1 /*-------------------------------------------------------------------------
4 * Routines to find possible search paths for processing a query
6 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
11 * src/backend/optimizer/path/allpaths.c
13 *-------------------------------------------------------------------------
20 #include "catalog/pg_class.h"
21 #include "foreign/fdwapi.h"
22 #include "nodes/nodeFuncs.h"
23 #ifdef OPTIMIZER_DEBUG
24 #include "nodes/print.h"
26 #include "optimizer/clauses.h"
27 #include "optimizer/cost.h"
28 #include "optimizer/geqo.h"
29 #include "optimizer/pathnode.h"
30 #include "optimizer/paths.h"
31 #include "optimizer/plancat.h"
32 #include "optimizer/planner.h"
33 #include "optimizer/prep.h"
34 #include "optimizer/restrictinfo.h"
35 #include "optimizer/var.h"
36 #include "parser/parse_clause.h"
37 #include "parser/parsetree.h"
38 #include "rewrite/rewriteManip.h"
39 #include "utils/lsyscache.h"
42 /* These parameters are set by GUC */
43 bool enable_geqo = false; /* just in case GUC doesn't set it */
46 /* Hook for plugins to replace standard_join_search() */
47 join_search_hook_type join_search_hook = NULL;
50 static void set_base_rel_sizes(PlannerInfo *root);
51 static void set_base_rel_pathlists(PlannerInfo *root);
52 static void set_rel_size(PlannerInfo *root, RelOptInfo *rel,
53 Index rti, RangeTblEntry *rte);
54 static void set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
55 Index rti, RangeTblEntry *rte);
56 static void set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel,
58 static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
60 static void set_foreign_size(PlannerInfo *root, RelOptInfo *rel,
62 static void set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel,
64 static void set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
65 Index rti, RangeTblEntry *rte);
66 static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
67 Index rti, RangeTblEntry *rte);
68 static void generate_mergeappend_paths(PlannerInfo *root, RelOptInfo *rel,
70 List *all_child_pathkeys);
71 static List *accumulate_append_subpath(List *subpaths, Path *path);
72 static void set_dummy_rel_pathlist(RelOptInfo *rel);
73 static void set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
74 Index rti, RangeTblEntry *rte);
75 static void set_function_pathlist(PlannerInfo *root, RelOptInfo *rel,
77 static void set_values_pathlist(PlannerInfo *root, RelOptInfo *rel,
79 static void set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel,
81 static void set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel,
83 static RelOptInfo *make_rel_from_joinlist(PlannerInfo *root, List *joinlist);
84 static bool subquery_is_pushdown_safe(Query *subquery, Query *topquery,
85 bool *differentTypes);
86 static bool recurse_pushdown_safe(Node *setOp, Query *topquery,
87 bool *differentTypes);
88 static void compare_tlist_datatypes(List *tlist, List *colTypes,
89 bool *differentTypes);
90 static bool qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual,
91 bool *differentTypes);
92 static void subquery_push_qual(Query *subquery,
93 RangeTblEntry *rte, Index rti, Node *qual);
94 static void recurse_push_qual(Node *setOp, Query *topquery,
95 RangeTblEntry *rte, Index rti, Node *qual);
100 * Finds all possible access paths for executing a query, returning a
101 * single rel that represents the join of all base rels in the query.
104 make_one_rel(PlannerInfo *root, List *joinlist)
110 * Construct the all_baserels Relids set.
112 root->all_baserels = NULL;
113 for (rti = 1; rti < root->simple_rel_array_size; rti++)
115 RelOptInfo *brel = root->simple_rel_array[rti];
117 /* there may be empty slots corresponding to non-baserel RTEs */
121 Assert(brel->relid == rti); /* sanity check on array */
123 /* ignore RTEs that are "other rels" */
124 if (brel->reloptkind != RELOPT_BASEREL)
127 root->all_baserels = bms_add_member(root->all_baserels, brel->relid);
131 * Generate access paths for the base rels.
133 set_base_rel_sizes(root);
134 set_base_rel_pathlists(root);
137 * Generate access paths for the entire join tree.
139 rel = make_rel_from_joinlist(root, joinlist);
142 * The result should join all and only the query's base rels.
144 Assert(bms_equal(rel->relids, root->all_baserels));
151 * Set the size estimates (rows and widths) for each base-relation entry.
153 * We do this in a separate pass over the base rels so that rowcount
154 * estimates are available for parameterized path generation.
157 set_base_rel_sizes(PlannerInfo *root)
161 for (rti = 1; rti < root->simple_rel_array_size; rti++)
163 RelOptInfo *rel = root->simple_rel_array[rti];
165 /* there may be empty slots corresponding to non-baserel RTEs */
169 Assert(rel->relid == rti); /* sanity check on array */
171 /* ignore RTEs that are "other rels" */
172 if (rel->reloptkind != RELOPT_BASEREL)
175 set_rel_size(root, rel, rti, root->simple_rte_array[rti]);
180 * set_base_rel_pathlists
181 * Finds all paths available for scanning each base-relation entry.
182 * Sequential scan and any available indices are considered.
183 * Each useful path is attached to its relation's 'pathlist' field.
186 set_base_rel_pathlists(PlannerInfo *root)
190 for (rti = 1; rti < root->simple_rel_array_size; rti++)
192 RelOptInfo *rel = root->simple_rel_array[rti];
194 /* there may be empty slots corresponding to non-baserel RTEs */
198 Assert(rel->relid == rti); /* sanity check on array */
200 /* ignore RTEs that are "other rels" */
201 if (rel->reloptkind != RELOPT_BASEREL)
204 set_rel_pathlist(root, rel, rti, root->simple_rte_array[rti]);
210 * Set size estimates for a base relation
213 set_rel_size(PlannerInfo *root, RelOptInfo *rel,
214 Index rti, RangeTblEntry *rte)
216 if (rel->reloptkind == RELOPT_BASEREL &&
217 relation_excluded_by_constraints(root, rel, rte))
220 * We proved we don't need to scan the rel via constraint exclusion,
221 * so set up a single dummy path for it. Here we only check this for
222 * regular baserels; if it's an otherrel, CE was already checked in
223 * set_append_rel_pathlist().
225 * In this case, we go ahead and set up the relation's path right away
226 * instead of leaving it for set_rel_pathlist to do. This is because
227 * we don't have a convention for marking a rel as dummy except by
228 * assigning a dummy path to it.
230 set_dummy_rel_pathlist(rel);
234 /* It's an "append relation", process accordingly */
235 set_append_rel_size(root, rel, rti, rte);
239 switch (rel->rtekind)
242 if (rte->relkind == RELKIND_FOREIGN_TABLE)
245 set_foreign_size(root, rel, rte);
250 set_plain_rel_size(root, rel, rte);
256 * Subqueries don't support making a choice between
257 * parameterized and unparameterized paths, so just go ahead
258 * and build their paths immediately.
260 set_subquery_pathlist(root, rel, rti, rte);
263 set_function_size_estimates(root, rel);
266 set_values_size_estimates(root, rel);
271 * CTEs don't support making a choice between parameterized
272 * and unparameterized paths, so just go ahead and build their
275 if (rte->self_reference)
276 set_worktable_pathlist(root, rel, rte);
278 set_cte_pathlist(root, rel, rte);
281 elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
289 * Build access paths for a base relation
292 set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
293 Index rti, RangeTblEntry *rte)
295 if (IS_DUMMY_REL(rel))
297 /* We already proved the relation empty, so nothing more to do */
301 /* It's an "append relation", process accordingly */
302 set_append_rel_pathlist(root, rel, rti, rte);
306 switch (rel->rtekind)
309 if (rte->relkind == RELKIND_FOREIGN_TABLE)
312 set_foreign_pathlist(root, rel, rte);
317 set_plain_rel_pathlist(root, rel, rte);
321 /* Subquery --- fully handled during set_rel_size */
325 set_function_pathlist(root, rel, rte);
329 set_values_pathlist(root, rel, rte);
332 /* CTE reference --- fully handled during set_rel_size */
335 elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
340 #ifdef OPTIMIZER_DEBUG
341 debug_print_rel(root, rel);
347 * Set size estimates for a plain relation (no subquery, no inheritance)
350 set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
353 * Test any partial indexes of rel for applicability. We must do this
354 * first since partial unique indexes can affect size estimates.
356 check_partial_indexes(root, rel);
358 /* Mark rel with estimated output rows, width, etc */
359 set_baserel_size_estimates(root, rel);
362 * Check to see if we can extract any restriction conditions from join
363 * quals that are OR-of-AND structures. If so, add them to the rel's
364 * restriction list, and redo the above steps.
366 if (create_or_index_quals(root, rel))
368 check_partial_indexes(root, rel);
369 set_baserel_size_estimates(root, rel);
374 * set_plain_rel_pathlist
375 * Build access paths for a plain relation (no subquery, no inheritance)
378 set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
380 Relids required_outer;
383 * We don't support pushing join clauses into the quals of a seqscan, but
384 * it could still have required parameterization due to LATERAL refs in
385 * its tlist. (That can only happen if the seqscan is on a relation
386 * pulled up out of a UNION ALL appendrel.)
388 required_outer = rel->lateral_relids;
390 /* Consider sequential scan */
391 add_path(rel, create_seqscan_path(root, rel, required_outer));
393 /* Consider index scans */
394 create_index_paths(root, rel);
396 /* Consider TID scans */
397 create_tidscan_paths(root, rel);
399 /* Now find the cheapest of the paths for this rel */
405 * Set size estimates for a foreign table RTE
408 set_foreign_size(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
410 /* Mark rel with estimated output rows, width, etc */
411 set_foreign_size_estimates(root, rel);
413 /* Get FDW routine pointers for the rel */
414 rel->fdwroutine = GetFdwRoutineByRelId(rte->relid);
416 /* Let FDW adjust the size estimates, if it can */
417 rel->fdwroutine->GetForeignRelSize(root, rel, rte->relid);
421 * set_foreign_pathlist
422 * Build access paths for a foreign table RTE
425 set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
427 /* Call the FDW's GetForeignPaths function to generate path(s) */
428 rel->fdwroutine->GetForeignPaths(root, rel, rte->relid);
430 /* Select cheapest path */
435 * set_append_rel_size
436 * Set size estimates for an "append relation"
438 * The passed-in rel and RTE represent the entire append relation. The
439 * relation's contents are computed by appending together the output of
440 * the individual member relations. Note that in the inheritance case,
441 * the first member relation is actually the same table as is mentioned in
442 * the parent RTE ... but it has a different RTE and RelOptInfo. This is
443 * a good thing because their outputs are not the same size.
446 set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
447 Index rti, RangeTblEntry *rte)
449 int parentRTindex = rti;
452 double *parent_attrsizes;
457 * Initialize to compute size estimates for whole append relation.
459 * We handle width estimates by weighting the widths of different child
460 * rels proportionally to their number of rows. This is sensible because
461 * the use of width estimates is mainly to compute the total relation
462 * "footprint" if we have to sort or hash it. To do this, we sum the
463 * total equivalent size (in "double" arithmetic) and then divide by the
464 * total rowcount estimate. This is done separately for the total rel
465 * width and each attribute.
467 * Note: if you consider changing this logic, beware that child rels could
468 * have zero rows and/or width, if they were excluded by constraints.
472 nattrs = rel->max_attr - rel->min_attr + 1;
473 parent_attrsizes = (double *) palloc0(nattrs * sizeof(double));
475 foreach(l, root->append_rel_list)
477 AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
479 RangeTblEntry *childRTE;
480 RelOptInfo *childrel;
483 ListCell *parentvars;
486 /* append_rel_list contains all append rels; ignore others */
487 if (appinfo->parent_relid != parentRTindex)
490 childRTindex = appinfo->child_relid;
491 childRTE = root->simple_rte_array[childRTindex];
494 * The child rel's RelOptInfo was already created during
495 * add_base_rels_to_query.
497 childrel = find_base_rel(root, childRTindex);
498 Assert(childrel->reloptkind == RELOPT_OTHER_MEMBER_REL);
501 * We have to copy the parent's targetlist and quals to the child,
502 * with appropriate substitution of variables. However, only the
503 * baserestrictinfo quals are needed before we can check for
504 * constraint exclusion; so do that first and then check to see if we
505 * can disregard this child.
507 * As of 8.4, the child rel's targetlist might contain non-Var
508 * expressions, which means that substitution into the quals could
509 * produce opportunities for const-simplification, and perhaps even
510 * pseudoconstant quals. To deal with this, we strip the RestrictInfo
511 * nodes, do the substitution, do const-simplification, and then
512 * reconstitute the RestrictInfo layer.
514 childquals = get_all_actual_clauses(rel->baserestrictinfo);
515 childquals = (List *) adjust_appendrel_attrs(root,
518 childqual = eval_const_expressions(root, (Node *)
519 make_ands_explicit(childquals));
520 if (childqual && IsA(childqual, Const) &&
521 (((Const *) childqual)->constisnull ||
522 !DatumGetBool(((Const *) childqual)->constvalue)))
525 * Restriction reduces to constant FALSE or constant NULL after
526 * substitution, so this child need not be scanned.
528 set_dummy_rel_pathlist(childrel);
531 childquals = make_ands_implicit((Expr *) childqual);
532 childquals = make_restrictinfos_from_actual_clauses(root,
534 childrel->baserestrictinfo = childquals;
536 if (relation_excluded_by_constraints(root, childrel, childRTE))
539 * This child need not be scanned, so we can omit it from the
542 set_dummy_rel_pathlist(childrel);
547 * CE failed, so finish copying/modifying targetlist and join quals.
549 * Note: the resulting childrel->reltargetlist may contain arbitrary
550 * expressions, which otherwise would not occur in a reltargetlist.
551 * Code that might be looking at an appendrel child must cope with
552 * such. Note in particular that "arbitrary expression" can include
553 * "Var belonging to another relation", due to LATERAL references.
555 childrel->joininfo = (List *)
556 adjust_appendrel_attrs(root,
557 (Node *) rel->joininfo,
559 childrel->reltargetlist = (List *)
560 adjust_appendrel_attrs(root,
561 (Node *) rel->reltargetlist,
565 * We have to make child entries in the EquivalenceClass data
566 * structures as well. This is needed either if the parent
567 * participates in some eclass joins (because we will want to consider
568 * inner-indexscan joins on the individual children) or if the parent
569 * has useful pathkeys (because we should try to build MergeAppend
570 * paths that produce those sort orderings).
572 if (rel->has_eclass_joins || has_useful_pathkeys(root, rel))
573 add_child_rel_equivalences(root, appinfo, rel, childrel);
574 childrel->has_eclass_joins = rel->has_eclass_joins;
577 * Note: we could compute appropriate attr_needed data for the child's
578 * variables, by transforming the parent's attr_needed through the
579 * translated_vars mapping. However, currently there's no need
580 * because attr_needed is only examined for base relations not
581 * otherrels. So we just leave the child's attr_needed empty.
585 * Compute the child's size.
587 set_rel_size(root, childrel, childRTindex, childRTE);
590 * It is possible that constraint exclusion detected a contradiction
591 * within a child subquery, even though we didn't prove one above. If
592 * so, we can skip this child.
594 if (IS_DUMMY_REL(childrel))
598 * Accumulate size information from each live child.
600 if (childrel->rows > 0)
602 parent_rows += childrel->rows;
603 parent_size += childrel->width * childrel->rows;
606 * Accumulate per-column estimates too. We need not do anything
607 * for PlaceHolderVars in the parent list. If child expression
608 * isn't a Var, or we didn't record a width estimate for it, we
609 * have to fall back on a datatype-based estimate.
611 * By construction, child's reltargetlist is 1-to-1 with parent's.
613 forboth(parentvars, rel->reltargetlist,
614 childvars, childrel->reltargetlist)
616 Var *parentvar = (Var *) lfirst(parentvars);
617 Node *childvar = (Node *) lfirst(childvars);
619 if (IsA(parentvar, Var))
621 int pndx = parentvar->varattno - rel->min_attr;
622 int32 child_width = 0;
624 if (IsA(childvar, Var) &&
625 ((Var *) childvar)->varno == childrel->relid)
627 int cndx = ((Var *) childvar)->varattno - childrel->min_attr;
629 child_width = childrel->attr_widths[cndx];
631 if (child_width <= 0)
632 child_width = get_typavgwidth(exprType(childvar),
633 exprTypmod(childvar));
634 Assert(child_width > 0);
635 parent_attrsizes[pndx] += child_width * childrel->rows;
642 * Save the finished size estimates.
644 rel->rows = parent_rows;
649 rel->width = rint(parent_size / parent_rows);
650 for (i = 0; i < nattrs; i++)
651 rel->attr_widths[i] = rint(parent_attrsizes[i] / parent_rows);
654 rel->width = 0; /* attr_widths should be zero already */
657 * Set "raw tuples" count equal to "rows" for the appendrel; needed
658 * because some places assume rel->tuples is valid for any baserel.
660 rel->tuples = parent_rows;
662 pfree(parent_attrsizes);
666 * set_append_rel_pathlist
667 * Build access paths for an "append relation"
670 set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
671 Index rti, RangeTblEntry *rte)
673 int parentRTindex = rti;
674 List *live_childrels = NIL;
675 List *subpaths = NIL;
676 bool subpaths_valid = true;
677 List *all_child_pathkeys = NIL;
678 List *all_child_outers = NIL;
682 * Generate access paths for each member relation, and remember the
683 * cheapest path for each one. Also, identify all pathkeys (orderings)
684 * and parameterizations (required_outer sets) available for the member
687 foreach(l, root->append_rel_list)
689 AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
691 RangeTblEntry *childRTE;
692 RelOptInfo *childrel;
695 /* append_rel_list contains all append rels; ignore others */
696 if (appinfo->parent_relid != parentRTindex)
699 /* Re-locate the child RTE and RelOptInfo */
700 childRTindex = appinfo->child_relid;
701 childRTE = root->simple_rte_array[childRTindex];
702 childrel = root->simple_rel_array[childRTindex];
705 * Compute the child's access paths.
707 set_rel_pathlist(root, childrel, childRTindex, childRTE);
710 * If child is dummy, ignore it.
712 if (IS_DUMMY_REL(childrel))
716 * Child is live, so add it to the live_childrels list for use below.
718 live_childrels = lappend(live_childrels, childrel);
721 * If child has an unparameterized cheapest-total path, add that to
722 * the unparameterized Append path we are constructing for the parent.
723 * If not, there's no workable unparameterized path.
725 if (childrel->cheapest_total_path->param_info == NULL)
726 subpaths = accumulate_append_subpath(subpaths,
727 childrel->cheapest_total_path);
729 subpaths_valid = false;
732 * Collect lists of all the available path orderings and
733 * parameterizations for all the children. We use these as a
734 * heuristic to indicate which sort orderings and parameterizations we
735 * should build Append and MergeAppend paths for.
737 foreach(lcp, childrel->pathlist)
739 Path *childpath = (Path *) lfirst(lcp);
740 List *childkeys = childpath->pathkeys;
741 Relids childouter = PATH_REQ_OUTER(childpath);
743 /* Unsorted paths don't contribute to pathkey list */
744 if (childkeys != NIL)
749 /* Have we already seen this ordering? */
750 foreach(lpk, all_child_pathkeys)
752 List *existing_pathkeys = (List *) lfirst(lpk);
754 if (compare_pathkeys(existing_pathkeys,
755 childkeys) == PATHKEYS_EQUAL)
763 /* No, so add it to all_child_pathkeys */
764 all_child_pathkeys = lappend(all_child_pathkeys,
769 /* Unparameterized paths don't contribute to param-set list */
775 /* Have we already seen this param set? */
776 foreach(lco, all_child_outers)
778 Relids existing_outers = (Relids) lfirst(lco);
780 if (bms_equal(existing_outers, childouter))
788 /* No, so add it to all_child_outers */
789 all_child_outers = lappend(all_child_outers,
797 * If we found unparameterized paths for all children, build an unordered,
798 * unparameterized Append path for the rel. (Note: this is correct even
799 * if we have zero or one live subpath due to constraint exclusion.)
802 add_path(rel, (Path *) create_append_path(rel, subpaths, NULL));
805 * Also build unparameterized MergeAppend paths based on the collected
806 * list of child pathkeys.
809 generate_mergeappend_paths(root, rel, live_childrels,
813 * Build Append paths for each parameterization seen among the child rels.
814 * (This may look pretty expensive, but in most cases of practical
815 * interest, the child rels will expose mostly the same parameterizations,
816 * so that not that many cases actually get considered here.)
818 * The Append node itself cannot enforce quals, so all qual checking must
819 * be done in the child paths. This means that to have a parameterized
820 * Append path, we must have the exact same parameterization for each
821 * child path; otherwise some children might be failing to check the
822 * moved-down quals. To make them match up, we can try to increase the
823 * parameterization of lesser-parameterized paths.
825 foreach(l, all_child_outers)
827 Relids required_outer = (Relids) lfirst(l);
830 /* Select the child paths for an Append with this parameterization */
832 subpaths_valid = true;
833 foreach(lcr, live_childrels)
835 RelOptInfo *childrel = (RelOptInfo *) lfirst(lcr);
836 Path *cheapest_total;
839 get_cheapest_path_for_pathkeys(childrel->pathlist,
843 Assert(cheapest_total != NULL);
845 /* Children must have exactly the desired parameterization */
846 if (!bms_equal(PATH_REQ_OUTER(cheapest_total), required_outer))
848 cheapest_total = reparameterize_path(root, cheapest_total,
849 required_outer, 1.0);
850 if (cheapest_total == NULL)
852 subpaths_valid = false;
857 subpaths = accumulate_append_subpath(subpaths, cheapest_total);
861 add_path(rel, (Path *)
862 create_append_path(rel, subpaths, required_outer));
865 /* Select cheapest paths */
870 * generate_mergeappend_paths
871 * Generate MergeAppend paths for an append relation
873 * Generate a path for each ordering (pathkey list) appearing in
874 * all_child_pathkeys.
876 * We consider both cheapest-startup and cheapest-total cases, ie, for each
877 * interesting ordering, collect all the cheapest startup subpaths and all the
878 * cheapest total paths, and build a MergeAppend path for each case.
880 * We don't currently generate any parameterized MergeAppend paths. While
881 * it would not take much more code here to do so, it's very unclear that it
882 * is worth the planning cycles to investigate such paths: there's little
883 * use for an ordered path on the inside of a nestloop. In fact, it's likely
884 * that the current coding of add_path would reject such paths out of hand,
885 * because add_path gives no credit for sort ordering of parameterized paths,
886 * and a parameterized MergeAppend is going to be more expensive than the
887 * corresponding parameterized Append path. If we ever try harder to support
888 * parameterized mergejoin plans, it might be worth adding support for
889 * parameterized MergeAppends to feed such joins. (See notes in
890 * optimizer/README for why that might not ever happen, though.)
893 generate_mergeappend_paths(PlannerInfo *root, RelOptInfo *rel,
894 List *live_childrels,
895 List *all_child_pathkeys)
899 foreach(lcp, all_child_pathkeys)
901 List *pathkeys = (List *) lfirst(lcp);
902 List *startup_subpaths = NIL;
903 List *total_subpaths = NIL;
904 bool startup_neq_total = false;
907 /* Select the child paths for this ordering... */
908 foreach(lcr, live_childrels)
910 RelOptInfo *childrel = (RelOptInfo *) lfirst(lcr);
911 Path *cheapest_startup,
914 /* Locate the right paths, if they are available. */
916 get_cheapest_path_for_pathkeys(childrel->pathlist,
921 get_cheapest_path_for_pathkeys(childrel->pathlist,
927 * If we can't find any paths with the right order just use the
928 * cheapest-total path; we'll have to sort it later.
930 if (cheapest_startup == NULL || cheapest_total == NULL)
932 cheapest_startup = cheapest_total =
933 childrel->cheapest_total_path;
934 /* Assert we do have an unparameterized path for this child */
935 Assert(cheapest_total->param_info == NULL);
939 * Notice whether we actually have different paths for the
940 * "cheapest" and "total" cases; frequently there will be no point
941 * in two create_merge_append_path() calls.
943 if (cheapest_startup != cheapest_total)
944 startup_neq_total = true;
947 accumulate_append_subpath(startup_subpaths, cheapest_startup);
949 accumulate_append_subpath(total_subpaths, cheapest_total);
952 /* ... and build the MergeAppend paths */
953 add_path(rel, (Path *) create_merge_append_path(root,
958 if (startup_neq_total)
959 add_path(rel, (Path *) create_merge_append_path(root,
968 * accumulate_append_subpath
969 * Add a subpath to the list being built for an Append or MergeAppend
971 * It's possible that the child is itself an Append path, in which case
972 * we can "cut out the middleman" and just add its child paths to our
973 * own list. (We don't try to do this earlier because we need to
974 * apply both levels of transformation to the quals.)
977 accumulate_append_subpath(List *subpaths, Path *path)
979 if (IsA(path, AppendPath))
981 AppendPath *apath = (AppendPath *) path;
983 /* list_copy is important here to avoid sharing list substructure */
984 return list_concat(subpaths, list_copy(apath->subpaths));
987 return lappend(subpaths, path);
991 * set_dummy_rel_pathlist
992 * Build a dummy path for a relation that's been excluded by constraints
994 * Rather than inventing a special "dummy" path type, we represent this as an
995 * AppendPath with no members (see also IS_DUMMY_PATH/IS_DUMMY_REL macros).
998 set_dummy_rel_pathlist(RelOptInfo *rel)
1000 /* Set dummy size estimates --- we leave attr_widths[] as zeroes */
1004 /* Discard any pre-existing paths; no further need for them */
1005 rel->pathlist = NIL;
1007 add_path(rel, (Path *) create_append_path(rel, NIL, NULL));
1009 /* Select cheapest path (pretty easy in this case...) */
1013 /* quick-and-dirty test to see if any joining is needed */
1015 has_multiple_baserels(PlannerInfo *root)
1017 int num_base_rels = 0;
1020 for (rti = 1; rti < root->simple_rel_array_size; rti++)
1022 RelOptInfo *brel = root->simple_rel_array[rti];
1027 /* ignore RTEs that are "other rels" */
1028 if (brel->reloptkind == RELOPT_BASEREL)
1029 if (++num_base_rels > 1)
1036 * set_subquery_pathlist
1037 * Build the (single) access path for a subquery RTE
1039 * We don't currently support generating parameterized paths for subqueries
1040 * by pushing join clauses down into them; it seems too expensive to re-plan
1041 * the subquery multiple times to consider different alternatives. So the
1042 * subquery will have exactly one path. (The path will be parameterized
1043 * if the subquery contains LATERAL references, otherwise not.) Since there's
1044 * no freedom of action here, there's no need for a separate set_subquery_size
1045 * phase: we just make the path right away.
1048 set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
1049 Index rti, RangeTblEntry *rte)
1051 Query *parse = root->parse;
1052 Query *subquery = rte->subquery;
1053 Relids required_outer;
1054 bool *differentTypes;
1055 double tuple_fraction;
1056 PlannerInfo *subroot;
1060 * Must copy the Query so that planning doesn't mess up the RTE contents
1061 * (really really need to fix the planner to not scribble on its input,
1064 subquery = copyObject(subquery);
1067 * If it's a LATERAL subquery, it might contain some Vars of the current
1068 * query level, requiring it to be treated as parameterized, even though
1069 * we don't support pushing down join quals into subqueries.
1071 required_outer = rel->lateral_relids;
1073 /* We need a workspace for keeping track of set-op type coercions */
1074 differentTypes = (bool *)
1075 palloc0((list_length(subquery->targetList) + 1) * sizeof(bool));
1078 * If there are any restriction clauses that have been attached to the
1079 * subquery relation, consider pushing them down to become WHERE or HAVING
1080 * quals of the subquery itself. This transformation is useful because it
1081 * may allow us to generate a better plan for the subquery than evaluating
1082 * all the subquery output rows and then filtering them.
1084 * There are several cases where we cannot push down clauses. Restrictions
1085 * involving the subquery are checked by subquery_is_pushdown_safe().
1086 * Restrictions on individual clauses are checked by
1087 * qual_is_pushdown_safe(). Also, we don't want to push down
1088 * pseudoconstant clauses; better to have the gating node above the
1091 * Also, if the sub-query has the "security_barrier" flag, it means the
1092 * sub-query originated from a view that must enforce row-level security.
1093 * Then we must not push down quals that contain leaky functions.
1095 * Non-pushed-down clauses will get evaluated as qpquals of the
1096 * SubqueryScan node.
1098 * XXX Are there any cases where we want to make a policy decision not to
1099 * push down a pushable qual, because it'd result in a worse plan?
1101 if (rel->baserestrictinfo != NIL &&
1102 subquery_is_pushdown_safe(subquery, subquery, differentTypes))
1104 /* OK to consider pushing down individual quals */
1105 List *upperrestrictlist = NIL;
1108 foreach(l, rel->baserestrictinfo)
1110 RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
1111 Node *clause = (Node *) rinfo->clause;
1113 if (!rinfo->pseudoconstant &&
1114 (!rte->security_barrier ||
1115 !contain_leaky_functions(clause)) &&
1116 qual_is_pushdown_safe(subquery, rti, clause, differentTypes))
1119 subquery_push_qual(subquery, rte, rti, clause);
1123 /* Keep it in the upper query */
1124 upperrestrictlist = lappend(upperrestrictlist, rinfo);
1127 rel->baserestrictinfo = upperrestrictlist;
1130 pfree(differentTypes);
1133 * We can safely pass the outer tuple_fraction down to the subquery if the
1134 * outer level has no joining, aggregation, or sorting to do. Otherwise
1135 * we'd better tell the subquery to plan for full retrieval. (XXX This
1136 * could probably be made more intelligent ...)
1138 if (parse->hasAggs ||
1139 parse->groupClause ||
1140 parse->havingQual ||
1141 parse->distinctClause ||
1142 parse->sortClause ||
1143 has_multiple_baserels(root))
1144 tuple_fraction = 0.0; /* default case */
1146 tuple_fraction = root->tuple_fraction;
1148 /* plan_params should not be in use in current query level */
1149 Assert(root->plan_params == NIL);
1151 /* Generate the plan for the subquery */
1152 rel->subplan = subquery_planner(root->glob, subquery,
1154 false, tuple_fraction,
1156 rel->subroot = subroot;
1158 /* Isolate the params needed by this specific subplan */
1159 rel->subplan_params = root->plan_params;
1160 root->plan_params = NIL;
1163 * It's possible that constraint exclusion proved the subquery empty. If
1164 * so, it's convenient to turn it back into a dummy path so that we will
1165 * recognize appropriate optimizations at this level.
1167 if (is_dummy_plan(rel->subplan))
1169 set_dummy_rel_pathlist(rel);
1173 /* Mark rel with estimated output rows, width, etc */
1174 set_subquery_size_estimates(root, rel);
1176 /* Convert subquery pathkeys to outer representation */
1177 pathkeys = convert_subquery_pathkeys(root, rel, subroot->query_pathkeys);
1179 /* Generate appropriate path */
1180 add_path(rel, create_subqueryscan_path(root, rel, pathkeys, required_outer));
1182 /* Select cheapest path (pretty easy in this case...) */
1187 * set_function_pathlist
1188 * Build the (single) access path for a function RTE
1191 set_function_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
1193 Relids required_outer;
1196 * We don't support pushing join clauses into the quals of a function
1197 * scan, but it could still have required parameterization due to LATERAL
1198 * refs in the function expression.
1200 required_outer = rel->lateral_relids;
1202 /* Generate appropriate path */
1203 add_path(rel, create_functionscan_path(root, rel, required_outer));
1205 /* Select cheapest path (pretty easy in this case...) */
1210 * set_values_pathlist
1211 * Build the (single) access path for a VALUES RTE
1214 set_values_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
1216 Relids required_outer;
1219 * We don't support pushing join clauses into the quals of a values scan,
1220 * but it could still have required parameterization due to LATERAL refs
1221 * in the values expressions.
1223 required_outer = rel->lateral_relids;
1225 /* Generate appropriate path */
1226 add_path(rel, create_valuesscan_path(root, rel, required_outer));
1228 /* Select cheapest path (pretty easy in this case...) */
1234 * Build the (single) access path for a non-self-reference CTE RTE
1236 * There's no need for a separate set_cte_size phase, since we don't
1237 * support join-qual-parameterized paths for CTEs.
1240 set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
1243 PlannerInfo *cteroot;
1248 Relids required_outer;
1251 * Find the referenced CTE, and locate the plan previously made for it.
1253 levelsup = rte->ctelevelsup;
1255 while (levelsup-- > 0)
1257 cteroot = cteroot->parent_root;
1258 if (!cteroot) /* shouldn't happen */
1259 elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
1263 * Note: cte_plan_ids can be shorter than cteList, if we are still working
1264 * on planning the CTEs (ie, this is a side-reference from another CTE).
1265 * So we mustn't use forboth here.
1268 foreach(lc, cteroot->parse->cteList)
1270 CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
1272 if (strcmp(cte->ctename, rte->ctename) == 0)
1276 if (lc == NULL) /* shouldn't happen */
1277 elog(ERROR, "could not find CTE \"%s\"", rte->ctename);
1278 if (ndx >= list_length(cteroot->cte_plan_ids))
1279 elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
1280 plan_id = list_nth_int(cteroot->cte_plan_ids, ndx);
1281 Assert(plan_id > 0);
1282 cteplan = (Plan *) list_nth(root->glob->subplans, plan_id - 1);
1284 /* Mark rel with estimated output rows, width, etc */
1285 set_cte_size_estimates(root, rel, cteplan);
1288 * We don't support pushing join clauses into the quals of a CTE scan, but
1289 * it could still have required parameterization due to LATERAL refs in
1290 * its tlist. (That can only happen if the CTE scan is on a relation
1291 * pulled up out of a UNION ALL appendrel.)
1293 required_outer = rel->lateral_relids;
1295 /* Generate appropriate path */
1296 add_path(rel, create_ctescan_path(root, rel, required_outer));
1298 /* Select cheapest path (pretty easy in this case...) */
1303 * set_worktable_pathlist
1304 * Build the (single) access path for a self-reference CTE RTE
1306 * There's no need for a separate set_worktable_size phase, since we don't
1307 * support join-qual-parameterized paths for CTEs.
1310 set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
1313 PlannerInfo *cteroot;
1315 Relids required_outer;
1318 * We need to find the non-recursive term's plan, which is in the plan
1319 * level that's processing the recursive UNION, which is one level *below*
1320 * where the CTE comes from.
1322 levelsup = rte->ctelevelsup;
1323 if (levelsup == 0) /* shouldn't happen */
1324 elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
1327 while (levelsup-- > 0)
1329 cteroot = cteroot->parent_root;
1330 if (!cteroot) /* shouldn't happen */
1331 elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
1333 cteplan = cteroot->non_recursive_plan;
1334 if (!cteplan) /* shouldn't happen */
1335 elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
1337 /* Mark rel with estimated output rows, width, etc */
1338 set_cte_size_estimates(root, rel, cteplan);
1341 * We don't support pushing join clauses into the quals of a worktable
1342 * scan, but it could still have required parameterization due to LATERAL
1343 * refs in its tlist. (That can only happen if the worktable scan is on a
1344 * relation pulled up out of a UNION ALL appendrel. I'm not sure this is
1345 * actually possible given the restrictions on recursive references, but
1346 * it's easy enough to support.)
1348 required_outer = rel->lateral_relids;
1350 /* Generate appropriate path */
1351 add_path(rel, create_worktablescan_path(root, rel, required_outer));
1353 /* Select cheapest path (pretty easy in this case...) */
1358 * make_rel_from_joinlist
1359 * Build access paths using a "joinlist" to guide the join path search.
1361 * See comments for deconstruct_jointree() for definition of the joinlist
1365 make_rel_from_joinlist(PlannerInfo *root, List *joinlist)
1372 * Count the number of child joinlist nodes. This is the depth of the
1373 * dynamic-programming algorithm we must employ to consider all ways of
1374 * joining the child nodes.
1376 levels_needed = list_length(joinlist);
1378 if (levels_needed <= 0)
1379 return NULL; /* nothing to do? */
1382 * Construct a list of rels corresponding to the child joinlist nodes.
1383 * This may contain both base rels and rels constructed according to
1387 foreach(jl, joinlist)
1389 Node *jlnode = (Node *) lfirst(jl);
1390 RelOptInfo *thisrel;
1392 if (IsA(jlnode, RangeTblRef))
1394 int varno = ((RangeTblRef *) jlnode)->rtindex;
1396 thisrel = find_base_rel(root, varno);
1398 else if (IsA(jlnode, List))
1400 /* Recurse to handle subproblem */
1401 thisrel = make_rel_from_joinlist(root, (List *) jlnode);
1405 elog(ERROR, "unrecognized joinlist node type: %d",
1406 (int) nodeTag(jlnode));
1407 thisrel = NULL; /* keep compiler quiet */
1410 initial_rels = lappend(initial_rels, thisrel);
1413 if (levels_needed == 1)
1416 * Single joinlist node, so we're done.
1418 return (RelOptInfo *) linitial(initial_rels);
1423 * Consider the different orders in which we could join the rels,
1424 * using a plugin, GEQO, or the regular join search code.
1426 * We put the initial_rels list into a PlannerInfo field because
1427 * has_legal_joinclause() needs to look at it (ugly :-().
1429 root->initial_rels = initial_rels;
1431 if (join_search_hook)
1432 return (*join_search_hook) (root, levels_needed, initial_rels);
1433 else if (enable_geqo && levels_needed >= geqo_threshold)
1434 return geqo(root, levels_needed, initial_rels);
1436 return standard_join_search(root, levels_needed, initial_rels);
1441 * standard_join_search
1442 * Find possible joinpaths for a query by successively finding ways
1443 * to join component relations into join relations.
1445 * 'levels_needed' is the number of iterations needed, ie, the number of
1446 * independent jointree items in the query. This is > 1.
1448 * 'initial_rels' is a list of RelOptInfo nodes for each independent
1449 * jointree item. These are the components to be joined together.
1450 * Note that levels_needed == list_length(initial_rels).
1452 * Returns the final level of join relations, i.e., the relation that is
1453 * the result of joining all the original relations together.
1454 * At least one implementation path must be provided for this relation and
1455 * all required sub-relations.
1457 * To support loadable plugins that modify planner behavior by changing the
1458 * join searching algorithm, we provide a hook variable that lets a plugin
1459 * replace or supplement this function. Any such hook must return the same
1460 * final join relation as the standard code would, but it might have a
1461 * different set of implementation paths attached, and only the sub-joinrels
1462 * needed for these paths need have been instantiated.
1464 * Note to plugin authors: the functions invoked during standard_join_search()
1465 * modify root->join_rel_list and root->join_rel_hash. If you want to do more
1466 * than one join-order search, you'll probably need to save and restore the
1467 * original states of those data structures. See geqo_eval() for an example.
1470 standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
1476 * This function cannot be invoked recursively within any one planning
1477 * problem, so join_rel_level[] can't be in use already.
1479 Assert(root->join_rel_level == NULL);
1482 * We employ a simple "dynamic programming" algorithm: we first find all
1483 * ways to build joins of two jointree items, then all ways to build joins
1484 * of three items (from two-item joins and single items), then four-item
1485 * joins, and so on until we have considered all ways to join all the
1486 * items into one rel.
1488 * root->join_rel_level[j] is a list of all the j-item rels. Initially we
1489 * set root->join_rel_level[1] to represent all the single-jointree-item
1492 root->join_rel_level = (List **) palloc0((levels_needed + 1) * sizeof(List *));
1494 root->join_rel_level[1] = initial_rels;
1496 for (lev = 2; lev <= levels_needed; lev++)
1501 * Determine all possible pairs of relations to be joined at this
1502 * level, and build paths for making each one from every available
1503 * pair of lower-level relations.
1505 join_search_one_level(root, lev);
1508 * Do cleanup work on each just-processed rel.
1510 foreach(lc, root->join_rel_level[lev])
1512 rel = (RelOptInfo *) lfirst(lc);
1514 /* Find and save the cheapest paths for this rel */
1517 #ifdef OPTIMIZER_DEBUG
1518 debug_print_rel(root, rel);
1524 * We should have a single rel at the final level.
1526 if (root->join_rel_level[levels_needed] == NIL)
1527 elog(ERROR, "failed to build any %d-way joins", levels_needed);
1528 Assert(list_length(root->join_rel_level[levels_needed]) == 1);
1530 rel = (RelOptInfo *) linitial(root->join_rel_level[levels_needed]);
1532 root->join_rel_level = NULL;
1537 /*****************************************************************************
1538 * PUSHING QUALS DOWN INTO SUBQUERIES
1539 *****************************************************************************/
1542 * subquery_is_pushdown_safe - is a subquery safe for pushing down quals?
1544 * subquery is the particular component query being checked. topquery
1545 * is the top component of a set-operations tree (the same Query if no
1546 * set-op is involved).
1548 * Conditions checked here:
1550 * 1. If the subquery has a LIMIT clause, we must not push down any quals,
1551 * since that could change the set of rows returned.
1553 * 2. If the subquery contains any window functions, we can't push quals
1554 * into it, because that could change the results.
1556 * 3. If the subquery contains EXCEPT or EXCEPT ALL set ops we cannot push
1557 * quals into it, because that could change the results.
1559 * 4. For subqueries using UNION/UNION ALL/INTERSECT/INTERSECT ALL, we can
1560 * push quals into each component query, but the quals can only reference
1561 * subquery columns that suffer no type coercions in the set operation.
1562 * Otherwise there are possible semantic gotchas. So, we check the
1563 * component queries to see if any of them have different output types;
1564 * differentTypes[k] is set true if column k has different type in any
1568 subquery_is_pushdown_safe(Query *subquery, Query *topquery,
1569 bool *differentTypes)
1571 SetOperationStmt *topop;
1574 if (subquery->limitOffset != NULL || subquery->limitCount != NULL)
1578 if (subquery->hasWindowFuncs)
1581 /* Are we at top level, or looking at a setop component? */
1582 if (subquery == topquery)
1584 /* Top level, so check any component queries */
1585 if (subquery->setOperations != NULL)
1586 if (!recurse_pushdown_safe(subquery->setOperations, topquery,
1592 /* Setop component must not have more components (too weird) */
1593 if (subquery->setOperations != NULL)
1595 /* Check whether setop component output types match top level */
1596 topop = (SetOperationStmt *) topquery->setOperations;
1597 Assert(topop && IsA(topop, SetOperationStmt));
1598 compare_tlist_datatypes(subquery->targetList,
1606 * Helper routine to recurse through setOperations tree
1609 recurse_pushdown_safe(Node *setOp, Query *topquery,
1610 bool *differentTypes)
1612 if (IsA(setOp, RangeTblRef))
1614 RangeTblRef *rtr = (RangeTblRef *) setOp;
1615 RangeTblEntry *rte = rt_fetch(rtr->rtindex, topquery->rtable);
1616 Query *subquery = rte->subquery;
1618 Assert(subquery != NULL);
1619 return subquery_is_pushdown_safe(subquery, topquery, differentTypes);
1621 else if (IsA(setOp, SetOperationStmt))
1623 SetOperationStmt *op = (SetOperationStmt *) setOp;
1625 /* EXCEPT is no good */
1626 if (op->op == SETOP_EXCEPT)
1629 if (!recurse_pushdown_safe(op->larg, topquery, differentTypes))
1631 if (!recurse_pushdown_safe(op->rarg, topquery, differentTypes))
1636 elog(ERROR, "unrecognized node type: %d",
1637 (int) nodeTag(setOp));
1643 * Compare tlist's datatypes against the list of set-operation result types.
1644 * For any items that are different, mark the appropriate element of
1645 * differentTypes[] to show that this column will have type conversions.
1647 * We don't have to care about typmods here: the only allowed difference
1648 * between set-op input and output typmods is input is a specific typmod
1649 * and output is -1, and that does not require a coercion.
1652 compare_tlist_datatypes(List *tlist, List *colTypes,
1653 bool *differentTypes)
1656 ListCell *colType = list_head(colTypes);
1660 TargetEntry *tle = (TargetEntry *) lfirst(l);
1663 continue; /* ignore resjunk columns */
1664 if (colType == NULL)
1665 elog(ERROR, "wrong number of tlist entries");
1666 if (exprType((Node *) tle->expr) != lfirst_oid(colType))
1667 differentTypes[tle->resno] = true;
1668 colType = lnext(colType);
1670 if (colType != NULL)
1671 elog(ERROR, "wrong number of tlist entries");
1675 * qual_is_pushdown_safe - is a particular qual safe to push down?
1677 * qual is a restriction clause applying to the given subquery (whose RTE
1678 * has index rti in the parent query).
1680 * Conditions checked here:
1682 * 1. The qual must not contain any subselects (mainly because I'm not sure
1683 * it will work correctly: sublinks will already have been transformed into
1684 * subplans in the qual, but not in the subquery).
1686 * 2. The qual must not refer to the whole-row output of the subquery
1687 * (since there is no easy way to name that within the subquery itself).
1689 * 3. The qual must not refer to any subquery output columns that were
1690 * found to have inconsistent types across a set operation tree by
1691 * subquery_is_pushdown_safe().
1693 * 4. If the subquery uses DISTINCT ON, we must not push down any quals that
1694 * refer to non-DISTINCT output columns, because that could change the set
1695 * of rows returned. (This condition is vacuous for DISTINCT, because then
1696 * there are no non-DISTINCT output columns, so we needn't check. But note
1697 * we are assuming that the qual can't distinguish values that the DISTINCT
1698 * operator sees as equal. This is a bit shaky but we have no way to test
1699 * for the case, and it's unlikely enough that we shouldn't refuse the
1700 * optimization just because it could theoretically happen.)
1702 * 5. We must not push down any quals that refer to subselect outputs that
1703 * return sets, else we'd introduce functions-returning-sets into the
1704 * subquery's WHERE/HAVING quals.
1706 * 6. We must not push down any quals that refer to subselect outputs that
1707 * contain volatile functions, for fear of introducing strange results due
1708 * to multiple evaluation of a volatile function.
1711 qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual,
1712 bool *differentTypes)
1717 Bitmapset *tested = NULL;
1719 /* Refuse subselects (point 1) */
1720 if (contain_subplans(qual))
1724 * It would be unsafe to push down window function calls, but at least for
1725 * the moment we could never see any in a qual anyhow. (The same applies
1726 * to aggregates, which we check for in pull_var_clause below.)
1728 Assert(!contain_window_function(qual));
1731 * Examine all Vars used in clause; since it's a restriction clause, all
1732 * such Vars must refer to subselect output columns.
1734 vars = pull_var_clause(qual,
1735 PVC_REJECT_AGGREGATES,
1736 PVC_INCLUDE_PLACEHOLDERS);
1739 Var *var = (Var *) lfirst(vl);
1743 * XXX Punt if we find any PlaceHolderVars in the restriction clause.
1744 * It's not clear whether a PHV could safely be pushed down, and even
1745 * less clear whether such a situation could arise in any cases of
1746 * practical interest anyway. So for the moment, just refuse to push
1755 Assert(var->varno == rti);
1758 if (var->varattno == 0)
1765 * We use a bitmapset to avoid testing the same attno more than once.
1766 * (NB: this only works because subquery outputs can't have negative
1769 if (bms_is_member(var->varattno, tested))
1771 tested = bms_add_member(tested, var->varattno);
1774 if (differentTypes[var->varattno])
1780 /* Must find the tlist element referenced by the Var */
1781 tle = get_tle_by_resno(subquery->targetList, var->varattno);
1782 Assert(tle != NULL);
1783 Assert(!tle->resjunk);
1785 /* If subquery uses DISTINCT ON, check point 4 */
1786 if (subquery->hasDistinctOn &&
1787 !targetIsInSortList(tle, InvalidOid, subquery->distinctClause))
1789 /* non-DISTINCT column, so fail */
1794 /* Refuse functions returning sets (point 5) */
1795 if (expression_returns_set((Node *) tle->expr))
1801 /* Refuse volatile functions (point 6) */
1802 if (contain_volatile_functions((Node *) tle->expr))
1816 * subquery_push_qual - push down a qual that we have determined is safe
1819 subquery_push_qual(Query *subquery, RangeTblEntry *rte, Index rti, Node *qual)
1821 if (subquery->setOperations != NULL)
1823 /* Recurse to push it separately to each component query */
1824 recurse_push_qual(subquery->setOperations, subquery,
1830 * We need to replace Vars in the qual (which must refer to outputs of
1831 * the subquery) with copies of the subquery's targetlist expressions.
1832 * Note that at this point, any uplevel Vars in the qual should have
1833 * been replaced with Params, so they need no work.
1835 * This step also ensures that when we are pushing into a setop tree,
1836 * each component query gets its own copy of the qual.
1838 qual = ResolveNew(qual, rti, 0, rte,
1839 subquery->targetList,
1841 &subquery->hasSubLinks);
1844 * Now attach the qual to the proper place: normally WHERE, but if the
1845 * subquery uses grouping or aggregation, put it in HAVING (since the
1846 * qual really refers to the group-result rows).
1848 if (subquery->hasAggs || subquery->groupClause || subquery->havingQual)
1849 subquery->havingQual = make_and_qual(subquery->havingQual, qual);
1851 subquery->jointree->quals =
1852 make_and_qual(subquery->jointree->quals, qual);
1855 * We need not change the subquery's hasAggs or hasSublinks flags,
1856 * since we can't be pushing down any aggregates that weren't there
1857 * before, and we don't push down subselects at all.
1863 * Helper routine to recurse through setOperations tree
1866 recurse_push_qual(Node *setOp, Query *topquery,
1867 RangeTblEntry *rte, Index rti, Node *qual)
1869 if (IsA(setOp, RangeTblRef))
1871 RangeTblRef *rtr = (RangeTblRef *) setOp;
1872 RangeTblEntry *subrte = rt_fetch(rtr->rtindex, topquery->rtable);
1873 Query *subquery = subrte->subquery;
1875 Assert(subquery != NULL);
1876 subquery_push_qual(subquery, rte, rti, qual);
1878 else if (IsA(setOp, SetOperationStmt))
1880 SetOperationStmt *op = (SetOperationStmt *) setOp;
1882 recurse_push_qual(op->larg, topquery, rte, rti, qual);
1883 recurse_push_qual(op->rarg, topquery, rte, rti, qual);
1887 elog(ERROR, "unrecognized node type: %d",
1888 (int) nodeTag(setOp));
1892 /*****************************************************************************
1894 *****************************************************************************/
1896 #ifdef OPTIMIZER_DEBUG
1899 print_relids(Relids relids)
1905 tmprelids = bms_copy(relids);
1906 while ((x = bms_first_member(tmprelids)) >= 0)
1913 bms_free(tmprelids);
1917 print_restrictclauses(PlannerInfo *root, List *clauses)
1923 RestrictInfo *c = lfirst(l);
1925 print_expr((Node *) c->clause, root->parse->rtable);
1932 print_path(PlannerInfo *root, Path *path, int indent)
1936 Path *subpath = NULL;
1939 switch (nodeTag(path))
1947 case T_BitmapHeapPath:
1948 ptype = "BitmapHeapScan";
1950 case T_BitmapAndPath:
1951 ptype = "BitmapAndPath";
1953 case T_BitmapOrPath:
1954 ptype = "BitmapOrPath";
1960 ptype = "ForeignScan";
1965 case T_MergeAppendPath:
1966 ptype = "MergeAppend";
1971 case T_MaterialPath:
1973 subpath = ((MaterialPath *) path)->subpath;
1977 subpath = ((UniquePath *) path)->subpath;
1984 ptype = "MergeJoin";
1996 for (i = 0; i < indent; i++)
1998 printf("%s", ptype);
2003 print_relids(path->parent->relids);
2004 printf(") rows=%.0f", path->parent->rows);
2006 printf(" cost=%.2f..%.2f\n", path->startup_cost, path->total_cost);
2010 for (i = 0; i < indent; i++)
2012 printf(" pathkeys: ");
2013 print_pathkeys(path->pathkeys, root->parse->rtable);
2018 JoinPath *jp = (JoinPath *) path;
2020 for (i = 0; i < indent; i++)
2022 printf(" clauses: ");
2023 print_restrictclauses(root, jp->joinrestrictinfo);
2026 if (IsA(path, MergePath))
2028 MergePath *mp = (MergePath *) path;
2030 for (i = 0; i < indent; i++)
2032 printf(" sortouter=%d sortinner=%d materializeinner=%d\n",
2033 ((mp->outersortkeys) ? 1 : 0),
2034 ((mp->innersortkeys) ? 1 : 0),
2035 ((mp->materialize_inner) ? 1 : 0));
2038 print_path(root, jp->outerjoinpath, indent + 1);
2039 print_path(root, jp->innerjoinpath, indent + 1);
2043 print_path(root, subpath, indent + 1);
2047 debug_print_rel(PlannerInfo *root, RelOptInfo *rel)
2051 printf("RELOPTINFO (");
2052 print_relids(rel->relids);
2053 printf("): rows=%.0f width=%d\n", rel->rows, rel->width);
2055 if (rel->baserestrictinfo)
2057 printf("\tbaserestrictinfo: ");
2058 print_restrictclauses(root, rel->baserestrictinfo);
2064 printf("\tjoininfo: ");
2065 print_restrictclauses(root, rel->joininfo);
2069 printf("\tpath list:\n");
2070 foreach(l, rel->pathlist)
2071 print_path(root, lfirst(l), 1);
2072 if (rel->cheapest_startup_path)
2074 printf("\n\tcheapest startup path:\n");
2075 print_path(root, rel->cheapest_startup_path, 1);
2077 if (rel->cheapest_total_path)
2079 printf("\n\tcheapest total path:\n");
2080 print_path(root, rel->cheapest_total_path, 1);
2086 #endif /* OPTIMIZER_DEBUG */