1 /*-------------------------------------------------------------------------
4 * The query optimizer external interface.
6 * Portions Copyright (c) 1996-2007, 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 1.218 2007/04/27 22:05:47 tgl 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 /* Expression kind codes for preprocess_expression */
46 #define EXPRKIND_QUAL 0
47 #define EXPRKIND_TARGET 1
48 #define EXPRKIND_RTFUNC 2
49 #define EXPRKIND_VALUES 3
50 #define EXPRKIND_LIMIT 4
51 #define EXPRKIND_ININFO 5
52 #define EXPRKIND_APPINFO 6
55 static Node *preprocess_expression(PlannerInfo *root, Node *expr, int kind);
56 static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode);
57 static Plan *inheritance_planner(PlannerInfo *root);
58 static Plan *grouping_planner(PlannerInfo *root, double tuple_fraction);
59 static bool is_dummy_plan(Plan *plan);
60 static double preprocess_limit(PlannerInfo *root,
61 double tuple_fraction,
62 int64 *offset_est, int64 *count_est);
63 static Oid *extract_grouping_ops(List *groupClause);
64 static bool choose_hashed_grouping(PlannerInfo *root, double tuple_fraction,
65 Path *cheapest_path, Path *sorted_path,
66 Oid *groupOperators, double dNumGroups,
67 AggClauseCounts *agg_counts);
68 static List *make_subplanTargetList(PlannerInfo *root, List *tlist,
69 AttrNumber **groupColIdx, bool *need_tlist_eval);
70 static void locate_grouping_columns(PlannerInfo *root,
73 AttrNumber *groupColIdx);
74 static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
77 /*****************************************************************************
79 * Query optimizer entry point
81 *****************************************************************************/
83 planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
87 double tuple_fraction;
93 /* Cursor options may come from caller or from DECLARE CURSOR stmt */
94 if (parse->utilityStmt &&
95 IsA(parse->utilityStmt, DeclareCursorStmt))
96 cursorOptions |= ((DeclareCursorStmt *) parse->utilityStmt)->options;
99 * Set up global state for this planner invocation. This data is needed
100 * across all levels of sub-Query that might exist in the given command,
101 * so we keep it in a separate struct that's linked to by each per-Query
104 glob = makeNode(PlannerGlobal);
106 glob->boundParams = boundParams;
107 glob->paramlist = NIL;
108 glob->subplans = NIL;
109 glob->subrtables = NIL;
110 glob->rewindPlanIDs = NULL;
111 glob->finalrtable = NIL;
113 /* Determine what fraction of the plan is likely to be scanned */
114 if (cursorOptions & CURSOR_OPT_FAST_PLAN)
117 * We have no real idea how many tuples the user will ultimately FETCH
118 * from a cursor, but it seems a good bet that he doesn't want 'em
119 * all. Optimize for 10% retrieval (you gotta better number? Should
120 * this be a SETtable parameter?)
122 tuple_fraction = 0.10;
126 /* Default assumption is we need all the tuples */
127 tuple_fraction = 0.0;
130 /* primary planning entry point (may recurse for subqueries) */
131 top_plan = subquery_planner(glob, parse, 1, tuple_fraction, &root);
134 * If creating a plan for a scrollable cursor, make sure it can run
135 * backwards on demand. Add a Material node at the top at need.
137 if (cursorOptions & CURSOR_OPT_SCROLL)
139 if (!ExecSupportsBackwardScan(top_plan))
140 top_plan = materialize_finished_plan(top_plan);
143 /* final cleanup of the plan */
144 Assert(glob->finalrtable == NIL);
145 top_plan = set_plan_references(glob, top_plan, root->parse->rtable);
146 /* ... and the subplans (both regular subplans and initplans) */
147 Assert(list_length(glob->subplans) == list_length(glob->subrtables));
148 forboth(lp, glob->subplans, lr, glob->subrtables)
150 Plan *subplan = (Plan *) lfirst(lp);
151 List *subrtable = (List *) lfirst(lr);
153 lfirst(lp) = set_plan_references(glob, subplan, subrtable);
156 /* build the PlannedStmt result */
157 result = makeNode(PlannedStmt);
159 result->commandType = parse->commandType;
160 result->canSetTag = parse->canSetTag;
161 result->planTree = top_plan;
162 result->rtable = glob->finalrtable;
163 result->resultRelations = root->resultRelations;
164 result->utilityStmt = parse->utilityStmt;
165 result->intoClause = parse->intoClause;
166 result->subplans = glob->subplans;
167 result->rewindPlanIDs = glob->rewindPlanIDs;
168 result->returningLists = root->returningLists;
169 result->rowMarks = parse->rowMarks;
170 result->nParamExec = list_length(glob->paramlist);
176 /*--------------------
178 * Invokes the planner on a subquery. We recurse to here for each
179 * sub-SELECT found in the query tree.
181 * glob is the global state for the current planner run.
182 * parse is the querytree produced by the parser & rewriter.
183 * level is the current recursion depth (1 at the top-level Query).
184 * tuple_fraction is the fraction of tuples we expect will be retrieved.
185 * tuple_fraction is interpreted as explained for grouping_planner, below.
187 * If subroot isn't NULL, we pass back the query's final PlannerInfo struct;
188 * among other things this tells the output sort ordering of the plan.
190 * Basically, this routine does the stuff that should only be done once
191 * per Query object. It then calls grouping_planner. At one time,
192 * grouping_planner could be invoked recursively on the same Query object;
193 * that's not currently true, but we keep the separation between the two
194 * routines anyway, in case we need it again someday.
196 * subquery_planner will be called recursively to handle sub-Query nodes
197 * found within the query's expressions and rangetable.
199 * Returns a query plan.
200 *--------------------
203 subquery_planner(PlannerGlobal *glob, Query *parse,
204 Index level, double tuple_fraction,
205 PlannerInfo **subroot)
207 int num_old_subplans = list_length(glob->subplans);
213 /* Create a PlannerInfo data structure for this subquery */
214 root = makeNode(PlannerInfo);
217 root->query_level = level;
218 root->planner_cxt = CurrentMemoryContext;
219 root->init_plans = NIL;
220 root->eq_classes = NIL;
221 root->in_info_list = NIL;
222 root->append_rel_list = NIL;
225 * Look for IN clauses at the top level of WHERE, and transform them into
226 * joins. Note that this step only handles IN clauses originally at top
227 * level of WHERE; if we pull up any subqueries in the next step, their
228 * INs are processed just before pulling them up.
230 if (parse->hasSubLinks)
231 parse->jointree->quals = pull_up_IN_clauses(root,
232 parse->jointree->quals);
235 * Check to see if any subqueries in the rangetable can be merged into
238 parse->jointree = (FromExpr *)
239 pull_up_subqueries(root, (Node *) parse->jointree, false, false);
242 * Detect whether any rangetable entries are RTE_JOIN kind; if not, we can
243 * avoid the expense of doing flatten_join_alias_vars(). Also check for
244 * outer joins --- if none, we can skip reduce_outer_joins() and some
245 * other processing. This must be done after we have done
246 * pull_up_subqueries, of course.
248 * Note: if reduce_outer_joins manages to eliminate all outer joins,
249 * root->hasOuterJoins is not reset currently. This is OK since its
250 * purpose is merely to suppress unnecessary processing in simple cases.
252 root->hasJoinRTEs = false;
253 root->hasOuterJoins = false;
254 foreach(l, parse->rtable)
256 RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
258 if (rte->rtekind == RTE_JOIN)
260 root->hasJoinRTEs = true;
261 if (IS_OUTER_JOIN(rte->jointype))
263 root->hasOuterJoins = true;
264 /* Can quit scanning once we find an outer join */
271 * Expand any rangetable entries that are inheritance sets into "append
272 * relations". This can add entries to the rangetable, but they must be
273 * plain base relations not joins, so it's OK (and marginally more
274 * efficient) to do it after checking for join RTEs. We must do it after
275 * pulling up subqueries, else we'd fail to handle inherited tables in
278 expand_inherited_tables(root);
281 * Set hasHavingQual to remember if HAVING clause is present. Needed
282 * because preprocess_expression will reduce a constant-true condition to
283 * an empty qual list ... but "HAVING TRUE" is not a semantic no-op.
285 root->hasHavingQual = (parse->havingQual != NULL);
287 /* Clear this flag; might get set in distribute_qual_to_rels */
288 root->hasPseudoConstantQuals = false;
291 * Do expression preprocessing on targetlist and quals.
293 parse->targetList = (List *)
294 preprocess_expression(root, (Node *) parse->targetList,
297 parse->returningList = (List *)
298 preprocess_expression(root, (Node *) parse->returningList,
301 preprocess_qual_conditions(root, (Node *) parse->jointree);
303 parse->havingQual = preprocess_expression(root, parse->havingQual,
306 parse->limitOffset = preprocess_expression(root, parse->limitOffset,
308 parse->limitCount = preprocess_expression(root, parse->limitCount,
311 root->in_info_list = (List *)
312 preprocess_expression(root, (Node *) root->in_info_list,
314 root->append_rel_list = (List *)
315 preprocess_expression(root, (Node *) root->append_rel_list,
318 /* Also need to preprocess expressions for function and values RTEs */
319 foreach(l, parse->rtable)
321 RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
323 if (rte->rtekind == RTE_FUNCTION)
324 rte->funcexpr = preprocess_expression(root, rte->funcexpr,
326 else if (rte->rtekind == RTE_VALUES)
327 rte->values_lists = (List *)
328 preprocess_expression(root, (Node *) rte->values_lists,
333 * In some cases we may want to transfer a HAVING clause into WHERE. We
334 * cannot do so if the HAVING clause contains aggregates (obviously) or
335 * volatile functions (since a HAVING clause is supposed to be executed
336 * only once per group). Also, it may be that the clause is so expensive
337 * to execute that we're better off doing it only once per group, despite
338 * the loss of selectivity. This is hard to estimate short of doing the
339 * entire planning process twice, so we use a heuristic: clauses
340 * containing subplans are left in HAVING. Otherwise, we move or copy the
341 * HAVING clause into WHERE, in hopes of eliminating tuples before
342 * aggregation instead of after.
344 * If the query has explicit grouping then we can simply move such a
345 * clause into WHERE; any group that fails the clause will not be in the
346 * output because none of its tuples will reach the grouping or
347 * aggregation stage. Otherwise we must have a degenerate (variable-free)
348 * HAVING clause, which we put in WHERE so that query_planner() can use it
349 * in a gating Result node, but also keep in HAVING to ensure that we
350 * don't emit a bogus aggregated row. (This could be done better, but it
351 * seems not worth optimizing.)
353 * Note that both havingQual and parse->jointree->quals are in
354 * implicitly-ANDed-list form at this point, even though they are declared
358 foreach(l, (List *) parse->havingQual)
360 Node *havingclause = (Node *) lfirst(l);
362 if (contain_agg_clause(havingclause) ||
363 contain_volatile_functions(havingclause) ||
364 contain_subplans(havingclause))
366 /* keep it in HAVING */
367 newHaving = lappend(newHaving, havingclause);
369 else if (parse->groupClause)
371 /* move it to WHERE */
372 parse->jointree->quals = (Node *)
373 lappend((List *) parse->jointree->quals, havingclause);
377 /* put a copy in WHERE, keep it in HAVING */
378 parse->jointree->quals = (Node *)
379 lappend((List *) parse->jointree->quals,
380 copyObject(havingclause));
381 newHaving = lappend(newHaving, havingclause);
384 parse->havingQual = (Node *) newHaving;
387 * If we have any outer joins, try to reduce them to plain inner joins.
388 * This step is most easily done after we've done expression
391 if (root->hasOuterJoins)
392 reduce_outer_joins(root);
395 * Do the main planning. If we have an inherited target relation, that
396 * needs special processing, else go straight to grouping_planner.
398 if (parse->resultRelation &&
399 rt_fetch(parse->resultRelation, parse->rtable)->inh)
400 plan = inheritance_planner(root);
402 plan = grouping_planner(root, tuple_fraction);
405 * If any subplans were generated, or if we're inside a subplan, build
406 * initPlan list and extParam/allParam sets for plan nodes, and attach the
407 * initPlans to the top plan node.
409 if (list_length(glob->subplans) != num_old_subplans ||
410 root->query_level > 1)
411 SS_finalize_plan(root, plan);
413 /* Return internal info if caller wants it */
421 * preprocess_expression
422 * Do subquery_planner's preprocessing work for an expression,
423 * which can be a targetlist, a WHERE clause (including JOIN/ON
424 * conditions), or a HAVING clause.
427 preprocess_expression(PlannerInfo *root, Node *expr, int kind)
430 * Fall out quickly if expression is empty. This occurs often enough to
431 * be worth checking. Note that null->null is the correct conversion for
432 * implicit-AND result format, too.
438 * If the query has any join RTEs, replace join alias variables with
439 * base-relation variables. We must do this before sublink processing,
440 * else sublinks expanded out from join aliases wouldn't get processed. We
441 * can skip it in VALUES lists, however, since they can't contain any Vars
444 if (root->hasJoinRTEs && kind != EXPRKIND_VALUES)
445 expr = flatten_join_alias_vars(root, expr);
448 * Simplify constant expressions.
450 * Note: this also flattens nested AND and OR expressions into N-argument
451 * form. All processing of a qual expression after this point must be
452 * careful to maintain AND/OR flatness --- that is, do not generate a tree
453 * with AND directly under AND, nor OR directly under OR.
455 * Because this is a relatively expensive process, we skip it when the
456 * query is trivial, such as "SELECT 2+2;" or "INSERT ... VALUES()". The
457 * expression will only be evaluated once anyway, so no point in
458 * pre-simplifying; we can't execute it any faster than the executor can,
459 * and we will waste cycles copying the tree. Notice however that we
460 * still must do it for quals (to get AND/OR flatness); and if we are in a
461 * subquery we should not assume it will be done only once.
463 * For VALUES lists we never do this at all, again on the grounds that we
464 * should optimize for one-time evaluation.
466 if (kind != EXPRKIND_VALUES &&
467 (root->parse->jointree->fromlist != NIL ||
468 kind == EXPRKIND_QUAL ||
469 root->query_level > 1))
470 expr = eval_const_expressions(expr);
473 * If it's a qual or havingQual, canonicalize it.
475 if (kind == EXPRKIND_QUAL)
477 expr = (Node *) canonicalize_qual((Expr *) expr);
479 #ifdef OPTIMIZER_DEBUG
480 printf("After canonicalize_qual()\n");
485 /* Expand SubLinks to SubPlans */
486 if (root->parse->hasSubLinks)
487 expr = SS_process_sublinks(root, expr, (kind == EXPRKIND_QUAL));
490 * XXX do not insert anything here unless you have grokked the comments in
491 * SS_replace_correlation_vars ...
494 /* Replace uplevel vars with Param nodes (this IS possible in VALUES) */
495 if (root->query_level > 1)
496 expr = SS_replace_correlation_vars(root, expr);
499 * If it's a qual or havingQual, convert it to implicit-AND format. (We
500 * don't want to do this before eval_const_expressions, since the latter
501 * would be unable to simplify a top-level AND correctly. Also,
502 * SS_process_sublinks expects explicit-AND format.)
504 if (kind == EXPRKIND_QUAL)
505 expr = (Node *) make_ands_implicit((Expr *) expr);
511 * preprocess_qual_conditions
512 * Recursively scan the query's jointree and do subquery_planner's
513 * preprocessing work on each qual condition found therein.
516 preprocess_qual_conditions(PlannerInfo *root, Node *jtnode)
520 if (IsA(jtnode, RangeTblRef))
522 /* nothing to do here */
524 else if (IsA(jtnode, FromExpr))
526 FromExpr *f = (FromExpr *) jtnode;
529 foreach(l, f->fromlist)
530 preprocess_qual_conditions(root, lfirst(l));
532 f->quals = preprocess_expression(root, f->quals, EXPRKIND_QUAL);
534 else if (IsA(jtnode, JoinExpr))
536 JoinExpr *j = (JoinExpr *) jtnode;
538 preprocess_qual_conditions(root, j->larg);
539 preprocess_qual_conditions(root, j->rarg);
541 j->quals = preprocess_expression(root, j->quals, EXPRKIND_QUAL);
544 elog(ERROR, "unrecognized node type: %d",
545 (int) nodeTag(jtnode));
549 * inheritance_planner
550 * Generate a plan in the case where the result relation is an
553 * We have to handle this case differently from cases where a source relation
554 * is an inheritance set. Source inheritance is expanded at the bottom of the
555 * plan tree (see allpaths.c), but target inheritance has to be expanded at
556 * the top. The reason is that for UPDATE, each target relation needs a
557 * different targetlist matching its own column set. Also, for both UPDATE
558 * and DELETE, the executor needs the Append plan node at the top, else it
559 * can't keep track of which table is the current target table. Fortunately,
560 * the UPDATE/DELETE target can never be the nullable side of an outer join,
561 * so it's OK to generate the plan this way.
563 * Returns a query plan.
566 inheritance_planner(PlannerInfo *root)
568 Query *parse = root->parse;
569 int parentRTindex = parse->resultRelation;
570 List *subplans = NIL;
571 List *resultRelations = NIL;
572 List *returningLists = NIL;
578 foreach(l, root->append_rel_list)
580 AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
583 /* append_rel_list contains all append rels; ignore others */
584 if (appinfo->parent_relid != parentRTindex)
588 * Generate modified query with this rel as target. We have to be
589 * prepared to translate varnos in in_info_list as well as in the
592 memcpy(&subroot, root, sizeof(PlannerInfo));
593 subroot.parse = (Query *)
594 adjust_appendrel_attrs((Node *) parse,
596 subroot.in_info_list = (List *)
597 adjust_appendrel_attrs((Node *) root->in_info_list,
599 subroot.init_plans = NIL;
600 /* There shouldn't be any OJ info to translate, as yet */
601 Assert(subroot.oj_info_list == NIL);
604 subplan = grouping_planner(&subroot, 0.0 /* retrieve all tuples */ );
607 * If this child rel was excluded by constraint exclusion, exclude it
610 if (is_dummy_plan(subplan))
613 /* Save rtable and tlist from first rel for use below */
616 rtable = subroot.parse->rtable;
617 tlist = subplan->targetlist;
620 subplans = lappend(subplans, subplan);
622 /* Make sure any initplans from this rel get into the outer list */
623 root->init_plans = list_concat(root->init_plans, subroot.init_plans);
625 /* Build target-relations list for the executor */
626 resultRelations = lappend_int(resultRelations, appinfo->child_relid);
628 /* Build list of per-relation RETURNING targetlists */
629 if (parse->returningList)
631 Assert(list_length(subroot.returningLists) == 1);
632 returningLists = list_concat(returningLists,
633 subroot.returningLists);
637 root->resultRelations = resultRelations;
638 root->returningLists = returningLists;
640 /* Mark result as unordered (probably unnecessary) */
641 root->query_pathkeys = NIL;
644 * If we managed to exclude every child rel, return a dummy plan
647 return (Plan *) make_result(root,
649 (Node *) list_make1(makeBoolConst(false,
654 * Planning might have modified the rangetable, due to changes of the
655 * Query structures inside subquery RTEs. We have to ensure that this
656 * gets propagated back to the master copy. But can't do this until we
657 * are done planning, because all the calls to grouping_planner need
658 * virgin sub-Queries to work from. (We are effectively assuming that
659 * sub-Queries will get planned identically each time, or at least that
660 * the impacts on their rangetables will be the same each time.)
662 * XXX should clean this up someday
664 parse->rtable = rtable;
666 /* Suppress Append if there's only one surviving child rel */
667 if (list_length(subplans) == 1)
668 return (Plan *) linitial(subplans);
670 return (Plan *) make_append(subplans, true, tlist);
673 /*--------------------
675 * Perform planning steps related to grouping, aggregation, etc.
676 * This primarily means adding top-level processing to the basic
677 * query plan produced by query_planner.
679 * tuple_fraction is the fraction of tuples we expect will be retrieved
681 * tuple_fraction is interpreted as follows:
682 * 0: expect all tuples to be retrieved (normal case)
683 * 0 < tuple_fraction < 1: expect the given fraction of tuples available
684 * from the plan to be retrieved
685 * tuple_fraction >= 1: tuple_fraction is the absolute number of tuples
686 * expected to be retrieved (ie, a LIMIT specification)
688 * Returns a query plan. Also, root->query_pathkeys is returned as the
689 * actual output ordering of the plan (in pathkey format).
690 *--------------------
693 grouping_planner(PlannerInfo *root, double tuple_fraction)
695 Query *parse = root->parse;
696 List *tlist = parse->targetList;
697 int64 offset_est = 0;
700 List *current_pathkeys;
702 double dNumGroups = 0;
704 /* Tweak caller-supplied tuple_fraction if have LIMIT/OFFSET */
705 if (parse->limitCount || parse->limitOffset)
706 tuple_fraction = preprocess_limit(root, tuple_fraction,
707 &offset_est, &count_est);
709 if (parse->setOperations)
711 List *set_sortclauses;
714 * If there's a top-level ORDER BY, assume we have to fetch all the
715 * tuples. This might seem too simplistic given all the hackery below
716 * to possibly avoid the sort ... but a nonzero tuple_fraction is only
717 * of use to plan_set_operations() when the setop is UNION ALL, and
718 * the result of UNION ALL is always unsorted.
720 if (parse->sortClause)
721 tuple_fraction = 0.0;
724 * Construct the plan for set operations. The result will not need
725 * any work except perhaps a top-level sort and/or LIMIT.
727 result_plan = plan_set_operations(root, tuple_fraction,
731 * Calculate pathkeys representing the sort order (if any) of the set
732 * operation's result. We have to do this before overwriting the sort
735 current_pathkeys = make_pathkeys_for_sortclauses(root,
737 result_plan->targetlist,
741 * We should not need to call preprocess_targetlist, since we must be
742 * in a SELECT query node. Instead, use the targetlist returned by
743 * plan_set_operations (since this tells whether it returned any
744 * resjunk columns!), and transfer any sort key information from the
747 Assert(parse->commandType == CMD_SELECT);
749 tlist = postprocess_setop_tlist(result_plan->targetlist, tlist);
752 * Can't handle FOR UPDATE/SHARE here (parser should have checked
753 * already, but let's make sure).
757 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
758 errmsg("SELECT FOR UPDATE/SHARE is not allowed with UNION/INTERSECT/EXCEPT")));
761 * Calculate pathkeys that represent result ordering requirements
763 sort_pathkeys = make_pathkeys_for_sortclauses(root,
770 /* No set operations, do regular planning */
772 List *group_pathkeys;
773 AttrNumber *groupColIdx = NULL;
774 Oid *groupOperators = NULL;
775 bool need_tlist_eval = true;
781 AggClauseCounts agg_counts;
782 int numGroupCols = list_length(parse->groupClause);
783 bool use_hashed_grouping = false;
785 MemSet(&agg_counts, 0, sizeof(AggClauseCounts));
787 /* Preprocess targetlist */
788 tlist = preprocess_targetlist(root, tlist);
791 * Generate appropriate target list for subplan; may be different from
792 * tlist if grouping or aggregation is needed.
794 sub_tlist = make_subplanTargetList(root, tlist,
795 &groupColIdx, &need_tlist_eval);
798 * Calculate pathkeys that represent grouping/ordering requirements.
799 * Stash them in PlannerInfo so that query_planner can canonicalize
800 * them after EquivalenceClasses have been formed.
802 root->group_pathkeys =
803 make_pathkeys_for_sortclauses(root,
807 root->sort_pathkeys =
808 make_pathkeys_for_sortclauses(root,
814 * Will need actual number of aggregates for estimating costs.
816 * Note: we do not attempt to detect duplicate aggregates here; a
817 * somewhat-overestimated count is okay for our present purposes.
819 * Note: think not that we can turn off hasAggs if we find no aggs. It
820 * is possible for constant-expression simplification to remove all
821 * explicit references to aggs, but we still have to follow the
822 * aggregate semantics (eg, producing only one output row).
826 count_agg_clauses((Node *) tlist, &agg_counts);
827 count_agg_clauses(parse->havingQual, &agg_counts);
831 * Figure out whether we need a sorted result from query_planner.
833 * If we have a GROUP BY clause, then we want a result sorted properly
834 * for grouping. Otherwise, if there is an ORDER BY clause, we want
835 * to sort by the ORDER BY clause. (Note: if we have both, and ORDER
836 * BY is a superset of GROUP BY, it would be tempting to request sort
837 * by ORDER BY --- but that might just leave us failing to exploit an
838 * available sort order at all. Needs more thought...)
840 if (parse->groupClause)
841 root->query_pathkeys = root->group_pathkeys;
842 else if (parse->sortClause)
843 root->query_pathkeys = root->sort_pathkeys;
845 root->query_pathkeys = NIL;
848 * Generate the best unsorted and presorted paths for this Query (but
849 * note there may not be any presorted path). query_planner will also
850 * estimate the number of groups in the query, and canonicalize all
853 query_planner(root, sub_tlist, tuple_fraction,
854 &cheapest_path, &sorted_path, &dNumGroups);
856 group_pathkeys = root->group_pathkeys;
857 sort_pathkeys = root->sort_pathkeys;
860 * If grouping, extract the grouping operators and decide whether we
861 * want to use hashed grouping.
863 if (parse->groupClause)
865 groupOperators = extract_grouping_ops(parse->groupClause);
866 use_hashed_grouping =
867 choose_hashed_grouping(root, tuple_fraction,
868 cheapest_path, sorted_path,
869 groupOperators, dNumGroups,
872 /* Also convert # groups to long int --- but 'ware overflow! */
873 numGroups = (long) Min(dNumGroups, (double) LONG_MAX);
877 * Select the best path. If we are doing hashed grouping, we will
878 * always read all the input tuples, so use the cheapest-total path.
879 * Otherwise, trust query_planner's decision about which to use.
881 if (use_hashed_grouping || !sorted_path)
882 best_path = cheapest_path;
884 best_path = sorted_path;
887 * Check to see if it's possible to optimize MIN/MAX aggregates. If
888 * so, we will forget all the work we did so far to choose a "regular"
889 * path ... but we had to do it anyway to be able to tell which way is
892 result_plan = optimize_minmax_aggregates(root,
895 if (result_plan != NULL)
898 * optimize_minmax_aggregates generated the full plan, with the
899 * right tlist, and it has no sort order.
901 current_pathkeys = NIL;
906 * Normal case --- create a plan according to query_planner's
909 result_plan = create_plan(root, best_path);
910 current_pathkeys = best_path->pathkeys;
913 * create_plan() returns a plan with just a "flat" tlist of
914 * required Vars. Usually we need to insert the sub_tlist as the
915 * tlist of the top plan node. However, we can skip that if we
916 * determined that whatever query_planner chose to return will be
922 * If the top-level plan node is one that cannot do expression
923 * evaluation, we must insert a Result node to project the
926 if (!is_projection_capable_plan(result_plan))
928 result_plan = (Plan *) make_result(root,
936 * Otherwise, just replace the subplan's flat tlist with
939 result_plan->targetlist = sub_tlist;
943 * Also, account for the cost of evaluation of the sub_tlist.
945 * Up to now, we have only been dealing with "flat" tlists,
946 * containing just Vars. So their evaluation cost is zero
947 * according to the model used by cost_qual_eval() (or if you
948 * prefer, the cost is factored into cpu_tuple_cost). Thus we
949 * can avoid accounting for tlist cost throughout
950 * query_planner() and subroutines. But now we've inserted a
951 * tlist that might contain actual operators, sub-selects, etc
952 * --- so we'd better account for its cost.
954 * Below this point, any tlist eval cost for added-on nodes
955 * should be accounted for as we create those nodes.
956 * Presently, of the node types we can add on, only Agg and
957 * Group project new tlists (the rest just copy their input
958 * tuples) --- so make_agg() and make_group() are responsible
959 * for computing the added cost.
961 cost_qual_eval(&tlist_cost, sub_tlist, root);
962 result_plan->startup_cost += tlist_cost.startup;
963 result_plan->total_cost += tlist_cost.startup +
964 tlist_cost.per_tuple * result_plan->plan_rows;
969 * Since we're using query_planner's tlist and not the one
970 * make_subplanTargetList calculated, we have to refigure any
971 * grouping-column indexes make_subplanTargetList computed.
973 locate_grouping_columns(root, tlist, result_plan->targetlist,
978 * Insert AGG or GROUP node if needed, plus an explicit sort step
981 * HAVING clause, if any, becomes qual of the Agg or Group node.
983 if (use_hashed_grouping)
985 /* Hashed aggregate plan --- no sort needed */
986 result_plan = (Plan *) make_agg(root,
988 (List *) parse->havingQual,
996 /* Hashed aggregation produces randomly-ordered results */
997 current_pathkeys = NIL;
999 else if (parse->hasAggs)
1001 /* Plain aggregate plan --- sort if needed */
1002 AggStrategy aggstrategy;
1004 if (parse->groupClause)
1006 if (!pathkeys_contained_in(group_pathkeys,
1009 result_plan = (Plan *)
1010 make_sort_from_groupcols(root,
1014 current_pathkeys = group_pathkeys;
1016 aggstrategy = AGG_SORTED;
1019 * The AGG node will not change the sort ordering of its
1020 * groups, so current_pathkeys describes the result too.
1025 aggstrategy = AGG_PLAIN;
1026 /* Result will be only one row anyway; no sort order */
1027 current_pathkeys = NIL;
1030 result_plan = (Plan *) make_agg(root,
1032 (List *) parse->havingQual,
1041 else if (parse->groupClause)
1044 * GROUP BY without aggregation, so insert a group node (plus
1045 * the appropriate sort node, if necessary).
1047 * Add an explicit sort if we couldn't make the path come out
1048 * the way the GROUP node needs it.
1050 if (!pathkeys_contained_in(group_pathkeys, current_pathkeys))
1052 result_plan = (Plan *)
1053 make_sort_from_groupcols(root,
1057 current_pathkeys = group_pathkeys;
1060 result_plan = (Plan *) make_group(root,
1062 (List *) parse->havingQual,
1068 /* The Group node won't change sort ordering */
1070 else if (root->hasHavingQual)
1073 * No aggregates, and no GROUP BY, but we have a HAVING qual.
1074 * This is a degenerate case in which we are supposed to emit
1075 * either 0 or 1 row depending on whether HAVING succeeds.
1076 * Furthermore, there cannot be any variables in either HAVING
1077 * or the targetlist, so we actually do not need the FROM
1078 * table at all! We can just throw away the plan-so-far and
1079 * generate a Result node. This is a sufficiently unusual
1080 * corner case that it's not worth contorting the structure of
1081 * this routine to avoid having to generate the plan in the
1084 result_plan = (Plan *) make_result(root,
1089 } /* end of non-minmax-aggregate case */
1090 } /* end of if (setOperations) */
1093 * If we were not able to make the plan come out in the right order, add
1094 * an explicit sort step.
1096 if (parse->sortClause)
1098 if (!pathkeys_contained_in(sort_pathkeys, current_pathkeys))
1100 result_plan = (Plan *) make_sort_from_pathkeys(root,
1103 current_pathkeys = sort_pathkeys;
1108 * If there is a DISTINCT clause, add the UNIQUE node.
1110 if (parse->distinctClause)
1112 result_plan = (Plan *) make_unique(result_plan, parse->distinctClause);
1115 * If there was grouping or aggregation, leave plan_rows as-is (ie,
1116 * assume the result was already mostly unique). If not, use the
1117 * number of distinct-groups calculated by query_planner.
1119 if (!parse->groupClause && !root->hasHavingQual && !parse->hasAggs)
1120 result_plan->plan_rows = dNumGroups;
1124 * Finally, if there is a LIMIT/OFFSET clause, add the LIMIT node.
1126 if (parse->limitCount || parse->limitOffset)
1128 result_plan = (Plan *) make_limit(result_plan,
1136 * Deal with the RETURNING clause if any. It's convenient to pass the
1137 * returningList through setrefs.c now rather than at top level (if we
1138 * waited, handling inherited UPDATE/DELETE would be much harder).
1140 if (parse->returningList)
1144 Assert(parse->resultRelation);
1145 rlist = set_returning_clause_references(parse->returningList,
1147 parse->resultRelation);
1148 root->returningLists = list_make1(rlist);
1151 root->returningLists = NIL;
1153 /* Compute result-relations list if needed */
1154 if (parse->resultRelation)
1155 root->resultRelations = list_make1_int(parse->resultRelation);
1157 root->resultRelations = NIL;
1160 * Return the actual output ordering in query_pathkeys for possible use by
1161 * an outer query level.
1163 root->query_pathkeys = current_pathkeys;
1169 * Detect whether a plan node is a "dummy" plan created when a relation
1170 * is deemed not to need scanning due to constraint exclusion.
1172 * Currently, such dummy plans are Result nodes with constant FALSE
1176 is_dummy_plan(Plan *plan)
1178 if (IsA(plan, Result))
1180 List *rcqual = (List *) ((Result *) plan)->resconstantqual;
1182 if (list_length(rcqual) == 1)
1184 Const *constqual = (Const *) linitial(rcqual);
1186 if (constqual && IsA(constqual, Const))
1188 if (!constqual->constisnull &&
1189 !DatumGetBool(constqual->constvalue))
1198 * preprocess_limit - do pre-estimation for LIMIT and/or OFFSET clauses
1200 * We try to estimate the values of the LIMIT/OFFSET clauses, and pass the
1201 * results back in *count_est and *offset_est. These variables are set to
1202 * 0 if the corresponding clause is not present, and -1 if it's present
1203 * but we couldn't estimate the value for it. (The "0" convention is OK
1204 * for OFFSET but a little bit bogus for LIMIT: effectively we estimate
1205 * LIMIT 0 as though it were LIMIT 1. But this is in line with the planner's
1206 * usual practice of never estimating less than one row.) These values will
1207 * be passed to make_limit, which see if you change this code.
1209 * The return value is the suitably adjusted tuple_fraction to use for
1210 * planning the query. This adjustment is not overridable, since it reflects
1211 * plan actions that grouping_planner() will certainly take, not assumptions
1215 preprocess_limit(PlannerInfo *root, double tuple_fraction,
1216 int64 *offset_est, int64 *count_est)
1218 Query *parse = root->parse;
1220 double limit_fraction;
1222 /* Should not be called unless LIMIT or OFFSET */
1223 Assert(parse->limitCount || parse->limitOffset);
1226 * Try to obtain the clause values. We use estimate_expression_value
1227 * primarily because it can sometimes do something useful with Params.
1229 if (parse->limitCount)
1231 est = estimate_expression_value(root, parse->limitCount);
1232 if (est && IsA(est, Const))
1234 if (((Const *) est)->constisnull)
1236 /* NULL indicates LIMIT ALL, ie, no limit */
1237 *count_est = 0; /* treat as not present */
1241 *count_est = DatumGetInt64(((Const *) est)->constvalue);
1242 if (*count_est <= 0)
1243 *count_est = 1; /* force to at least 1 */
1247 *count_est = -1; /* can't estimate */
1250 *count_est = 0; /* not present */
1252 if (parse->limitOffset)
1254 est = estimate_expression_value(root, parse->limitOffset);
1255 if (est && IsA(est, Const))
1257 if (((Const *) est)->constisnull)
1259 /* Treat NULL as no offset; the executor will too */
1260 *offset_est = 0; /* treat as not present */
1264 *offset_est = DatumGetInt64(((Const *) est)->constvalue);
1265 if (*offset_est < 0)
1266 *offset_est = 0; /* less than 0 is same as 0 */
1270 *offset_est = -1; /* can't estimate */
1273 *offset_est = 0; /* not present */
1275 if (*count_est != 0)
1278 * A LIMIT clause limits the absolute number of tuples returned.
1279 * However, if it's not a constant LIMIT then we have to guess; for
1280 * lack of a better idea, assume 10% of the plan's result is wanted.
1282 if (*count_est < 0 || *offset_est < 0)
1284 /* LIMIT or OFFSET is an expression ... punt ... */
1285 limit_fraction = 0.10;
1289 /* LIMIT (plus OFFSET, if any) is max number of tuples needed */
1290 limit_fraction = (double) *count_est + (double) *offset_est;
1294 * If we have absolute limits from both caller and LIMIT, use the
1295 * smaller value; likewise if they are both fractional. If one is
1296 * fractional and the other absolute, we can't easily determine which
1297 * is smaller, but we use the heuristic that the absolute will usually
1300 if (tuple_fraction >= 1.0)
1302 if (limit_fraction >= 1.0)
1305 tuple_fraction = Min(tuple_fraction, limit_fraction);
1309 /* caller absolute, limit fractional; use caller's value */
1312 else if (tuple_fraction > 0.0)
1314 if (limit_fraction >= 1.0)
1316 /* caller fractional, limit absolute; use limit */
1317 tuple_fraction = limit_fraction;
1321 /* both fractional */
1322 tuple_fraction = Min(tuple_fraction, limit_fraction);
1327 /* no info from caller, just use limit */
1328 tuple_fraction = limit_fraction;
1331 else if (*offset_est != 0 && tuple_fraction > 0.0)
1334 * We have an OFFSET but no LIMIT. This acts entirely differently
1335 * from the LIMIT case: here, we need to increase rather than decrease
1336 * the caller's tuple_fraction, because the OFFSET acts to cause more
1337 * tuples to be fetched instead of fewer. This only matters if we got
1338 * a tuple_fraction > 0, however.
1340 * As above, use 10% if OFFSET is present but unestimatable.
1342 if (*offset_est < 0)
1343 limit_fraction = 0.10;
1345 limit_fraction = (double) *offset_est;
1348 * If we have absolute counts from both caller and OFFSET, add them
1349 * together; likewise if they are both fractional. If one is
1350 * fractional and the other absolute, we want to take the larger, and
1351 * we heuristically assume that's the fractional one.
1353 if (tuple_fraction >= 1.0)
1355 if (limit_fraction >= 1.0)
1357 /* both absolute, so add them together */
1358 tuple_fraction += limit_fraction;
1362 /* caller absolute, limit fractional; use limit */
1363 tuple_fraction = limit_fraction;
1368 if (limit_fraction >= 1.0)
1370 /* caller fractional, limit absolute; use caller's value */
1374 /* both fractional, so add them together */
1375 tuple_fraction += limit_fraction;
1376 if (tuple_fraction >= 1.0)
1377 tuple_fraction = 0.0; /* assume fetch all */
1382 return tuple_fraction;
1386 * extract_grouping_ops - make an array of the equality operator OIDs
1387 * for the GROUP BY clause
1390 extract_grouping_ops(List *groupClause)
1392 int numCols = list_length(groupClause);
1394 Oid *groupOperators;
1397 groupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
1399 foreach(glitem, groupClause)
1401 GroupClause *groupcl = (GroupClause *) lfirst(glitem);
1403 groupOperators[colno] = get_equality_op_for_ordering_op(groupcl->sortop);
1404 if (!OidIsValid(groupOperators[colno])) /* shouldn't happen */
1405 elog(ERROR, "could not find equality operator for ordering operator %u",
1410 return groupOperators;
1414 * choose_hashed_grouping - should we use hashed grouping?
1417 choose_hashed_grouping(PlannerInfo *root, double tuple_fraction,
1418 Path *cheapest_path, Path *sorted_path,
1419 Oid *groupOperators, double dNumGroups,
1420 AggClauseCounts *agg_counts)
1422 int numGroupCols = list_length(root->parse->groupClause);
1423 double cheapest_path_rows;
1424 int cheapest_path_width;
1426 List *current_pathkeys;
1432 * Check can't-do-it conditions, including whether the grouping operators
1433 * are hashjoinable. (We assume hashing is OK if they are marked
1434 * oprcanhash. If there isn't actually a supporting hash function,
1435 * the executor will complain at runtime.)
1437 * Executor doesn't support hashed aggregation with DISTINCT aggregates.
1438 * (Doing so would imply storing *all* the input values in the hash table,
1439 * which seems like a certain loser.)
1441 if (!enable_hashagg)
1443 if (agg_counts->numDistinctAggs != 0)
1445 for (i = 0; i < numGroupCols; i++)
1447 if (!op_hashjoinable(groupOperators[i]))
1452 * Don't do it if it doesn't look like the hashtable will fit into
1455 * Beware here of the possibility that cheapest_path->parent is NULL. This
1456 * could happen if user does something silly like SELECT 'foo' GROUP BY 1;
1458 if (cheapest_path->parent)
1460 cheapest_path_rows = cheapest_path->parent->rows;
1461 cheapest_path_width = cheapest_path->parent->width;
1465 cheapest_path_rows = 1; /* assume non-set result */
1466 cheapest_path_width = 100; /* arbitrary */
1469 /* Estimate per-hash-entry space at tuple width... */
1470 hashentrysize = MAXALIGN(cheapest_path_width) + MAXALIGN(sizeof(MinimalTupleData));
1471 /* plus space for pass-by-ref transition values... */
1472 hashentrysize += agg_counts->transitionSpace;
1473 /* plus the per-hash-entry overhead */
1474 hashentrysize += hash_agg_entry_size(agg_counts->numAggs);
1476 if (hashentrysize * dNumGroups > work_mem * 1024L)
1480 * See if the estimated cost is no more than doing it the other way. While
1481 * avoiding the need for sorted input is usually a win, the fact that the
1482 * output won't be sorted may be a loss; so we need to do an actual cost
1485 * We need to consider cheapest_path + hashagg [+ final sort] versus
1486 * either cheapest_path [+ sort] + group or agg [+ final sort] or
1487 * presorted_path + group or agg [+ final sort] where brackets indicate a
1488 * step that may not be needed. We assume query_planner() will have
1489 * returned a presorted path only if it's a winner compared to
1490 * cheapest_path for this purpose.
1492 * These path variables are dummies that just hold cost fields; we don't
1493 * make actual Paths for these steps.
1495 cost_agg(&hashed_p, root, AGG_HASHED, agg_counts->numAggs,
1496 numGroupCols, dNumGroups,
1497 cheapest_path->startup_cost, cheapest_path->total_cost,
1498 cheapest_path_rows);
1499 /* Result of hashed agg is always unsorted */
1500 if (root->sort_pathkeys)
1501 cost_sort(&hashed_p, root, root->sort_pathkeys, hashed_p.total_cost,
1502 dNumGroups, cheapest_path_width);
1506 sorted_p.startup_cost = sorted_path->startup_cost;
1507 sorted_p.total_cost = sorted_path->total_cost;
1508 current_pathkeys = sorted_path->pathkeys;
1512 sorted_p.startup_cost = cheapest_path->startup_cost;
1513 sorted_p.total_cost = cheapest_path->total_cost;
1514 current_pathkeys = cheapest_path->pathkeys;
1516 if (!pathkeys_contained_in(root->group_pathkeys, current_pathkeys))
1518 cost_sort(&sorted_p, root, root->group_pathkeys, sorted_p.total_cost,
1519 cheapest_path_rows, cheapest_path_width);
1520 current_pathkeys = root->group_pathkeys;
1523 if (root->parse->hasAggs)
1524 cost_agg(&sorted_p, root, AGG_SORTED, agg_counts->numAggs,
1525 numGroupCols, dNumGroups,
1526 sorted_p.startup_cost, sorted_p.total_cost,
1527 cheapest_path_rows);
1529 cost_group(&sorted_p, root, numGroupCols, dNumGroups,
1530 sorted_p.startup_cost, sorted_p.total_cost,
1531 cheapest_path_rows);
1532 /* The Agg or Group node will preserve ordering */
1533 if (root->sort_pathkeys &&
1534 !pathkeys_contained_in(root->sort_pathkeys, current_pathkeys))
1535 cost_sort(&sorted_p, root, root->sort_pathkeys, sorted_p.total_cost,
1536 dNumGroups, cheapest_path_width);
1539 * Now make the decision using the top-level tuple fraction. First we
1540 * have to convert an absolute count (LIMIT) into fractional form.
1542 if (tuple_fraction >= 1.0)
1543 tuple_fraction /= dNumGroups;
1545 if (compare_fractional_path_costs(&hashed_p, &sorted_p,
1546 tuple_fraction) < 0)
1548 /* Hashed is cheaper, so use it */
1555 * make_subplanTargetList
1556 * Generate appropriate target list when grouping is required.
1558 * When grouping_planner inserts Aggregate, Group, or Result plan nodes
1559 * above the result of query_planner, we typically want to pass a different
1560 * target list to query_planner than the outer plan nodes should have.
1561 * This routine generates the correct target list for the subplan.
1563 * The initial target list passed from the parser already contains entries
1564 * for all ORDER BY and GROUP BY expressions, but it will not have entries
1565 * for variables used only in HAVING clauses; so we need to add those
1566 * variables to the subplan target list. Also, we flatten all expressions
1567 * except GROUP BY items into their component variables; the other expressions
1568 * will be computed by the inserted nodes rather than by the subplan.
1569 * For example, given a query like
1570 * SELECT a+b,SUM(c+d) FROM table GROUP BY a+b;
1571 * we want to pass this targetlist to the subplan:
1573 * where the a+b target will be used by the Sort/Group steps, and the
1574 * other targets will be used for computing the final results. (In the
1575 * above example we could theoretically suppress the a and b targets and
1576 * pass down only c,d,a+b, but it's not really worth the trouble to
1577 * eliminate simple var references from the subplan. We will avoid doing
1578 * the extra computation to recompute a+b at the outer level; see
1579 * fix_upper_expr() in setrefs.c.)
1581 * If we are grouping or aggregating, *and* there are no non-Var grouping
1582 * expressions, then the returned tlist is effectively dummy; we do not
1583 * need to force it to be evaluated, because all the Vars it contains
1584 * should be present in the output of query_planner anyway.
1586 * 'tlist' is the query's target list.
1587 * 'groupColIdx' receives an array of column numbers for the GROUP BY
1588 * expressions (if there are any) in the subplan's target list.
1589 * 'need_tlist_eval' is set true if we really need to evaluate the
1592 * The result is the targetlist to be passed to the subplan.
1596 make_subplanTargetList(PlannerInfo *root,
1598 AttrNumber **groupColIdx,
1599 bool *need_tlist_eval)
1601 Query *parse = root->parse;
1606 *groupColIdx = NULL;
1609 * If we're not grouping or aggregating, there's nothing to do here;
1610 * query_planner should receive the unmodified target list.
1612 if (!parse->hasAggs && !parse->groupClause && !root->hasHavingQual)
1614 *need_tlist_eval = true;
1619 * Otherwise, start with a "flattened" tlist (having just the vars
1620 * mentioned in the targetlist and HAVING qual --- but not upper- level
1621 * Vars; they will be replaced by Params later on).
1623 sub_tlist = flatten_tlist(tlist);
1624 extravars = pull_var_clause(parse->havingQual, false);
1625 sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
1626 list_free(extravars);
1627 *need_tlist_eval = false; /* only eval if not flat tlist */
1630 * If grouping, create sub_tlist entries for all GROUP BY expressions
1631 * (GROUP BY items that are simple Vars should be in the list already),
1632 * and make an array showing where the group columns are in the sub_tlist.
1634 numCols = list_length(parse->groupClause);
1638 AttrNumber *grpColIdx;
1641 grpColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
1642 *groupColIdx = grpColIdx;
1644 foreach(gl, parse->groupClause)
1646 GroupClause *grpcl = (GroupClause *) lfirst(gl);
1647 Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
1648 TargetEntry *te = NULL;
1651 /* Find or make a matching sub_tlist entry */
1652 foreach(sl, sub_tlist)
1654 te = (TargetEntry *) lfirst(sl);
1655 if (equal(groupexpr, te->expr))
1660 te = makeTargetEntry((Expr *) groupexpr,
1661 list_length(sub_tlist) + 1,
1664 sub_tlist = lappend(sub_tlist, te);
1665 *need_tlist_eval = true; /* it's not flat anymore */
1668 /* and save its resno */
1669 grpColIdx[keyno++] = te->resno;
1677 * locate_grouping_columns
1678 * Locate grouping columns in the tlist chosen by query_planner.
1680 * This is only needed if we don't use the sub_tlist chosen by
1681 * make_subplanTargetList. We have to forget the column indexes found
1682 * by that routine and re-locate the grouping vars in the real sub_tlist.
1685 locate_grouping_columns(PlannerInfo *root,
1688 AttrNumber *groupColIdx)
1694 * No work unless grouping.
1696 if (!root->parse->groupClause)
1698 Assert(groupColIdx == NULL);
1701 Assert(groupColIdx != NULL);
1703 foreach(gl, root->parse->groupClause)
1705 GroupClause *grpcl = (GroupClause *) lfirst(gl);
1706 Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
1707 TargetEntry *te = NULL;
1710 foreach(sl, sub_tlist)
1712 te = (TargetEntry *) lfirst(sl);
1713 if (equal(groupexpr, te->expr))
1717 elog(ERROR, "failed to locate grouping columns");
1719 groupColIdx[keyno++] = te->resno;
1724 * postprocess_setop_tlist
1725 * Fix up targetlist returned by plan_set_operations().
1727 * We need to transpose sort key info from the orig_tlist into new_tlist.
1728 * NOTE: this would not be good enough if we supported resjunk sort keys
1729 * for results of set operations --- then, we'd need to project a whole
1730 * new tlist to evaluate the resjunk columns. For now, just ereport if we
1731 * find any resjunk columns in orig_tlist.
1734 postprocess_setop_tlist(List *new_tlist, List *orig_tlist)
1737 ListCell *orig_tlist_item = list_head(orig_tlist);
1739 foreach(l, new_tlist)
1741 TargetEntry *new_tle = (TargetEntry *) lfirst(l);
1742 TargetEntry *orig_tle;
1744 /* ignore resjunk columns in setop result */
1745 if (new_tle->resjunk)
1748 Assert(orig_tlist_item != NULL);
1749 orig_tle = (TargetEntry *) lfirst(orig_tlist_item);
1750 orig_tlist_item = lnext(orig_tlist_item);
1751 if (orig_tle->resjunk) /* should not happen */
1752 elog(ERROR, "resjunk output columns are not implemented");
1753 Assert(new_tle->resno == orig_tle->resno);
1754 new_tle->ressortgroupref = orig_tle->ressortgroupref;
1756 if (orig_tlist_item != NULL)
1757 elog(ERROR, "resjunk output columns are not implemented");