JoinExpr has larg = NULL and rarg = the jointree
995 * item representing the pulled-up subquery. The caller must set larg to
996 * represent the relation(s) on the lefthand side of the new join, and insert
997 * the JoinExpr into the upper query's jointree at an appropriate place
998 * (typically, where the lefthand relation(s) had been). Note that the
999 * passed-in SubLink must also be removed from its original position in the
1000 * query quals, since the quals of the returned JoinExpr replace it.
1001 * (Notionally, we replace the SubLink with a constant TRUE, then elide the
1002 * redundant constant from the qual.)
1003 *
1004 * On success, the caller is also responsible for recursively applying
1005 * pull_up_sublinks processing to the rarg and quals of the returned JoinExpr.
1006 * (On failure, there is no need to do anything, since pull_up_sublinks will
1007 * be applied when we recursively plan the sub-select.)
1008 *
1009 * Side effects of a successful conversion include adding the SubLink's
1010 * subselect to the query's rangetable, so that it can be referenced in
1011 * the JoinExpr's rarg.
1012 */
1013 JoinExpr *
convert_ANY_sublink_to_join(PlannerInfo * root,SubLink * sublink,Relids available_rels)1014 convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink,
1015 Relids available_rels)
1016 {
1017 JoinExpr *result;
1018 Query *parse = root->parse;
1019 Query *subselect = (Query *) sublink->subselect;
1020 Relids upper_varnos;
1021 int rtindex;
1022 RangeTblEntry *rte;
1023 RangeTblRef *rtr;
1024 List *subquery_vars;
1025 Node *quals;
1026 ParseState *pstate;
1027
1028 Assert(sublink->subLinkType == ANY_SUBLINK);
1029
1030 /*
1031 * The sub-select must not refer to any Vars of the parent query. (Vars of
1032 * higher levels should be okay, though.)
1033 */
1034 if (contain_vars_of_level((Node *) subselect, 1))
1035 return NULL;
1036
1037 /*
1038 * The test expression must contain some Vars of the parent query, else
1039 * it's not gonna be a join. (Note that it won't have Vars referring to
1040 * the subquery, rather Params.)
1041 */
1042 upper_varnos = pull_varnos(sublink->testexpr);
1043 if (bms_is_empty(upper_varnos))
1044 return NULL;
1045
1046 /*
1047 * However, it can't refer to anything outside available_rels.
1048 */
1049 if (!bms_is_subset(upper_varnos, available_rels))
1050 return NULL;
1051
1052 /*
1053 * The combining operators and left-hand expressions mustn't be volatile.
1054 */
1055 if (contain_volatile_functions(sublink->testexpr))
1056 return NULL;
1057
1058 /* Create a dummy ParseState for addRangeTableEntryForSubquery */
1059 pstate = make_parsestate(NULL);
1060
1061 /*
1062 * Okay, pull up the sub-select into upper range table.
1063 *
1064 * We rely here on the assumption that the outer query has no references
1065 * to the inner (necessarily true, other than the Vars that we build
1066 * below). Therefore this is a lot easier than what pull_up_subqueries has
1067 * to go through.
1068 */
1069 rte = addRangeTableEntryForSubquery(pstate,
1070 subselect,
1071 makeAlias("ANY_subquery", NIL),
1072 false,
1073 false);
1074 parse->rtable = lappend(parse->rtable, rte);
1075 rtindex = list_length(parse->rtable);
1076
1077 /*
1078 * Form a RangeTblRef for the pulled-up sub-select.
1079 */
1080 rtr = makeNode(RangeTblRef);
1081 rtr->rtindex = rtindex;
1082
1083 /*
1084 * Build a list of Vars representing the subselect outputs.
1085 */
1086 subquery_vars = generate_subquery_vars(root,
1087 subselect->targetList,
1088 rtindex);
1089
1090 /*
1091 * Build the new join's qual expression, replacing Params with these Vars.
1092 */
1093 quals = convert_testexpr(root, sublink->testexpr, subquery_vars);
1094
1095 /*
1096 * And finally, build the JoinExpr node.
1097 */
1098 result = makeNode(JoinExpr);
1099 result->jointype = JOIN_SEMI;
1100 result->isNatural = false;
1101 result->larg = NULL; /* caller must fill this in */
1102 result->rarg = (Node *) rtr;
1103 result->usingClause = NIL;
1104 result->quals = quals;
1105 result->alias = NULL;
1106 result->rtindex = 0; /* we don't need an RTE for it */
1107
1108 return result;
1109 }
1110
1111 /*
1112 * convert_EXISTS_sublink_to_join: try to convert an EXISTS SubLink to a join
1113 *
1114 * The API of this function is identical to convert_ANY_sublink_to_join's,
1115 * except that we also support the case where the caller has found NOT EXISTS,
1116 * so we need an additional input parameter "under_not".
1117 */
1118 JoinExpr *
convert_EXISTS_sublink_to_join(PlannerInfo * root,SubLink * sublink,bool under_not,Relids available_rels)1119 convert_EXISTS_sublink_to_join(PlannerInfo *root, SubLink *sublink,
1120 bool under_not, Relids available_rels)
1121 {
1122 JoinExpr *result;
1123 Query *parse = root->parse;
1124 Query *subselect = (Query *) sublink->subselect;
1125 Node *whereClause;
1126 int rtoffset;
1127 int varno;
1128 Relids clause_varnos;
1129 Relids upper_varnos;
1130
1131 Assert(sublink->subLinkType == EXISTS_SUBLINK);
1132
1133 /*
1134 * Can't flatten if it contains WITH. (We could arrange to pull up the
1135 * WITH into the parent query's cteList, but that risks changing the
1136 * semantics, since a WITH ought to be executed once per associated query
1137 * call.) Note that convert_ANY_sublink_to_join doesn't have to reject
1138 * this case, since it just produces a subquery RTE that doesn't have to
1139 * get flattened into the parent query.
1140 */
1141 if (subselect->cteList)
1142 return NULL;
1143
1144 /*
1145 * Copy the subquery so we can modify it safely (see comments in
1146 * make_subplan).
1147 */
1148 subselect = (Query *) copyObject(subselect);
1149
1150 /*
1151 * See if the subquery can be simplified based on the knowledge that it's
1152 * being used in EXISTS(). If we aren't able to get rid of its
1153 * targetlist, we have to fail, because the pullup operation leaves us
1154 * with noplace to evaluate the targetlist.
1155 */
1156 if (!simplify_EXISTS_query(root, subselect))
1157 return NULL;
1158
1159 /*
1160 * The subquery must have a nonempty jointree, else we won't have a join.
1161 */
1162 if (subselect->jointree->fromlist == NIL)
1163 return NULL;
1164
1165 /*
1166 * Separate out the WHERE clause. (We could theoretically also remove
1167 * top-level plain JOIN/ON clauses, but it's probably not worth the
1168 * trouble.)
1169 */
1170 whereClause = subselect->jointree->quals;
1171 subselect->jointree->quals = NULL;
1172
1173 /*
1174 * The rest of the sub-select must not refer to any Vars of the parent
1175 * query. (Vars of higher levels should be okay, though.)
1176 */
1177 if (contain_vars_of_level((Node *) subselect, 1))
1178 return NULL;
1179
1180 /*
1181 * On the other hand, the WHERE clause must contain some Vars of the
1182 * parent query, else it's not gonna be a join.
1183 */
1184 if (!contain_vars_of_level(whereClause, 1))
1185 return NULL;
1186
1187 /*
1188 * We don't risk optimizing if the WHERE clause is volatile, either.
1189 */
1190 if (contain_volatile_functions(whereClause))
1191 return NULL;
1192
1193 /*
1194 * Prepare to pull up the sub-select into top range table.
1195 *
1196 * We rely here on the assumption that the outer query has no references
1197 * to the inner (necessarily true). Therefore this is a lot easier than
1198 * what pull_up_subqueries has to go through.
1199 *
1200 * In fact, it's even easier than what convert_ANY_sublink_to_join has to
1201 * do. The machinations of simplify_EXISTS_query ensured that there is
1202 * nothing interesting in the subquery except an rtable and jointree, and
1203 * even the jointree FromExpr no longer has quals. So we can just append
1204 * the rtable to our own and use the FromExpr in our jointree. But first,
1205 * adjust all level-zero varnos in the subquery to account for the rtable
1206 * merger.
1207 */
1208 rtoffset = list_length(parse->rtable);
1209 OffsetVarNodes((Node *) subselect, rtoffset, 0);
1210 OffsetVarNodes(whereClause, rtoffset, 0);
1211
1212 /*
1213 * Upper-level vars in subquery will now be one level closer to their
1214 * parent than before; in particular, anything that had been level 1
1215 * becomes level zero.
1216 */
1217 IncrementVarSublevelsUp((Node *) subselect, -1, 1);
1218 IncrementVarSublevelsUp(whereClause, -1, 1);
1219
1220 /*
1221 * Now that the WHERE clause is adjusted to match the parent query
1222 * environment, we can easily identify all the level-zero rels it uses.
1223 * The ones <= rtoffset belong to the upper query; the ones > rtoffset do
1224 * not.
1225 */
1226 clause_varnos = pull_varnos(whereClause);
1227 upper_varnos = NULL;
1228 while ((varno = bms_first_member(clause_varnos)) >= 0)
1229 {
1230 if (varno <= rtoffset)
1231 upper_varnos = bms_add_member(upper_varnos, varno);
1232 }
1233 bms_free(clause_varnos);
1234 Assert(!bms_is_empty(upper_varnos));
1235
1236 /*
1237 * Now that we've got the set of upper-level varnos, we can make the last
1238 * check: only available_rels can be referenced.
1239 */
1240 if (!bms_is_subset(upper_varnos, available_rels))
1241 return NULL;
1242
1243 /* Now we can attach the modified subquery rtable to the parent */
1244 parse->rtable = list_concat(parse->rtable, subselect->rtable);
1245
1246 /*
1247 * And finally, build the JoinExpr node.
1248 */
1249 result = makeNode(JoinExpr);
1250 result->jointype = under_not ? JOIN_ANTI : JOIN_SEMI;
1251 result->isNatural = false;
1252 result->larg = NULL; /* caller must fill this in */
1253 /* flatten out the FromExpr node if it's useless */
1254 if (list_length(subselect->jointree->fromlist) == 1)
1255 result->rarg = (Node *) linitial(subselect->jointree->fromlist);
1256 else
1257 result->rarg = (Node *) subselect->jointree;
1258 result->usingClause = NIL;
1259 result->quals = whereClause;
1260 result->alias = NULL;
1261 result->rtindex = 0; /* we don't need an RTE for it */
1262
1263 return result;
1264 }
1265
1266 /*
1267 * simplify_EXISTS_query: remove any useless stuff in an EXISTS's subquery
1268 *
1269 * The only thing that matters about an EXISTS query is whether it returns
1270 * zero or more than zero rows. Therefore, we can remove certain SQL features
1271 * that won't affect that. The only part that is really likely to matter in
1272 * typical usage is simplifying the targetlist: it's a common habit to write
1273 * "SELECT * FROM" even though there is no need to evaluate any columns.
1274 *
1275 * Note: by suppressing the targetlist we could cause an observable behavioral
1276 * change, namely that any errors that might occur in evaluating the tlist
1277 * won't occur, nor will other side-effects of volatile functions. This seems
1278 * unlikely to bother anyone in practice.
1279 *
1280 * Returns TRUE if was able to discard the targetlist, else FALSE.
1281 */
1282 static bool
simplify_EXISTS_query(PlannerInfo * root,Query * query)1283 simplify_EXISTS_query(PlannerInfo *root, Query *query)
1284 {
1285 /*
1286 * We don't try to simplify at all if the query uses set operations,
1287 * aggregates, grouping sets, modifying CTEs, HAVING, OFFSET, or FOR
1288 * UPDATE/SHARE; none of these seem likely in normal usage and their
1289 * possible effects are complex. (Note: we could ignore an "OFFSET 0"
1290 * clause, but that traditionally is used as an optimization fence, so we
1291 * don't.)
1292 */
1293 if (query->commandType != CMD_SELECT ||
1294 query->setOperations ||
1295 query->hasAggs ||
1296 query->groupingSets ||
1297 query->hasWindowFuncs ||
1298 query->hasModifyingCTE ||
1299 query->havingQual ||
1300 query->limitOffset ||
1301 query->rowMarks)
1302 return false;
1303
1304 /*
1305 * LIMIT with a constant positive (or NULL) value doesn't affect the
1306 * semantics of EXISTS, so let's ignore such clauses. This is worth doing
1307 * because people accustomed to certain other DBMSes may be in the habit
1308 * of writing EXISTS(SELECT ... LIMIT 1) as an optimization. If there's a
1309 * LIMIT with anything else as argument, though, we can't simplify.
1310 */
1311 if (query->limitCount)
1312 {
1313 /*
1314 * The LIMIT clause has not yet been through eval_const_expressions,
1315 * so we have to apply that here. It might seem like this is a waste
1316 * of cycles, since the only case plausibly worth worrying about is
1317 * "LIMIT 1" ... but what we'll actually see is "LIMIT int8(1::int4)",
1318 * so we have to fold constants or we're not going to recognize it.
1319 */
1320 Node *node = eval_const_expressions(root, query->limitCount);
1321 Const *limit;
1322
1323 /* Might as well update the query if we simplified the clause. */
1324 query->limitCount = node;
1325
1326 if (!IsA(node, Const))
1327 return false;
1328
1329 limit = (Const *) node;
1330 Assert(limit->consttype == INT8OID);
1331 if (!limit->constisnull && DatumGetInt64(limit->constvalue) <= 0)
1332 return false;
1333
1334 /* Whether or not the targetlist is safe, we can drop the LIMIT. */
1335 query->limitCount = NULL;
1336 }
1337
1338 /*
1339 * Mustn't throw away the targetlist if it contains set-returning
1340 * functions; those could affect whether zero rows are returned!
1341 */
1342 if (expression_returns_set((Node *) query->targetList))
1343 return false;
1344
1345 /*
1346 * Otherwise, we can throw away the targetlist, as well as any GROUP,
1347 * WINDOW, DISTINCT, and ORDER BY clauses; none of those clauses will
1348 * change a nonzero-rows result to zero rows or vice versa. (Furthermore,
1349 * since our parsetree representation of these clauses depends on the
1350 * targetlist, we'd better throw them away if we drop the targetlist.)
1351 */
1352 query->targetList = NIL;
1353 query->groupClause = NIL;
1354 query->windowClause = NIL;
1355 query->distinctClause = NIL;
1356 query->sortClause = NIL;
1357 query->hasDistinctOn = false;
1358
1359 return true;
1360 }
1361
1362 /*
1363 * convert_EXISTS_to_ANY: try to convert EXISTS to a hashable ANY sublink
1364 *
1365 * The subselect is expected to be a fresh copy that we can munge up,
1366 * and to have been successfully passed through simplify_EXISTS_query.
1367 *
1368 * On success, the modified subselect is returned, and we store a suitable
1369 * upper-level test expression at *testexpr, plus a list of the subselect's
1370 * output Params at *paramIds. (The test expression is already Param-ified
1371 * and hence need not go through convert_testexpr, which is why we have to
1372 * deal with the Param IDs specially.)
1373 *
1374 * On failure, returns NULL.
1375 */
1376 static Query *
convert_EXISTS_to_ANY(PlannerInfo * root,Query * subselect,Node ** testexpr,List ** paramIds)1377 convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect,
1378 Node **testexpr, List **paramIds)
1379 {
1380 Node *whereClause;
1381 List *leftargs,
1382 *rightargs,
1383 *opids,
1384 *opcollations,
1385 *newWhere,
1386 *tlist,
1387 *testlist,
1388 *paramids;
1389 ListCell *lc,
1390 *rc,
1391 *oc,
1392 *cc;
1393 AttrNumber resno;
1394
1395 /*
1396 * Query must not require a targetlist, since we have to insert a new one.
1397 * Caller should have dealt with the case already.
1398 */
1399 Assert(subselect->targetList == NIL);
1400
1401 /*
1402 * Separate out the WHERE clause. (We could theoretically also remove
1403 * top-level plain JOIN/ON clauses, but it's probably not worth the
1404 * trouble.)
1405 */
1406 whereClause = subselect->jointree->quals;
1407 subselect->jointree->quals = NULL;
1408
1409 /*
1410 * The rest of the sub-select must not refer to any Vars of the parent
1411 * query. (Vars of higher levels should be okay, though.)
1412 *
1413 * Note: we need not check for Aggrefs separately because we know the
1414 * sub-select is as yet unoptimized; any uplevel Aggref must therefore
1415 * contain an uplevel Var reference. This is not the case below ...
1416 */
1417 if (contain_vars_of_level((Node *) subselect, 1))
1418 return NULL;
1419
1420 /*
1421 * We don't risk optimizing if the WHERE clause is volatile, either.
1422 */
1423 if (contain_volatile_functions(whereClause))
1424 return NULL;
1425
1426 /*
1427 * Clean up the WHERE clause by doing const-simplification etc on it.
1428 * Aside from simplifying the processing we're about to do, this is
1429 * important for being able to pull chunks of the WHERE clause up into the
1430 * parent query. Since we are invoked partway through the parent's
1431 * preprocess_expression() work, earlier steps of preprocess_expression()
1432 * wouldn't get applied to the pulled-up stuff unless we do them here. For
1433 * the parts of the WHERE clause that get put back into the child query,
1434 * this work is partially duplicative, but it shouldn't hurt.
1435 *
1436 * Note: we do not run flatten_join_alias_vars. This is OK because any
1437 * parent aliases were flattened already, and we're not going to pull any
1438 * child Vars (of any description) into the parent.
1439 *
1440 * Note: passing the parent's root to eval_const_expressions is
1441 * technically wrong, but we can get away with it since only the
1442 * boundParams (if any) are used, and those would be the same in a
1443 * subroot.
1444 */
1445 whereClause = eval_const_expressions(root, whereClause);
1446 whereClause = (Node *) canonicalize_qual_ext((Expr *) whereClause, false);
1447 whereClause = (Node *) make_ands_implicit((Expr *) whereClause);
1448
1449 /*
1450 * We now have a flattened implicit-AND list of clauses, which we try to
1451 * break apart into "outervar = innervar" hash clauses. Anything that
1452 * can't be broken apart just goes back into the newWhere list. Note that
1453 * we aren't trying hard yet to ensure that we have only outer or only
1454 * inner on each side; we'll check that if we get to the end.
1455 */
1456 leftargs = rightargs = opids = opcollations = newWhere = NIL;
1457 foreach(lc, (List *) whereClause)
1458 {
1459 OpExpr *expr = (OpExpr *) lfirst(lc);
1460
1461 if (IsA(expr, OpExpr) &&
1462 hash_ok_operator(expr))
1463 {
1464 Node *leftarg = (Node *) linitial(expr->args);
1465 Node *rightarg = (Node *) lsecond(expr->args);
1466
1467 if (contain_vars_of_level(leftarg, 1))
1468 {
1469 leftargs = lappend(leftargs, leftarg);
1470 rightargs = lappend(rightargs, rightarg);
1471 opids = lappend_oid(opids, expr->opno);
1472 opcollations = lappend_oid(opcollations, expr->inputcollid);
1473 continue;
1474 }
1475 if (contain_vars_of_level(rightarg, 1))
1476 {
1477 /*
1478 * We must commute the clause to put the outer var on the
1479 * left, because the hashing code in nodeSubplan.c expects
1480 * that. This probably shouldn't ever fail, since hashable
1481 * operators ought to have commutators, but be paranoid.
1482 */
1483 expr->opno = get_commutator(expr->opno);
1484 if (OidIsValid(expr->opno) && hash_ok_operator(expr))
1485 {
1486 leftargs = lappend(leftargs, rightarg);
1487 rightargs = lappend(rightargs, leftarg);
1488 opids = lappend_oid(opids, expr->opno);
1489 opcollations = lappend_oid(opcollations, expr->inputcollid);
1490 continue;
1491 }
1492 /* If no commutator, no chance to optimize the WHERE clause */
1493 return NULL;
1494 }
1495 }
1496 /* Couldn't handle it as a hash clause */
1497 newWhere = lappend(newWhere, expr);
1498 }
1499
1500 /*
1501 * If we didn't find anything we could convert, fail.
1502 */
1503 if (leftargs == NIL)
1504 return NULL;
1505
1506 /*
1507 * There mustn't be any parent Vars or Aggs in the stuff that we intend to
1508 * put back into the child query. Note: you might think we don't need to
1509 * check for Aggs separately, because an uplevel Agg must contain an
1510 * uplevel Var in its argument. But it is possible that the uplevel Var
1511 * got optimized away by eval_const_expressions. Consider
1512 *
1513 * SUM(CASE WHEN false THEN uplevelvar ELSE 0 END)
1514 */
1515 if (contain_vars_of_level((Node *) newWhere, 1) ||
1516 contain_vars_of_level((Node *) rightargs, 1))
1517 return NULL;
1518 if (root->parse->hasAggs &&
1519 (contain_aggs_of_level((Node *) newWhere, 1) ||
1520 contain_aggs_of_level((Node *) rightargs, 1)))
1521 return NULL;
1522
1523 /*
1524 * And there can't be any child Vars in the stuff we intend to pull up.
1525 * (Note: we'd need to check for child Aggs too, except we know the child
1526 * has no aggs at all because of simplify_EXISTS_query's check. The same
1527 * goes for window functions.)
1528 */
1529 if (contain_vars_of_level((Node *) leftargs, 0))
1530 return NULL;
1531
1532 /*
1533 * Also reject sublinks in the stuff we intend to pull up. (It might be
1534 * possible to support this, but doesn't seem worth the complication.)
1535 */
1536 if (contain_subplans((Node *) leftargs))
1537 return NULL;
1538
1539 /*
1540 * Okay, adjust the sublevelsup in the stuff we're pulling up.
1541 */
1542 IncrementVarSublevelsUp((Node *) leftargs, -1, 1);
1543
1544 /*
1545 * Put back any child-level-only WHERE clauses.
1546 */
1547 if (newWhere)
1548 subselect->jointree->quals = (Node *) make_ands_explicit(newWhere);
1549
1550 /*
1551 * Build a new targetlist for the child that emits the expressions we
1552 * need. Concurrently, build a testexpr for the parent using Params to
1553 * reference the child outputs. (Since we generate Params directly here,
1554 * there will be no need to convert the testexpr in build_subplan.)
1555 */
1556 tlist = testlist = paramids = NIL;
1557 resno = 1;
1558 /* there's no "forfour" so we have to chase one of the lists manually */
1559 cc = list_head(opcollations);
1560 forthree(lc, leftargs, rc, rightargs, oc, opids)
1561 {
1562 Node *leftarg = (Node *) lfirst(lc);
1563 Node *rightarg = (Node *) lfirst(rc);
1564 Oid opid = lfirst_oid(oc);
1565 Oid opcollation = lfirst_oid(cc);
1566 Param *param;
1567
1568 cc = lnext(cc);
1569 param = generate_new_exec_param(root,
1570 exprType(rightarg),
1571 exprTypmod(rightarg),
1572 exprCollation(rightarg));
1573 tlist = lappend(tlist,
1574 makeTargetEntry((Expr *) rightarg,
1575 resno++,
1576 NULL,
1577 false));
1578 testlist = lappend(testlist,
1579 make_opclause(opid, BOOLOID, false,
1580 (Expr *) leftarg, (Expr *) param,
1581 InvalidOid, opcollation));
1582 paramids = lappend_int(paramids, param->paramid);
1583 }
1584
1585 /* Put everything where it should go, and we're done */
1586 subselect->targetList = tlist;
1587 *testexpr = (Node *) make_ands_explicit(testlist);
1588 *paramIds = paramids;
1589
1590 return subselect;
1591 }
1592
1593
1594 /*
1595 * Replace correlation vars (uplevel vars) with Params.
1596 *
1597 * Uplevel PlaceHolderVars and aggregates are replaced, too.
1598 *
1599 * Note: it is critical that this runs immediately after SS_process_sublinks.
1600 * Since we do not recurse into the arguments of uplevel PHVs and aggregates,
1601 * they will get copied to the appropriate subplan args list in the parent
1602 * query with uplevel vars not replaced by Params, but only adjusted in level
1603 * (see replace_outer_placeholdervar and replace_outer_agg). That's exactly
1604 * what we want for the vars of the parent level --- but if a PHV's or
1605 * aggregate's argument contains any further-up variables, they have to be
1606 * replaced with Params in their turn. That will happen when the parent level
1607 * runs SS_replace_correlation_vars. Therefore it must do so after expanding
1608 * its sublinks to subplans. And we don't want any steps in between, else
1609 * those steps would never get applied to the argument expressions, either in
1610 * the parent or the child level.
1611 *
1612 * Another fairly tricky thing going on here is the handling of SubLinks in
1613 * the arguments of uplevel PHVs/aggregates. Those are not touched inside the
1614 * intermediate query level, either. Instead, SS_process_sublinks recurses on
1615 * them after copying the PHV or Aggref expression into the parent plan level
1616 * (this is actually taken care of in build_subplan).
1617 */
1618 Node *
SS_replace_correlation_vars(PlannerInfo * root,Node * expr)1619 SS_replace_correlation_vars(PlannerInfo *root, Node *expr)
1620 {
1621 /* No setup needed for tree walk, so away we go */
1622 return replace_correlation_vars_mutator(expr, root);
1623 }
1624
1625 static Node *
replace_correlation_vars_mutator(Node * node,PlannerInfo * root)1626 replace_correlation_vars_mutator(Node *node, PlannerInfo *root)
1627 {
1628 if (node == NULL)
1629 return NULL;
1630 if (IsA(node, Var))
1631 {
1632 if (((Var *) node)->varlevelsup > 0)
1633 return (Node *) replace_outer_var(root, (Var *) node);
1634 }
1635 if (IsA(node, PlaceHolderVar))
1636 {
1637 if (((PlaceHolderVar *) node)->phlevelsup > 0)
1638 return (Node *) replace_outer_placeholdervar(root,
1639 (PlaceHolderVar *) node);
1640 }
1641 if (IsA(node, Aggref))
1642 {
1643 if (((Aggref *) node)->agglevelsup > 0)
1644 return (Node *) replace_outer_agg(root, (Aggref *) node);
1645 }
1646 if (IsA(node, GroupingFunc))
1647 {
1648 if (((GroupingFunc *) node)->agglevelsup > 0)
1649 return (Node *) replace_outer_grouping(root, (GroupingFunc *) node);
1650 }
1651 return expression_tree_mutator(node,
1652 replace_correlation_vars_mutator,
1653 (void *) root);
1654 }
1655
1656 /*
1657 * Expand SubLinks to SubPlans in the given expression.
1658 *
1659 * The isQual argument tells whether or not this expression is a WHERE/HAVING
1660 * qualifier expression. If it is, any sublinks appearing at top level need
1661 * not distinguish FALSE from UNKNOWN return values.
1662 */
1663 Node *
SS_process_sublinks(PlannerInfo * root,Node * expr,bool isQual)1664 SS_process_sublinks(PlannerInfo *root, Node *expr, bool isQual)
1665 {
1666 process_sublinks_context context;
1667
1668 context.root = root;
1669 context.isTopQual = isQual;
1670 return process_sublinks_mutator(expr, &context);
1671 }
1672
1673 static Node *
process_sublinks_mutator(Node * node,process_sublinks_context * context)1674 process_sublinks_mutator(Node *node, process_sublinks_context *context)
1675 {
1676 process_sublinks_context locContext;
1677
1678 locContext.root = context->root;
1679
1680 if (node == NULL)
1681 return NULL;
1682 if (IsA(node, SubLink))
1683 {
1684 SubLink *sublink = (SubLink *) node;
1685 Node *testexpr;
1686
1687 /*
1688 * First, recursively process the lefthand-side expressions, if any.
1689 * They're not top-level anymore.
1690 */
1691 locContext.isTopQual = false;
1692 testexpr = process_sublinks_mutator(sublink->testexpr, &locContext);
1693
1694 /*
1695 * Now build the SubPlan node and make the expr to return.
1696 */
1697 return make_subplan(context->root,
1698 (Query *) sublink->subselect,
1699 sublink->subLinkType,
1700 sublink->subLinkId,
1701 testexpr,
1702 context->isTopQual);
1703 }
1704
1705 /*
1706 * Don't recurse into the arguments of an outer PHV or aggregate here. Any
1707 * SubLinks in the arguments have to be dealt with at the outer query
1708 * level; they'll be handled when build_subplan collects the PHV or Aggref
1709 * into the arguments to be passed down to the current subplan.
1710 */
1711 if (IsA(node, PlaceHolderVar))
1712 {
1713 if (((PlaceHolderVar *) node)->phlevelsup > 0)
1714 return node;
1715 }
1716 else if (IsA(node, Aggref))
1717 {
1718 if (((Aggref *) node)->agglevelsup > 0)
1719 return node;
1720 }
1721
1722 /*
1723 * We should never see a SubPlan expression in the input (since this is
1724 * the very routine that creates 'em to begin with). We shouldn't find
1725 * ourselves invoked directly on a Query, either.
1726 */
1727 Assert(!IsA(node, SubPlan));
1728 Assert(!IsA(node, AlternativeSubPlan));
1729 Assert(!IsA(node, Query));
1730
1731 /*
1732 * Because make_subplan() could return an AND or OR clause, we have to
1733 * take steps to preserve AND/OR flatness of a qual. We assume the input
1734 * has been AND/OR flattened and so we need no recursion here.
1735 *
1736 * (Due to the coding here, we will not get called on the List subnodes of
1737 * an AND; and the input is *not* yet in implicit-AND format. So no check
1738 * is needed for a bare List.)
1739 *
1740 * Anywhere within the top-level AND/OR clause structure, we can tell
1741 * make_subplan() that NULL and FALSE are interchangeable. So isTopQual
1742 * propagates down in both cases. (Note that this is unlike the meaning
1743 * of "top level qual" used in most other places in Postgres.)
1744 */
1745 if (and_clause(node))
1746 {
1747 List *newargs = NIL;
1748 ListCell *l;
1749
1750 /* Still at qual top-level */
1751 locContext.isTopQual = context->isTopQual;
1752
1753 foreach(l, ((BoolExpr *) node)->args)
1754 {
1755 Node *newarg;
1756
1757 newarg = process_sublinks_mutator(lfirst(l), &locContext);
1758 if (and_clause(newarg))
1759 newargs = list_concat(newargs, ((BoolExpr *) newarg)->args);
1760 else
1761 newargs = lappend(newargs, newarg);
1762 }
1763 return (Node *) make_andclause(newargs);
1764 }
1765
1766 if (or_clause(node))
1767 {
1768 List *newargs = NIL;
1769 ListCell *l;
1770
1771 /* Still at qual top-level */
1772 locContext.isTopQual = context->isTopQual;
1773
1774 foreach(l, ((BoolExpr *) node)->args)
1775 {
1776 Node *newarg;
1777
1778 newarg = process_sublinks_mutator(lfirst(l), &locContext);
1779 if (or_clause(newarg))
1780 newargs = list_concat(newargs, ((BoolExpr *) newarg)->args);
1781 else
1782 newargs = lappend(newargs, newarg);
1783 }
1784 return (Node *) make_orclause(newargs);
1785 }
1786
1787 /*
1788 * If we recurse down through anything other than an AND or OR node, we
1789 * are definitely not at top qual level anymore.
1790 */
1791 locContext.isTopQual = false;
1792
1793 return expression_tree_mutator(node,
1794 process_sublinks_mutator,
1795 (void *) &locContext);
1796 }
1797
1798 /*
1799 * SS_identify_outer_params - identify the Params available from outer levels
1800 *
1801 * This must be run after SS_replace_correlation_vars and SS_process_sublinks
1802 * processing is complete in a given query level as well as all of its
1803 * descendant levels (which means it's most practical to do it at the end of
1804 * processing the query level). We compute the set of paramIds that outer
1805 * levels will make available to this level+descendants, and record it in
1806 * root->outer_params for use while computing extParam/allParam sets in final
1807 * plan cleanup. (We can't just compute it then, because the upper levels'
1808 * plan_params lists are transient and will be gone by then.)
1809 */
1810 void
SS_identify_outer_params(PlannerInfo * root)1811 SS_identify_outer_params(PlannerInfo *root)
1812 {
1813 Bitmapset *outer_params;
1814 PlannerInfo *proot;
1815 ListCell *l;
1816
1817 /*
1818 * If no parameters have been assigned anywhere in the tree, we certainly
1819 * don't need to do anything here.
1820 */
1821 if (root->glob->nParamExec == 0)
1822 return;
1823
1824 /*
1825 * Scan all query levels above this one to see which parameters are due to
1826 * be available from them, either because lower query levels have
1827 * requested them (via plan_params) or because they will be available from
1828 * initPlans of those levels.
1829 */
1830 outer_params = NULL;
1831 for (proot = root->parent_root; proot != NULL; proot = proot->parent_root)
1832 {
1833 /* Include ordinary Var/PHV/Aggref params */
1834 foreach(l, proot->plan_params)
1835 {
1836 PlannerParamItem *pitem = (PlannerParamItem *) lfirst(l);
1837
1838 outer_params = bms_add_member(outer_params, pitem->paramId);
1839 }
1840 /* Include any outputs of outer-level initPlans */
1841 foreach(l, proot->init_plans)
1842 {
1843 SubPlan *initsubplan = (SubPlan *) lfirst(l);
1844 ListCell *l2;
1845
1846 foreach(l2, initsubplan->setParam)
1847 {
1848 outer_params = bms_add_member(outer_params, lfirst_int(l2));
1849 }
1850 }
1851 /* Include worktable ID, if a recursive query is being planned */
1852 if (proot->wt_param_id >= 0)
1853 outer_params = bms_add_member(outer_params, proot->wt_param_id);
1854 }
1855 root->outer_params = outer_params;
1856 }
1857
1858 /*
1859 * SS_charge_for_initplans - account for initplans in Path costs & parallelism
1860 *
1861 * If any initPlans have been created in the current query level, they will
1862 * get attached to the Plan tree created from whichever Path we select from
1863 * the given rel. Increment all that rel's Paths' costs to account for them,
1864 * and make sure the paths get marked as parallel-unsafe, since we can't
1865 * currently transmit initPlans to parallel workers.
1866 *
1867 * This is separate from SS_attach_initplans because we might conditionally
1868 * create more initPlans during create_plan(), depending on which Path we
1869 * select. However, Paths that would generate such initPlans are expected
1870 * to have included their cost already.
1871 */
1872 void
SS_charge_for_initplans(PlannerInfo * root,RelOptInfo * final_rel)1873 SS_charge_for_initplans(PlannerInfo *root, RelOptInfo *final_rel)
1874 {
1875 Cost initplan_cost;
1876 ListCell *lc;
1877
1878 /* Nothing to do if no initPlans */
1879 if (root->init_plans == NIL)
1880 return;
1881
1882 /*
1883 * Compute the cost increment just once, since it will be the same for all
1884 * Paths. We assume each initPlan gets run once during top plan startup.
1885 * This is a conservative overestimate, since in fact an initPlan might be
1886 * executed later than plan startup, or even not at all.
1887 */
1888 initplan_cost = 0;
1889 foreach(lc, root->init_plans)
1890 {
1891 SubPlan *initsubplan = (SubPlan *) lfirst(lc);
1892
1893 initplan_cost += initsubplan->startup_cost + initsubplan->per_call_cost;
1894 }
1895
1896 /*
1897 * Now adjust the costs and parallel_safe flags.
1898 */
1899 foreach(lc, final_rel->pathlist)
1900 {
1901 Path *path = (Path *) lfirst(lc);
1902
1903 path->startup_cost += initplan_cost;
1904 path->total_cost += initplan_cost;
1905 path->parallel_safe = false;
1906 }
1907
1908 /* We needn't do set_cheapest() here, caller will do it */
1909 }
1910
1911 /*
1912 * SS_attach_initplans - attach initplans to topmost plan node
1913 *
1914 * Attach any initplans created in the current query level to the specified
1915 * plan node, which should normally be the topmost node for the query level.
1916 * (In principle the initPlans could go in any node at or above where they're
1917 * referenced; but there seems no reason to put them any lower than the
1918 * topmost node, so we don't bother to track exactly where they came from.)
1919 * We do not touch the plan node's cost; the initplans should have been
1920 * accounted for in path costing.
1921 */
1922 void
SS_attach_initplans(PlannerInfo * root,Plan * plan)1923 SS_attach_initplans(PlannerInfo *root, Plan *plan)
1924 {
1925 plan->initPlan = root->init_plans;
1926 }
1927
1928 /*
1929 * SS_finalize_plan - do final parameter processing for a completed Plan.
1930 *
1931 * This recursively computes the extParam and allParam sets for every Plan
1932 * node in the given plan tree. (Oh, and RangeTblFunction.funcparams too.)
1933 *
1934 * We assume that SS_finalize_plan has already been run on any initplans or
1935 * subplans the plan tree could reference.
1936 */
1937 void
SS_finalize_plan(PlannerInfo * root,Plan * plan)1938 SS_finalize_plan(PlannerInfo *root, Plan *plan)
1939 {
1940 /* No setup needed, just recurse through plan tree. */
1941 (void) finalize_plan(root, plan, root->outer_params, NULL);
1942 }
1943
1944 /*
1945 * Recursive processing of all nodes in the plan tree
1946 *
1947 * valid_params is the set of param IDs supplied by outer plan levels
1948 * that are valid to reference in this plan node or its children.
1949 *
1950 * scan_params is a set of param IDs to force scan plan nodes to reference.
1951 * This is for EvalPlanQual support, and is always NULL at the top of the
1952 * recursion.
1953 *
1954 * The return value is the computed allParam set for the given Plan node.
1955 * This is just an internal notational convenience: we can add a child
1956 * plan's allParams to the set of param IDs of interest to this level
1957 * in the same statement that recurses to that child.
1958 *
1959 * Do not scribble on caller's values of valid_params or scan_params!
1960 *
1961 * Note: although we attempt to deal with initPlans anywhere in the tree, the
1962 * logic is not really right. The problem is that a plan node might return an
1963 * output Param of its initPlan as a targetlist item, in which case it's valid
1964 * for the parent plan level to reference that same Param; the parent's usage
1965 * will be converted into a Var referencing the child plan node by setrefs.c.
1966 * But this function would see the parent's reference as out of scope and
1967 * complain about it. For now, this does not matter because the planner only
1968 * attaches initPlans to the topmost plan node in a query level, so the case
1969 * doesn't arise. If we ever merge this processing into setrefs.c, maybe it
1970 * can be handled more cleanly.
1971 */
1972 static Bitmapset *
finalize_plan(PlannerInfo * root,Plan * plan,Bitmapset * valid_params,Bitmapset * scan_params)1973 finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params,
1974 Bitmapset *scan_params)
1975 {
1976 finalize_primnode_context context;
1977 int locally_added_param;
1978 Bitmapset *nestloop_params;
1979 Bitmapset *initExtParam;
1980 Bitmapset *initSetParam;
1981 Bitmapset *child_params;
1982 ListCell *l;
1983
1984 if (plan == NULL)
1985 return NULL;
1986
1987 context.root = root;
1988 context.paramids = NULL; /* initialize set to empty */
1989 locally_added_param = -1; /* there isn't one */
1990 nestloop_params = NULL; /* there aren't any */
1991
1992 /*
1993 * Examine any initPlans to determine the set of external params they
1994 * reference and the set of output params they supply. (We assume
1995 * SS_finalize_plan was run on them already.)
1996 */
1997 initExtParam = initSetParam = NULL;
1998 foreach(l, plan->initPlan)
1999 {
2000 SubPlan *initsubplan = (SubPlan *) lfirst(l);
2001 Plan *initplan = planner_subplan_get_plan(root, initsubplan);
2002 ListCell *l2;
2003
2004 initExtParam = bms_add_members(initExtParam, initplan->extParam);
2005 foreach(l2, initsubplan->setParam)
2006 {
2007 initSetParam = bms_add_member(initSetParam, lfirst_int(l2));
2008 }
2009 }
2010
2011 /* Any setParams are validly referenceable in this node and children */
2012 if (initSetParam)
2013 valid_params = bms_union(valid_params, initSetParam);
2014
2015 /*
2016 * When we call finalize_primnode, context.paramids sets are automatically
2017 * merged together. But when recursing to self, we have to do it the hard
2018 * way. We want the paramids set to include params in subplans as well as
2019 * at this level.
2020 */
2021
2022 /* Find params in targetlist and qual */
2023 finalize_primnode((Node *) plan->targetlist, &context);
2024 finalize_primnode((Node *) plan->qual, &context);
2025
2026 /* Check additional node-type-specific fields */
2027 switch (nodeTag(plan))
2028 {
2029 case T_Result:
2030 finalize_primnode(((Result *) plan)->resconstantqual,
2031 &context);
2032 break;
2033
2034 case T_SeqScan:
2035 context.paramids = bms_add_members(context.paramids, scan_params);
2036 break;
2037
2038 case T_SampleScan:
2039 finalize_primnode((Node *) ((SampleScan *) plan)->tablesample,
2040 &context);
2041 context.paramids = bms_add_members(context.paramids, scan_params);
2042 break;
2043
2044 case T_IndexScan:
2045 finalize_primnode((Node *) ((IndexScan *) plan)->indexqual,
2046 &context);
2047 finalize_primnode((Node *) ((IndexScan *) plan)->indexorderby,
2048 &context);
2049
2050 /*
2051 * we need not look at indexqualorig, since it will have the same
2052 * param references as indexqual. Likewise, we can ignore
2053 * indexorderbyorig.
2054 */
2055 context.paramids = bms_add_members(context.paramids, scan_params);
2056 break;
2057
2058 case T_IndexOnlyScan:
2059 finalize_primnode((Node *) ((IndexOnlyScan *) plan)->indexqual,
2060 &context);
2061 finalize_primnode((Node *) ((IndexOnlyScan *) plan)->indexorderby,
2062 &context);
2063
2064 /*
2065 * we need not look at indextlist, since it cannot contain Params.
2066 */
2067 context.paramids = bms_add_members(context.paramids, scan_params);
2068 break;
2069
2070 case T_BitmapIndexScan:
2071 finalize_primnode((Node *) ((BitmapIndexScan *) plan)->indexqual,
2072 &context);
2073
2074 /*
2075 * we need not look at indexqualorig, since it will have the same
2076 * param references as indexqual.
2077 */
2078 break;
2079
2080 case T_BitmapHeapScan:
2081 finalize_primnode((Node *) ((BitmapHeapScan *) plan)->bitmapqualorig,
2082 &context);
2083 context.paramids = bms_add_members(context.paramids, scan_params);
2084 break;
2085
2086 case T_TidScan:
2087 finalize_primnode((Node *) ((TidScan *) plan)->tidquals,
2088 &context);
2089 context.paramids = bms_add_members(context.paramids, scan_params);
2090 break;
2091
2092 case T_SubqueryScan:
2093 {
2094 SubqueryScan *sscan = (SubqueryScan *) plan;
2095 RelOptInfo *rel;
2096
2097 /* We must run SS_finalize_plan on the subquery */
2098 rel = find_base_rel(root, sscan->scan.scanrelid);
2099 SS_finalize_plan(rel->subroot, sscan->subplan);
2100
2101 /* Now we can add its extParams to the parent's params */
2102 context.paramids = bms_add_members(context.paramids,
2103 sscan->subplan->extParam);
2104 /* We need scan_params too, though */
2105 context.paramids = bms_add_members(context.paramids,
2106 scan_params);
2107 }
2108 break;
2109
2110 case T_FunctionScan:
2111 {
2112 FunctionScan *fscan = (FunctionScan *) plan;
2113 ListCell *lc;
2114
2115 /*
2116 * Call finalize_primnode independently on each function
2117 * expression, so that we can record which params are
2118 * referenced in each, in order to decide which need
2119 * re-evaluating during rescan.
2120 */
2121 foreach(lc, fscan->functions)
2122 {
2123 RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
2124 finalize_primnode_context funccontext;
2125
2126 funccontext = context;
2127 funccontext.paramids = NULL;
2128
2129 finalize_primnode(rtfunc->funcexpr, &funccontext);
2130
2131 /* remember results for execution */
2132 rtfunc->funcparams = funccontext.paramids;
2133
2134 /* add the function's params to the overall set */
2135 context.paramids = bms_add_members(context.paramids,
2136 funccontext.paramids);
2137 }
2138
2139 context.paramids = bms_add_members(context.paramids,
2140 scan_params);
2141 }
2142 break;
2143
2144 case T_ValuesScan:
2145 finalize_primnode((Node *) ((ValuesScan *) plan)->values_lists,
2146 &context);
2147 context.paramids = bms_add_members(context.paramids, scan_params);
2148 break;
2149
2150 case T_CteScan:
2151 {
2152 /*
2153 * You might think we should add the node's cteParam to
2154 * paramids, but we shouldn't because that param is just a
2155 * linkage mechanism for multiple CteScan nodes for the same
2156 * CTE; it is never used for changed-param signaling. What we
2157 * have to do instead is to find the referenced CTE plan and
2158 * incorporate its external paramids, so that the correct
2159 * things will happen if the CTE references outer-level
2160 * variables. See test cases for bug #4902. (We assume
2161 * SS_finalize_plan was run on the CTE plan already.)
2162 */
2163 int plan_id = ((CteScan *) plan)->ctePlanId;
2164 Plan *cteplan;
2165
2166 /* so, do this ... */
2167 if (plan_id < 1 || plan_id > list_length(root->glob->subplans))
2168 elog(ERROR, "could not find plan for CteScan referencing plan ID %d",
2169 plan_id);
2170 cteplan = (Plan *) list_nth(root->glob->subplans, plan_id - 1);
2171 context.paramids =
2172 bms_add_members(context.paramids, cteplan->extParam);
2173
2174 #ifdef NOT_USED
2175 /* ... but not this */
2176 context.paramids =
2177 bms_add_member(context.paramids,
2178 ((CteScan *) plan)->cteParam);
2179 #endif
2180
2181 context.paramids = bms_add_members(context.paramids,
2182 scan_params);
2183 }
2184 break;
2185
2186 case T_WorkTableScan:
2187 context.paramids =
2188 bms_add_member(context.paramids,
2189 ((WorkTableScan *) plan)->wtParam);
2190 context.paramids = bms_add_members(context.paramids, scan_params);
2191 break;
2192
2193 case T_ForeignScan:
2194 {
2195 ForeignScan *fscan = (ForeignScan *) plan;
2196
2197 finalize_primnode((Node *) fscan->fdw_exprs,
2198 &context);
2199 finalize_primnode((Node *) fscan->fdw_recheck_quals,
2200 &context);
2201
2202 /* We assume fdw_scan_tlist cannot contain Params */
2203 context.paramids = bms_add_members(context.paramids,
2204 scan_params);
2205 }
2206 break;
2207
2208 case T_CustomScan:
2209 {
2210 CustomScan *cscan = (CustomScan *) plan;
2211 ListCell *lc;
2212
2213 finalize_primnode((Node *) cscan->custom_exprs,
2214 &context);
2215 /* We assume custom_scan_tlist cannot contain Params */
2216 context.paramids =
2217 bms_add_members(context.paramids, scan_params);
2218
2219 /* child nodes if any */
2220 foreach(lc, cscan->custom_plans)
2221 {
2222 context.paramids =
2223 bms_add_members(context.paramids,
2224 finalize_plan(root,
2225 (Plan *) lfirst(lc),
2226 valid_params,
2227 scan_params));
2228 }
2229 }
2230 break;
2231
2232 case T_ModifyTable:
2233 {
2234 ModifyTable *mtplan = (ModifyTable *) plan;
2235 ListCell *l;
2236
2237 /* Force descendant scan nodes to reference epqParam */
2238 locally_added_param = mtplan->epqParam;
2239 valid_params = bms_add_member(bms_copy(valid_params),
2240 locally_added_param);
2241 scan_params = bms_add_member(bms_copy(scan_params),
2242 locally_added_param);
2243 finalize_primnode((Node *) mtplan->returningLists,
2244 &context);
2245 finalize_primnode((Node *) mtplan->onConflictSet,
2246 &context);
2247 finalize_primnode((Node *) mtplan->onConflictWhere,
2248 &context);
2249 /* exclRelTlist contains only Vars, doesn't need examination */
2250 foreach(l, mtplan->plans)
2251 {
2252 context.paramids =
2253 bms_add_members(context.paramids,
2254 finalize_plan(root,
2255 (Plan *) lfirst(l),
2256 valid_params,
2257 scan_params));
2258 }
2259 }
2260 break;
2261
2262 case T_Append:
2263 {
2264 ListCell *l;
2265
2266 foreach(l, ((Append *) plan)->appendplans)
2267 {
2268 context.paramids =
2269 bms_add_members(context.paramids,
2270 finalize_plan(root,
2271 (Plan *) lfirst(l),
2272 valid_params,
2273 scan_params));
2274 }
2275 }
2276 break;
2277
2278 case T_MergeAppend:
2279 {
2280 ListCell *l;
2281
2282 foreach(l, ((MergeAppend *) plan)->mergeplans)
2283 {
2284 context.paramids =
2285 bms_add_members(context.paramids,
2286 finalize_plan(root,
2287 (Plan *) lfirst(l),
2288 valid_params,
2289 scan_params));
2290 }
2291 }
2292 break;
2293
2294 case T_BitmapAnd:
2295 {
2296 ListCell *l;
2297
2298 foreach(l, ((BitmapAnd *) plan)->bitmapplans)
2299 {
2300 context.paramids =
2301 bms_add_members(context.paramids,
2302 finalize_plan(root,
2303 (Plan *) lfirst(l),
2304 valid_params,
2305 scan_params));
2306 }
2307 }
2308 break;
2309
2310 case T_BitmapOr:
2311 {
2312 ListCell *l;
2313
2314 foreach(l, ((BitmapOr *) plan)->bitmapplans)
2315 {
2316 context.paramids =
2317 bms_add_members(context.paramids,
2318 finalize_plan(root,
2319 (Plan *) lfirst(l),
2320 valid_params,
2321 scan_params));
2322 }
2323 }
2324 break;
2325
2326 case T_NestLoop:
2327 {
2328 ListCell *l;
2329
2330 finalize_primnode((Node *) ((Join *) plan)->joinqual,
2331 &context);
2332 /* collect set of params that will be passed to right child */
2333 foreach(l, ((NestLoop *) plan)->nestParams)
2334 {
2335 NestLoopParam *nlp = (NestLoopParam *) lfirst(l);
2336
2337 nestloop_params = bms_add_member(nestloop_params,
2338 nlp->paramno);
2339 }
2340 }
2341 break;
2342
2343 case T_MergeJoin:
2344 finalize_primnode((Node *) ((Join *) plan)->joinqual,
2345 &context);
2346 finalize_primnode((Node *) ((MergeJoin *) plan)->mergeclauses,
2347 &context);
2348 break;
2349
2350 case T_HashJoin:
2351 finalize_primnode((Node *) ((Join *) plan)->joinqual,
2352 &context);
2353 finalize_primnode((Node *) ((HashJoin *) plan)->hashclauses,
2354 &context);
2355 break;
2356
2357 case T_Limit:
2358 finalize_primnode(((Limit *) plan)->limitOffset,
2359 &context);
2360 finalize_primnode(((Limit *) plan)->limitCount,
2361 &context);
2362 break;
2363
2364 case T_RecursiveUnion:
2365 /* child nodes are allowed to reference wtParam */
2366 locally_added_param = ((RecursiveUnion *) plan)->wtParam;
2367 valid_params = bms_add_member(bms_copy(valid_params),
2368 locally_added_param);
2369 /* wtParam does *not* get added to scan_params */
2370 break;
2371
2372 case T_LockRows:
2373 /* Force descendant scan nodes to reference epqParam */
2374 locally_added_param = ((LockRows *) plan)->epqParam;
2375 valid_params = bms_add_member(bms_copy(valid_params),
2376 locally_added_param);
2377 scan_params = bms_add_member(bms_copy(scan_params),
2378 locally_added_param);
2379 break;
2380
2381 case T_Agg:
2382 {
2383 Agg *agg = (Agg *) plan;
2384
2385 /*
2386 * AGG_HASHED plans need to know which Params are referenced
2387 * in aggregate calls. Do a separate scan to identify them.
2388 */
2389 if (agg->aggstrategy == AGG_HASHED)
2390 {
2391 finalize_primnode_context aggcontext;
2392
2393 aggcontext.root = root;
2394 aggcontext.paramids = NULL;
2395 finalize_agg_primnode((Node *) agg->plan.targetlist,
2396 &aggcontext);
2397 finalize_agg_primnode((Node *) agg->plan.qual,
2398 &aggcontext);
2399 agg->aggParams = aggcontext.paramids;
2400 }
2401 }
2402 break;
2403
2404 case T_WindowAgg:
2405 finalize_primnode(((WindowAgg *) plan)->startOffset,
2406 &context);
2407 finalize_primnode(((WindowAgg *) plan)->endOffset,
2408 &context);
2409 break;
2410
2411 case T_Hash:
2412 case T_Material:
2413 case T_Sort:
2414 case T_Unique:
2415 case T_Gather:
2416 case T_SetOp:
2417 case T_Group:
2418 break;
2419
2420 default:
2421 elog(ERROR, "unrecognized node type: %d",
2422 (int) nodeTag(plan));
2423 }
2424
2425 /* Process left and right child plans, if any */
2426 child_params = finalize_plan(root,
2427 plan->lefttree,
2428 valid_params,
2429 scan_params);
2430 context.paramids = bms_add_members(context.paramids, child_params);
2431
2432 if (nestloop_params)
2433 {
2434 /* right child can reference nestloop_params as well as valid_params */
2435 child_params = finalize_plan(root,
2436 plan->righttree,
2437 bms_union(nestloop_params, valid_params),
2438 scan_params);
2439 /* ... and they don't count as parameters used at my level */
2440 child_params = bms_difference(child_params, nestloop_params);
2441 bms_free(nestloop_params);
2442 }
2443 else
2444 {
2445 /* easy case */
2446 child_params = finalize_plan(root,
2447 plan->righttree,
2448 valid_params,
2449 scan_params);
2450 }
2451 context.paramids = bms_add_members(context.paramids, child_params);
2452
2453 /*
2454 * Any locally generated parameter doesn't count towards its generating
2455 * plan node's external dependencies. (Note: if we changed valid_params
2456 * and/or scan_params, we leak those bitmapsets; not worth the notational
2457 * trouble to clean them up.)
2458 */
2459 if (locally_added_param >= 0)
2460 {
2461 context.paramids = bms_del_member(context.paramids,
2462 locally_added_param);
2463 }
2464
2465 /* Now we have all the paramids referenced in this node and children */
2466
2467 if (!bms_is_subset(context.paramids, valid_params))
2468 elog(ERROR, "plan should not reference subplan's variable");
2469
2470 /*
2471 * The plan node's allParam and extParam fields should include all its
2472 * referenced paramids, plus contributions from any child initPlans.
2473 * However, any setParams of the initPlans should not be present in the
2474 * parent node's extParams, only in its allParams. (It's possible that
2475 * some initPlans have extParams that are setParams of other initPlans.)
2476 */
2477
2478 /* allParam must include initplans' extParams and setParams */
2479 plan->allParam = bms_union(context.paramids, initExtParam);
2480 plan->allParam = bms_add_members(plan->allParam, initSetParam);
2481 /* extParam must include any initplan extParams */
2482 plan->extParam = bms_union(context.paramids, initExtParam);
2483 /* but not any initplan setParams */
2484 plan->extParam = bms_del_members(plan->extParam, initSetParam);
2485
2486 /*
2487 * For speed at execution time, make sure extParam/allParam are actually
2488 * NULL if they are empty sets.
2489 */
2490 if (bms_is_empty(plan->extParam))
2491 plan->extParam = NULL;
2492 if (bms_is_empty(plan->allParam))
2493 plan->allParam = NULL;
2494
2495 return plan->allParam;
2496 }
2497
2498 /*
2499 * finalize_primnode: add IDs of all PARAM_EXEC params appearing in the given
2500 * expression tree to the result set.
2501 */
2502 static bool
finalize_primnode(Node * node,finalize_primnode_context * context)2503 finalize_primnode(Node *node, finalize_primnode_context *context)
2504 {
2505 if (node == NULL)
2506 return false;
2507 if (IsA(node, Param))
2508 {
2509 if (((Param *) node)->paramkind == PARAM_EXEC)
2510 {
2511 int paramid = ((Param *) node)->paramid;
2512
2513 context->paramids = bms_add_member(context->paramids, paramid);
2514 }
2515 return false; /* no more to do here */
2516 }
2517 if (IsA(node, SubPlan))
2518 {
2519 SubPlan *subplan = (SubPlan *) node;
2520 Plan *plan = planner_subplan_get_plan(context->root, subplan);
2521 ListCell *lc;
2522 Bitmapset *subparamids;
2523
2524 /* Recurse into the testexpr, but not into the Plan */
2525 finalize_primnode(subplan->testexpr, context);
2526
2527 /*
2528 * Remove any param IDs of output parameters of the subplan that were
2529 * referenced in the testexpr. These are not interesting for
2530 * parameter change signaling since we always re-evaluate the subplan.
2531 * Note that this wouldn't work too well if there might be uses of the
2532 * same param IDs elsewhere in the plan, but that can't happen because
2533 * generate_new_exec_param never tries to merge params.
2534 */
2535 foreach(lc, subplan->paramIds)
2536 {
2537 context->paramids = bms_del_member(context->paramids,
2538 lfirst_int(lc));
2539 }
2540
2541 /* Also examine args list */
2542 finalize_primnode((Node *) subplan->args, context);
2543
2544 /*
2545 * Add params needed by the subplan to paramids, but excluding those
2546 * we will pass down to it. (We assume SS_finalize_plan was run on
2547 * the subplan already.)
2548 */
2549 subparamids = bms_copy(plan->extParam);
2550 foreach(lc, subplan->parParam)
2551 {
2552 subparamids = bms_del_member(subparamids, lfirst_int(lc));
2553 }
2554 context->paramids = bms_join(context->paramids, subparamids);
2555
2556 return false; /* no more to do here */
2557 }
2558 return expression_tree_walker(node, finalize_primnode,
2559 (void *) context);
2560 }
2561
2562 /*
2563 * finalize_agg_primnode: find all Aggref nodes in the given expression tree,
2564 * and add IDs of all PARAM_EXEC params appearing within their aggregated
2565 * arguments to the result set.
2566 */
2567 static bool
finalize_agg_primnode(Node * node,finalize_primnode_context * context)2568 finalize_agg_primnode(Node *node, finalize_primnode_context *context)
2569 {
2570 if (node == NULL)
2571 return false;
2572 if (IsA(node, Aggref))
2573 {
2574 Aggref *agg = (Aggref *) node;
2575
2576 /* we should not consider the direct arguments, if any */
2577 finalize_primnode((Node *) agg->args, context);
2578 finalize_primnode((Node *) agg->aggfilter, context);
2579 return false; /* there can't be any Aggrefs below here */
2580 }
2581 return expression_tree_walker(node, finalize_agg_primnode,
2582 (void *) context);
2583 }
2584
2585 /*
2586 * SS_make_initplan_output_param - make a Param for an initPlan's output
2587 *
2588 * The plan is expected to return a scalar value of the given type/collation.
2589 *
2590 * Note that in some cases the initplan may not ever appear in the finished
2591 * plan tree. If that happens, we'll have wasted a PARAM_EXEC slot, which
2592 * is no big deal.
2593 */
2594 Param *
SS_make_initplan_output_param(PlannerInfo * root,Oid resulttype,int32 resulttypmod,Oid resultcollation)2595 SS_make_initplan_output_param(PlannerInfo *root,
2596 Oid resulttype, int32 resulttypmod,
2597 Oid resultcollation)
2598 {
2599 return generate_new_exec_param(root, resulttype,
2600 resulttypmod, resultcollation);
2601 }
2602
2603 /*
2604 * SS_make_initplan_from_plan - given a plan tree, make it an InitPlan
2605 *
2606 * We build an EXPR_SUBLINK SubPlan node and put it into the initplan
2607 * list for the outer query level. A Param that represents the initplan's
2608 * output has already been assigned using SS_make_initplan_output_param.
2609 */
2610 void
SS_make_initplan_from_plan(PlannerInfo * root,PlannerInfo * subroot,Plan * plan,Param * prm)2611 SS_make_initplan_from_plan(PlannerInfo *root,
2612 PlannerInfo *subroot, Plan *plan,
2613 Param *prm)
2614 {
2615 SubPlan *node;
2616
2617 /*
2618 * Add the subplan and its PlannerInfo to the global lists.
2619 */
2620 root->glob->subplans = lappend(root->glob->subplans, plan);
2621 root->glob->subroots = lappend(root->glob->subroots, subroot);
2622
2623 /*
2624 * Create a SubPlan node and add it to the outer list of InitPlans. Note
2625 * it has to appear after any other InitPlans it might depend on (see
2626 * comments in ExecReScan).
2627 */
2628 node = makeNode(SubPlan);
2629 node->subLinkType = EXPR_SUBLINK;
2630 node->plan_id = list_length(root->glob->subplans);
2631 node->plan_name = psprintf("InitPlan %d (returns $%d)",
2632 node->plan_id, prm->paramid);
2633 get_first_col_type(plan, &node->firstColType, &node->firstColTypmod,
2634 &node->firstColCollation);
2635 node->setParam = list_make1_int(prm->paramid);
2636
2637 root->init_plans = lappend(root->init_plans, node);
2638
2639 /*
2640 * The node can't have any inputs (since it's an initplan), so the
2641 * parParam and args lists remain empty.
2642 */
2643
2644 /* Set costs of SubPlan using info from the plan tree */
2645 cost_subplan(subroot, node, plan);
2646 }
2647