1 /*-------------------------------------------------------------------------
4 * The query optimizer external interface.
6 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
11 * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.226 2008/01/01 19:45:50 momjian Exp $
13 *-------------------------------------------------------------------------
20 #include "catalog/pg_operator.h"
21 #include "executor/executor.h"
22 #include "executor/nodeAgg.h"
23 #include "miscadmin.h"
24 #include "nodes/makefuncs.h"
25 #include "optimizer/clauses.h"
26 #include "optimizer/cost.h"
27 #include "optimizer/pathnode.h"
28 #include "optimizer/paths.h"
29 #include "optimizer/planmain.h"
30 #include "optimizer/planner.h"
31 #include "optimizer/prep.h"
32 #include "optimizer/subselect.h"
33 #include "optimizer/tlist.h"
34 #include "optimizer/var.h"
35 #ifdef OPTIMIZER_DEBUG
36 #include "nodes/print.h"
38 #include "parser/parse_expr.h"
39 #include "parser/parse_oper.h"
40 #include "parser/parsetree.h"
41 #include "utils/lsyscache.h"
42 #include "utils/syscache.h"
45 /* Hook for plugins to get control in planner() */
46 planner_hook_type planner_hook = NULL;
49 /* Expression kind codes for preprocess_expression */
50 #define EXPRKIND_QUAL 0
51 #define EXPRKIND_TARGET 1
52 #define EXPRKIND_RTFUNC 2
53 #define EXPRKIND_VALUES 3
54 #define EXPRKIND_LIMIT 4
55 #define EXPRKIND_ININFO 5
56 #define EXPRKIND_APPINFO 6
59 static Node *preprocess_expression(PlannerInfo *root, Node *expr, int kind);
60 static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode);
61 static Plan *inheritance_planner(PlannerInfo *root);
62 static Plan *grouping_planner(PlannerInfo *root, double tuple_fraction);
63 static bool is_dummy_plan(Plan *plan);
64 static double preprocess_limit(PlannerInfo *root,
65 double tuple_fraction,
66 int64 *offset_est, int64 *count_est);
67 static Oid *extract_grouping_ops(List *groupClause);
68 static bool choose_hashed_grouping(PlannerInfo *root,
69 double tuple_fraction, double limit_tuples,
70 Path *cheapest_path, Path *sorted_path,
71 Oid *groupOperators, double dNumGroups,
72 AggClauseCounts *agg_counts);
73 static List *make_subplanTargetList(PlannerInfo *root, List *tlist,
74 AttrNumber **groupColIdx, bool *need_tlist_eval);
75 static void locate_grouping_columns(PlannerInfo *root,
78 AttrNumber *groupColIdx);
79 static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
82 /*****************************************************************************
84 * Query optimizer entry point
86 * To support loadable plugins that monitor or modify planner behavior,
87 * we provide a hook variable that lets a plugin get control before and
88 * after the standard planning process. The plugin would normally call
91 * Note to plugin authors: standard_planner() scribbles on its Query input,
92 * so you'd better copy that data structure if you want to plan more than once.
94 *****************************************************************************/
96 planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
101 result = (*planner_hook) (parse, cursorOptions, boundParams);
103 result = standard_planner(parse, cursorOptions, boundParams);
108 standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
112 double tuple_fraction;
118 /* Cursor options may come from caller or from DECLARE CURSOR stmt */
119 if (parse->utilityStmt &&
120 IsA(parse->utilityStmt, DeclareCursorStmt))
121 cursorOptions |= ((DeclareCursorStmt *) parse->utilityStmt)->options;
124 * Set up global state for this planner invocation. This data is needed
125 * across all levels of sub-Query that might exist in the given command,
126 * so we keep it in a separate struct that's linked to by each per-Query
129 glob = makeNode(PlannerGlobal);
131 glob->boundParams = boundParams;
132 glob->paramlist = NIL;
133 glob->subplans = NIL;
134 glob->subrtables = NIL;
135 glob->rewindPlanIDs = NULL;
136 glob->finalrtable = NIL;
137 glob->relationOids = NIL;
138 glob->transientPlan = false;
140 /* Determine what fraction of the plan is likely to be scanned */
141 if (cursorOptions & CURSOR_OPT_FAST_PLAN)
144 * We have no real idea how many tuples the user will ultimately FETCH
145 * from a cursor, but it seems a good bet that he doesn't want 'em
146 * all. Optimize for 10% retrieval (you gotta better number? Should
147 * this be a SETtable parameter?)
149 tuple_fraction = 0.10;
153 /* Default assumption is we need all the tuples */
154 tuple_fraction = 0.0;
157 /* primary planning entry point (may recurse for subqueries) */
158 top_plan = subquery_planner(glob, parse, 1, tuple_fraction, &root);
161 * If creating a plan for a scrollable cursor, make sure it can run
162 * backwards on demand. Add a Material node at the top at need.
164 if (cursorOptions & CURSOR_OPT_SCROLL)
166 if (!ExecSupportsBackwardScan(top_plan))
167 top_plan = materialize_finished_plan(top_plan);
170 /* final cleanup of the plan */
171 Assert(glob->finalrtable == NIL);
172 top_plan = set_plan_references(glob, top_plan, root->parse->rtable);
173 /* ... and the subplans (both regular subplans and initplans) */
174 Assert(list_length(glob->subplans) == list_length(glob->subrtables));
175 forboth(lp, glob->subplans, lr, glob->subrtables)
177 Plan *subplan = (Plan *) lfirst(lp);
178 List *subrtable = (List *) lfirst(lr);
180 lfirst(lp) = set_plan_references(glob, subplan, subrtable);
183 /* build the PlannedStmt result */
184 result = makeNode(PlannedStmt);
186 result->commandType = parse->commandType;
187 result->canSetTag = parse->canSetTag;
188 result->transientPlan = glob->transientPlan;
189 result->planTree = top_plan;
190 result->rtable = glob->finalrtable;
191 result->resultRelations = root->resultRelations;
192 result->utilityStmt = parse->utilityStmt;
193 result->intoClause = parse->intoClause;
194 result->subplans = glob->subplans;
195 result->rewindPlanIDs = glob->rewindPlanIDs;
196 result->returningLists = root->returningLists;
197 result->rowMarks = parse->rowMarks;
198 result->relationOids = glob->relationOids;
199 result->nParamExec = list_length(glob->paramlist);
205 /*--------------------
207 * Invokes the planner on a subquery. We recurse to here for each
208 * sub-SELECT found in the query tree.
210 * glob is the global state for the current planner run.
211 * parse is the querytree produced by the parser & rewriter.
212 * level is the current recursion depth (1 at the top-level Query).
213 * tuple_fraction is the fraction of tuples we expect will be retrieved.
214 * tuple_fraction is interpreted as explained for grouping_planner, below.
216 * If subroot isn't NULL, we pass back the query's final PlannerInfo struct;
217 * among other things this tells the output sort ordering of the plan.
219 * Basically, this routine does the stuff that should only be done once
220 * per Query object. It then calls grouping_planner. At one time,
221 * grouping_planner could be invoked recursively on the same Query object;
222 * that's not currently true, but we keep the separation between the two
223 * routines anyway, in case we need it again someday.
225 * subquery_planner will be called recursively to handle sub-Query nodes
226 * found within the query's expressions and rangetable.
228 * Returns a query plan.
229 *--------------------
232 subquery_planner(PlannerGlobal *glob, Query *parse,
233 Index level, double tuple_fraction,
234 PlannerInfo **subroot)
236 int num_old_subplans = list_length(glob->subplans);
242 /* Create a PlannerInfo data structure for this subquery */
243 root = makeNode(PlannerInfo);
246 root->query_level = level;
247 root->planner_cxt = CurrentMemoryContext;
248 root->init_plans = NIL;
249 root->eq_classes = NIL;
250 root->in_info_list = NIL;
251 root->append_rel_list = NIL;
254 * Look for IN clauses at the top level of WHERE, and transform them into
255 * joins. Note that this step only handles IN clauses originally at top
256 * level of WHERE; if we pull up any subqueries in the next step, their
257 * INs are processed just before pulling them up.
259 if (parse->hasSubLinks)
260 parse->jointree->quals = pull_up_IN_clauses(root,
261 parse->jointree->quals);
264 * Check to see if any subqueries in the rangetable can be merged into
267 parse->jointree = (FromExpr *)
268 pull_up_subqueries(root, (Node *) parse->jointree, false, false);
271 * Detect whether any rangetable entries are RTE_JOIN kind; if not, we can
272 * avoid the expense of doing flatten_join_alias_vars(). Also check for
273 * outer joins --- if none, we can skip reduce_outer_joins() and some
274 * other processing. This must be done after we have done
275 * pull_up_subqueries, of course.
277 * Note: if reduce_outer_joins manages to eliminate all outer joins,
278 * root->hasOuterJoins is not reset currently. This is OK since its
279 * purpose is merely to suppress unnecessary processing in simple cases.
281 root->hasJoinRTEs = false;
282 root->hasOuterJoins = false;
283 foreach(l, parse->rtable)
285 RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
287 if (rte->rtekind == RTE_JOIN)
289 root->hasJoinRTEs = true;
290 if (IS_OUTER_JOIN(rte->jointype))
292 root->hasOuterJoins = true;
293 /* Can quit scanning once we find an outer join */
300 * Expand any rangetable entries that are inheritance sets into "append
301 * relations". This can add entries to the rangetable, but they must be
302 * plain base relations not joins, so it's OK (and marginally more
303 * efficient) to do it after checking for join RTEs. We must do it after
304 * pulling up subqueries, else we'd fail to handle inherited tables in
307 expand_inherited_tables(root);
310 * Set hasHavingQual to remember if HAVING clause is present. Needed
311 * because preprocess_expression will reduce a constant-true condition to
312 * an empty qual list ... but "HAVING TRUE" is not a semantic no-op.
314 root->hasHavingQual = (parse->havingQual != NULL);
316 /* Clear this flag; might get set in distribute_qual_to_rels */
317 root->hasPseudoConstantQuals = false;
320 * Do expression preprocessing on targetlist and quals.
322 parse->targetList = (List *)
323 preprocess_expression(root, (Node *) parse->targetList,
326 parse->returningList = (List *)
327 preprocess_expression(root, (Node *) parse->returningList,
330 preprocess_qual_conditions(root, (Node *) parse->jointree);
332 parse->havingQual = preprocess_expression(root, parse->havingQual,
335 parse->limitOffset = preprocess_expression(root, parse->limitOffset,
337 parse->limitCount = preprocess_expression(root, parse->limitCount,
340 root->in_info_list = (List *)
341 preprocess_expression(root, (Node *) root->in_info_list,
343 root->append_rel_list = (List *)
344 preprocess_expression(root, (Node *) root->append_rel_list,
347 /* Also need to preprocess expressions for function and values RTEs */
348 foreach(l, parse->rtable)
350 RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
352 if (rte->rtekind == RTE_FUNCTION)
353 rte->funcexpr = preprocess_expression(root, rte->funcexpr,
355 else if (rte->rtekind == RTE_VALUES)
356 rte->values_lists = (List *)
357 preprocess_expression(root, (Node *) rte->values_lists,
362 * In some cases we may want to transfer a HAVING clause into WHERE. We
363 * cannot do so if the HAVING clause contains aggregates (obviously) or
364 * volatile functions (since a HAVING clause is supposed to be executed
365 * only once per group). Also, it may be that the clause is so expensive
366 * to execute that we're better off doing it only once per group, despite
367 * the loss of selectivity. This is hard to estimate short of doing the
368 * entire planning process twice, so we use a heuristic: clauses
369 * containing subplans are left in HAVING. Otherwise, we move or copy the
370 * HAVING clause into WHERE, in hopes of eliminating tuples before
371 * aggregation instead of after.
373 * If the query has explicit grouping then we can simply move such a
374 * clause into WHERE; any group that fails the clause will not be in the
375 * output because none of its tuples will reach the grouping or
376 * aggregation stage. Otherwise we must have a degenerate (variable-free)
377 * HAVING clause, which we put in WHERE so that query_planner() can use it
378 * in a gating Result node, but also keep in HAVING to ensure that we
379 * don't emit a bogus aggregated row. (This could be done better, but it
380 * seems not worth optimizing.)
382 * Note that both havingQual and parse->jointree->quals are in
383 * implicitly-ANDed-list form at this point, even though they are declared
387 foreach(l, (List *) parse->havingQual)
389 Node *havingclause = (Node *) lfirst(l);
391 if (contain_agg_clause(havingclause) ||
392 contain_volatile_functions(havingclause) ||
393 contain_subplans(havingclause))
395 /* keep it in HAVING */
396 newHaving = lappend(newHaving, havingclause);
398 else if (parse->groupClause)
400 /* move it to WHERE */
401 parse->jointree->quals = (Node *)
402 lappend((List *) parse->jointree->quals, havingclause);
406 /* put a copy in WHERE, keep it in HAVING */
407 parse->jointree->quals = (Node *)
408 lappend((List *) parse->jointree->quals,
409 copyObject(havingclause));
410 newHaving = lappend(newHaving, havingclause);
413 parse->havingQual = (Node *) newHaving;
416 * If we have any outer joins, try to reduce them to plain inner joins.
417 * This step is most easily done after we've done expression
420 if (root->hasOuterJoins)
421 reduce_outer_joins(root);
424 * Do the main planning. If we have an inherited target relation, that
425 * needs special processing, else go straight to grouping_planner.
427 if (parse->resultRelation &&
428 rt_fetch(parse->resultRelation, parse->rtable)->inh)
429 plan = inheritance_planner(root);
431 plan = grouping_planner(root, tuple_fraction);
434 * If any subplans were generated, or if we're inside a subplan, build
435 * initPlan list and extParam/allParam sets for plan nodes, and attach the
436 * initPlans to the top plan node.
438 if (list_length(glob->subplans) != num_old_subplans ||
439 root->query_level > 1)
440 SS_finalize_plan(root, plan);
442 /* Return internal info if caller wants it */
450 * preprocess_expression
451 * Do subquery_planner's preprocessing work for an expression,
452 * which can be a targetlist, a WHERE clause (including JOIN/ON
453 * conditions), or a HAVING clause.
456 preprocess_expression(PlannerInfo *root, Node *expr, int kind)
459 * Fall out quickly if expression is empty. This occurs often enough to
460 * be worth checking. Note that null->null is the correct conversion for
461 * implicit-AND result format, too.
467 * If the query has any join RTEs, replace join alias variables with
468 * base-relation variables. We must do this before sublink processing,
469 * else sublinks expanded out from join aliases wouldn't get processed. We
470 * can skip it in VALUES lists, however, since they can't contain any Vars
473 if (root->hasJoinRTEs && kind != EXPRKIND_VALUES)
474 expr = flatten_join_alias_vars(root, expr);
477 * Simplify constant expressions.
479 * Note: this also flattens nested AND and OR expressions into N-argument
480 * form. All processing of a qual expression after this point must be
481 * careful to maintain AND/OR flatness --- that is, do not generate a tree
482 * with AND directly under AND, nor OR directly under OR.
484 * Because this is a relatively expensive process, we skip it when the
485 * query is trivial, such as "SELECT 2+2;" or "INSERT ... VALUES()". The
486 * expression will only be evaluated once anyway, so no point in
487 * pre-simplifying; we can't execute it any faster than the executor can,
488 * and we will waste cycles copying the tree. Notice however that we
489 * still must do it for quals (to get AND/OR flatness); and if we are in a
490 * subquery we should not assume it will be done only once.
492 * For VALUES lists we never do this at all, again on the grounds that we
493 * should optimize for one-time evaluation.
495 if (kind != EXPRKIND_VALUES &&
496 (root->parse->jointree->fromlist != NIL ||
497 kind == EXPRKIND_QUAL ||
498 root->query_level > 1))
499 expr = eval_const_expressions(expr);
502 * If it's a qual or havingQual, canonicalize it.
504 if (kind == EXPRKIND_QUAL)
506 expr = (Node *) canonicalize_qual((Expr *) expr);
508 #ifdef OPTIMIZER_DEBUG
509 printf("After canonicalize_qual()\n");
514 /* Expand SubLinks to SubPlans */
515 if (root->parse->hasSubLinks)
516 expr = SS_process_sublinks(root, expr, (kind == EXPRKIND_QUAL));
519 * XXX do not insert anything here unless you have grokked the comments in
520 * SS_replace_correlation_vars ...
523 /* Replace uplevel vars with Param nodes (this IS possible in VALUES) */
524 if (root->query_level > 1)
525 expr = SS_replace_correlation_vars(root, expr);
528 * If it's a qual or havingQual, convert it to implicit-AND format. (We
529 * don't want to do this before eval_const_expressions, since the latter
530 * would be unable to simplify a top-level AND correctly. Also,
531 * SS_process_sublinks expects explicit-AND format.)
533 if (kind == EXPRKIND_QUAL)
534 expr = (Node *) make_ands_implicit((Expr *) expr);
540 * preprocess_qual_conditions
541 * Recursively scan the query's jointree and do subquery_planner's
542 * preprocessing work on each qual condition found therein.
545 preprocess_qual_conditions(PlannerInfo *root, Node *jtnode)
549 if (IsA(jtnode, RangeTblRef))
551 /* nothing to do here */
553 else if (IsA(jtnode, FromExpr))
555 FromExpr *f = (FromExpr *) jtnode;
558 foreach(l, f->fromlist)
559 preprocess_qual_conditions(root, lfirst(l));
561 f->quals = preprocess_expression(root, f->quals, EXPRKIND_QUAL);
563 else if (IsA(jtnode, JoinExpr))
565 JoinExpr *j = (JoinExpr *) jtnode;
567 preprocess_qual_conditions(root, j->larg);
568 preprocess_qual_conditions(root, j->rarg);
570 j->quals = preprocess_expression(root, j->quals, EXPRKIND_QUAL);
573 elog(ERROR, "unrecognized node type: %d",
574 (int) nodeTag(jtnode));
578 * inheritance_planner
579 * Generate a plan in the case where the result relation is an
582 * We have to handle this case differently from cases where a source relation
583 * is an inheritance set. Source inheritance is expanded at the bottom of the
584 * plan tree (see allpaths.c), but target inheritance has to be expanded at
585 * the top. The reason is that for UPDATE, each target relation needs a
586 * different targetlist matching its own column set. Also, for both UPDATE
587 * and DELETE, the executor needs the Append plan node at the top, else it
588 * can't keep track of which table is the current target table. Fortunately,
589 * the UPDATE/DELETE target can never be the nullable side of an outer join,
590 * so it's OK to generate the plan this way.
592 * Returns a query plan.
595 inheritance_planner(PlannerInfo *root)
597 Query *parse = root->parse;
598 int parentRTindex = parse->resultRelation;
599 List *subplans = NIL;
600 List *resultRelations = NIL;
601 List *returningLists = NIL;
607 foreach(l, root->append_rel_list)
609 AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
612 /* append_rel_list contains all append rels; ignore others */
613 if (appinfo->parent_relid != parentRTindex)
617 * Generate modified query with this rel as target. We have to be
618 * prepared to translate varnos in in_info_list as well as in the
621 memcpy(&subroot, root, sizeof(PlannerInfo));
622 subroot.parse = (Query *)
623 adjust_appendrel_attrs((Node *) parse,
625 subroot.in_info_list = (List *)
626 adjust_appendrel_attrs((Node *) root->in_info_list,
628 subroot.init_plans = NIL;
629 /* There shouldn't be any OJ info to translate, as yet */
630 Assert(subroot.oj_info_list == NIL);
633 subplan = grouping_planner(&subroot, 0.0 /* retrieve all tuples */ );
636 * If this child rel was excluded by constraint exclusion, exclude it
639 if (is_dummy_plan(subplan))
642 /* Save rtable and tlist from first rel for use below */
645 rtable = subroot.parse->rtable;
646 tlist = subplan->targetlist;
649 subplans = lappend(subplans, subplan);
651 /* Make sure any initplans from this rel get into the outer list */
652 root->init_plans = list_concat(root->init_plans, subroot.init_plans);
654 /* Build target-relations list for the executor */
655 resultRelations = lappend_int(resultRelations, appinfo->child_relid);
657 /* Build list of per-relation RETURNING targetlists */
658 if (parse->returningList)
660 Assert(list_length(subroot.returningLists) == 1);
661 returningLists = list_concat(returningLists,
662 subroot.returningLists);
666 root->resultRelations = resultRelations;
667 root->returningLists = returningLists;
669 /* Mark result as unordered (probably unnecessary) */
670 root->query_pathkeys = NIL;
673 * If we managed to exclude every child rel, return a dummy plan
677 root->resultRelations = list_make1_int(parentRTindex);
678 /* although dummy, it must have a valid tlist for executor */
679 tlist = preprocess_targetlist(root, parse->targetList);
680 return (Plan *) make_result(root,
682 (Node *) list_make1(makeBoolConst(false,
688 * Planning might have modified the rangetable, due to changes of the
689 * Query structures inside subquery RTEs. We have to ensure that this
690 * gets propagated back to the master copy. But can't do this until we
691 * are done planning, because all the calls to grouping_planner need
692 * virgin sub-Queries to work from. (We are effectively assuming that
693 * sub-Queries will get planned identically each time, or at least that
694 * the impacts on their rangetables will be the same each time.)
696 * XXX should clean this up someday
698 parse->rtable = rtable;
700 /* Suppress Append if there's only one surviving child rel */
701 if (list_length(subplans) == 1)
702 return (Plan *) linitial(subplans);
704 return (Plan *) make_append(subplans, true, tlist);
707 /*--------------------
709 * Perform planning steps related to grouping, aggregation, etc.
710 * This primarily means adding top-level processing to the basic
711 * query plan produced by query_planner.
713 * tuple_fraction is the fraction of tuples we expect will be retrieved
715 * tuple_fraction is interpreted as follows:
716 * 0: expect all tuples to be retrieved (normal case)
717 * 0 < tuple_fraction < 1: expect the given fraction of tuples available
718 * from the plan to be retrieved
719 * tuple_fraction >= 1: tuple_fraction is the absolute number of tuples
720 * expected to be retrieved (ie, a LIMIT specification)
722 * Returns a query plan. Also, root->query_pathkeys is returned as the
723 * actual output ordering of the plan (in pathkey format).
724 *--------------------
727 grouping_planner(PlannerInfo *root, double tuple_fraction)
729 Query *parse = root->parse;
730 List *tlist = parse->targetList;
731 int64 offset_est = 0;
733 double limit_tuples = -1.0;
735 List *current_pathkeys;
737 double dNumGroups = 0;
739 /* Tweak caller-supplied tuple_fraction if have LIMIT/OFFSET */
740 if (parse->limitCount || parse->limitOffset)
742 tuple_fraction = preprocess_limit(root, tuple_fraction,
743 &offset_est, &count_est);
746 * If we have a known LIMIT, and don't have an unknown OFFSET, we can
747 * estimate the effects of using a bounded sort.
749 if (count_est > 0 && offset_est >= 0)
750 limit_tuples = (double) count_est + (double) offset_est;
753 if (parse->setOperations)
755 List *set_sortclauses;
758 * If there's a top-level ORDER BY, assume we have to fetch all the
759 * tuples. This might seem too simplistic given all the hackery below
760 * to possibly avoid the sort ... but a nonzero tuple_fraction is only
761 * of use to plan_set_operations() when the setop is UNION ALL, and
762 * the result of UNION ALL is always unsorted.
764 if (parse->sortClause)
765 tuple_fraction = 0.0;
768 * Construct the plan for set operations. The result will not need
769 * any work except perhaps a top-level sort and/or LIMIT.
771 result_plan = plan_set_operations(root, tuple_fraction,
775 * Calculate pathkeys representing the sort order (if any) of the set
776 * operation's result. We have to do this before overwriting the sort
779 current_pathkeys = make_pathkeys_for_sortclauses(root,
781 result_plan->targetlist,
785 * We should not need to call preprocess_targetlist, since we must be
786 * in a SELECT query node. Instead, use the targetlist returned by
787 * plan_set_operations (since this tells whether it returned any
788 * resjunk columns!), and transfer any sort key information from the
791 Assert(parse->commandType == CMD_SELECT);
793 tlist = postprocess_setop_tlist(result_plan->targetlist, tlist);
796 * Can't handle FOR UPDATE/SHARE here (parser should have checked
797 * already, but let's make sure).
801 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
802 errmsg("SELECT FOR UPDATE/SHARE is not allowed with UNION/INTERSECT/EXCEPT")));
805 * Calculate pathkeys that represent result ordering requirements
807 sort_pathkeys = make_pathkeys_for_sortclauses(root,
814 /* No set operations, do regular planning */
816 List *group_pathkeys;
817 AttrNumber *groupColIdx = NULL;
818 Oid *groupOperators = NULL;
819 bool need_tlist_eval = true;
825 AggClauseCounts agg_counts;
826 int numGroupCols = list_length(parse->groupClause);
827 bool use_hashed_grouping = false;
829 MemSet(&agg_counts, 0, sizeof(AggClauseCounts));
831 /* Preprocess targetlist */
832 tlist = preprocess_targetlist(root, tlist);
835 * Generate appropriate target list for subplan; may be different from
836 * tlist if grouping or aggregation is needed.
838 sub_tlist = make_subplanTargetList(root, tlist,
839 &groupColIdx, &need_tlist_eval);
842 * Calculate pathkeys that represent grouping/ordering requirements.
843 * Stash them in PlannerInfo so that query_planner can canonicalize
844 * them after EquivalenceClasses have been formed.
846 root->group_pathkeys =
847 make_pathkeys_for_sortclauses(root,
851 root->sort_pathkeys =
852 make_pathkeys_for_sortclauses(root,
858 * Will need actual number of aggregates for estimating costs.
860 * Note: we do not attempt to detect duplicate aggregates here; a
861 * somewhat-overestimated count is okay for our present purposes.
863 * Note: think not that we can turn off hasAggs if we find no aggs. It
864 * is possible for constant-expression simplification to remove all
865 * explicit references to aggs, but we still have to follow the
866 * aggregate semantics (eg, producing only one output row).
870 count_agg_clauses((Node *) tlist, &agg_counts);
871 count_agg_clauses(parse->havingQual, &agg_counts);
875 * Figure out whether we need a sorted result from query_planner.
877 * If we have a GROUP BY clause, then we want a result sorted properly
878 * for grouping. Otherwise, if there is an ORDER BY clause, we want
879 * to sort by the ORDER BY clause. (Note: if we have both, and ORDER
880 * BY is a superset of GROUP BY, it would be tempting to request sort
881 * by ORDER BY --- but that might just leave us failing to exploit an
882 * available sort order at all. Needs more thought...)
884 if (parse->groupClause)
885 root->query_pathkeys = root->group_pathkeys;
886 else if (parse->sortClause)
887 root->query_pathkeys = root->sort_pathkeys;
889 root->query_pathkeys = NIL;
892 * Generate the best unsorted and presorted paths for this Query (but
893 * note there may not be any presorted path). query_planner will also
894 * estimate the number of groups in the query, and canonicalize all
897 query_planner(root, sub_tlist, tuple_fraction, limit_tuples,
898 &cheapest_path, &sorted_path, &dNumGroups);
900 group_pathkeys = root->group_pathkeys;
901 sort_pathkeys = root->sort_pathkeys;
904 * If grouping, extract the grouping operators and decide whether we
905 * want to use hashed grouping.
907 if (parse->groupClause)
909 groupOperators = extract_grouping_ops(parse->groupClause);
910 use_hashed_grouping =
911 choose_hashed_grouping(root, tuple_fraction, limit_tuples,
912 cheapest_path, sorted_path,
913 groupOperators, dNumGroups,
916 /* Also convert # groups to long int --- but 'ware overflow! */
917 numGroups = (long) Min(dNumGroups, (double) LONG_MAX);
921 * Select the best path. If we are doing hashed grouping, we will
922 * always read all the input tuples, so use the cheapest-total path.
923 * Otherwise, trust query_planner's decision about which to use.
925 if (use_hashed_grouping || !sorted_path)
926 best_path = cheapest_path;
928 best_path = sorted_path;
931 * Check to see if it's possible to optimize MIN/MAX aggregates. If
932 * so, we will forget all the work we did so far to choose a "regular"
933 * path ... but we had to do it anyway to be able to tell which way is
936 result_plan = optimize_minmax_aggregates(root,
939 if (result_plan != NULL)
942 * optimize_minmax_aggregates generated the full plan, with the
943 * right tlist, and it has no sort order.
945 current_pathkeys = NIL;
950 * Normal case --- create a plan according to query_planner's
953 result_plan = create_plan(root, best_path);
954 current_pathkeys = best_path->pathkeys;
957 * create_plan() returns a plan with just a "flat" tlist of
958 * required Vars. Usually we need to insert the sub_tlist as the
959 * tlist of the top plan node. However, we can skip that if we
960 * determined that whatever query_planner chose to return will be
966 * If the top-level plan node is one that cannot do expression
967 * evaluation, we must insert a Result node to project the
970 if (!is_projection_capable_plan(result_plan))
972 result_plan = (Plan *) make_result(root,
980 * Otherwise, just replace the subplan's flat tlist with
983 result_plan->targetlist = sub_tlist;
987 * Also, account for the cost of evaluation of the sub_tlist.
989 * Up to now, we have only been dealing with "flat" tlists,
990 * containing just Vars. So their evaluation cost is zero
991 * according to the model used by cost_qual_eval() (or if you
992 * prefer, the cost is factored into cpu_tuple_cost). Thus we
993 * can avoid accounting for tlist cost throughout
994 * query_planner() and subroutines. But now we've inserted a
995 * tlist that might contain actual operators, sub-selects, etc
996 * --- so we'd better account for its cost.
998 * Below this point, any tlist eval cost for added-on nodes
999 * should be accounted for as we create those nodes.
1000 * Presently, of the node types we can add on, only Agg and
1001 * Group project new tlists (the rest just copy their input
1002 * tuples) --- so make_agg() and make_group() are responsible
1003 * for computing the added cost.
1005 cost_qual_eval(&tlist_cost, sub_tlist, root);
1006 result_plan->startup_cost += tlist_cost.startup;
1007 result_plan->total_cost += tlist_cost.startup +
1008 tlist_cost.per_tuple * result_plan->plan_rows;
1013 * Since we're using query_planner's tlist and not the one
1014 * make_subplanTargetList calculated, we have to refigure any
1015 * grouping-column indexes make_subplanTargetList computed.
1017 locate_grouping_columns(root, tlist, result_plan->targetlist,
1022 * Insert AGG or GROUP node if needed, plus an explicit sort step
1025 * HAVING clause, if any, becomes qual of the Agg or Group node.
1027 if (use_hashed_grouping)
1029 /* Hashed aggregate plan --- no sort needed */
1030 result_plan = (Plan *) make_agg(root,
1032 (List *) parse->havingQual,
1040 /* Hashed aggregation produces randomly-ordered results */
1041 current_pathkeys = NIL;
1043 else if (parse->hasAggs)
1045 /* Plain aggregate plan --- sort if needed */
1046 AggStrategy aggstrategy;
1048 if (parse->groupClause)
1050 if (!pathkeys_contained_in(group_pathkeys,
1053 result_plan = (Plan *)
1054 make_sort_from_groupcols(root,
1058 current_pathkeys = group_pathkeys;
1060 aggstrategy = AGG_SORTED;
1063 * The AGG node will not change the sort ordering of its
1064 * groups, so current_pathkeys describes the result too.
1069 aggstrategy = AGG_PLAIN;
1070 /* Result will be only one row anyway; no sort order */
1071 current_pathkeys = NIL;
1074 result_plan = (Plan *) make_agg(root,
1076 (List *) parse->havingQual,
1085 else if (parse->groupClause)
1088 * GROUP BY without aggregation, so insert a group node (plus
1089 * the appropriate sort node, if necessary).
1091 * Add an explicit sort if we couldn't make the path come out
1092 * the way the GROUP node needs it.
1094 if (!pathkeys_contained_in(group_pathkeys, current_pathkeys))
1096 result_plan = (Plan *)
1097 make_sort_from_groupcols(root,
1101 current_pathkeys = group_pathkeys;
1104 result_plan = (Plan *) make_group(root,
1106 (List *) parse->havingQual,
1112 /* The Group node won't change sort ordering */
1114 else if (root->hasHavingQual)
1117 * No aggregates, and no GROUP BY, but we have a HAVING qual.
1118 * This is a degenerate case in which we are supposed to emit
1119 * either 0 or 1 row depending on whether HAVING succeeds.
1120 * Furthermore, there cannot be any variables in either HAVING
1121 * or the targetlist, so we actually do not need the FROM
1122 * table at all! We can just throw away the plan-so-far and
1123 * generate a Result node. This is a sufficiently unusual
1124 * corner case that it's not worth contorting the structure of
1125 * this routine to avoid having to generate the plan in the
1128 result_plan = (Plan *) make_result(root,
1133 } /* end of non-minmax-aggregate case */
1134 } /* end of if (setOperations) */
1137 * If we were not able to make the plan come out in the right order, add
1138 * an explicit sort step.
1140 if (parse->sortClause)
1142 if (!pathkeys_contained_in(sort_pathkeys, current_pathkeys))
1144 result_plan = (Plan *) make_sort_from_pathkeys(root,
1148 current_pathkeys = sort_pathkeys;
1153 * If there is a DISTINCT clause, add the UNIQUE node.
1155 if (parse->distinctClause)
1157 result_plan = (Plan *) make_unique(result_plan, parse->distinctClause);
1160 * If there was grouping or aggregation, leave plan_rows as-is (ie,
1161 * assume the result was already mostly unique). If not, use the
1162 * number of distinct-groups calculated by query_planner.
1164 if (!parse->groupClause && !root->hasHavingQual && !parse->hasAggs)
1165 result_plan->plan_rows = dNumGroups;
1169 * Finally, if there is a LIMIT/OFFSET clause, add the LIMIT node.
1171 if (parse->limitCount || parse->limitOffset)
1173 result_plan = (Plan *) make_limit(result_plan,
1181 * Deal with the RETURNING clause if any. It's convenient to pass the
1182 * returningList through setrefs.c now rather than at top level (if we
1183 * waited, handling inherited UPDATE/DELETE would be much harder).
1185 if (parse->returningList)
1189 Assert(parse->resultRelation);
1190 rlist = set_returning_clause_references(root->glob,
1191 parse->returningList,
1193 parse->resultRelation);
1194 root->returningLists = list_make1(rlist);
1197 root->returningLists = NIL;
1199 /* Compute result-relations list if needed */
1200 if (parse->resultRelation)
1201 root->resultRelations = list_make1_int(parse->resultRelation);
1203 root->resultRelations = NIL;
1206 * Return the actual output ordering in query_pathkeys for possible use by
1207 * an outer query level.
1209 root->query_pathkeys = current_pathkeys;
1215 * Detect whether a plan node is a "dummy" plan created when a relation
1216 * is deemed not to need scanning due to constraint exclusion.
1218 * Currently, such dummy plans are Result nodes with constant FALSE
1222 is_dummy_plan(Plan *plan)
1224 if (IsA(plan, Result))
1226 List *rcqual = (List *) ((Result *) plan)->resconstantqual;
1228 if (list_length(rcqual) == 1)
1230 Const *constqual = (Const *) linitial(rcqual);
1232 if (constqual && IsA(constqual, Const))
1234 if (!constqual->constisnull &&
1235 !DatumGetBool(constqual->constvalue))
1244 * preprocess_limit - do pre-estimation for LIMIT and/or OFFSET clauses
1246 * We try to estimate the values of the LIMIT/OFFSET clauses, and pass the
1247 * results back in *count_est and *offset_est. These variables are set to
1248 * 0 if the corresponding clause is not present, and -1 if it's present
1249 * but we couldn't estimate the value for it. (The "0" convention is OK
1250 * for OFFSET but a little bit bogus for LIMIT: effectively we estimate
1251 * LIMIT 0 as though it were LIMIT 1. But this is in line with the planner's
1252 * usual practice of never estimating less than one row.) These values will
1253 * be passed to make_limit, which see if you change this code.
1255 * The return value is the suitably adjusted tuple_fraction to use for
1256 * planning the query. This adjustment is not overridable, since it reflects
1257 * plan actions that grouping_planner() will certainly take, not assumptions
1261 preprocess_limit(PlannerInfo *root, double tuple_fraction,
1262 int64 *offset_est, int64 *count_est)
1264 Query *parse = root->parse;
1266 double limit_fraction;
1268 /* Should not be called unless LIMIT or OFFSET */
1269 Assert(parse->limitCount || parse->limitOffset);
1272 * Try to obtain the clause values. We use estimate_expression_value
1273 * primarily because it can sometimes do something useful with Params.
1275 if (parse->limitCount)
1277 est = estimate_expression_value(root, parse->limitCount);
1278 if (est && IsA(est, Const))
1280 if (((Const *) est)->constisnull)
1282 /* NULL indicates LIMIT ALL, ie, no limit */
1283 *count_est = 0; /* treat as not present */
1287 *count_est = DatumGetInt64(((Const *) est)->constvalue);
1288 if (*count_est <= 0)
1289 *count_est = 1; /* force to at least 1 */
1293 *count_est = -1; /* can't estimate */
1296 *count_est = 0; /* not present */
1298 if (parse->limitOffset)
1300 est = estimate_expression_value(root, parse->limitOffset);
1301 if (est && IsA(est, Const))
1303 if (((Const *) est)->constisnull)
1305 /* Treat NULL as no offset; the executor will too */
1306 *offset_est = 0; /* treat as not present */
1310 *offset_est = DatumGetInt64(((Const *) est)->constvalue);
1311 if (*offset_est < 0)
1312 *offset_est = 0; /* less than 0 is same as 0 */
1316 *offset_est = -1; /* can't estimate */
1319 *offset_est = 0; /* not present */
1321 if (*count_est != 0)
1324 * A LIMIT clause limits the absolute number of tuples returned.
1325 * However, if it's not a constant LIMIT then we have to guess; for
1326 * lack of a better idea, assume 10% of the plan's result is wanted.
1328 if (*count_est < 0 || *offset_est < 0)
1330 /* LIMIT or OFFSET is an expression ... punt ... */
1331 limit_fraction = 0.10;
1335 /* LIMIT (plus OFFSET, if any) is max number of tuples needed */
1336 limit_fraction = (double) *count_est + (double) *offset_est;
1340 * If we have absolute limits from both caller and LIMIT, use the
1341 * smaller value; likewise if they are both fractional. If one is
1342 * fractional and the other absolute, we can't easily determine which
1343 * is smaller, but we use the heuristic that the absolute will usually
1346 if (tuple_fraction >= 1.0)
1348 if (limit_fraction >= 1.0)
1351 tuple_fraction = Min(tuple_fraction, limit_fraction);
1355 /* caller absolute, limit fractional; use caller's value */
1358 else if (tuple_fraction > 0.0)
1360 if (limit_fraction >= 1.0)
1362 /* caller fractional, limit absolute; use limit */
1363 tuple_fraction = limit_fraction;
1367 /* both fractional */
1368 tuple_fraction = Min(tuple_fraction, limit_fraction);
1373 /* no info from caller, just use limit */
1374 tuple_fraction = limit_fraction;
1377 else if (*offset_est != 0 && tuple_fraction > 0.0)
1380 * We have an OFFSET but no LIMIT. This acts entirely differently
1381 * from the LIMIT case: here, we need to increase rather than decrease
1382 * the caller's tuple_fraction, because the OFFSET acts to cause more
1383 * tuples to be fetched instead of fewer. This only matters if we got
1384 * a tuple_fraction > 0, however.
1386 * As above, use 10% if OFFSET is present but unestimatable.
1388 if (*offset_est < 0)
1389 limit_fraction = 0.10;
1391 limit_fraction = (double) *offset_est;
1394 * If we have absolute counts from both caller and OFFSET, add them
1395 * together; likewise if they are both fractional. If one is
1396 * fractional and the other absolute, we want to take the larger, and
1397 * we heuristically assume that's the fractional one.
1399 if (tuple_fraction >= 1.0)
1401 if (limit_fraction >= 1.0)
1403 /* both absolute, so add them together */
1404 tuple_fraction += limit_fraction;
1408 /* caller absolute, limit fractional; use limit */
1409 tuple_fraction = limit_fraction;
1414 if (limit_fraction >= 1.0)
1416 /* caller fractional, limit absolute; use caller's value */
1420 /* both fractional, so add them together */
1421 tuple_fraction += limit_fraction;
1422 if (tuple_fraction >= 1.0)
1423 tuple_fraction = 0.0; /* assume fetch all */
1428 return tuple_fraction;
1432 * extract_grouping_ops - make an array of the equality operator OIDs
1433 * for the GROUP BY clause
1436 extract_grouping_ops(List *groupClause)
1438 int numCols = list_length(groupClause);
1440 Oid *groupOperators;
1443 groupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
1445 foreach(glitem, groupClause)
1447 GroupClause *groupcl = (GroupClause *) lfirst(glitem);
1449 groupOperators[colno] = get_equality_op_for_ordering_op(groupcl->sortop);
1450 if (!OidIsValid(groupOperators[colno])) /* shouldn't happen */
1451 elog(ERROR, "could not find equality operator for ordering operator %u",
1456 return groupOperators;
1460 * choose_hashed_grouping - should we use hashed grouping?
1463 choose_hashed_grouping(PlannerInfo *root,
1464 double tuple_fraction, double limit_tuples,
1465 Path *cheapest_path, Path *sorted_path,
1466 Oid *groupOperators, double dNumGroups,
1467 AggClauseCounts *agg_counts)
1469 int numGroupCols = list_length(root->parse->groupClause);
1470 double cheapest_path_rows;
1471 int cheapest_path_width;
1473 List *current_pathkeys;
1479 * Check can't-do-it conditions, including whether the grouping operators
1480 * are hashjoinable. (We assume hashing is OK if they are marked
1481 * oprcanhash. If there isn't actually a supporting hash function, the
1482 * executor will complain at runtime.)
1484 * Executor doesn't support hashed aggregation with DISTINCT aggregates.
1485 * (Doing so would imply storing *all* the input values in the hash table,
1486 * which seems like a certain loser.)
1488 if (!enable_hashagg)
1490 if (agg_counts->numDistinctAggs != 0)
1492 for (i = 0; i < numGroupCols; i++)
1494 if (!op_hashjoinable(groupOperators[i]))
1499 * Don't do it if it doesn't look like the hashtable will fit into
1502 * Beware here of the possibility that cheapest_path->parent is NULL. This
1503 * could happen if user does something silly like SELECT 'foo' GROUP BY 1;
1505 if (cheapest_path->parent)
1507 cheapest_path_rows = cheapest_path->parent->rows;
1508 cheapest_path_width = cheapest_path->parent->width;
1512 cheapest_path_rows = 1; /* assume non-set result */
1513 cheapest_path_width = 100; /* arbitrary */
1516 /* Estimate per-hash-entry space at tuple width... */
1517 hashentrysize = MAXALIGN(cheapest_path_width) + MAXALIGN(sizeof(MinimalTupleData));
1518 /* plus space for pass-by-ref transition values... */
1519 hashentrysize += agg_counts->transitionSpace;
1520 /* plus the per-hash-entry overhead */
1521 hashentrysize += hash_agg_entry_size(agg_counts->numAggs);
1523 if (hashentrysize * dNumGroups > work_mem * 1024L)
1527 * See if the estimated cost is no more than doing it the other way. While
1528 * avoiding the need for sorted input is usually a win, the fact that the
1529 * output won't be sorted may be a loss; so we need to do an actual cost
1532 * We need to consider cheapest_path + hashagg [+ final sort] versus
1533 * either cheapest_path [+ sort] + group or agg [+ final sort] or
1534 * presorted_path + group or agg [+ final sort] where brackets indicate a
1535 * step that may not be needed. We assume query_planner() will have
1536 * returned a presorted path only if it's a winner compared to
1537 * cheapest_path for this purpose.
1539 * These path variables are dummies that just hold cost fields; we don't
1540 * make actual Paths for these steps.
1542 cost_agg(&hashed_p, root, AGG_HASHED, agg_counts->numAggs,
1543 numGroupCols, dNumGroups,
1544 cheapest_path->startup_cost, cheapest_path->total_cost,
1545 cheapest_path_rows);
1546 /* Result of hashed agg is always unsorted */
1547 if (root->sort_pathkeys)
1548 cost_sort(&hashed_p, root, root->sort_pathkeys, hashed_p.total_cost,
1549 dNumGroups, cheapest_path_width, limit_tuples);
1553 sorted_p.startup_cost = sorted_path->startup_cost;
1554 sorted_p.total_cost = sorted_path->total_cost;
1555 current_pathkeys = sorted_path->pathkeys;
1559 sorted_p.startup_cost = cheapest_path->startup_cost;
1560 sorted_p.total_cost = cheapest_path->total_cost;
1561 current_pathkeys = cheapest_path->pathkeys;
1563 if (!pathkeys_contained_in(root->group_pathkeys, current_pathkeys))
1565 cost_sort(&sorted_p, root, root->group_pathkeys, sorted_p.total_cost,
1566 cheapest_path_rows, cheapest_path_width, -1.0);
1567 current_pathkeys = root->group_pathkeys;
1570 if (root->parse->hasAggs)
1571 cost_agg(&sorted_p, root, AGG_SORTED, agg_counts->numAggs,
1572 numGroupCols, dNumGroups,
1573 sorted_p.startup_cost, sorted_p.total_cost,
1574 cheapest_path_rows);
1576 cost_group(&sorted_p, root, numGroupCols, dNumGroups,
1577 sorted_p.startup_cost, sorted_p.total_cost,
1578 cheapest_path_rows);
1579 /* The Agg or Group node will preserve ordering */
1580 if (root->sort_pathkeys &&
1581 !pathkeys_contained_in(root->sort_pathkeys, current_pathkeys))
1582 cost_sort(&sorted_p, root, root->sort_pathkeys, sorted_p.total_cost,
1583 dNumGroups, cheapest_path_width, limit_tuples);
1586 * Now make the decision using the top-level tuple fraction. First we
1587 * have to convert an absolute count (LIMIT) into fractional form.
1589 if (tuple_fraction >= 1.0)
1590 tuple_fraction /= dNumGroups;
1592 if (compare_fractional_path_costs(&hashed_p, &sorted_p,
1593 tuple_fraction) < 0)
1595 /* Hashed is cheaper, so use it */
1602 * make_subplanTargetList
1603 * Generate appropriate target list when grouping is required.
1605 * When grouping_planner inserts Aggregate, Group, or Result plan nodes
1606 * above the result of query_planner, we typically want to pass a different
1607 * target list to query_planner than the outer plan nodes should have.
1608 * This routine generates the correct target list for the subplan.
1610 * The initial target list passed from the parser already contains entries
1611 * for all ORDER BY and GROUP BY expressions, but it will not have entries
1612 * for variables used only in HAVING clauses; so we need to add those
1613 * variables to the subplan target list. Also, we flatten all expressions
1614 * except GROUP BY items into their component variables; the other expressions
1615 * will be computed by the inserted nodes rather than by the subplan.
1616 * For example, given a query like
1617 * SELECT a+b,SUM(c+d) FROM table GROUP BY a+b;
1618 * we want to pass this targetlist to the subplan:
1620 * where the a+b target will be used by the Sort/Group steps, and the
1621 * other targets will be used for computing the final results. (In the
1622 * above example we could theoretically suppress the a and b targets and
1623 * pass down only c,d,a+b, but it's not really worth the trouble to
1624 * eliminate simple var references from the subplan. We will avoid doing
1625 * the extra computation to recompute a+b at the outer level; see
1626 * fix_upper_expr() in setrefs.c.)
1628 * If we are grouping or aggregating, *and* there are no non-Var grouping
1629 * expressions, then the returned tlist is effectively dummy; we do not
1630 * need to force it to be evaluated, because all the Vars it contains
1631 * should be present in the output of query_planner anyway.
1633 * 'tlist' is the query's target list.
1634 * 'groupColIdx' receives an array of column numbers for the GROUP BY
1635 * expressions (if there are any) in the subplan's target list.
1636 * 'need_tlist_eval' is set true if we really need to evaluate the
1639 * The result is the targetlist to be passed to the subplan.
1643 make_subplanTargetList(PlannerInfo *root,
1645 AttrNumber **groupColIdx,
1646 bool *need_tlist_eval)
1648 Query *parse = root->parse;
1653 *groupColIdx = NULL;
1656 * If we're not grouping or aggregating, there's nothing to do here;
1657 * query_planner should receive the unmodified target list.
1659 if (!parse->hasAggs && !parse->groupClause && !root->hasHavingQual)
1661 *need_tlist_eval = true;
1666 * Otherwise, start with a "flattened" tlist (having just the vars
1667 * mentioned in the targetlist and HAVING qual --- but not upper- level
1668 * Vars; they will be replaced by Params later on).
1670 sub_tlist = flatten_tlist(tlist);
1671 extravars = pull_var_clause(parse->havingQual, false);
1672 sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
1673 list_free(extravars);
1674 *need_tlist_eval = false; /* only eval if not flat tlist */
1677 * If grouping, create sub_tlist entries for all GROUP BY expressions
1678 * (GROUP BY items that are simple Vars should be in the list already),
1679 * and make an array showing where the group columns are in the sub_tlist.
1681 numCols = list_length(parse->groupClause);
1685 AttrNumber *grpColIdx;
1688 grpColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
1689 *groupColIdx = grpColIdx;
1691 foreach(gl, parse->groupClause)
1693 GroupClause *grpcl = (GroupClause *) lfirst(gl);
1694 Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
1695 TargetEntry *te = NULL;
1698 /* Find or make a matching sub_tlist entry */
1699 foreach(sl, sub_tlist)
1701 te = (TargetEntry *) lfirst(sl);
1702 if (equal(groupexpr, te->expr))
1707 te = makeTargetEntry((Expr *) groupexpr,
1708 list_length(sub_tlist) + 1,
1711 sub_tlist = lappend(sub_tlist, te);
1712 *need_tlist_eval = true; /* it's not flat anymore */
1715 /* and save its resno */
1716 grpColIdx[keyno++] = te->resno;
1724 * locate_grouping_columns
1725 * Locate grouping columns in the tlist chosen by query_planner.
1727 * This is only needed if we don't use the sub_tlist chosen by
1728 * make_subplanTargetList. We have to forget the column indexes found
1729 * by that routine and re-locate the grouping vars in the real sub_tlist.
1732 locate_grouping_columns(PlannerInfo *root,
1735 AttrNumber *groupColIdx)
1741 * No work unless grouping.
1743 if (!root->parse->groupClause)
1745 Assert(groupColIdx == NULL);
1748 Assert(groupColIdx != NULL);
1750 foreach(gl, root->parse->groupClause)
1752 GroupClause *grpcl = (GroupClause *) lfirst(gl);
1753 Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
1754 TargetEntry *te = NULL;
1757 foreach(sl, sub_tlist)
1759 te = (TargetEntry *) lfirst(sl);
1760 if (equal(groupexpr, te->expr))
1764 elog(ERROR, "failed to locate grouping columns");
1766 groupColIdx[keyno++] = te->resno;
1771 * postprocess_setop_tlist
1772 * Fix up targetlist returned by plan_set_operations().
1774 * We need to transpose sort key info from the orig_tlist into new_tlist.
1775 * NOTE: this would not be good enough if we supported resjunk sort keys
1776 * for results of set operations --- then, we'd need to project a whole
1777 * new tlist to evaluate the resjunk columns. For now, just ereport if we
1778 * find any resjunk columns in orig_tlist.
1781 postprocess_setop_tlist(List *new_tlist, List *orig_tlist)
1784 ListCell *orig_tlist_item = list_head(orig_tlist);
1786 foreach(l, new_tlist)
1788 TargetEntry *new_tle = (TargetEntry *) lfirst(l);
1789 TargetEntry *orig_tle;
1791 /* ignore resjunk columns in setop result */
1792 if (new_tle->resjunk)
1795 Assert(orig_tlist_item != NULL);
1796 orig_tle = (TargetEntry *) lfirst(orig_tlist_item);
1797 orig_tlist_item = lnext(orig_tlist_item);
1798 if (orig_tle->resjunk) /* should not happen */
1799 elog(ERROR, "resjunk output columns are not implemented");
1800 Assert(new_tle->resno == orig_tle->resno);
1801 new_tle->ressortgroupref = orig_tle->ressortgroupref;
1803 if (orig_tlist_item != NULL)
1804 elog(ERROR, "resjunk output columns are not implemented");