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) 1996-2019, 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/optimizer.h"
29#include "optimizer/paramassign.h"
30#include "optimizer/pathnode.h"
31#include "optimizer/planmain.h"
32#include "optimizer/planner.h"
33#include "optimizer/prep.h"
34#include "optimizer/subselect.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
42typedef struct convert_testexpr_context
43{
44 PlannerInfo *root;
45 List *subst_nodes; /* Nodes to substitute for Params */
46} convert_testexpr_context;
47
48typedef struct process_sublinks_context
49{
50 PlannerInfo *root;
51 bool isTopQual;
52} process_sublinks_context;
53
54typedef struct finalize_primnode_context
55{
56 PlannerInfo *root;
57 Bitmapset *paramids; /* Non-local PARAM_EXEC paramids found */
58} finalize_primnode_context;
59
60typedef struct inline_cte_walker_context
61{
62 const char *ctename; /* name and relative level of target CTE */
63 int levelsup;
64 int refcount; /* number of remaining references */
65 Query *ctequery; /* query to substitute */
66} inline_cte_walker_context;
67
68
69static Node *build_subplan(PlannerInfo *root, Plan *plan, PlannerInfo *subroot,
70 List *plan_params,
71 SubLinkType subLinkType, int subLinkId,
72 Node *testexpr, bool adjust_testexpr,
73 bool unknownEqFalse);
74static List *generate_subquery_params(PlannerInfo *root, List *tlist,
75 List **paramIds);
76static List *generate_subquery_vars(PlannerInfo *root, List *tlist,
77 Index varno);
78static Node *convert_testexpr(PlannerInfo *root,
79 Node *testexpr,
80 List *subst_nodes);
81static Node *convert_testexpr_mutator(Node *node,
82 convert_testexpr_context *context);
83static bool subplan_is_hashable(Plan *plan);
84static bool testexpr_is_hashable(Node *testexpr);
85static bool hash_ok_operator(OpExpr *expr);
86static bool contain_dml(Node *node);
87static bool contain_dml_walker(Node *node, void *context);
88static bool contain_outer_selfref(Node *node);
89static bool contain_outer_selfref_walker(Node *node, Index *depth);
90static void inline_cte(PlannerInfo *root, CommonTableExpr *cte);
91static bool inline_cte_walker(Node *node, inline_cte_walker_context *context);
92static bool simplify_EXISTS_query(PlannerInfo *root, Query *query);
93static Query *convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect,
94 Node **testexpr, List **paramIds);
95static Node *replace_correlation_vars_mutator(Node *node, PlannerInfo *root);
96static Node *process_sublinks_mutator(Node *node,
97 process_sublinks_context *context);
98static Bitmapset *finalize_plan(PlannerInfo *root,
99 Plan *plan,
100 int gather_param,
101 Bitmapset *valid_params,
102 Bitmapset *scan_params);
103static bool finalize_primnode(Node *node, finalize_primnode_context *context);
104static bool finalize_agg_primnode(Node *node, finalize_primnode_context *context);
105
106
107/*
108 * Get the datatype/typmod/collation of the first column of the plan's output.
109 *
110 * This information is stored for ARRAY_SUBLINK execution and for
111 * exprType()/exprTypmod()/exprCollation(), which have no way to get at the
112 * plan associated with a SubPlan node. We really only need the info for
113 * EXPR_SUBLINK and ARRAY_SUBLINK subplans, but for consistency we save it
114 * always.
115 */
116static void
117get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod,
118 Oid *colcollation)
119{
120 /* In cases such as EXISTS, tlist might be empty; arbitrarily use VOID */
121 if (plan->targetlist)
122 {
123 TargetEntry *tent = linitial_node(TargetEntry, plan->targetlist);
124
125 if (!tent->resjunk)
126 {
127 *coltype = exprType((Node *) tent->expr);
128 *coltypmod = exprTypmod((Node *) tent->expr);
129 *colcollation = exprCollation((Node *) tent->expr);
130 return;
131 }
132 }
133 *coltype = VOIDOID;
134 *coltypmod = -1;
135 *colcollation = InvalidOid;
136}
137
138/*
139 * Convert a SubLink (as created by the parser) into a SubPlan.
140 *
141 * We are given the SubLink's contained query, type, ID, and testexpr. We are
142 * also told if this expression appears at top level of a WHERE/HAVING qual.
143 *
144 * Note: we assume that the testexpr has been AND/OR flattened (actually,
145 * it's been through eval_const_expressions), but not converted to
146 * implicit-AND form; and any SubLinks in it should already have been
147 * converted to SubPlans. The subquery is as yet untouched, however.
148 *
149 * The result is whatever we need to substitute in place of the SubLink node
150 * in the executable expression. If we're going to do the subplan as a
151 * regular subplan, this will be the constructed SubPlan node. If we're going
152 * to do the subplan as an InitPlan, the SubPlan node instead goes into
153 * root->init_plans, and what we return here is an expression tree
154 * representing the InitPlan's result: usually just a Param node representing
155 * a single scalar result, but possibly a row comparison tree containing
156 * multiple Param nodes, or for a MULTIEXPR subquery a simple NULL constant
157 * (since the real output Params are elsewhere in the tree, and the MULTIEXPR
158 * subquery itself is in a resjunk tlist entry whose value is uninteresting).
159 */
160static Node *
161make_subplan(PlannerInfo *root, Query *orig_subquery,
162 SubLinkType subLinkType, int subLinkId,
163 Node *testexpr, bool isTopQual)
164{
165 Query *subquery;
166 bool simple_exists = false;
167 double tuple_fraction;
168 PlannerInfo *subroot;
169 RelOptInfo *final_rel;
170 Path *best_path;
171 Plan *plan;
172 List *plan_params;
173 Node *result;
174
175 /*
176 * Copy the source Query node. This is a quick and dirty kluge to resolve
177 * the fact that the parser can generate trees with multiple links to the
178 * same sub-Query node, but the planner wants to scribble on the Query.
179 * Try to clean this up when we do querytree redesign...
180 */
181 subquery = copyObject(orig_subquery);
182
183 /*
184 * If it's an EXISTS subplan, we might be able to simplify it.
185 */
186 if (subLinkType == EXISTS_SUBLINK)
187 simple_exists = simplify_EXISTS_query(root, subquery);
188
189 /*
190 * For an EXISTS subplan, tell lower-level planner to expect that only the
191 * first tuple will be retrieved. For ALL and ANY subplans, we will be
192 * able to stop evaluating if the test condition fails or matches, so very
193 * often not all the tuples will be retrieved; for lack of a better idea,
194 * specify 50% retrieval. For EXPR, MULTIEXPR, and ROWCOMPARE subplans,
195 * use default behavior (we're only expecting one row out, anyway).
196 *
197 * NOTE: if you change these numbers, also change cost_subplan() in
198 * path/costsize.c.
199 *
200 * XXX If an ANY subplan is uncorrelated, build_subplan may decide to hash
201 * its output. In that case it would've been better to specify full
202 * retrieval. At present, however, we can only check hashability after
203 * we've made the subplan :-(. (Determining whether it'll fit in work_mem
204 * is the really hard part.) Therefore, we don't want to be too
205 * optimistic about the percentage of tuples retrieved, for fear of
206 * selecting a plan that's bad for the materialization case.
207 */
208 if (subLinkType == EXISTS_SUBLINK)
209 tuple_fraction = 1.0; /* just like a LIMIT 1 */
210 else if (subLinkType == ALL_SUBLINK ||
211 subLinkType == ANY_SUBLINK)
212 tuple_fraction = 0.5; /* 50% */
213 else
214 tuple_fraction = 0.0; /* default behavior */
215
216 /* plan_params should not be in use in current query level */
217 Assert(root->plan_params == NIL);
218
219 /* Generate Paths for the subquery */
220 subroot = subquery_planner(root->glob, subquery,
221 root,
222 false, tuple_fraction);
223
224 /* Isolate the params needed by this specific subplan */
225 plan_params = root->plan_params;
226 root->plan_params = NIL;
227
228 /*
229 * Select best Path and turn it into a Plan. At least for now, there
230 * seems no reason to postpone doing that.
231 */
232 final_rel = fetch_upper_rel(subroot, UPPERREL_FINAL, NULL);
233 best_path = get_cheapest_fractional_path(final_rel, tuple_fraction);
234
235 plan = create_plan(subroot, best_path);
236
237 /* And convert to SubPlan or InitPlan format. */
238 result = build_subplan(root, plan, subroot, plan_params,
239 subLinkType, subLinkId,
240 testexpr, true, isTopQual);
241
242 /*
243 * If it's a correlated EXISTS with an unimportant targetlist, we might be
244 * able to transform it to the equivalent of an IN and then implement it
245 * by hashing. We don't have enough information yet to tell which way is
246 * likely to be better (it depends on the expected number of executions of
247 * the EXISTS qual, and we are much too early in planning the outer query
248 * to be able to guess that). So we generate both plans, if possible, and
249 * leave it to the executor to decide which to use.
250 */
251 if (simple_exists && IsA(result, SubPlan))
252 {
253 Node *newtestexpr;
254 List *paramIds;
255
256 /* Make a second copy of the original subquery */
257 subquery = copyObject(orig_subquery);
258 /* and re-simplify */
259 simple_exists = simplify_EXISTS_query(root, subquery);
260 Assert(simple_exists);
261 /* See if it can be converted to an ANY query */
262 subquery = convert_EXISTS_to_ANY(root, subquery,
263 &newtestexpr, &paramIds);
264 if (subquery)
265 {
266 /* Generate Paths for the ANY subquery; we'll need all rows */
267 subroot = subquery_planner(root->glob, subquery,
268 root,
269 false, 0.0);
270
271 /* Isolate the params needed by this specific subplan */
272 plan_params = root->plan_params;
273 root->plan_params = NIL;
274
275 /* Select best Path and turn it into a Plan */
276 final_rel = fetch_upper_rel(subroot, UPPERREL_FINAL, NULL);
277 best_path = final_rel->cheapest_total_path;
278
279 plan = create_plan(subroot, best_path);
280
281 /* Now we can check if it'll fit in work_mem */
282 /* XXX can we check this at the Path stage? */
283 if (subplan_is_hashable(plan))
284 {
285 SubPlan *hashplan;
286 AlternativeSubPlan *asplan;
287
288 /* OK, convert to SubPlan format. */
289 hashplan = castNode(SubPlan,
290 build_subplan(root, plan, subroot,
291 plan_params,
292 ANY_SUBLINK, 0,
293 newtestexpr,
294 false, true));
295 /* Check we got what we expected */
296 Assert(hashplan->parParam == NIL);
297 Assert(hashplan->useHashTable);
298 /* build_subplan won't have filled in paramIds */
299 hashplan->paramIds = paramIds;
300
301 /* Leave it to the executor to decide which plan to use */
302 asplan = makeNode(AlternativeSubPlan);
303 asplan->subplans = list_make2(result, hashplan);
304 result = (Node *) asplan;
305 }
306 }
307 }
308
309 return result;
310}
311
312/*
313 * Build a SubPlan node given the raw inputs --- subroutine for make_subplan
314 *
315 * Returns either the SubPlan, or a replacement expression if we decide to
316 * make it an InitPlan, as explained in the comments for make_subplan.
317 */
318static Node *
319build_subplan(PlannerInfo *root, Plan *plan, PlannerInfo *subroot,
320 List *plan_params,
321 SubLinkType subLinkType, int subLinkId,
322 Node *testexpr, bool adjust_testexpr,
323 bool unknownEqFalse)
324{
325 Node *result;
326 SubPlan *splan;
327 bool isInitPlan;
328 ListCell *lc;
329
330 /*
331 * Initialize the SubPlan node. Note plan_id, plan_name, and cost fields
332 * are set further down.
333 */
334 splan = makeNode(SubPlan);
335 splan->subLinkType = subLinkType;
336 splan->testexpr = NULL;
337 splan->paramIds = NIL;
338 get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod,
339 &splan->firstColCollation);
340 splan->useHashTable = false;
341 splan->unknownEqFalse = unknownEqFalse;
342 splan->parallel_safe = plan->parallel_safe;
343 splan->setParam = NIL;
344 splan->parParam = NIL;
345 splan->args = NIL;
346
347 /*
348 * Make parParam and args lists of param IDs and expressions that current
349 * query level will pass to this child plan.
350 */
351 foreach(lc, plan_params)
352 {
353 PlannerParamItem *pitem = (PlannerParamItem *) lfirst(lc);
354 Node *arg = pitem->item;
355
356 /*
357 * The Var, PlaceHolderVar, or Aggref has already been adjusted to
358 * have the correct varlevelsup, phlevelsup, or agglevelsup.
359 *
360 * If it's a PlaceHolderVar or Aggref, its arguments might contain
361 * SubLinks, which have not yet been processed (see the comments for
362 * SS_replace_correlation_vars). Do that now.
363 */
364 if (IsA(arg, PlaceHolderVar) ||
365 IsA(arg, Aggref))
366 arg = SS_process_sublinks(root, arg, false);
367
368 splan->parParam = lappend_int(splan->parParam, pitem->paramId);
369 splan->args = lappend(splan->args, arg);
370 }
371
372 /*
373 * Un-correlated or undirect correlated plans of EXISTS, EXPR, ARRAY,
374 * ROWCOMPARE, or MULTIEXPR types can be used as initPlans. For EXISTS,
375 * EXPR, or ARRAY, we return a Param referring to the result of evaluating
376 * the initPlan. For ROWCOMPARE, we must modify the testexpr tree to
377 * contain PARAM_EXEC Params instead of the PARAM_SUBLINK Params emitted
378 * by the parser, and then return that tree. For MULTIEXPR, we return a
379 * null constant: the resjunk targetlist item containing the SubLink does
380 * not need to return anything useful, since the referencing Params are
381 * elsewhere.
382 */
383 if (splan->parParam == NIL && subLinkType == EXISTS_SUBLINK)
384 {
385 Param *prm;
386
387 Assert(testexpr == NULL);
388 prm = generate_new_exec_param(root, BOOLOID, -1, InvalidOid);
389 splan->setParam = list_make1_int(prm->paramid);
390 isInitPlan = true;
391 result = (Node *) prm;
392 }
393 else if (splan->parParam == NIL && subLinkType == EXPR_SUBLINK)
394 {
395 TargetEntry *te = linitial(plan->targetlist);
396 Param *prm;
397
398 Assert(!te->resjunk);
399 Assert(testexpr == NULL);
400 prm = generate_new_exec_param(root,
401 exprType((Node *) te->expr),
402 exprTypmod((Node *) te->expr),
403 exprCollation((Node *) te->expr));
404 splan->setParam = list_make1_int(prm->paramid);
405 isInitPlan = true;
406 result = (Node *) prm;
407 }
408 else if (splan->parParam == NIL && subLinkType == ARRAY_SUBLINK)
409 {
410 TargetEntry *te = linitial(plan->targetlist);
411 Oid arraytype;
412 Param *prm;
413
414 Assert(!te->resjunk);
415 Assert(testexpr == NULL);
416 arraytype = get_promoted_array_type(exprType((Node *) te->expr));
417 if (!OidIsValid(arraytype))
418 elog(ERROR, "could not find array type for datatype %s",
419 format_type_be(exprType((Node *) te->expr)));
420 prm = generate_new_exec_param(root,
421 arraytype,
422 exprTypmod((Node *) te->expr),
423 exprCollation((Node *) te->expr));
424 splan->setParam = list_make1_int(prm->paramid);
425 isInitPlan = true;
426 result = (Node *) prm;
427 }
428 else if (splan->parParam == NIL && subLinkType == ROWCOMPARE_SUBLINK)
429 {
430 /* Adjust the Params */
431 List *params;
432
433 Assert(testexpr != NULL);
434 params = generate_subquery_params(root,
435 plan->targetlist,
436 &splan->paramIds);
437 result = convert_testexpr(root,
438 testexpr,
439 params);
440 splan->setParam = list_copy(splan->paramIds);
441 isInitPlan = true;
442
443 /*
444 * The executable expression is returned to become part of the outer
445 * plan's expression tree; it is not kept in the initplan node.
446 */
447 }
448 else if (subLinkType == MULTIEXPR_SUBLINK)
449 {
450 /*
451 * Whether it's an initplan or not, it needs to set a PARAM_EXEC Param
452 * for each output column.
453 */
454 List *params;
455
456 Assert(testexpr == NULL);
457 params = generate_subquery_params(root,
458 plan->targetlist,
459 &splan->setParam);
460
461 /*
462 * Save the list of replacement Params in the n'th cell of
463 * root->multiexpr_params; setrefs.c will use it to replace
464 * PARAM_MULTIEXPR Params.
465 */
466 while (list_length(root->multiexpr_params) < subLinkId)
467 root->multiexpr_params = lappend(root->multiexpr_params, NIL);
468 lc = list_nth_cell(root->multiexpr_params, subLinkId - 1);
469 Assert(lfirst(lc) == NIL);
470 lfirst(lc) = params;
471
472 /* It can be an initplan if there are no parParams. */
473 if (splan->parParam == NIL)
474 {
475 isInitPlan = true;
476 result = (Node *) makeNullConst(RECORDOID, -1, InvalidOid);
477 }
478 else
479 {
480 isInitPlan = false;
481 result = (Node *) splan;
482 }
483 }
484 else
485 {
486 /*
487 * Adjust the Params in the testexpr, unless caller said it's not
488 * needed.
489 */
490 if (testexpr && adjust_testexpr)
491 {
492 List *params;
493
494 params = generate_subquery_params(root,
495 plan->targetlist,
496 &splan->paramIds);
497 splan->testexpr = convert_testexpr(root,
498 testexpr,
499 params);
500 }
501 else
502 splan->testexpr = testexpr;
503
504 /*
505 * We can't convert subplans of ALL_SUBLINK or ANY_SUBLINK types to
506 * initPlans, even when they are uncorrelated or undirect correlated,
507 * because we need to scan the output of the subplan for each outer
508 * tuple. But if it's a not-direct-correlated IN (= ANY) test, we
509 * might be able to use a hashtable to avoid comparing all the tuples.
510 */
511 if (subLinkType == ANY_SUBLINK &&
512 splan->parParam == NIL &&
513 subplan_is_hashable(plan) &&
514 testexpr_is_hashable(splan->testexpr))
515 splan->useHashTable = true;
516
517 /*
518 * Otherwise, we have the option to tack a Material node onto the top
519 * of the subplan, to reduce the cost of reading it repeatedly. This
520 * is pointless for a direct-correlated subplan, since we'd have to
521 * recompute its results each time anyway. For uncorrelated/undirect
522 * correlated subplans, we add Material unless the subplan's top plan
523 * node would materialize its output anyway. Also, if enable_material
524 * is false, then the user does not want us to materialize anything
525 * unnecessarily, so we don't.
526 */
527 else if (splan->parParam == NIL && enable_material &&
528 !ExecMaterializesOutput(nodeTag(plan)))
529 plan = materialize_finished_plan(plan);
530
531 result = (Node *) splan;
532 isInitPlan = false;
533 }
534
535 /*
536 * Add the subplan and its PlannerInfo to the global lists.
537 */
538 root->glob->subplans = lappend(root->glob->subplans, plan);
539 root->glob->subroots = lappend(root->glob->subroots, subroot);
540 splan->plan_id = list_length(root->glob->subplans);
541
542 if (isInitPlan)
543 root->init_plans = lappend(root->init_plans, splan);
544
545 /*
546 * A parameterless subplan (not initplan) should be prepared to handle
547 * REWIND efficiently. If it has direct parameters then there's no point
548 * since it'll be reset on each scan anyway; and if it's an initplan then
549 * there's no point since it won't get re-run without parameter changes
550 * anyway. The input of a hashed subplan doesn't need REWIND either.
551 */
552 if (splan->parParam == NIL && !isInitPlan && !splan->useHashTable)
553 root->glob->rewindPlanIDs = bms_add_member(root->glob->rewindPlanIDs,
554 splan->plan_id);
555
556 /* Label the subplan for EXPLAIN purposes */
557 splan->plan_name = palloc(32 + 12 * list_length(splan->setParam));
558 sprintf(splan->plan_name, "%s %d",
559 isInitPlan ? "InitPlan" : "SubPlan",
560 splan->plan_id);
561 if (splan->setParam)
562 {
563 char *ptr = splan->plan_name + strlen(splan->plan_name);
564
565 ptr += sprintf(ptr, " (returns ");
566 foreach(lc, splan->setParam)
567 {
568 ptr += sprintf(ptr, "$%d%s",
569 lfirst_int(lc),
570 lnext(lc) ? "," : ")");
571 }
572 }
573
574 /* Lastly, fill in the cost estimates for use later */
575 cost_subplan(root, splan, plan);
576
577 return result;
578}
579
580/*
581 * generate_subquery_params: build a list of Params representing the output
582 * columns of a sublink's sub-select, given the sub-select's targetlist.
583 *
584 * We also return an integer list of the paramids of the Params.
585 */
586static List *
587generate_subquery_params(PlannerInfo *root, List *tlist, List **paramIds)
588{
589 List *result;
590 List *ids;
591 ListCell *lc;
592
593 result = ids = NIL;
594 foreach(lc, tlist)
595 {
596 TargetEntry *tent = (TargetEntry *) lfirst(lc);
597 Param *param;
598
599 if (tent->resjunk)
600 continue;
601
602 param = generate_new_exec_param(root,
603 exprType((Node *) tent->expr),
604 exprTypmod((Node *) tent->expr),
605 exprCollation((Node *) tent->expr));
606 result = lappend(result, param);
607 ids = lappend_int(ids, param->paramid);
608 }
609
610 *paramIds = ids;
611 return result;
612}
613
614/*
615 * generate_subquery_vars: build a list of Vars representing the output
616 * columns of a sublink's sub-select, given the sub-select's targetlist.
617 * The Vars have the specified varno (RTE index).
618 */
619static List *
620generate_subquery_vars(PlannerInfo *root, List *tlist, Index varno)
621{
622 List *result;
623 ListCell *lc;
624
625 result = NIL;
626 foreach(lc, tlist)
627 {
628 TargetEntry *tent = (TargetEntry *) lfirst(lc);
629 Var *var;
630
631 if (tent->resjunk)
632 continue;
633
634 var = makeVarFromTargetEntry(varno, tent);
635 result = lappend(result, var);
636 }
637
638 return result;
639}
640
641/*
642 * convert_testexpr: convert the testexpr given by the parser into
643 * actually executable form. This entails replacing PARAM_SUBLINK Params
644 * with Params or Vars representing the results of the sub-select. The
645 * nodes to be substituted are passed in as the List result from
646 * generate_subquery_params or generate_subquery_vars.
647 */
648static Node *
649convert_testexpr(PlannerInfo *root,
650 Node *testexpr,
651 List *subst_nodes)
652{
653 convert_testexpr_context context;
654
655 context.root = root;
656 context.subst_nodes = subst_nodes;
657 return convert_testexpr_mutator(testexpr, &context);
658}
659
660static Node *
661convert_testexpr_mutator(Node *node,
662 convert_testexpr_context *context)
663{
664 if (node == NULL)
665 return NULL;
666 if (IsA(node, Param))
667 {
668 Param *param = (Param *) node;
669
670 if (param->paramkind == PARAM_SUBLINK)
671 {
672 if (param->paramid <= 0 ||
673 param->paramid > list_length(context->subst_nodes))
674 elog(ERROR, "unexpected PARAM_SUBLINK ID: %d", param->paramid);
675
676 /*
677 * We copy the list item to avoid having doubly-linked
678 * substructure in the modified parse tree. This is probably
679 * unnecessary when it's a Param, but be safe.
680 */
681 return (Node *) copyObject(list_nth(context->subst_nodes,
682 param->paramid - 1));
683 }
684 }
685 if (IsA(node, SubLink))
686 {
687 /*
688 * If we come across a nested SubLink, it is neither necessary nor
689 * correct to recurse into it: any PARAM_SUBLINKs we might find inside
690 * belong to the inner SubLink not the outer. So just return it as-is.
691 *
692 * This reasoning depends on the assumption that nothing will pull
693 * subexpressions into or out of the testexpr field of a SubLink, at
694 * least not without replacing PARAM_SUBLINKs first. If we did want
695 * to do that we'd need to rethink the parser-output representation
696 * altogether, since currently PARAM_SUBLINKs are only unique per
697 * SubLink not globally across the query. The whole point of
698 * replacing them with Vars or PARAM_EXEC nodes is to make them
699 * globally unique before they escape from the SubLink's testexpr.
700 *
701 * Note: this can't happen when called during SS_process_sublinks,
702 * because that recursively processes inner SubLinks first. It can
703 * happen when called from convert_ANY_sublink_to_join, though.
704 */
705 return node;
706 }
707 return expression_tree_mutator(node,
708 convert_testexpr_mutator,
709 (void *) context);
710}
711
712/*
713 * subplan_is_hashable: can we implement an ANY subplan by hashing?
714 */
715static bool
716subplan_is_hashable(Plan *plan)
717{
718 double subquery_size;
719
720 /*
721 * The estimated size of the subquery result must fit in work_mem. (Note:
722 * we use heap tuple overhead here even though the tuples will actually be
723 * stored as MinimalTuples; this provides some fudge factor for hashtable
724 * overhead.)
725 */
726 subquery_size = plan->plan_rows *
727 (MAXALIGN(plan->plan_width) + MAXALIGN(SizeofHeapTupleHeader));
728 if (subquery_size > work_mem * 1024L)
729 return false;
730
731 return true;
732}
733
734/*
735 * testexpr_is_hashable: is an ANY SubLink's test expression hashable?
736 */
737static bool
738testexpr_is_hashable(Node *testexpr)
739{
740 /*
741 * The testexpr must be a single OpExpr, or an AND-clause containing only
742 * OpExprs.
743 *
744 * The combining operators must be hashable and strict. The need for
745 * hashability is obvious, since we want to use hashing. Without
746 * strictness, behavior in the presence of nulls is too unpredictable. We
747 * actually must assume even more than plain strictness: they can't yield
748 * NULL for non-null inputs, either (see nodeSubplan.c). However, hash
749 * indexes and hash joins assume that too.
750 */
751 if (testexpr && IsA(testexpr, OpExpr))
752 {
753 if (hash_ok_operator((OpExpr *) testexpr))
754 return true;
755 }
756 else if (is_andclause(testexpr))
757 {
758 ListCell *l;
759
760 foreach(l, ((BoolExpr *) testexpr)->args)
761 {
762 Node *andarg = (Node *) lfirst(l);
763
764 if (!IsA(andarg, OpExpr))
765 return false;
766 if (!hash_ok_operator((OpExpr *) andarg))
767 return false;
768 }
769 return true;
770 }
771
772 return false;
773}
774
775/*
776 * Check expression is hashable + strict
777 *
778 * We could use op_hashjoinable() and op_strict(), but do it like this to
779 * avoid a redundant cache lookup.
780 */
781static bool
782hash_ok_operator(OpExpr *expr)
783{
784 Oid opid = expr->opno;
785
786 /* quick out if not a binary operator */
787 if (list_length(expr->args) != 2)
788 return false;
789 if (opid == ARRAY_EQ_OP)
790 {
791 /* array_eq is strict, but must check input type to ensure hashable */
792 /* XXX record_eq will need same treatment when it becomes hashable */
793 Node *leftarg = linitial(expr->args);
794
795 return op_hashjoinable(opid, exprType(leftarg));
796 }
797 else
798 {
799 /* else must look up the operator properties */
800 HeapTuple tup;
801 Form_pg_operator optup;
802
803 tup = SearchSysCache1(OPEROID, ObjectIdGetDatum(opid));
804 if (!HeapTupleIsValid(tup))
805 elog(ERROR, "cache lookup failed for operator %u", opid);
806 optup = (Form_pg_operator) GETSTRUCT(tup);
807 if (!optup->oprcanhash || !func_strict(optup->oprcode))
808 {
809 ReleaseSysCache(tup);
810 return false;
811 }
812 ReleaseSysCache(tup);
813 return true;
814 }
815}
816
817
818/*
819 * SS_process_ctes: process a query's WITH list
820 *
821 * Consider each CTE in the WITH list and either ignore it (if it's an
822 * unreferenced SELECT), "inline" it to create a regular sub-SELECT-in-FROM,
823 * or convert it to an initplan.
824 *
825 * A side effect is to fill in root->cte_plan_ids with a list that
826 * parallels root->parse->cteList and provides the subplan ID for
827 * each CTE's initplan, or a dummy ID (-1) if we didn't make an initplan.
828 */
829void
830SS_process_ctes(PlannerInfo *root)
831{
832 ListCell *lc;
833
834 Assert(root->cte_plan_ids == NIL);
835
836 foreach(lc, root->parse->cteList)
837 {
838 CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
839 CmdType cmdType = ((Query *) cte->ctequery)->commandType;
840 Query *subquery;
841 PlannerInfo *subroot;
842 RelOptInfo *final_rel;
843 Path *best_path;
844 Plan *plan;
845 SubPlan *splan;
846 int paramid;
847
848 /*
849 * Ignore SELECT CTEs that are not actually referenced anywhere.
850 */
851 if (cte->cterefcount == 0 && cmdType == CMD_SELECT)
852 {
853 /* Make a dummy entry in cte_plan_ids */
854 root->cte_plan_ids = lappend_int(root->cte_plan_ids, -1);
855 continue;
856 }
857
858 /*
859 * Consider inlining the CTE (creating RTE_SUBQUERY RTE(s)) instead of
860 * implementing it as a separately-planned CTE.
861 *
862 * We cannot inline if any of these conditions hold:
863 *
864 * 1. The user said not to (the CTEMaterializeAlways option).
865 *
866 * 2. The CTE is recursive.
867 *
868 * 3. The CTE has side-effects; this includes either not being a plain
869 * SELECT, or containing volatile functions. Inlining might change
870 * the side-effects, which would be bad.
871 *
872 * 4. The CTE is multiply-referenced and contains a self-reference to
873 * a recursive CTE outside itself. Inlining would result in multiple
874 * recursive self-references, which we don't support.
875 *
876 * Otherwise, we have an option whether to inline or not. That should
877 * always be a win if there's just a single reference, but if the CTE
878 * is multiply-referenced then it's unclear: inlining adds duplicate
879 * computations, but the ability to absorb restrictions from the outer
880 * query level could outweigh that. We do not have nearly enough
881 * information at this point to tell whether that's true, so we let
882 * the user express a preference. Our default behavior is to inline
883 * only singly-referenced CTEs, but a CTE marked CTEMaterializeNever
884 * will be inlined even if multiply referenced.
885 *
886 * Note: we check for volatile functions last, because that's more
887 * expensive than the other tests needed.
888 */
889 if ((cte->ctematerialized == CTEMaterializeNever ||
890 (cte->ctematerialized == CTEMaterializeDefault &&
891 cte->cterefcount == 1)) &&
892 !cte->cterecursive &&
893 cmdType == CMD_SELECT &&
894 !contain_dml(cte->ctequery) &&
895 (cte->cterefcount <= 1 ||
896 !contain_outer_selfref(cte->ctequery)) &&
897 !contain_volatile_functions(cte->ctequery))
898 {
899 inline_cte(root, cte);
900 /* Make a dummy entry in cte_plan_ids */
901 root->cte_plan_ids = lappend_int(root->cte_plan_ids, -1);
902 continue;
903 }
904
905 /*
906 * Copy the source Query node. Probably not necessary, but let's keep
907 * this similar to make_subplan.
908 */
909 subquery = (Query *) copyObject(cte->ctequery);
910
911 /* plan_params should not be in use in current query level */
912 Assert(root->plan_params == NIL);
913
914 /*
915 * Generate Paths for the CTE query. Always plan for full retrieval
916 * --- we don't have enough info to predict otherwise.
917 */
918 subroot = subquery_planner(root->glob, subquery,
919 root,
920 cte->cterecursive, 0.0);
921
922 /*
923 * Since the current query level doesn't yet contain any RTEs, it
924 * should not be possible for the CTE to have requested parameters of
925 * this level.
926 */
927 if (root->plan_params)
928 elog(ERROR, "unexpected outer reference in CTE query");
929
930 /*
931 * Select best Path and turn it into a Plan. At least for now, there
932 * seems no reason to postpone doing that.
933 */
934 final_rel = fetch_upper_rel(subroot, UPPERREL_FINAL, NULL);
935 best_path = final_rel->cheapest_total_path;
936
937 plan = create_plan(subroot, best_path);
938
939 /*
940 * Make a SubPlan node for it. This is just enough unlike
941 * build_subplan that we can't share code.
942 *
943 * Note plan_id, plan_name, and cost fields are set further down.
944 */
945 splan = makeNode(SubPlan);
946 splan->subLinkType = CTE_SUBLINK;
947 splan->testexpr = NULL;
948 splan->paramIds = NIL;
949 get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod,
950 &splan->firstColCollation);
951 splan->useHashTable = false;
952 splan->unknownEqFalse = false;
953
954 /*
955 * CTE scans are not considered for parallelism (cf
956 * set_rel_consider_parallel), and even if they were, initPlans aren't
957 * parallel-safe.
958 */
959 splan->parallel_safe = false;
960 splan->setParam = NIL;
961 splan->parParam = NIL;
962 splan->args = NIL;
963
964 /*
965 * The node can't have any inputs (since it's an initplan), so the
966 * parParam and args lists remain empty. (It could contain references
967 * to earlier CTEs' output param IDs, but CTE outputs are not
968 * propagated via the args list.)
969 */
970
971 /*
972 * Assign a param ID to represent the CTE's output. No ordinary
973 * "evaluation" of this param slot ever happens, but we use the param
974 * ID for setParam/chgParam signaling just as if the CTE plan were
975 * returning a simple scalar output. (Also, the executor abuses the
976 * ParamExecData slot for this param ID for communication among
977 * multiple CteScan nodes that might be scanning this CTE.)
978 */
979 paramid = assign_special_exec_param(root);
980 splan->setParam = list_make1_int(paramid);
981
982 /*
983 * Add the subplan and its PlannerInfo to the global lists.
984 */
985 root->glob->subplans = lappend(root->glob->subplans, plan);
986 root->glob->subroots = lappend(root->glob->subroots, subroot);
987 splan->plan_id = list_length(root->glob->subplans);
988
989 root->init_plans = lappend(root->init_plans, splan);
990
991 root->cte_plan_ids = lappend_int(root->cte_plan_ids, splan->plan_id);
992
993 /* Label the subplan for EXPLAIN purposes */
994 splan->plan_name = psprintf("CTE %s", cte->ctename);
995
996 /* Lastly, fill in the cost estimates for use later */
997 cost_subplan(root, splan, plan);
998 }
999}
1000
1001/*
1002 * contain_dml: is any subquery not a plain SELECT?
1003 *
1004 * We reject SELECT FOR UPDATE/SHARE as well as INSERT etc.
1005 */
1006static bool
1007contain_dml(Node *node)
1008{
1009 return contain_dml_walker(node, NULL);
1010}
1011
1012static bool
1013contain_dml_walker(Node *node, void *context)
1014{
1015 if (node == NULL)
1016 return false;
1017 if (IsA(node, Query))
1018 {
1019 Query *query = (Query *) node;
1020
1021 if (query->commandType != CMD_SELECT ||
1022 query->rowMarks != NIL)
1023 return true;
1024
1025 return query_tree_walker(query, contain_dml_walker, context, 0);
1026 }
1027 return expression_tree_walker(node, contain_dml_walker, context);
1028}
1029
1030/*
1031 * contain_outer_selfref: is there an external recursive self-reference?
1032 */
1033static bool
1034contain_outer_selfref(Node *node)
1035{
1036 Index depth = 0;
1037
1038 /*
1039 * We should be starting with a Query, so that depth will be 1 while
1040 * examining its immediate contents.
1041 */
1042 Assert(IsA(node, Query));
1043
1044 return contain_outer_selfref_walker(node, &depth);
1045}
1046
1047static bool
1048contain_outer_selfref_walker(Node *node, Index *depth)
1049{
1050 if (node == NULL)
1051 return false;
1052 if (IsA(node, RangeTblEntry))
1053 {
1054 RangeTblEntry *rte = (RangeTblEntry *) node;
1055
1056 /*
1057 * Check for a self-reference to a CTE that's above the Query that our
1058 * search started at.
1059 */
1060 if (rte->rtekind == RTE_CTE &&
1061 rte->self_reference &&
1062 rte->ctelevelsup >= *depth)
1063 return true;
1064 return false; /* allow range_table_walker to continue */
1065 }
1066 if (IsA(node, Query))
1067 {
1068 /* Recurse into subquery, tracking nesting depth properly */
1069 Query *query = (Query *) node;
1070 bool result;
1071
1072 (*depth)++;
1073
1074 result = query_tree_walker(query, contain_outer_selfref_walker,
1075 (void *) depth, QTW_EXAMINE_RTES_BEFORE);
1076
1077 (*depth)--;
1078
1079 return result;
1080 }
1081 return expression_tree_walker(node, contain_outer_selfref_walker,
1082 (void *) depth);
1083}
1084
1085/*
1086 * inline_cte: convert RTE_CTE references to given CTE into RTE_SUBQUERYs
1087 */
1088static void
1089inline_cte(PlannerInfo *root, CommonTableExpr *cte)
1090{
1091 struct inline_cte_walker_context context;
1092
1093 context.ctename = cte->ctename;
1094 /* Start at levelsup = -1 because we'll immediately increment it */
1095 context.levelsup = -1;
1096 context.refcount = cte->cterefcount;
1097 context.ctequery = castNode(Query, cte->ctequery);
1098
1099 (void) inline_cte_walker((Node *) root->parse, &context);
1100
1101 /* Assert we replaced all references */
1102 Assert(context.refcount == 0);
1103}
1104
1105static bool
1106inline_cte_walker(Node *node, inline_cte_walker_context *context)
1107{
1108 if (node == NULL)
1109 return false;
1110 if (IsA(node, Query))
1111 {
1112 Query *query = (Query *) node;
1113
1114 context->levelsup++;
1115
1116 /*
1117 * Visit the query's RTE nodes after their contents; otherwise
1118 * query_tree_walker would descend into the newly inlined CTE query,
1119 * which we don't want.
1120 */
1121 (void) query_tree_walker(query, inline_cte_walker, context,
1122 QTW_EXAMINE_RTES_AFTER);
1123
1124 context->levelsup--;
1125
1126 return false;
1127 }
1128 else if (IsA(node, RangeTblEntry))
1129 {
1130 RangeTblEntry *rte = (RangeTblEntry *) node;
1131
1132 if (rte->rtekind == RTE_CTE &&
1133 strcmp(rte->ctename, context->ctename) == 0 &&
1134 rte->ctelevelsup == context->levelsup)
1135 {
1136 /*
1137 * Found a reference to replace. Generate a copy of the CTE query
1138 * with appropriate level adjustment for outer references (e.g.,
1139 * to other CTEs).
1140 */
1141 Query *newquery = copyObject(context->ctequery);
1142
1143 if (context->levelsup > 0)
1144 IncrementVarSublevelsUp((Node *) newquery, context->levelsup, 1);
1145
1146 /*
1147 * Convert the RTE_CTE RTE into a RTE_SUBQUERY.
1148 *
1149 * Historically, a FOR UPDATE clause has been treated as extending
1150 * into views and subqueries, but not into CTEs. We preserve this
1151 * distinction by not trying to push rowmarks into the new
1152 * subquery.
1153 */
1154 rte->rtekind = RTE_SUBQUERY;
1155 rte->subquery = newquery;
1156 rte->security_barrier = false;
1157
1158 /* Zero out CTE-specific fields */
1159 rte->ctename = NULL;
1160 rte->ctelevelsup = 0;
1161 rte->self_reference = false;
1162 rte->coltypes = NIL;
1163 rte->coltypmods = NIL;
1164 rte->colcollations = NIL;
1165
1166 /* Count the number of replacements we've done */
1167 context->refcount--;
1168 }
1169
1170 return false;
1171 }
1172
1173 return expression_tree_walker(node, inline_cte_walker, context);
1174}
1175
1176
1177/*
1178 * convert_ANY_sublink_to_join: try to convert an ANY SubLink to a join
1179 *
1180 * The caller has found an ANY SubLink at the top level of one of the query's
1181 * qual clauses, but has not checked the properties of the SubLink further.
1182 * Decide whether it is appropriate to process this SubLink in join style.
1183 * If so, form a JoinExpr and return it. Return NULL if the SubLink cannot
1184 * be converted to a join.
1185 *
1186 * The only non-obvious input parameter is available_rels: this is the set
1187 * of query rels that can safely be referenced in the sublink expression.
1188 * (We must restrict this to avoid changing the semantics when a sublink
1189 * is present in an outer join's ON qual.) The conversion must fail if
1190 * the converted qual would reference any but these parent-query relids.
1191 *
1192 * On success, the returned JoinExpr has larg = NULL and rarg = the jointree
1193 * item representing the pulled-up subquery. The caller must set larg to
1194 * represent the relation(s) on the lefthand side of the new join, and insert
1195 * the JoinExpr into the upper query's jointree at an appropriate place
1196 * (typically, where the lefthand relation(s) had been). Note that the
1197 * passed-in SubLink must also be removed from its original position in the
1198 * query quals, since the quals of the returned JoinExpr replace it.
1199 * (Notionally, we replace the SubLink with a constant TRUE, then elide the
1200 * redundant constant from the qual.)
1201 *
1202 * On success, the caller is also responsible for recursively applying
1203 * pull_up_sublinks processing to the rarg and quals of the returned JoinExpr.
1204 * (On failure, there is no need to do anything, since pull_up_sublinks will
1205 * be applied when we recursively plan the sub-select.)
1206 *
1207 * Side effects of a successful conversion include adding the SubLink's
1208 * subselect to the query's rangetable, so that it can be referenced in
1209 * the JoinExpr's rarg.
1210 */
1211JoinExpr *
1212convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink,
1213 Relids available_rels)
1214{
1215 JoinExpr *result;
1216 Query *parse = root->parse;
1217 Query *subselect = (Query *) sublink->subselect;
1218 Relids upper_varnos;
1219 int rtindex;
1220 RangeTblEntry *rte;
1221 RangeTblRef *rtr;
1222 List *subquery_vars;
1223 Node *quals;
1224 ParseState *pstate;
1225
1226 Assert(sublink->subLinkType == ANY_SUBLINK);
1227
1228 /*
1229 * The sub-select must not refer to any Vars of the parent query. (Vars of
1230 * higher levels should be okay, though.)
1231 */
1232 if (contain_vars_of_level((Node *) subselect, 1))
1233 return NULL;
1234
1235 /*
1236 * The test expression must contain some Vars of the parent query, else
1237 * it's not gonna be a join. (Note that it won't have Vars referring to
1238 * the subquery, rather Params.)
1239 */
1240 upper_varnos = pull_varnos(sublink->testexpr);
1241 if (bms_is_empty(upper_varnos))
1242 return NULL;
1243
1244 /*
1245 * However, it can't refer to anything outside available_rels.
1246 */
1247 if (!bms_is_subset(upper_varnos, available_rels))
1248 return NULL;
1249
1250 /*
1251 * The combining operators and left-hand expressions mustn't be volatile.
1252 */
1253 if (contain_volatile_functions(sublink->testexpr))
1254 return NULL;
1255
1256 /* Create a dummy ParseState for addRangeTableEntryForSubquery */
1257 pstate = make_parsestate(NULL);
1258
1259 /*
1260 * Okay, pull up the sub-select into upper range table.
1261 *
1262 * We rely here on the assumption that the outer query has no references
1263 * to the inner (necessarily true, other than the Vars that we build
1264 * below). Therefore this is a lot easier than what pull_up_subqueries has
1265 * to go through.
1266 */
1267 rte = addRangeTableEntryForSubquery(pstate,
1268 subselect,
1269 makeAlias("ANY_subquery", NIL),
1270 false,
1271 false);
1272 parse->rtable = lappend(parse->rtable, rte);
1273 rtindex = list_length(parse->rtable);
1274
1275 /*
1276 * Form a RangeTblRef for the pulled-up sub-select.
1277 */
1278 rtr = makeNode(RangeTblRef);
1279 rtr->rtindex = rtindex;
1280
1281 /*
1282 * Build a list of Vars representing the subselect outputs.
1283 */
1284 subquery_vars = generate_subquery_vars(root,
1285 subselect->targetList,
1286 rtindex);
1287
1288 /*
1289 * Build the new join's qual expression, replacing Params with these Vars.
1290 */
1291 quals = convert_testexpr(root, sublink->testexpr, subquery_vars);
1292
1293 /*
1294 * And finally, build the JoinExpr node.
1295 */
1296 result = makeNode(JoinExpr);
1297 result->jointype = JOIN_SEMI;
1298 result->isNatural = false;
1299 result->larg = NULL; /* caller must fill this in */
1300 result->rarg = (Node *) rtr;
1301 result->usingClause = NIL;
1302 result->quals = quals;
1303 result->alias = NULL;
1304 result->rtindex = 0; /* we don't need an RTE for it */
1305
1306 return result;
1307}
1308
1309/*
1310 * convert_EXISTS_sublink_to_join: try to convert an EXISTS SubLink to a join
1311 *
1312 * The API of this function is identical to convert_ANY_sublink_to_join's,
1313 * except that we also support the case where the caller has found NOT EXISTS,
1314 * so we need an additional input parameter "under_not".
1315 */
1316JoinExpr *
1317convert_EXISTS_sublink_to_join(PlannerInfo *root, SubLink *sublink,
1318 bool under_not, Relids available_rels)
1319{
1320 JoinExpr *result;
1321 Query *parse = root->parse;
1322 Query *subselect = (Query *) sublink->subselect;
1323 Node *whereClause;
1324 int rtoffset;
1325 int varno;
1326 Relids clause_varnos;
1327 Relids upper_varnos;
1328
1329 Assert(sublink->subLinkType == EXISTS_SUBLINK);
1330
1331 /*
1332 * Can't flatten if it contains WITH. (We could arrange to pull up the
1333 * WITH into the parent query's cteList, but that risks changing the
1334 * semantics, since a WITH ought to be executed once per associated query
1335 * call.) Note that convert_ANY_sublink_to_join doesn't have to reject
1336 * this case, since it just produces a subquery RTE that doesn't have to
1337 * get flattened into the parent query.
1338 */
1339 if (subselect->cteList)
1340 return NULL;
1341
1342 /*
1343 * Copy the subquery so we can modify it safely (see comments in
1344 * make_subplan).
1345 */
1346 subselect = copyObject(subselect);
1347
1348 /*
1349 * See if the subquery can be simplified based on the knowledge that it's
1350 * being used in EXISTS(). If we aren't able to get rid of its
1351 * targetlist, we have to fail, because the pullup operation leaves us
1352 * with noplace to evaluate the targetlist.
1353 */
1354 if (!simplify_EXISTS_query(root, subselect))
1355 return NULL;
1356
1357 /*
1358 * Separate out the WHERE clause. (We could theoretically also remove
1359 * top-level plain JOIN/ON clauses, but it's probably not worth the
1360 * trouble.)
1361 */
1362 whereClause = subselect->jointree->quals;
1363 subselect->jointree->quals = NULL;
1364
1365 /*
1366 * The rest of the sub-select must not refer to any Vars of the parent
1367 * query. (Vars of higher levels should be okay, though.)
1368 */
1369 if (contain_vars_of_level((Node *) subselect, 1))
1370 return NULL;
1371
1372 /*
1373 * On the other hand, the WHERE clause must contain some Vars of the
1374 * parent query, else it's not gonna be a join.
1375 */
1376 if (!contain_vars_of_level(whereClause, 1))
1377 return NULL;
1378
1379 /*
1380 * We don't risk optimizing if the WHERE clause is volatile, either.
1381 */
1382 if (contain_volatile_functions(whereClause))
1383 return NULL;
1384
1385 /*
1386 * The subquery must have a nonempty jointree, but we can make it so.
1387 */
1388 replace_empty_jointree(subselect);
1389
1390 /*
1391 * Prepare to pull up the sub-select into top range table.
1392 *
1393 * We rely here on the assumption that the outer query has no references
1394 * to the inner (necessarily true). Therefore this is a lot easier than
1395 * what pull_up_subqueries has to go through.
1396 *
1397 * In fact, it's even easier than what convert_ANY_sublink_to_join has to
1398 * do. The machinations of simplify_EXISTS_query ensured that there is
1399 * nothing interesting in the subquery except an rtable and jointree, and
1400 * even the jointree FromExpr no longer has quals. So we can just append
1401 * the rtable to our own and use the FromExpr in our jointree. But first,
1402 * adjust all level-zero varnos in the subquery to account for the rtable
1403 * merger.
1404 */
1405 rtoffset = list_length(parse->rtable);
1406 OffsetVarNodes((Node *) subselect, rtoffset, 0);
1407 OffsetVarNodes(whereClause, rtoffset, 0);
1408
1409 /*
1410 * Upper-level vars in subquery will now be one level closer to their
1411 * parent than before; in particular, anything that had been level 1
1412 * becomes level zero.
1413 */
1414 IncrementVarSublevelsUp((Node *) subselect, -1, 1);
1415 IncrementVarSublevelsUp(whereClause, -1, 1);
1416
1417 /*
1418 * Now that the WHERE clause is adjusted to match the parent query
1419 * environment, we can easily identify all the level-zero rels it uses.
1420 * The ones <= rtoffset belong to the upper query; the ones > rtoffset do
1421 * not.
1422 */
1423 clause_varnos = pull_varnos(whereClause);
1424 upper_varnos = NULL;
1425 while ((varno = bms_first_member(clause_varnos)) >= 0)
1426 {
1427 if (varno <= rtoffset)
1428 upper_varnos = bms_add_member(upper_varnos, varno);
1429 }
1430 bms_free(clause_varnos);
1431 Assert(!bms_is_empty(upper_varnos));
1432
1433 /*
1434 * Now that we've got the set of upper-level varnos, we can make the last
1435 * check: only available_rels can be referenced.
1436 */
1437 if (!bms_is_subset(upper_varnos, available_rels))
1438 return NULL;
1439
1440 /* Now we can attach the modified subquery rtable to the parent */
1441 parse->rtable = list_concat(parse->rtable, subselect->rtable);
1442
1443 /*
1444 * And finally, build the JoinExpr node.
1445 */
1446 result = makeNode(JoinExpr);
1447 result->jointype = under_not ? JOIN_ANTI : JOIN_SEMI;
1448 result->isNatural = false;
1449 result->larg = NULL; /* caller must fill this in */
1450 /* flatten out the FromExpr node if it's useless */
1451 if (list_length(subselect->jointree->fromlist) == 1)
1452 result->rarg = (Node *) linitial(subselect->jointree->fromlist);
1453 else
1454 result->rarg = (Node *) subselect->jointree;
1455 result->usingClause = NIL;
1456 result->quals = whereClause;
1457 result->alias = NULL;
1458 result->rtindex = 0; /* we don't need an RTE for it */
1459
1460 return result;
1461}
1462
1463/*
1464 * simplify_EXISTS_query: remove any useless stuff in an EXISTS's subquery
1465 *
1466 * The only thing that matters about an EXISTS query is whether it returns
1467 * zero or more than zero rows. Therefore, we can remove certain SQL features
1468 * that won't affect that. The only part that is really likely to matter in
1469 * typical usage is simplifying the targetlist: it's a common habit to write
1470 * "SELECT * FROM" even though there is no need to evaluate any columns.
1471 *
1472 * Note: by suppressing the targetlist we could cause an observable behavioral
1473 * change, namely that any errors that might occur in evaluating the tlist
1474 * won't occur, nor will other side-effects of volatile functions. This seems
1475 * unlikely to bother anyone in practice.
1476 *
1477 * Returns true if was able to discard the targetlist, else false.
1478 */
1479static bool
1480simplify_EXISTS_query(PlannerInfo *root, Query *query)
1481{
1482 /*
1483 * We don't try to simplify at all if the query uses set operations,
1484 * aggregates, grouping sets, SRFs, modifying CTEs, HAVING, OFFSET, or FOR
1485 * UPDATE/SHARE; none of these seem likely in normal usage and their
1486 * possible effects are complex. (Note: we could ignore an "OFFSET 0"
1487 * clause, but that traditionally is used as an optimization fence, so we
1488 * don't.)
1489 */
1490 if (query->commandType != CMD_SELECT ||
1491 query->setOperations ||
1492 query->hasAggs ||
1493 query->groupingSets ||
1494 query->hasWindowFuncs ||
1495 query->hasTargetSRFs ||
1496 query->hasModifyingCTE ||
1497 query->havingQual ||
1498 query->limitOffset ||
1499 query->rowMarks)
1500 return false;
1501
1502 /*
1503 * LIMIT with a constant positive (or NULL) value doesn't affect the
1504 * semantics of EXISTS, so let's ignore such clauses. This is worth doing
1505 * because people accustomed to certain other DBMSes may be in the habit
1506 * of writing EXISTS(SELECT ... LIMIT 1) as an optimization. If there's a
1507 * LIMIT with anything else as argument, though, we can't simplify.
1508 */
1509 if (query->limitCount)
1510 {
1511 /*
1512 * The LIMIT clause has not yet been through eval_const_expressions,
1513 * so we have to apply that here. It might seem like this is a waste
1514 * of cycles, since the only case plausibly worth worrying about is
1515 * "LIMIT 1" ... but what we'll actually see is "LIMIT int8(1::int4)",
1516 * so we have to fold constants or we're not going to recognize it.
1517 */
1518 Node *node = eval_const_expressions(root, query->limitCount);
1519 Const *limit;
1520
1521 /* Might as well update the query if we simplified the clause. */
1522 query->limitCount = node;
1523
1524 if (!IsA(node, Const))
1525 return false;
1526
1527 limit = (Const *) node;
1528 Assert(limit->consttype == INT8OID);
1529 if (!limit->constisnull && DatumGetInt64(limit->constvalue) <= 0)
1530 return false;
1531
1532 /* Whether or not the targetlist is safe, we can drop the LIMIT. */
1533 query->limitCount = NULL;
1534 }
1535
1536 /*
1537 * Otherwise, we can throw away the targetlist, as well as any GROUP,
1538 * WINDOW, DISTINCT, and ORDER BY clauses; none of those clauses will
1539 * change a nonzero-rows result to zero rows or vice versa. (Furthermore,
1540 * since our parsetree representation of these clauses depends on the
1541 * targetlist, we'd better throw them away if we drop the targetlist.)
1542 */
1543 query->targetList = NIL;
1544 query->groupClause = NIL;
1545 query->windowClause = NIL;
1546 query->distinctClause = NIL;
1547 query->sortClause = NIL;
1548 query->hasDistinctOn = false;
1549
1550 return true;
1551}
1552
1553/*
1554 * convert_EXISTS_to_ANY: try to convert EXISTS to a hashable ANY sublink
1555 *
1556 * The subselect is expected to be a fresh copy that we can munge up,
1557 * and to have been successfully passed through simplify_EXISTS_query.
1558 *
1559 * On success, the modified subselect is returned, and we store a suitable
1560 * upper-level test expression at *testexpr, plus a list of the subselect's
1561 * output Params at *paramIds. (The test expression is already Param-ified
1562 * and hence need not go through convert_testexpr, which is why we have to
1563 * deal with the Param IDs specially.)
1564 *
1565 * On failure, returns NULL.
1566 */
1567static Query *
1568convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect,
1569 Node **testexpr, List **paramIds)
1570{
1571 Node *whereClause;
1572 List *leftargs,
1573 *rightargs,
1574 *opids,
1575 *opcollations,
1576 *newWhere,
1577 *tlist,
1578 *testlist,
1579 *paramids;
1580 ListCell *lc,
1581 *rc,
1582 *oc,
1583 *cc;
1584 AttrNumber resno;
1585
1586 /*
1587 * Query must not require a targetlist, since we have to insert a new one.
1588 * Caller should have dealt with the case already.
1589 */
1590 Assert(subselect->targetList == NIL);
1591
1592 /*
1593 * Separate out the WHERE clause. (We could theoretically also remove
1594 * top-level plain JOIN/ON clauses, but it's probably not worth the
1595 * trouble.)
1596 */
1597 whereClause = subselect->jointree->quals;
1598 subselect->jointree->quals = NULL;
1599
1600 /*
1601 * The rest of the sub-select must not refer to any Vars of the parent
1602 * query. (Vars of higher levels should be okay, though.)
1603 *
1604 * Note: we need not check for Aggrefs separately because we know the
1605 * sub-select is as yet unoptimized; any uplevel Aggref must therefore
1606 * contain an uplevel Var reference. This is not the case below ...
1607 */
1608 if (contain_vars_of_level((Node *) subselect, 1))
1609 return NULL;
1610
1611 /*
1612 * We don't risk optimizing if the WHERE clause is volatile, either.
1613 */
1614 if (contain_volatile_functions(whereClause))
1615 return NULL;
1616
1617 /*
1618 * Clean up the WHERE clause by doing const-simplification etc on it.
1619 * Aside from simplifying the processing we're about to do, this is
1620 * important for being able to pull chunks of the WHERE clause up into the
1621 * parent query. Since we are invoked partway through the parent's
1622 * preprocess_expression() work, earlier steps of preprocess_expression()
1623 * wouldn't get applied to the pulled-up stuff unless we do them here. For
1624 * the parts of the WHERE clause that get put back into the child query,
1625 * this work is partially duplicative, but it shouldn't hurt.
1626 *
1627 * Note: we do not run flatten_join_alias_vars. This is OK because any
1628 * parent aliases were flattened already, and we're not going to pull any
1629 * child Vars (of any description) into the parent.
1630 *
1631 * Note: passing the parent's root to eval_const_expressions is
1632 * technically wrong, but we can get away with it since only the
1633 * boundParams (if any) are used, and those would be the same in a
1634 * subroot.
1635 */
1636 whereClause = eval_const_expressions(root, whereClause);
1637 whereClause = (Node *) canonicalize_qual((Expr *) whereClause, false);
1638 whereClause = (Node *) make_ands_implicit((Expr *) whereClause);
1639
1640 /*
1641 * We now have a flattened implicit-AND list of clauses, which we try to
1642 * break apart into "outervar = innervar" hash clauses. Anything that
1643 * can't be broken apart just goes back into the newWhere list. Note that
1644 * we aren't trying hard yet to ensure that we have only outer or only
1645 * inner on each side; we'll check that if we get to the end.
1646 */
1647 leftargs = rightargs = opids = opcollations = newWhere = NIL;
1648 foreach(lc, (List *) whereClause)
1649 {
1650 OpExpr *expr = (OpExpr *) lfirst(lc);
1651
1652 if (IsA(expr, OpExpr) &&
1653 hash_ok_operator(expr))
1654 {
1655 Node *leftarg = (Node *) linitial(expr->args);
1656 Node *rightarg = (Node *) lsecond(expr->args);
1657
1658 if (contain_vars_of_level(leftarg, 1))
1659 {
1660 leftargs = lappend(leftargs, leftarg);
1661 rightargs = lappend(rightargs, rightarg);
1662 opids = lappend_oid(opids, expr->opno);
1663 opcollations = lappend_oid(opcollations, expr->inputcollid);
1664 continue;
1665 }
1666 if (contain_vars_of_level(rightarg, 1))
1667 {
1668 /*
1669 * We must commute the clause to put the outer var on the
1670 * left, because the hashing code in nodeSubplan.c expects
1671 * that. This probably shouldn't ever fail, since hashable
1672 * operators ought to have commutators, but be paranoid.
1673 */
1674 expr->opno = get_commutator(expr->opno);
1675 if (OidIsValid(expr->opno) && hash_ok_operator(expr))
1676 {
1677 leftargs = lappend(leftargs, rightarg);
1678 rightargs = lappend(rightargs, leftarg);
1679 opids = lappend_oid(opids, expr->opno);
1680 opcollations = lappend_oid(opcollations, expr->inputcollid);
1681 continue;
1682 }
1683 /* If no commutator, no chance to optimize the WHERE clause */
1684 return NULL;
1685 }
1686 }
1687 /* Couldn't handle it as a hash clause */
1688 newWhere = lappend(newWhere, expr);
1689 }
1690
1691 /*
1692 * If we didn't find anything we could convert, fail.
1693 */
1694 if (leftargs == NIL)
1695 return NULL;
1696
1697 /*
1698 * There mustn't be any parent Vars or Aggs in the stuff that we intend to
1699 * put back into the child query. Note: you might think we don't need to
1700 * check for Aggs separately, because an uplevel Agg must contain an
1701 * uplevel Var in its argument. But it is possible that the uplevel Var
1702 * got optimized away by eval_const_expressions. Consider
1703 *
1704 * SUM(CASE WHEN false THEN uplevelvar ELSE 0 END)
1705 */
1706 if (contain_vars_of_level((Node *) newWhere, 1) ||
1707 contain_vars_of_level((Node *) rightargs, 1))
1708 return NULL;
1709 if (root->parse->hasAggs &&
1710 (contain_aggs_of_level((Node *) newWhere, 1) ||
1711 contain_aggs_of_level((Node *) rightargs, 1)))
1712 return NULL;
1713
1714 /*
1715 * And there can't be any child Vars in the stuff we intend to pull up.
1716 * (Note: we'd need to check for child Aggs too, except we know the child
1717 * has no aggs at all because of simplify_EXISTS_query's check. The same
1718 * goes for window functions.)
1719 */
1720 if (contain_vars_of_level((Node *) leftargs, 0))
1721 return NULL;
1722
1723 /*
1724 * Also reject sublinks in the stuff we intend to pull up. (It might be
1725 * possible to support this, but doesn't seem worth the complication.)
1726 */
1727 if (contain_subplans((Node *) leftargs))
1728 return NULL;
1729
1730 /*
1731 * Okay, adjust the sublevelsup in the stuff we're pulling up.
1732 */
1733 IncrementVarSublevelsUp((Node *) leftargs, -1, 1);
1734
1735 /*
1736 * Put back any child-level-only WHERE clauses.
1737 */
1738 if (newWhere)
1739 subselect->jointree->quals = (Node *) make_ands_explicit(newWhere);
1740
1741 /*
1742 * Build a new targetlist for the child that emits the expressions we
1743 * need. Concurrently, build a testexpr for the parent using Params to
1744 * reference the child outputs. (Since we generate Params directly here,
1745 * there will be no need to convert the testexpr in build_subplan.)
1746 */
1747 tlist = testlist = paramids = NIL;
1748 resno = 1;
1749 forfour(lc, leftargs, rc, rightargs, oc, opids, cc, opcollations)
1750 {
1751 Node *leftarg = (Node *) lfirst(lc);
1752 Node *rightarg = (Node *) lfirst(rc);
1753 Oid opid = lfirst_oid(oc);
1754 Oid opcollation = lfirst_oid(cc);
1755 Param *param;
1756
1757 param = generate_new_exec_param(root,
1758 exprType(rightarg),
1759 exprTypmod(rightarg),
1760 exprCollation(rightarg));
1761 tlist = lappend(tlist,
1762 makeTargetEntry((Expr *) rightarg,
1763 resno++,
1764 NULL,
1765 false));
1766 testlist = lappend(testlist,
1767 make_opclause(opid, BOOLOID, false,
1768 (Expr *) leftarg, (Expr *) param,
1769 InvalidOid, opcollation));
1770 paramids = lappend_int(paramids, param->paramid);
1771 }
1772
1773 /* Put everything where it should go, and we're done */
1774 subselect->targetList = tlist;
1775 *testexpr = (Node *) make_ands_explicit(testlist);
1776 *paramIds = paramids;
1777
1778 return subselect;
1779}
1780
1781
1782/*
1783 * Replace correlation vars (uplevel vars) with Params.
1784 *
1785 * Uplevel PlaceHolderVars and aggregates are replaced, too.
1786 *
1787 * Note: it is critical that this runs immediately after SS_process_sublinks.
1788 * Since we do not recurse into the arguments of uplevel PHVs and aggregates,
1789 * they will get copied to the appropriate subplan args list in the parent
1790 * query with uplevel vars not replaced by Params, but only adjusted in level
1791 * (see replace_outer_placeholdervar and replace_outer_agg). That's exactly
1792 * what we want for the vars of the parent level --- but if a PHV's or
1793 * aggregate's argument contains any further-up variables, they have to be
1794 * replaced with Params in their turn. That will happen when the parent level
1795 * runs SS_replace_correlation_vars. Therefore it must do so after expanding
1796 * its sublinks to subplans. And we don't want any steps in between, else
1797 * those steps would never get applied to the argument expressions, either in
1798 * the parent or the child level.
1799 *
1800 * Another fairly tricky thing going on here is the handling of SubLinks in
1801 * the arguments of uplevel PHVs/aggregates. Those are not touched inside the
1802 * intermediate query level, either. Instead, SS_process_sublinks recurses on
1803 * them after copying the PHV or Aggref expression into the parent plan level
1804 * (this is actually taken care of in build_subplan).
1805 */
1806Node *
1807SS_replace_correlation_vars(PlannerInfo *root, Node *expr)
1808{
1809 /* No setup needed for tree walk, so away we go */
1810 return replace_correlation_vars_mutator(expr, root);
1811}
1812
1813static Node *
1814replace_correlation_vars_mutator(Node *node, PlannerInfo *root)
1815{
1816 if (node == NULL)
1817 return NULL;
1818 if (IsA(node, Var))
1819 {
1820 if (((Var *) node)->varlevelsup > 0)
1821 return (Node *) replace_outer_var(root, (Var *) node);
1822 }
1823 if (IsA(node, PlaceHolderVar))
1824 {
1825 if (((PlaceHolderVar *) node)->phlevelsup > 0)
1826 return (Node *) replace_outer_placeholdervar(root,
1827 (PlaceHolderVar *) node);
1828 }
1829 if (IsA(node, Aggref))
1830 {
1831 if (((Aggref *) node)->agglevelsup > 0)
1832 return (Node *) replace_outer_agg(root, (Aggref *) node);
1833 }
1834 if (IsA(node, GroupingFunc))
1835 {
1836 if (((GroupingFunc *) node)->agglevelsup > 0)
1837 return (Node *) replace_outer_grouping(root, (GroupingFunc *) node);
1838 }
1839 return expression_tree_mutator(node,
1840 replace_correlation_vars_mutator,
1841 (void *) root);
1842}
1843
1844/*
1845 * Expand SubLinks to SubPlans in the given expression.
1846 *
1847 * The isQual argument tells whether or not this expression is a WHERE/HAVING
1848 * qualifier expression. If it is, any sublinks appearing at top level need
1849 * not distinguish FALSE from UNKNOWN return values.
1850 */
1851Node *
1852SS_process_sublinks(PlannerInfo *root, Node *expr, bool isQual)
1853{
1854 process_sublinks_context context;
1855
1856 context.root = root;
1857 context.isTopQual = isQual;
1858 return process_sublinks_mutator(expr, &context);
1859}
1860
1861static Node *
1862process_sublinks_mutator(Node *node, process_sublinks_context *context)
1863{
1864 process_sublinks_context locContext;
1865
1866 locContext.root = context->root;
1867
1868 if (node == NULL)
1869 return NULL;
1870 if (IsA(node, SubLink))
1871 {
1872 SubLink *sublink = (SubLink *) node;
1873 Node *testexpr;
1874
1875 /*
1876 * First, recursively process the lefthand-side expressions, if any.
1877 * They're not top-level anymore.
1878 */
1879 locContext.isTopQual = false;
1880 testexpr = process_sublinks_mutator(sublink->testexpr, &locContext);
1881
1882 /*
1883 * Now build the SubPlan node and make the expr to return.
1884 */
1885 return make_subplan(context->root,
1886 (Query *) sublink->subselect,
1887 sublink->subLinkType,
1888 sublink->subLinkId,
1889 testexpr,
1890 context->isTopQual);
1891 }
1892
1893 /*
1894 * Don't recurse into the arguments of an outer PHV or aggregate here. Any
1895 * SubLinks in the arguments have to be dealt with at the outer query
1896 * level; they'll be handled when build_subplan collects the PHV or Aggref
1897 * into the arguments to be passed down to the current subplan.
1898 */
1899 if (IsA(node, PlaceHolderVar))
1900 {
1901 if (((PlaceHolderVar *) node)->phlevelsup > 0)
1902 return node;
1903 }
1904 else if (IsA(node, Aggref))
1905 {
1906 if (((Aggref *) node)->agglevelsup > 0)
1907 return node;
1908 }
1909
1910 /*
1911 * We should never see a SubPlan expression in the input (since this is
1912 * the very routine that creates 'em to begin with). We shouldn't find
1913 * ourselves invoked directly on a Query, either.
1914 */
1915 Assert(!IsA(node, SubPlan));
1916 Assert(!IsA(node, AlternativeSubPlan));
1917 Assert(!IsA(node, Query));
1918
1919 /*
1920 * Because make_subplan() could return an AND or OR clause, we have to
1921 * take steps to preserve AND/OR flatness of a qual. We assume the input
1922 * has been AND/OR flattened and so we need no recursion here.
1923 *
1924 * (Due to the coding here, we will not get called on the List subnodes of
1925 * an AND; and the input is *not* yet in implicit-AND format. So no check
1926 * is needed for a bare List.)
1927 *
1928 * Anywhere within the top-level AND/OR clause structure, we can tell
1929 * make_subplan() that NULL and FALSE are interchangeable. So isTopQual
1930 * propagates down in both cases. (Note that this is unlike the meaning
1931 * of "top level qual" used in most other places in Postgres.)
1932 */
1933 if (is_andclause(node))
1934 {
1935 List *newargs = NIL;
1936 ListCell *l;
1937
1938 /* Still at qual top-level */
1939 locContext.isTopQual = context->isTopQual;
1940
1941 foreach(l, ((BoolExpr *) node)->args)
1942 {
1943 Node *newarg;
1944
1945 newarg = process_sublinks_mutator(lfirst(l), &locContext);
1946 if (is_andclause(newarg))
1947 newargs = list_concat(newargs, ((BoolExpr *) newarg)->args);
1948 else
1949 newargs = lappend(newargs, newarg);
1950 }
1951 return (Node *) make_andclause(newargs);
1952 }
1953
1954 if (is_orclause(node))
1955 {
1956 List *newargs = NIL;
1957 ListCell *l;
1958
1959 /* Still at qual top-level */
1960 locContext.isTopQual = context->isTopQual;
1961
1962 foreach(l, ((BoolExpr *) node)->args)
1963 {
1964 Node *newarg;
1965
1966 newarg = process_sublinks_mutator(lfirst(l), &locContext);
1967 if (is_orclause(newarg))
1968 newargs = list_concat(newargs, ((BoolExpr *) newarg)->args);
1969 else
1970 newargs = lappend(newargs, newarg);
1971 }
1972 return (Node *) make_orclause(newargs);
1973 }
1974
1975 /*
1976 * If we recurse down through anything other than an AND or OR node, we
1977 * are definitely not at top qual level anymore.
1978 */
1979 locContext.isTopQual = false;
1980
1981 return expression_tree_mutator(node,
1982 process_sublinks_mutator,
1983 (void *) &locContext);
1984}
1985
1986/*
1987 * SS_identify_outer_params - identify the Params available from outer levels
1988 *
1989 * This must be run after SS_replace_correlation_vars and SS_process_sublinks
1990 * processing is complete in a given query level as well as all of its
1991 * descendant levels (which means it's most practical to do it at the end of
1992 * processing the query level). We compute the set of paramIds that outer
1993 * levels will make available to this level+descendants, and record it in
1994 * root->outer_params for use while computing extParam/allParam sets in final
1995 * plan cleanup. (We can't just compute it then, because the upper levels'
1996 * plan_params lists are transient and will be gone by then.)
1997 */
1998void
1999SS_identify_outer_params(PlannerInfo *root)
2000{
2001 Bitmapset *outer_params;
2002 PlannerInfo *proot;
2003 ListCell *l;
2004
2005 /*
2006 * If no parameters have been assigned anywhere in the tree, we certainly
2007 * don't need to do anything here.
2008 */
2009 if (root->glob->paramExecTypes == NIL)
2010 return;
2011
2012 /*
2013 * Scan all query levels above this one to see which parameters are due to
2014 * be available from them, either because lower query levels have
2015 * requested them (via plan_params) or because they will be available from
2016 * initPlans of those levels.
2017 */
2018 outer_params = NULL;
2019 for (proot = root->parent_root; proot != NULL; proot = proot->parent_root)
2020 {
2021 /* Include ordinary Var/PHV/Aggref params */
2022 foreach(l, proot->plan_params)
2023 {
2024 PlannerParamItem *pitem = (PlannerParamItem *) lfirst(l);
2025
2026 outer_params = bms_add_member(outer_params, pitem->paramId);
2027 }
2028 /* Include any outputs of outer-level initPlans */
2029 foreach(l, proot->init_plans)
2030 {
2031 SubPlan *initsubplan = (SubPlan *) lfirst(l);
2032 ListCell *l2;
2033
2034 foreach(l2, initsubplan->setParam)
2035 {
2036 outer_params = bms_add_member(outer_params, lfirst_int(l2));
2037 }
2038 }
2039 /* Include worktable ID, if a recursive query is being planned */
2040 if (proot->wt_param_id >= 0)
2041 outer_params = bms_add_member(outer_params, proot->wt_param_id);
2042 }
2043 root->outer_params = outer_params;
2044}
2045
2046/*
2047 * SS_charge_for_initplans - account for initplans in Path costs & parallelism
2048 *
2049 * If any initPlans have been created in the current query level, they will
2050 * get attached to the Plan tree created from whichever Path we select from
2051 * the given rel. Increment all that rel's Paths' costs to account for them,
2052 * and make sure the paths get marked as parallel-unsafe, since we can't
2053 * currently transmit initPlans to parallel workers.
2054 *
2055 * This is separate from SS_attach_initplans because we might conditionally
2056 * create more initPlans during create_plan(), depending on which Path we
2057 * select. However, Paths that would generate such initPlans are expected
2058 * to have included their cost already.
2059 */
2060void
2061SS_charge_for_initplans(PlannerInfo *root, RelOptInfo *final_rel)
2062{
2063 Cost initplan_cost;
2064 ListCell *lc;
2065
2066 /* Nothing to do if no initPlans */
2067 if (root->init_plans == NIL)
2068 return;
2069
2070 /*
2071 * Compute the cost increment just once, since it will be the same for all
2072 * Paths. We assume each initPlan gets run once during top plan startup.
2073 * This is a conservative overestimate, since in fact an initPlan might be
2074 * executed later than plan startup, or even not at all.
2075 */
2076 initplan_cost = 0;
2077 foreach(lc, root->init_plans)
2078 {
2079 SubPlan *initsubplan = (SubPlan *) lfirst(lc);
2080
2081 initplan_cost += initsubplan->startup_cost + initsubplan->per_call_cost;
2082 }
2083
2084 /*
2085 * Now adjust the costs and parallel_safe flags.
2086 */
2087 foreach(lc, final_rel->pathlist)
2088 {
2089 Path *path = (Path *) lfirst(lc);
2090
2091 path->startup_cost += initplan_cost;
2092 path->total_cost += initplan_cost;
2093 path->parallel_safe = false;
2094 }
2095
2096 /*
2097 * Forget about any partial paths and clear consider_parallel, too;
2098 * they're not usable if we attached an initPlan.
2099 */
2100 final_rel->partial_pathlist = NIL;
2101 final_rel->consider_parallel = false;
2102
2103 /* We needn't do set_cheapest() here, caller will do it */
2104}
2105
2106/*
2107 * SS_attach_initplans - attach initplans to topmost plan node
2108 *
2109 * Attach any initplans created in the current query level to the specified
2110 * plan node, which should normally be the topmost node for the query level.
2111 * (In principle the initPlans could go in any node at or above where they're
2112 * referenced; but there seems no reason to put them any lower than the
2113 * topmost node, so we don't bother to track exactly where they came from.)
2114 * We do not touch the plan node's cost; the initplans should have been
2115 * accounted for in path costing.
2116 */
2117void
2118SS_attach_initplans(PlannerInfo *root, Plan *plan)
2119{
2120 plan->initPlan = root->init_plans;
2121}
2122
2123/*
2124 * SS_finalize_plan - do final parameter processing for a completed Plan.
2125 *
2126 * This recursively computes the extParam and allParam sets for every Plan
2127 * node in the given plan tree. (Oh, and RangeTblFunction.funcparams too.)
2128 *
2129 * We assume that SS_finalize_plan has already been run on any initplans or
2130 * subplans the plan tree could reference.
2131 */
2132void
2133SS_finalize_plan(PlannerInfo *root, Plan *plan)
2134{
2135 /* No setup needed, just recurse through plan tree. */
2136 (void) finalize_plan(root, plan, -1, root->outer_params, NULL);
2137}
2138
2139/*
2140 * Recursive processing of all nodes in the plan tree
2141 *
2142 * gather_param is the rescan_param of an ancestral Gather/GatherMerge,
2143 * or -1 if there is none.
2144 *
2145 * valid_params is the set of param IDs supplied by outer plan levels
2146 * that are valid to reference in this plan node or its children.
2147 *
2148 * scan_params is a set of param IDs to force scan plan nodes to reference.
2149 * This is for EvalPlanQual support, and is always NULL at the top of the
2150 * recursion.
2151 *
2152 * The return value is the computed allParam set for the given Plan node.
2153 * This is just an internal notational convenience: we can add a child
2154 * plan's allParams to the set of param IDs of interest to this level
2155 * in the same statement that recurses to that child.
2156 *
2157 * Do not scribble on caller's values of valid_params or scan_params!
2158 *
2159 * Note: although we attempt to deal with initPlans anywhere in the tree, the
2160 * logic is not really right. The problem is that a plan node might return an
2161 * output Param of its initPlan as a targetlist item, in which case it's valid
2162 * for the parent plan level to reference that same Param; the parent's usage
2163 * will be converted into a Var referencing the child plan node by setrefs.c.
2164 * But this function would see the parent's reference as out of scope and
2165 * complain about it. For now, this does not matter because the planner only
2166 * attaches initPlans to the topmost plan node in a query level, so the case
2167 * doesn't arise. If we ever merge this processing into setrefs.c, maybe it
2168 * can be handled more cleanly.
2169 */
2170static Bitmapset *
2171finalize_plan(PlannerInfo *root, Plan *plan,
2172 int gather_param,
2173 Bitmapset *valid_params,
2174 Bitmapset *scan_params)
2175{
2176 finalize_primnode_context context;
2177 int locally_added_param;
2178 Bitmapset *nestloop_params;
2179 Bitmapset *initExtParam;
2180 Bitmapset *initSetParam;
2181 Bitmapset *child_params;
2182 ListCell *l;
2183
2184 if (plan == NULL)
2185 return NULL;
2186
2187 context.root = root;
2188 context.paramids = NULL; /* initialize set to empty */
2189 locally_added_param = -1; /* there isn't one */
2190 nestloop_params = NULL; /* there aren't any */
2191
2192 /*
2193 * Examine any initPlans to determine the set of external params they
2194 * reference and the set of output params they supply. (We assume
2195 * SS_finalize_plan was run on them already.)
2196 */
2197 initExtParam = initSetParam = NULL;
2198 foreach(l, plan->initPlan)
2199 {
2200 SubPlan *initsubplan = (SubPlan *) lfirst(l);
2201 Plan *initplan = planner_subplan_get_plan(root, initsubplan);
2202 ListCell *l2;
2203
2204 initExtParam = bms_add_members(initExtParam, initplan->extParam);
2205 foreach(l2, initsubplan->setParam)
2206 {
2207 initSetParam = bms_add_member(initSetParam, lfirst_int(l2));
2208 }
2209 }
2210
2211 /* Any setParams are validly referenceable in this node and children */
2212 if (initSetParam)
2213 valid_params = bms_union(valid_params, initSetParam);
2214
2215 /*
2216 * When we call finalize_primnode, context.paramids sets are automatically
2217 * merged together. But when recursing to self, we have to do it the hard
2218 * way. We want the paramids set to include params in subplans as well as
2219 * at this level.
2220 */
2221
2222 /* Find params in targetlist and qual */
2223 finalize_primnode((Node *) plan->targetlist, &context);
2224 finalize_primnode((Node *) plan->qual, &context);
2225
2226 /*
2227 * If it's a parallel-aware scan node, mark it as dependent on the parent
2228 * Gather/GatherMerge's rescan Param.
2229 */
2230 if (plan->parallel_aware)
2231 {
2232 if (gather_param < 0)
2233 elog(ERROR, "parallel-aware plan node is not below a Gather");
2234 context.paramids =
2235 bms_add_member(context.paramids, gather_param);
2236 }
2237
2238 /* Check additional node-type-specific fields */
2239 switch (nodeTag(plan))
2240 {
2241 case T_Result:
2242 finalize_primnode(((Result *) plan)->resconstantqual,
2243 &context);
2244 break;
2245
2246 case T_SeqScan:
2247 context.paramids = bms_add_members(context.paramids, scan_params);
2248 break;
2249
2250 case T_SampleScan:
2251 finalize_primnode((Node *) ((SampleScan *) plan)->tablesample,
2252 &context);
2253 context.paramids = bms_add_members(context.paramids, scan_params);
2254 break;
2255
2256 case T_IndexScan:
2257 finalize_primnode((Node *) ((IndexScan *) plan)->indexqual,
2258 &context);
2259 finalize_primnode((Node *) ((IndexScan *) plan)->indexorderby,
2260 &context);
2261
2262 /*
2263 * we need not look at indexqualorig, since it will have the same
2264 * param references as indexqual. Likewise, we can ignore
2265 * indexorderbyorig.
2266 */
2267 context.paramids = bms_add_members(context.paramids, scan_params);
2268 break;
2269
2270 case T_IndexOnlyScan:
2271 finalize_primnode((Node *) ((IndexOnlyScan *) plan)->indexqual,
2272 &context);
2273 finalize_primnode((Node *) ((IndexOnlyScan *) plan)->indexorderby,
2274 &context);
2275
2276 /*
2277 * we need not look at indextlist, since it cannot contain Params.
2278 */
2279 context.paramids = bms_add_members(context.paramids, scan_params);
2280 break;
2281
2282 case T_BitmapIndexScan:
2283 finalize_primnode((Node *) ((BitmapIndexScan *) plan)->indexqual,
2284 &context);
2285
2286 /*
2287 * we need not look at indexqualorig, since it will have the same
2288 * param references as indexqual.
2289 */
2290 break;
2291
2292 case T_BitmapHeapScan:
2293 finalize_primnode((Node *) ((BitmapHeapScan *) plan)->bitmapqualorig,
2294 &context);
2295 context.paramids = bms_add_members(context.paramids, scan_params);
2296 break;
2297
2298 case T_TidScan:
2299 finalize_primnode((Node *) ((TidScan *) plan)->tidquals,
2300 &context);
2301 context.paramids = bms_add_members(context.paramids, scan_params);
2302 break;
2303
2304 case T_SubqueryScan:
2305 {
2306 SubqueryScan *sscan = (SubqueryScan *) plan;
2307 RelOptInfo *rel;
2308 Bitmapset *subquery_params;
2309
2310 /* We must run finalize_plan on the subquery */
2311 rel = find_base_rel(root, sscan->scan.scanrelid);
2312 subquery_params = rel->subroot->outer_params;
2313 if (gather_param >= 0)
2314 subquery_params = bms_add_member(bms_copy(subquery_params),
2315 gather_param);
2316 finalize_plan(rel->subroot, sscan->subplan, gather_param,
2317 subquery_params, NULL);
2318
2319 /* Now we can add its extParams to the parent's params */
2320 context.paramids = bms_add_members(context.paramids,
2321 sscan->subplan->extParam);
2322 /* We need scan_params too, though */
2323 context.paramids = bms_add_members(context.paramids,
2324 scan_params);
2325 }
2326 break;
2327
2328 case T_FunctionScan:
2329 {
2330 FunctionScan *fscan = (FunctionScan *) plan;
2331 ListCell *lc;
2332
2333 /*
2334 * Call finalize_primnode independently on each function
2335 * expression, so that we can record which params are
2336 * referenced in each, in order to decide which need
2337 * re-evaluating during rescan.
2338 */
2339 foreach(lc, fscan->functions)
2340 {
2341 RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
2342 finalize_primnode_context funccontext;
2343
2344 funccontext = context;
2345 funccontext.paramids = NULL;
2346
2347 finalize_primnode(rtfunc->funcexpr, &funccontext);
2348
2349 /* remember results for execution */
2350 rtfunc->funcparams = funccontext.paramids;
2351
2352 /* add the function's params to the overall set */
2353 context.paramids = bms_add_members(context.paramids,
2354 funccontext.paramids);
2355 }
2356
2357 context.paramids = bms_add_members(context.paramids,
2358 scan_params);
2359 }
2360 break;
2361
2362 case T_TableFuncScan:
2363 finalize_primnode((Node *) ((TableFuncScan *) plan)->tablefunc,
2364 &context);
2365 context.paramids = bms_add_members(context.paramids, scan_params);
2366 break;
2367
2368 case T_ValuesScan:
2369 finalize_primnode((Node *) ((ValuesScan *) plan)->values_lists,
2370 &context);
2371 context.paramids = bms_add_members(context.paramids, scan_params);
2372 break;
2373
2374 case T_CteScan:
2375 {
2376 /*
2377 * You might think we should add the node's cteParam to
2378 * paramids, but we shouldn't because that param is just a
2379 * linkage mechanism for multiple CteScan nodes for the same
2380 * CTE; it is never used for changed-param signaling. What we
2381 * have to do instead is to find the referenced CTE plan and
2382 * incorporate its external paramids, so that the correct
2383 * things will happen if the CTE references outer-level
2384 * variables. See test cases for bug #4902. (We assume
2385 * SS_finalize_plan was run on the CTE plan already.)
2386 */
2387 int plan_id = ((CteScan *) plan)->ctePlanId;
2388 Plan *cteplan;
2389
2390 /* so, do this ... */
2391 if (plan_id < 1 || plan_id > list_length(root->glob->subplans))
2392 elog(ERROR, "could not find plan for CteScan referencing plan ID %d",
2393 plan_id);
2394 cteplan = (Plan *) list_nth(root->glob->subplans, plan_id - 1);
2395 context.paramids =
2396 bms_add_members(context.paramids, cteplan->extParam);
2397
2398#ifdef NOT_USED
2399 /* ... but not this */
2400 context.paramids =
2401 bms_add_member(context.paramids,
2402 ((CteScan *) plan)->cteParam);
2403#endif
2404
2405 context.paramids = bms_add_members(context.paramids,
2406 scan_params);
2407 }
2408 break;
2409
2410 case T_WorkTableScan:
2411 context.paramids =
2412 bms_add_member(context.paramids,
2413 ((WorkTableScan *) plan)->wtParam);
2414 context.paramids = bms_add_members(context.paramids, scan_params);
2415 break;
2416
2417 case T_NamedTuplestoreScan:
2418 context.paramids = bms_add_members(context.paramids, scan_params);
2419 break;
2420
2421 case T_ForeignScan:
2422 {
2423 ForeignScan *fscan = (ForeignScan *) plan;
2424
2425 finalize_primnode((Node *) fscan->fdw_exprs,
2426 &context);
2427 finalize_primnode((Node *) fscan->fdw_recheck_quals,
2428 &context);
2429
2430 /* We assume fdw_scan_tlist cannot contain Params */
2431 context.paramids = bms_add_members(context.paramids,
2432 scan_params);
2433 }
2434 break;
2435
2436 case T_CustomScan:
2437 {
2438 CustomScan *cscan = (CustomScan *) plan;
2439 ListCell *lc;
2440
2441 finalize_primnode((Node *) cscan->custom_exprs,
2442 &context);
2443 /* We assume custom_scan_tlist cannot contain Params */
2444 context.paramids =
2445 bms_add_members(context.paramids, scan_params);
2446
2447 /* child nodes if any */
2448 foreach(lc, cscan->custom_plans)
2449 {
2450 context.paramids =
2451 bms_add_members(context.paramids,
2452 finalize_plan(root,
2453 (Plan *) lfirst(lc),
2454 gather_param,
2455 valid_params,
2456 scan_params));
2457 }
2458 }
2459 break;
2460
2461 case T_ModifyTable:
2462 {
2463 ModifyTable *mtplan = (ModifyTable *) plan;
2464 ListCell *l;
2465
2466 /* Force descendant scan nodes to reference epqParam */
2467 locally_added_param = mtplan->epqParam;
2468 valid_params = bms_add_member(bms_copy(valid_params),
2469 locally_added_param);
2470 scan_params = bms_add_member(bms_copy(scan_params),
2471 locally_added_param);
2472 finalize_primnode((Node *) mtplan->returningLists,
2473 &context);
2474 finalize_primnode((Node *) mtplan->onConflictSet,
2475 &context);
2476 finalize_primnode((Node *) mtplan->onConflictWhere,
2477 &context);
2478 /* exclRelTlist contains only Vars, doesn't need examination */
2479 foreach(l, mtplan->plans)
2480 {
2481 context.paramids =
2482 bms_add_members(context.paramids,
2483 finalize_plan(root,
2484 (Plan *) lfirst(l),
2485 gather_param,
2486 valid_params,
2487 scan_params));
2488 }
2489 }
2490 break;
2491
2492 case T_Append:
2493 {
2494 ListCell *l;
2495
2496 foreach(l, ((Append *) plan)->appendplans)
2497 {
2498 context.paramids =
2499 bms_add_members(context.paramids,
2500 finalize_plan(root,
2501 (Plan *) lfirst(l),
2502 gather_param,
2503 valid_params,
2504 scan_params));
2505 }
2506 }
2507 break;
2508
2509 case T_MergeAppend:
2510 {
2511 ListCell *l;
2512
2513 foreach(l, ((MergeAppend *) plan)->mergeplans)
2514 {
2515 context.paramids =
2516 bms_add_members(context.paramids,
2517 finalize_plan(root,
2518 (Plan *) lfirst(l),
2519 gather_param,
2520 valid_params,
2521 scan_params));
2522 }
2523 }
2524 break;
2525
2526 case T_BitmapAnd:
2527 {
2528 ListCell *l;
2529
2530 foreach(l, ((BitmapAnd *) plan)->bitmapplans)
2531 {
2532 context.paramids =
2533 bms_add_members(context.paramids,
2534 finalize_plan(root,
2535 (Plan *) lfirst(l),
2536 gather_param,
2537 valid_params,
2538 scan_params));
2539 }
2540 }
2541 break;
2542
2543 case T_BitmapOr:
2544 {
2545 ListCell *l;
2546
2547 foreach(l, ((BitmapOr *) plan)->bitmapplans)
2548 {
2549 context.paramids =
2550 bms_add_members(context.paramids,
2551 finalize_plan(root,
2552 (Plan *) lfirst(l),
2553 gather_param,
2554 valid_params,
2555 scan_params));
2556 }
2557 }
2558 break;
2559
2560 case T_NestLoop:
2561 {
2562 ListCell *l;
2563
2564 finalize_primnode((Node *) ((Join *) plan)->joinqual,
2565 &context);
2566 /* collect set of params that will be passed to right child */
2567 foreach(l, ((NestLoop *) plan)->nestParams)
2568 {
2569 NestLoopParam *nlp = (NestLoopParam *) lfirst(l);
2570
2571 nestloop_params = bms_add_member(nestloop_params,
2572 nlp->paramno);
2573 }
2574 }
2575 break;
2576
2577 case T_MergeJoin:
2578 finalize_primnode((Node *) ((Join *) plan)->joinqual,
2579 &context);
2580 finalize_primnode((Node *) ((MergeJoin *) plan)->mergeclauses,
2581 &context);
2582 break;
2583
2584 case T_HashJoin:
2585 finalize_primnode((Node *) ((Join *) plan)->joinqual,
2586 &context);
2587 finalize_primnode((Node *) ((HashJoin *) plan)->hashclauses,
2588 &context);
2589 break;
2590
2591 case T_Limit:
2592 finalize_primnode(((Limit *) plan)->limitOffset,
2593 &context);
2594 finalize_primnode(((Limit *) plan)->limitCount,
2595 &context);
2596 break;
2597
2598 case T_RecursiveUnion:
2599 /* child nodes are allowed to reference wtParam */
2600 locally_added_param = ((RecursiveUnion *) plan)->wtParam;
2601 valid_params = bms_add_member(bms_copy(valid_params),
2602 locally_added_param);
2603 /* wtParam does *not* get added to scan_params */
2604 break;
2605
2606 case T_LockRows:
2607 /* Force descendant scan nodes to reference epqParam */
2608 locally_added_param = ((LockRows *) plan)->epqParam;
2609 valid_params = bms_add_member(bms_copy(valid_params),
2610 locally_added_param);
2611 scan_params = bms_add_member(bms_copy(scan_params),
2612 locally_added_param);
2613 break;
2614
2615 case T_Agg:
2616 {
2617 Agg *agg = (Agg *) plan;
2618
2619 /*
2620 * AGG_HASHED plans need to know which Params are referenced
2621 * in aggregate calls. Do a separate scan to identify them.
2622 */
2623 if (agg->aggstrategy == AGG_HASHED)
2624 {
2625 finalize_primnode_context aggcontext;
2626
2627 aggcontext.root = root;
2628 aggcontext.paramids = NULL;
2629 finalize_agg_primnode((Node *) agg->plan.targetlist,
2630 &aggcontext);
2631 finalize_agg_primnode((Node *) agg->plan.qual,
2632 &aggcontext);
2633 agg->aggParams = aggcontext.paramids;
2634 }
2635 }
2636 break;
2637
2638 case T_WindowAgg:
2639 finalize_primnode(((WindowAgg *) plan)->startOffset,
2640 &context);
2641 finalize_primnode(((WindowAgg *) plan)->endOffset,
2642 &context);
2643 break;
2644
2645 case T_Gather:
2646 /* child nodes are allowed to reference rescan_param, if any */
2647 locally_added_param = ((Gather *) plan)->rescan_param;
2648 if (locally_added_param >= 0)
2649 {
2650 valid_params = bms_add_member(bms_copy(valid_params),
2651 locally_added_param);
2652
2653 /*
2654 * We currently don't support nested Gathers. The issue so
2655 * far as this function is concerned would be how to identify
2656 * which child nodes depend on which Gather.
2657 */
2658 Assert(gather_param < 0);
2659 /* Pass down rescan_param to child parallel-aware nodes */
2660 gather_param = locally_added_param;
2661 }
2662 /* rescan_param does *not* get added to scan_params */
2663 break;
2664
2665 case T_GatherMerge:
2666 /* child nodes are allowed to reference rescan_param, if any */
2667 locally_added_param = ((GatherMerge *) plan)->rescan_param;
2668 if (locally_added_param >= 0)
2669 {
2670 valid_params = bms_add_member(bms_copy(valid_params),
2671 locally_added_param);
2672
2673 /*
2674 * We currently don't support nested Gathers. The issue so
2675 * far as this function is concerned would be how to identify
2676 * which child nodes depend on which Gather.
2677 */
2678 Assert(gather_param < 0);
2679 /* Pass down rescan_param to child parallel-aware nodes */
2680 gather_param = locally_added_param;
2681 }
2682 /* rescan_param does *not* get added to scan_params */
2683 break;
2684
2685 case T_ProjectSet:
2686 case T_Hash:
2687 case T_Material:
2688 case T_Sort:
2689 case T_Unique:
2690 case T_SetOp:
2691 case T_Group:
2692 /* no node-type-specific fields need fixing */
2693 break;
2694
2695 default:
2696 elog(ERROR, "unrecognized node type: %d",
2697 (int) nodeTag(plan));
2698 }
2699
2700 /* Process left and right child plans, if any */
2701 child_params = finalize_plan(root,
2702 plan->lefttree,
2703 gather_param,
2704 valid_params,
2705 scan_params);
2706 context.paramids = bms_add_members(context.paramids, child_params);
2707
2708 if (nestloop_params)
2709 {
2710 /* right child can reference nestloop_params as well as valid_params */
2711 child_params = finalize_plan(root,
2712 plan->righttree,
2713 gather_param,
2714 bms_union(nestloop_params, valid_params),
2715 scan_params);
2716 /* ... and they don't count as parameters used at my level */
2717 child_params = bms_difference(child_params, nestloop_params);
2718 bms_free(nestloop_params);
2719 }
2720 else
2721 {
2722 /* easy case */
2723 child_params = finalize_plan(root,
2724 plan->righttree,
2725 gather_param,
2726 valid_params,
2727 scan_params);
2728 }
2729 context.paramids = bms_add_members(context.paramids, child_params);
2730
2731 /*
2732 * Any locally generated parameter doesn't count towards its generating
2733 * plan node's external dependencies. (Note: if we changed valid_params
2734 * and/or scan_params, we leak those bitmapsets; not worth the notational
2735 * trouble to clean them up.)
2736 */
2737 if (locally_added_param >= 0)
2738 {
2739 context.paramids = bms_del_member(context.paramids,
2740 locally_added_param);
2741 }
2742
2743 /* Now we have all the paramids referenced in this node and children */
2744
2745 if (!bms_is_subset(context.paramids, valid_params))
2746 elog(ERROR, "plan should not reference subplan's variable");
2747
2748 /*
2749 * The plan node's allParam and extParam fields should include all its
2750 * referenced paramids, plus contributions from any child initPlans.
2751 * However, any setParams of the initPlans should not be present in the
2752 * parent node's extParams, only in its allParams. (It's possible that
2753 * some initPlans have extParams that are setParams of other initPlans.)
2754 */
2755
2756 /* allParam must include initplans' extParams and setParams */
2757 plan->allParam = bms_union(context.paramids, initExtParam);
2758 plan->allParam = bms_add_members(plan->allParam, initSetParam);
2759 /* extParam must include any initplan extParams */
2760 plan->extParam = bms_union(context.paramids, initExtParam);
2761 /* but not any initplan setParams */
2762 plan->extParam = bms_del_members(plan->extParam, initSetParam);
2763
2764 /*
2765 * For speed at execution time, make sure extParam/allParam are actually
2766 * NULL if they are empty sets.
2767 */
2768 if (bms_is_empty(plan->extParam))
2769 plan->extParam = NULL;
2770 if (bms_is_empty(plan->allParam))
2771 plan->allParam = NULL;
2772
2773 return plan->allParam;
2774}
2775
2776/*
2777 * finalize_primnode: add IDs of all PARAM_EXEC params appearing in the given
2778 * expression tree to the result set.
2779 */
2780static bool
2781finalize_primnode(Node *node, finalize_primnode_context *context)
2782{
2783 if (node == NULL)
2784 return false;
2785 if (IsA(node, Param))
2786 {
2787 if (((Param *) node)->paramkind == PARAM_EXEC)
2788 {
2789 int paramid = ((Param *) node)->paramid;
2790
2791 context->paramids = bms_add_member(context->paramids, paramid);
2792 }
2793 return false; /* no more to do here */
2794 }
2795 if (IsA(node, SubPlan))
2796 {
2797 SubPlan *subplan = (SubPlan *) node;
2798 Plan *plan = planner_subplan_get_plan(context->root, subplan);
2799 ListCell *lc;
2800 Bitmapset *subparamids;
2801
2802 /* Recurse into the testexpr, but not into the Plan */
2803 finalize_primnode(subplan->testexpr, context);
2804
2805 /*
2806 * Remove any param IDs of output parameters of the subplan that were
2807 * referenced in the testexpr. These are not interesting for
2808 * parameter change signaling since we always re-evaluate the subplan.
2809 * Note that this wouldn't work too well if there might be uses of the
2810 * same param IDs elsewhere in the plan, but that can't happen because
2811 * generate_new_exec_param never tries to merge params.
2812 */
2813 foreach(lc, subplan->paramIds)
2814 {
2815 context->paramids = bms_del_member(context->paramids,
2816 lfirst_int(lc));
2817 }
2818
2819 /* Also examine args list */
2820 finalize_primnode((Node *) subplan->args, context);
2821
2822 /*
2823 * Add params needed by the subplan to paramids, but excluding those
2824 * we will pass down to it. (We assume SS_finalize_plan was run on
2825 * the subplan already.)
2826 */
2827 subparamids = bms_copy(plan->extParam);
2828 foreach(lc, subplan->parParam)
2829 {
2830 subparamids = bms_del_member(subparamids, lfirst_int(lc));
2831 }
2832 context->paramids = bms_join(context->paramids, subparamids);
2833
2834 return false; /* no more to do here */
2835 }
2836 return expression_tree_walker(node, finalize_primnode,
2837 (void *) context);
2838}
2839
2840/*
2841 * finalize_agg_primnode: find all Aggref nodes in the given expression tree,
2842 * and add IDs of all PARAM_EXEC params appearing within their aggregated
2843 * arguments to the result set.
2844 */
2845static bool
2846finalize_agg_primnode(Node *node, finalize_primnode_context *context)
2847{
2848 if (node == NULL)
2849 return false;
2850 if (IsA(node, Aggref))
2851 {
2852 Aggref *agg = (Aggref *) node;
2853
2854 /* we should not consider the direct arguments, if any */
2855 finalize_primnode((Node *) agg->args, context);
2856 finalize_primnode((Node *) agg->aggfilter, context);
2857 return false; /* there can't be any Aggrefs below here */
2858 }
2859 return expression_tree_walker(node, finalize_agg_primnode,
2860 (void *) context);
2861}
2862
2863/*
2864 * SS_make_initplan_output_param - make a Param for an initPlan's output
2865 *
2866 * The plan is expected to return a scalar value of the given type/collation.
2867 *
2868 * Note that in some cases the initplan may not ever appear in the finished
2869 * plan tree. If that happens, we'll have wasted a PARAM_EXEC slot, which
2870 * is no big deal.
2871 */
2872Param *
2873SS_make_initplan_output_param(PlannerInfo *root,
2874 Oid resulttype, int32 resulttypmod,
2875 Oid resultcollation)
2876{
2877 return generate_new_exec_param(root, resulttype,
2878 resulttypmod, resultcollation);
2879}
2880
2881/*
2882 * SS_make_initplan_from_plan - given a plan tree, make it an InitPlan
2883 *
2884 * We build an EXPR_SUBLINK SubPlan node and put it into the initplan
2885 * list for the outer query level. A Param that represents the initplan's
2886 * output has already been assigned using SS_make_initplan_output_param.
2887 */
2888void
2889SS_make_initplan_from_plan(PlannerInfo *root,
2890 PlannerInfo *subroot, Plan *plan,
2891 Param *prm)
2892{
2893 SubPlan *node;
2894
2895 /*
2896 * Add the subplan and its PlannerInfo to the global lists.
2897 */
2898 root->glob->subplans = lappend(root->glob->subplans, plan);
2899 root->glob->subroots = lappend(root->glob->subroots, subroot);
2900
2901 /*
2902 * Create a SubPlan node and add it to the outer list of InitPlans. Note
2903 * it has to appear after any other InitPlans it might depend on (see
2904 * comments in ExecReScan).
2905 */
2906 node = makeNode(SubPlan);
2907 node->subLinkType = EXPR_SUBLINK;
2908 node->plan_id = list_length(root->glob->subplans);
2909 node->plan_name = psprintf("InitPlan %d (returns $%d)",
2910 node->plan_id, prm->paramid);
2911 get_first_col_type(plan, &node->firstColType, &node->firstColTypmod,
2912 &node->firstColCollation);
2913 node->setParam = list_make1_int(prm->paramid);
2914
2915 root->init_plans = lappend(root->init_plans, node);
2916
2917 /*
2918 * The node can't have any inputs (since it's an initplan), so the
2919 * parParam and args lists remain empty.
2920 */
2921
2922 /* Set costs of SubPlan using info from the plan tree */
2923 cost_subplan(subroot, node, plan);
2924}
2925