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equivclass.c File Reference
#include "postgres.h"#include <limits.h>#include "access/stratnum.h"#include "catalog/pg_type.h"#include "common/hashfn.h"#include "nodes/makefuncs.h"#include "nodes/nodeFuncs.h"#include "optimizer/appendinfo.h"#include "optimizer/clauses.h"#include "optimizer/optimizer.h"#include "optimizer/pathnode.h"#include "optimizer/paths.h"#include "optimizer/planmain.h"#include "optimizer/restrictinfo.h"#include "rewrite/rewriteManip.h"#include "utils/lsyscache.h"#include "lib/simplehash.h"
Include dependency graph for equivclass.c:
Go to the source code of this file.
Data Structures | |
| struct | ECDerivesKey |
| struct | ECDerivesEntry |
Macros | |
| #define | EC_DERIVES_HASH_THRESHOLD 32 |
| #define | SH_PREFIX derives |
| #define | SH_ELEMENT_TYPE ECDerivesEntry |
| #define | SH_KEY_TYPE ECDerivesKey |
| #define | SH_KEY key |
| #define | SH_HASH_KEY(tb, key) hash_bytes((const unsigned char *) &(key), sizeof(ECDerivesKey)) |
| #define | SH_EQUAL(tb, a, b) ((a).em1 == (b).em1 && (a).em2 == (b).em2 && (a).parent_ec == (b).parent_ec) |
| #define | SH_SCOPE static inline |
| #define | SH_DECLARE |
| #define | SH_DEFINE |
Macro Definition Documentation
◆ EC_DERIVES_HASH_THRESHOLD
| #define EC_DERIVES_HASH_THRESHOLD 32 |
Definition at line 124 of file equivclass.c.
◆ SH_DECLARE
| #define SH_DECLARE |
Definition at line 135 of file equivclass.c.
◆ SH_DEFINE
| #define SH_DEFINE |
Definition at line 136 of file equivclass.c.
◆ SH_ELEMENT_TYPE
| #define SH_ELEMENT_TYPE ECDerivesEntry |
Definition at line 127 of file equivclass.c.
◆ SH_EQUAL
| #define SH_EQUAL | ( | tb, | |
| a, | |||
| b | |||
| ) | ((a).em1 == (b).em1 && (a).em2 == (b).em2 && (a).parent_ec == (b).parent_ec) |
Definition at line 132 of file equivclass.c.
182{
185 Oid opno,
186 collation,
187 item1_type,
188 item2_type;
192 item2_relids;
195 *ec2;
196 EquivalenceMember *em1,
197 *em2;
200
201 /* Should not already be marked as having generated an eclass */
204
205 /* Reject if it is potentially postponable by security considerations */
207 return false;
208
209 /* Extract info from given clause */
211 opno = ((OpExpr *) clause)->opno;
212 collation = ((OpExpr *) clause)->inputcollid;
217
218 /*
219 * Ensure both input expressions expose the desired collation (their types
220 * should be OK already); see comments for canonicalize_ec_expression.
221 */
224 collation);
227 collation);
228
229 /*
230 * Clauses of the form X=X cannot be translated into EquivalenceClasses.
231 * We'd either end up with a single-entry EC, losing the knowledge that
232 * the clause was present at all, or else make an EC with duplicate
233 * entries, causing other issues.
234 */
236 {
237 /*
238 * If the operator is strict, then the clause can be treated as just
239 * "X IS NOT NULL". (Since we know we are considering a top-level
240 * qual, we can ignore the difference between FALSE and NULL results.)
241 * It's worth making the conversion because we'll typically get a much
242 * better selectivity estimate than we would for X=X.
243 *
244 * If the operator is not strict, we can't be sure what it will do
245 * with NULLs, so don't attempt to optimize it.
246 */
249 {
251
255 ntest->location = -1;
256
257 *p_restrictinfo =
260 restrictinfo->is_pushed_down,
261 restrictinfo->has_clone,
262 restrictinfo->is_clone,
263 restrictinfo->pseudoconstant,
264 restrictinfo->security_level,
265 NULL,
266 restrictinfo->incompatible_relids,
267 restrictinfo->outer_relids);
268 }
269 return false;
270 }
271
272 /*
273 * We use the declared input types of the operator, not exprType() of the
274 * inputs, as the nominal datatypes for opfamily lookup. This presumes
275 * that btree operators are always registered with amoplefttype and
276 * amoprighttype equal to their declared input types. We will need this
277 * info anyway to build EquivalenceMember nodes, and by extracting it now
278 * we can use type comparisons to short-circuit some equal() tests.
279 */
281
283
284 /*
285 * Sweep through the existing EquivalenceClasses looking for matches to
286 * item1 and item2. These are the possible outcomes:
287 *
288 * 1. We find both in the same EC. The equivalence is already known, so
289 * there's nothing to do.
290 *
291 * 2. We find both in different ECs. Merge the two ECs together.
292 *
293 * 3. We find just one. Add the other to its EC.
294 *
295 * 4. We find neither. Make a new, two-entry EC.
296 *
297 * Note: since all ECs are built through this process or the similar
298 * search in get_eclass_for_sort_expr(), it's impossible that we'd match
299 * an item in more than one existing nonvolatile EC. So it's okay to stop
300 * at the first match.
301 */
303 em1 = em2 = NULL;
304 ec2_idx = -1;
306 {
309
310 /* Never match to a volatile EC */
312 continue;
313
314 /*
315 * The collation has to match; check this first since it's cheaper
316 * than the opfamily comparison.
317 */
319 continue;
320
321 /*
322 * A "match" requires matching sets of btree opfamilies. Use of
323 * equal() for this test has implications discussed in the comments
324 * for get_mergejoin_opfamilies().
325 */
327 continue;
328
329 /* We don't expect any children yet */
331
333 {
335
336 /* Child members should not exist in ec_members */
338
339 /*
340 * Match constants only within the same JoinDomain (see
341 * optimizer/README).
342 */
344 continue;
345
349 {
351 em1 = cur_em;
353 break;
354 }
355
359 {
362 em2 = cur_em;
364 break;
365 }
366 }
367
369 break;
370 }
371
372 /* Sweep finished, what did we find? */
373
375 {
376 /* If case 1, nothing to do, except add to sources */
378 {
381 restrictinfo->security_level);
383 restrictinfo->security_level);
384 /* mark the RI as associated with this eclass */
387 /* mark the RI as usable with this pair of EMs */
388 restrictinfo->left_em = em1;
389 restrictinfo->right_em = em2;
390 return true;
391 }
392
393 /*
394 * Case 2: need to merge ec1 and ec2. This should never happen after
395 * the ECs have reached canonical state; otherwise, pathkeys could be
396 * rendered non-canonical by the merge, and relation eclass indexes
397 * would get broken by removal of an eq_classes list entry.
398 */
401
402 /*
403 * We add ec2's items to ec1, then set ec2's ec_merged link to point
404 * to ec1 and remove ec2 from the eq_classes list. We cannot simply
405 * delete ec2 because that could leave dangling pointers in existing
406 * PathKeys. We leave it behind with a link so that the merged EC can
407 * be found.
408 */
411
412 /*
413 * Appends ec2's derived clauses to ec1->ec_derives_list and adds them
414 * to ec1->ec_derives_hash if present.
415 */
419 /* can't need to set has_volatile */
421 ec2->ec_min_security);
423 ec2->ec_max_security);
426 /* just to avoid debugging confusion w/ dangling pointers: */
433 restrictinfo->security_level);
435 restrictinfo->security_level);
436 /* mark the RI as associated with this eclass */
439 /* mark the RI as usable with this pair of EMs */
440 restrictinfo->left_em = em1;
441 restrictinfo->right_em = em2;
442 }
444 {
445 /* Case 3: add item2 to ec1 */
447 jdomain, item2_type);
450 restrictinfo->security_level);
452 restrictinfo->security_level);
453 /* mark the RI as associated with this eclass */
456 /* mark the RI as usable with this pair of EMs */
457 restrictinfo->left_em = em1;
458 restrictinfo->right_em = em2;
459 }
461 {
462 /* Case 3: add item1 to ec2 */
464 jdomain, item1_type);
467 restrictinfo->security_level);
469 restrictinfo->security_level);
470 /* mark the RI as associated with this eclass */
473 /* mark the RI as usable with this pair of EMs */
474 restrictinfo->left_em = em1;
475 restrictinfo->right_em = em2;
476 }
477 else
478 {
479 /* Case 4: make a new, two-entry EC */
481
483 ec->ec_collation = collation;
484 ec->ec_childmembers_size = 0;
494 ec->ec_sortref = 0;
499 jdomain, item1_type);
501 jdomain, item2_type);
502
504
505 /* mark the RI as associated with this eclass */
506 restrictinfo->left_ec = ec;
507 restrictinfo->right_ec = ec;
508 /* mark the RI as usable with this pair of EMs */
509 restrictinfo->left_em = em1;
510 restrictinfo->right_em = em2;
511 }
512
513 return true;
514}
515
516/*
517 * canonicalize_ec_expression
518 *
519 * This function ensures that the expression exposes the expected type and
520 * collation, so that it will be equal() to other equivalence-class expressions
521 * that it ought to be equal() to.
522 *
523 * The rule for datatypes is that the exposed type should match what it would
524 * be for an input to an operator of the EC's opfamilies; which is usually
525 * the declared input type of the operator, but in the case of polymorphic
526 * operators no relabeling is wanted (compare the behavior of parse_coerce.c).
527 * Expressions coming in from quals will generally have the right type
528 * already, but expressions coming from indexkeys may not (because they are
529 * represented without any explicit relabel in pg_index), and the same problem
530 * occurs for sort expressions (because the parser is likewise cavalier about
531 * putting relabels on them). Such cases will be binary-compatible with the
532 * real operators, so adding a RelabelType is sufficient.
533 *
534 * Also, the expression's exposed collation must match the EC's collation.
535 * This is important because in comparisons like "foo < bar COLLATE baz",
536 * only one of the expressions has the correct exposed collation as we receive
537 * it from the parser. Forcing both of them to have it ensures that all
538 * variant spellings of such a construct behave the same. Again, we can
539 * stick on a RelabelType to force the right exposed collation. (It might
540 * work to not label the collation at all in EC members, but this is risky
541 * since some parts of the system expect exprCollation() to deliver the
542 * right answer for a sort key.)
543 */
544Expr *
546{
548
549 /*
550 * For a polymorphic-input-type opclass, just keep the same exposed type.
551 * RECORD opclasses work like polymorphic-type ones for this purpose.
552 */
555
556 /*
557 * No work if the expression exposes the right type/collation already.
558 */
561 {
562 /*
563 * If we have to change the type of the expression, set typmod to -1,
564 * since the new type may not have the same typmod interpretation.
565 * When we only have to change collation, preserve the exposed typmod.
566 */
568
570 req_typmod = -1;
571 else
573
574 /*
575 * Use applyRelabelType so that we preserve const-flatness. This is
576 * important since eval_const_expressions has already been applied.
577 */
581 }
582
583 return expr;
584}
585
586/*
587 * make_eq_member
588 * Build a new EquivalenceMember without adding it to an EC. If 'parent'
589 * is NULL, the result will be a parent member, otherwise a child member.
590 */
594{
596
597 em->em_expr = expr;
598 em->em_relids = relids;
601 em->em_datatype = datatype;
602 em->em_jdomain = jdomain;
603 em->em_parent = parent;
604
606 {
607 /*
608 * No Vars, assume it's a pseudoconstant. This is correct for entries
609 * generated from process_equivalence(), because a WHERE clause can't
610 * contain aggregates or SRFs, and non-volatility was checked before
611 * process_equivalence() ever got called. But
612 * get_eclass_for_sort_expr() has to work harder. We put the tests
613 * there not here to save cycles in the equivalence case.
614 */
615 Assert(!parent);
618 /* it can't affect ec_relids */
619 }
620
622}
623
624/*
625 * add_eq_member - build a new non-child EquivalenceMember and add it to 'ec'.
626 */
630{
632 NULL, datatype);
633
634 /* add to the members list */
636
637 /* record the relids for parent members */
639
641}
642
643/*
644 * add_child_eq_member
645 * Create an em_is_child=true EquivalenceMember and add it to 'ec'.
646 *
647 * 'root' is the PlannerInfo that 'ec' belongs to.
648 * 'ec' is the EquivalenceClass to add the child member to.
649 * 'ec_index' the index of 'ec' within root->eq_classes, or -1 if maintaining
650 * the RelOptInfo.eclass_indexes isn't needed.
651 * 'expr' is the em_expr for the new member.
652 * 'relids' is the 'em_relids' for the new member.
653 * 'jdomain' is the 'em_jdomain' for the new member.
654 * 'parent_em' is the parent member of the child to create.
655 * 'datatype' is the em_datatype of the new member.
656 * 'child_relid' defines which element of ec_childmembers to add this member
657 * to. This is generally a RELOPT_OTHER_MEMBER_REL, but for set operations
658 * can be a RELOPT_BASEREL representing the set-op children.
659 */
664 Index child_relid)
665{
667
669
670 /*
671 * Allocate the array to store child members; an array of Lists indexed by
672 * relid, or expand the existing one, if necessary.
673 */
675 {
678 else
680 ec->ec_childmembers_size,
681 root->simple_rel_array_size);
682
684 }
685
687
688 /* add member to the ec_childmembers List for the given child_relid */
690
691 /* Record this EC index for the child rel */
693 {
695
698 }
699
701}
702
703
704/*
705 * get_eclass_for_sort_expr
706 * Given an expression and opfamily/collation info, find an existing
707 * equivalence class it is a member of; if none, optionally build a new
708 * single-member EquivalenceClass for it.
709 *
710 * sortref is the SortGroupRef of the originating SortGroupClause, if any,
711 * or zero if not. (It should never be zero if the expression is volatile!)
712 *
713 * If rel is not NULL, it identifies a specific relation we're considering
714 * a path for, and indicates that child EC members for that relation can be
715 * considered. Otherwise child members are ignored. (Note: since child EC
716 * members aren't guaranteed unique, a non-NULL value means that there could
717 * be more than one EC that matches the expression; if so it's order-dependent
718 * which one you get. This is annoying but it only happens in corner cases,
719 * so for now we live with just reporting the first match. See also
720 * generate_implied_equalities_for_column and match_pathkeys_to_index.)
721 *
722 * If create_it is true, we'll build a new EquivalenceClass when there is no
723 * match. If create_it is false, we just return NULL when no match.
724 *
725 * This can be used safely both before and after EquivalenceClass merging;
726 * since it never causes merging it does not invalidate any existing ECs
727 * or PathKeys. However, ECs added after path generation has begun are
728 * of limited usefulness, so usually it's best to create them beforehand.
729 *
730 * Note: opfamilies must be chosen consistently with the way
731 * process_equivalence() would do; that is, generated from a mergejoinable
732 * equality operator. Else we might fail to detect valid equivalences,
733 * generating poor (but not incorrect) plans.
734 */
735EquivalenceClass *
737 Expr *expr,
739 Oid opcintype,
740 Oid collation,
742 Relids rel,
744{
745 JoinDomain *jdomain;
750 MemoryContext oldcontext;
751
752 /*
753 * Ensure the expression exposes the correct type and collation.
754 */
755 expr = canonicalize_ec_expression(expr, opcintype, collation);
756
757 /*
758 * Since SortGroupClause nodes are top-level expressions (GROUP BY, ORDER
759 * BY, etc), they can be presumed to belong to the top JoinDomain.
760 */
762
763 /*
764 * Scan through the existing EquivalenceClasses for a match
765 */
767 {
771
772 /*
773 * Never match to a volatile EC, except when we are looking at another
774 * reference to the same volatile SortGroupClause.
775 */
778 continue;
779
781 continue;
783 continue;
784
787 {
788 /*
789 * Ignore child members unless they match the request.
790 */
793 continue;
794
795 /*
796 * Match constants only within the same JoinDomain (see
797 * optimizer/README).
798 */
800 continue;
801
805 }
806 }
807
808 /* No match; does caller want a NULL result? */
811
812 /*
813 * OK, build a new single-member EC
814 *
815 * Here, we must be sure that we construct the EC in the right context.
816 */
818
821 newec->ec_collation = collation;
822 newec->ec_childmembers_size = 0;
834 newec->ec_max_security = 0;
836
839
840 /*
841 * Get the precise set of relids appearing in the expression.
842 */
844
846 jdomain, opcintype);
847
848 /*
849 * add_eq_member doesn't check for volatile functions, set-returning
850 * functions, aggregates, or window functions, but such could appear in
851 * sort expressions; so we have to check whether its const-marking was
852 * correct.
853 */
855 {
860 {
863 }
864 }
865
867
868 /*
869 * If EC merging is already complete, we have to mop up by adding the new
870 * EC to the eclass_indexes of the relation(s) mentioned in it.
871 */
873 {
876
878 {
880
881 /* ignore the RTE_GROUP RTE */
883 continue;
884
886 {
888 continue;
889 }
890
892
894 ec_index);
895 }
896 }
897
898 MemoryContextSwitchTo(oldcontext);
899
901}
902
903/*
904 * find_ec_member_matching_expr
905 * Locate an EquivalenceClass member matching the given expr, if any;
906 * return NULL if no match.
907 *
908 * "Matching" is defined as "equal after stripping RelabelTypes".
909 * This is used for identifying sort expressions, and we need to allow
910 * binary-compatible relabeling for some cases involving binary-compatible
911 * sort operators.
912 *
913 * Child EC members are ignored unless they belong to given 'relids'.
914 */
915EquivalenceMember *
917 Expr *expr,
918 Relids relids)
919{
922
923 /* We ignore binary-compatible relabeling on both ends */
925 expr = ((RelabelType *) expr)->arg;
926
929 {
931
932 /*
933 * We shouldn't be trying to sort by an equivalence class that
934 * contains a constant, so no need to consider such cases any further.
935 */
937 continue;
938
939 /*
940 * Ignore child members unless they belong to the requested rel.
941 */
944 continue;
945
946 /*
947 * Match if same expression (after stripping relabel).
948 */
952
955 }
956
958}
959
960/*
961 * find_computable_ec_member
962 * Locate an EquivalenceClass member that can be computed from the
963 * expressions appearing in "exprs"; return NULL if no match.
964 *
965 * "exprs" can be either a list of bare expression trees, or a list of
966 * TargetEntry nodes. Typically it will contain Vars and possibly Aggrefs
967 * and WindowFuncs; however, when considering an appendrel member the list
968 * could contain arbitrary expressions. We consider an EC member to be
969 * computable if all the Vars, PlaceHolderVars, Aggrefs, and WindowFuncs
970 * it needs are present in "exprs".
971 *
972 * There is some subtlety in that definition: for example, if an EC member is
973 * Var_A + 1 while what is in "exprs" is Var_A + 2, it's still computable.
974 * This works because in the final plan tree, the EC member's expression will
975 * be computed as part of the same plan node targetlist that is currently
976 * represented by "exprs". So if we have Var_A available for the existing
977 * tlist member, it must be OK to use it in the EC expression too.
978 *
979 * Unlike find_ec_member_matching_expr, there's no special provision here
980 * for binary-compatible relabeling. This is intentional: if we have to
981 * compute an expression in this way, setrefs.c is going to insist on exact
982 * matches of Vars to the source tlist.
983 *
984 * Child EC members are ignored unless they belong to given 'relids'.
985 * Also, non-parallel-safe expressions are ignored if 'require_parallel_safe'.
986 *
987 * Note: some callers pass root == NULL for notational reasons. This is OK
988 * when require_parallel_safe is false.
989 */
990EquivalenceMember *
992 EquivalenceClass *ec,
993 List *exprs,
994 Relids relids,
996{
1000
1001 /*
1002 * Pull out the Vars and quasi-Vars present in "exprs". In the typical
1003 * non-appendrel case, this is just another representation of the same
1004 * list. However, it does remove the distinction between the case of a
1005 * list of plain expressions and a list of TargetEntrys.
1006 */
1008 PVC_INCLUDE_AGGREGATES |
1009 PVC_INCLUDE_WINDOWFUNCS |
1010 PVC_INCLUDE_PLACEHOLDERS);
1011
1014 {
1017
1018 /*
1019 * We shouldn't be trying to sort by an equivalence class that
1020 * contains a constant, so no need to consider such cases any further.
1021 */
1023 continue;
1024
1025 /*
1026 * Ignore child members unless they belong to the requested rel.
1027 */
1030 continue;
1031
1032 /*
1033 * Match if all Vars and quasi-Vars are present in "exprs".
1034 */
1036 PVC_INCLUDE_AGGREGATES |
1037 PVC_INCLUDE_WINDOWFUNCS |
1038 PVC_INCLUDE_PLACEHOLDERS);
1040 {
1042 break;
1043 }
1046 continue; /* we hit a non-available Var */
1047
1048 /*
1049 * If requested, reject expressions that are not parallel-safe. We
1050 * check this last because it's a rather expensive test.
1051 */
1054 continue;
1055
1057 }
1058
1060}
1061
1062/*
1063 * relation_can_be_sorted_early
1064 * Can this relation be sorted on this EC before the final output step?
1065 *
1066 * To succeed, we must find an EC member that prepare_sort_from_pathkeys knows
1067 * how to sort on, given the rel's reltarget as input. There are also a few
1068 * additional constraints based on the fact that the desired sort will be done
1069 * "early", within the scan/join part of the plan. Also, non-parallel-safe
1070 * expressions are ignored if 'require_parallel_safe'.
1071 *
1072 * At some point we might want to return the identified EquivalenceMember,
1073 * but for now, callers only want to know if there is one.
1074 */
1075bool
1078{
1082
1083 /*
1084 * Reject volatile ECs immediately; such sorts must always be postponed.
1085 */
1087 return false;
1088
1089 /*
1090 * Try to find an EM directly matching some reltarget member.
1091 */
1093 {
1095
1098 continue;
1099
1100 /*
1101 * Reject expressions involving set-returning functions, as those
1102 * can't be computed early either. (Note: this test and the following
1103 * one are effectively checking properties of targetexpr, so there's
1104 * no point in asking whether some other EC member would be better.)
1105 */
1107 continue;
1108
1109 /*
1110 * If requested, reject expressions that are not parallel-safe. We
1111 * check this last because it's a rather expensive test.
1112 */
1115 continue;
1116
1117 return true;
1118 }
1119
1120 /*
1121 * Try to find an expression computable from the reltarget.
1122 */
1124 require_parallel_safe);
1126 return false;
1127
1128 /*
1129 * Reject expressions involving set-returning functions, as those can't be
1130 * computed early either. (There's no point in looking for another EC
1131 * member in this case; since SRFs can't appear in WHERE, they cannot
1132 * belong to multi-member ECs.)
1133 */
1135 return false;
1136
1137 return true;
1138}
1139
1140/*
1141 * generate_base_implied_equalities
1142 * Generate any restriction clauses that we can deduce from equivalence
1143 * classes.
1144 *
1145 * When an EC contains pseudoconstants, our strategy is to generate
1146 * "member = const1" clauses where const1 is the first constant member, for
1147 * every other member (including other constants). If we are able to do this
1148 * then we don't need any "var = var" comparisons because we've successfully
1149 * constrained all the vars at their points of creation. If we fail to
1150 * generate any of these clauses due to lack of cross-type operators, we fall
1151 * back to the "ec_broken" strategy described below. (XXX if there are
1152 * multiple constants of different types, it's possible that we might succeed
1153 * in forming all the required clauses if we started from a different const
1154 * member; but this seems a sufficiently hokey corner case to not be worth
1155 * spending lots of cycles on.)
1156 *
1157 * For ECs that contain no pseudoconstants, we generate derived clauses
1158 * "member1 = member2" for each pair of members belonging to the same base
1159 * relation (actually, if there are more than two for the same base relation,
1160 * we only need enough clauses to link each to each other). This provides
1161 * the base case for the recursion: each row emitted by a base relation scan
1162 * will constrain all computable members of the EC to be equal. As each
1163 * join path is formed, we'll add additional derived clauses on-the-fly
1164 * to maintain this invariant (see generate_join_implied_equalities).
1165 *
1166 * If the opfamilies used by the EC do not provide complete sets of cross-type
1167 * equality operators, it is possible that we will fail to generate a clause
1168 * that must be generated to maintain the invariant. (An example: given
1169 * "WHERE a.x = b.y AND b.y = a.z", the scheme breaks down if we cannot
1170 * generate "a.x = a.z" as a restriction clause for A.) In this case we mark
1171 * the EC "ec_broken" and fall back to regurgitating its original source
1172 * RestrictInfos at appropriate times. We do not try to retract any derived
1173 * clauses already generated from the broken EC, so the resulting plan could
1174 * be poor due to bad selectivity estimates caused by redundant clauses. But
1175 * the correct solution to that is to fix the opfamilies ...
1176 *
1177 * Equality clauses derived by this function are passed off to
1178 * process_implied_equality (in plan/initsplan.c) to be inserted into the
1179 * restrictinfo datastructures. Note that this must be called after initial
1180 * scanning of the quals and before Path construction begins.
1181 *
1182 * We make no attempt to avoid generating duplicate RestrictInfos here: we
1183 * don't search existing source or derived clauses in the EC for matches. It
1184 * doesn't really seem worth the trouble to do so.
1185 */
1186void
1188{
1191
1192 /*
1193 * At this point, we're done absorbing knowledge of equivalences in the
1194 * query, so no further EC merging should happen, and ECs remaining in the
1195 * eq_classes list can be considered canonical. (But note that it's still
1196 * possible for new single-member ECs to be added through
1197 * get_eclass_for_sort_expr().)
1198 */
1200
1201 ec_index = 0;
1203 {
1207
1210
1211 /*
1212 * Generate implied equalities that are restriction clauses.
1213 * Single-member ECs won't generate any deductions, either here or at
1214 * the join level.
1215 */
1217 {
1220 else
1222
1223 /* Recover if we failed to generate required derived clauses */
1226
1227 /* Detect whether this EC might generate join clauses */
1228 can_generate_joinclause =
1230 }
1231
1232 /*
1233 * Mark the base rels cited in each eclass (which should all exist by
1234 * now) with the eq_classes indexes of all eclasses mentioning them.
1235 * This will let us avoid searching in subsequent lookups. While
1236 * we're at it, we can mark base rels that have pending eclass joins;
1237 * this is a cheap version of has_relevant_eclass_joinclause().
1238 */
1239 i = -1;
1241 {
1243
1244 /* ignore the RTE_GROUP RTE */
1246 continue;
1247
1249 {
1251 continue;
1252 }
1253
1255
1257 ec_index);
1258
1261 }
1262
1263 ec_index++;
1264 }
1265}
1266
1267/*
1268 * generate_base_implied_equalities when EC contains pseudoconstant(s)
1269 */
1270static void
1272 EquivalenceClass *ec)
1273{
1276
1277 /*
1278 * In the trivial case where we just had one "var = const" clause, push
1279 * the original clause back into the main planner machinery. There is
1280 * nothing to be gained by doing it differently, and we save the effort to
1281 * re-build and re-analyze an equality clause that will be exactly
1282 * equivalent to the old one.
1283 */
1286 {
1288
1290 return;
1291 }
1292
1293 /* We don't expect any children yet */
1295
1296 /*
1297 * Find the constant member to use. We prefer an actual constant to
1298 * pseudo-constants (such as Params), because the constraint exclusion
1299 * machinery might be able to exclude relations on the basis of generated
1300 * "var = const" equalities, but "var = param" won't work for that.
1301 */
1303 {
1305
1307 {
1310 break;
1311 }
1312 }
1314
1315 /* Generate a derived equality against each other member */
1317 {
1320 RestrictInfo *rinfo;
1321
1322 /* Child members should not exist in ec_members */
1325 continue;
1327 cur_em->em_datatype,
1328 const_em->em_datatype);
1330 {
1331 /* failed... */
1333 break;
1334 }
1335
1336 /*
1337 * We use the constant's em_jdomain as qualscope, so that if the
1338 * generated clause is variable-free (i.e, both EMs are consts) it
1339 * will be enforced at the join domain level.
1340 */
1343 const_em->em_jdomain->jd_relids,
1344 ec->ec_min_security,
1345 cur_em->em_is_const);
1346
1347 /*
1348 * If the clause didn't degenerate to a constant, fill in the correct
1349 * markings for a mergejoinable clause, and save it as a derived
1350 * clause. (We will not re-use such clauses directly, but selectivity
1351 * estimation may consult those later. Note that this use of derived
1352 * clauses does not overlap with its use for join clauses, since we
1353 * never generate join clauses from an ec_has_const eclass.)
1354 */
1355 if (rinfo && rinfo->mergeopfamilies)
1356 {
1357 /* it's not redundant, so don't set parent_ec */
1358 rinfo->left_ec = rinfo->right_ec = ec;
1359 rinfo->left_em = cur_em;
1360 rinfo->right_em = const_em;
1361 ec_add_derived_clause(ec, rinfo);
1362 }
1363 }
1364}
1365
1366/*
1367 * generate_base_implied_equalities when EC contains no pseudoconstants
1368 */
1369static void
1371 EquivalenceClass *ec)
1372{
1375
1376 /*
1377 * We scan the EC members once and track the last-seen member for each
1378 * base relation. When we see another member of the same base relation,
1379 * we generate "prev_em = cur_em". This results in the minimum number of
1380 * derived clauses, but it's possible that it will fail when a different
1381 * ordering would succeed. XXX FIXME: use a UNION-FIND algorithm similar
1382 * to the way we build merged ECs. (Use a list-of-lists for each rel.)
1383 */
1386
1387 /* We don't expect any children yet */
1389
1391 {
1393 int relid;
1394
1395 /* Child members should not exist in ec_members */
1397
1399 continue;
1401
1403 {
1406 RestrictInfo *rinfo;
1407
1409 prev_em->em_datatype,
1410 cur_em->em_datatype);
1412 {
1413 /* failed... */
1415 break;
1416 }
1417
1418 /*
1419 * The expressions aren't constants, so the passed qualscope will
1420 * never be used to place the generated clause. We just need to
1421 * be sure it covers both expressions, which em_relids should do.
1422 */
1425 cur_em->em_relids,
1426 ec->ec_min_security,
1427 false);
1428
1429 /*
1430 * If the clause didn't degenerate to a constant, fill in the
1431 * correct markings for a mergejoinable clause. We don't record
1432 * it as a derived clause, since we don't currently need to
1433 * re-find such clauses, and don't want to clutter the
1434 * derived-clause set with non-join clauses.
1435 */
1436 if (rinfo && rinfo->mergeopfamilies)
1437 {
1438 /* it's not redundant, so don't set parent_ec */
1439 rinfo->left_ec = rinfo->right_ec = ec;
1440 rinfo->left_em = prev_em;
1441 rinfo->right_em = cur_em;
1442 }
1443 }
1445 }
1446
1448
1449 /*
1450 * We also have to make sure that all the Vars used in the member clauses
1451 * will be available at any join node we might try to reference them at.
1452 * For the moment we force all the Vars to be available at all join nodes
1453 * for this eclass. Perhaps this could be improved by doing some
1454 * pre-analysis of which members we prefer to join, but it's no worse than
1455 * what happened in the pre-8.3 code. (Note: rebuild_eclass_attr_needed
1456 * needs to match this code.)
1457 */
1459 {
1462 PVC_RECURSE_AGGREGATES |
1463 PVC_RECURSE_WINDOWFUNCS |
1464 PVC_INCLUDE_PLACEHOLDERS);
1465
1468 }
1469}
1470
1471/*
1472 * generate_base_implied_equalities cleanup after failure
1473 *
1474 * What we must do here is push any zero- or one-relation source RestrictInfos
1475 * of the EC back into the main restrictinfo datastructures. Multi-relation
1476 * clauses will be regurgitated later by generate_join_implied_equalities().
1477 * (We do it this way to maintain continuity with the case that ec_broken
1478 * becomes set only after we've gone up a join level or two.) However, for
1479 * an EC that contains constants, we can adopt a simpler strategy and just
1480 * throw back all the source RestrictInfos immediately; that works because
1481 * we know that such an EC can't become broken later. (This rule justifies
1482 * ignoring ec_has_const ECs in generate_join_implied_equalities, even when
1483 * they are broken.)
1484 */
1485static void
1487 EquivalenceClass *ec)
1488{
1490
1492 {
1494
1498 }
1499}
1500
1501
1502/*
1503 * generate_join_implied_equalities
1504 * Generate any join clauses that we can deduce from equivalence classes.
1505 *
1506 * At a join node, we must enforce restriction clauses sufficient to ensure
1507 * that all equivalence-class members computable at that node are equal.
1508 * Since the set of clauses to enforce can vary depending on which subset
1509 * relations are the inputs, we have to compute this afresh for each join
1510 * relation pair. Hence a fresh List of RestrictInfo nodes is built and
1511 * passed back on each call.
1512 *
1513 * In addition to its use at join nodes, this can be applied to generate
1514 * eclass-based join clauses for use in a parameterized scan of a base rel.
1515 * The reason for the asymmetry of specifying the inner rel as a RelOptInfo
1516 * and the outer rel by Relids is that this usage occurs before we have
1517 * built any join RelOptInfos.
1518 *
1519 * An annoying special case for parameterized scans is that the inner rel can
1520 * be an appendrel child (an "other rel"). In this case we must generate
1521 * appropriate clauses using child EC members. add_child_rel_equivalences
1522 * must already have been done for the child rel.
1523 *
1524 * The results are sufficient for use in merge, hash, and plain nestloop join
1525 * methods. We do not worry here about selecting clauses that are optimal
1526 * for use in a parameterized indexscan. indxpath.c makes its own selections
1527 * of clauses to use, and if the ones we pick here are redundant with those,
1528 * the extras will be eliminated at createplan time, using the parent_ec
1529 * markers that we provide (see is_redundant_derived_clause()).
1530 *
1531 * Because the same join clauses are likely to be needed multiple times as
1532 * we consider different join paths, we avoid generating multiple copies:
1533 * whenever we select a particular pair of EquivalenceMembers to join,
1534 * we check to see if the pair matches any original clause (in ec_sources)
1535 * or previously-built derived clause. This saves memory and allows
1536 * re-use of information cached in RestrictInfos. We also avoid generating
1537 * commutative duplicates, i.e. if the algorithm selects "a.x = b.y" but
1538 * we already have "b.y = a.x", we return the existing clause.
1539 *
1540 * If we are considering an outer join, sjinfo is the associated OJ info,
1541 * otherwise it can be NULL.
1542 *
1543 * join_relids should always equal bms_union(outer_relids, inner_rel->relids)
1544 * plus whatever add_outer_joins_to_relids() would add. We could simplify
1545 * this function's API by computing it internally, but most callers have the
1546 * value at hand anyway.
1547 */
1548List *
1550 Relids join_relids,
1551 Relids outer_relids,
1553 SpecialJoinInfo *sjinfo)
1554{
1561
1562 /* If inner rel is a child, extra setup work is needed */
1564 {
1566
1567 /* Fetch relid set for the topmost parent rel */
1569 /* ECs will be marked with the parent's relid, not the child's */
1572 nominal_join_relids,
1573 sjinfo,
1574 NULL);
1575 }
1576 else
1577 {
1579 nominal_join_relids = join_relids;
1580 }
1581
1582 /*
1583 * Examine all potentially-relevant eclasses.
1584 *
1585 * If we are considering an outer join, we must include "join" clauses
1586 * that mention either input rel plus the outer join's relid; these
1587 * represent post-join filter clauses that have to be applied at this
1588 * join. We don't have infrastructure that would let us identify such
1589 * eclasses cheaply, so just fall back to considering all eclasses
1590 * mentioning anything in nominal_join_relids.
1591 *
1592 * At inner joins, we can be smarter: only consider eclasses mentioning
1593 * both input rels.
1594 */
1597 else
1599 outer_relids);
1600
1601 i = -1;
1603 {
1606
1607 /* ECs containing consts do not need any further enforcement */
1609 continue;
1610
1611 /* Single-member ECs won't generate any deductions */
1613 continue;
1614
1615 /* Sanity check that this eclass overlaps the join */
1617
1620 ec,
1621 join_relids,
1622 outer_relids,
1623 inner_relids);
1624
1625 /* Recover if we failed to generate required derived clauses */
1628 ec,
1629 nominal_join_relids,
1630 outer_relids,
1631 nominal_inner_relids,
1632 inner_rel);
1633
1635 }
1636
1637 return result;
1638}
1639
1640/*
1641 * generate_join_implied_equalities_for_ecs
1642 * As above, but consider only the listed ECs.
1643 *
1644 * For the sole current caller, we can assume sjinfo == NULL, that is we are
1645 * not interested in outer-join filter clauses. This might need to change
1646 * in future.
1647 */
1648List *
1651 Relids join_relids,
1652 Relids outer_relids,
1654{
1660
1661 /* If inner rel is a child, extra setup work is needed */
1663 {
1665
1666 /* Fetch relid set for the topmost parent rel */
1668 /* ECs will be marked with the parent's relid, not the child's */
1670 }
1671 else
1672 {
1674 nominal_join_relids = join_relids;
1675 }
1676
1678 {
1681
1682 /* ECs containing consts do not need any further enforcement */
1684 continue;
1685
1686 /* Single-member ECs won't generate any deductions */
1688 continue;
1689
1690 /* We can quickly ignore any that don't overlap the join, too */
1692 continue;
1693
1696 ec,
1697 join_relids,
1698 outer_relids,
1699 inner_relids);
1700
1701 /* Recover if we failed to generate required derived clauses */
1704 ec,
1705 nominal_join_relids,
1706 outer_relids,
1707 nominal_inner_relids,
1708 inner_rel);
1709
1711 }
1712
1713 return result;
1714}
1715
1716/*
1717 * generate_join_implied_equalities for a still-valid EC
1718 */
1721 EquivalenceClass *ec,
1722 Relids join_relids,
1723 Relids outer_relids,
1725{
1732
1733 /*
1734 * First, scan the EC to identify member values that are computable at the
1735 * outer rel, at the inner rel, or at this relation but not in either
1736 * input rel. The outer-rel members should already be enforced equal,
1737 * likewise for the inner-rel members. We'll need to create clauses to
1738 * enforce that any newly computable members are all equal to each other
1739 * as well as to at least one input member, plus enforce at least one
1740 * outer-rel member equal to at least one inner-rel member.
1741 */
1744 {
1745 /*
1746 * We don't need to check explicitly for child EC members. This test
1747 * against join_relids will cause them to be ignored except when
1748 * considering a child inner rel, which is what we want.
1749 */
1751 continue; /* not computable yet, or wrong child */
1752
1757 else
1759 }
1760
1761 /*
1762 * First, select the joinclause if needed. We can equate any one outer
1763 * member to any one inner member, but we have to find a datatype
1764 * combination for which an opfamily member operator exists. If we have
1765 * choices, we prefer simple Var members (possibly with RelabelType) since
1766 * these are (a) cheapest to compute at runtime and (b) most likely to
1767 * have useful statistics. Also, prefer operators that are also
1768 * hashjoinable.
1769 */
1771 {
1776 RestrictInfo *rinfo;
1778
1780 {
1783
1785 {
1789
1791 outer_em->em_datatype,
1792 inner_em->em_datatype);
1794 continue;
1795 score = 0;
1799 score++;
1803 score++;
1806 score++;
1808 {
1814 break; /* no need to look further */
1815 }
1816 }
1818 break; /* no need to look further */
1819 }
1821 {
1822 /* failed... */
1825 }
1826
1827 /*
1828 * Create clause, setting parent_ec to mark it as redundant with other
1829 * joinclauses
1830 */
1833 ec);
1834
1835 result = lappend(result, rinfo);
1836 }
1837
1838 /*
1839 * Now deal with building restrictions for any expressions that involve
1840 * Vars from both sides of the join. We have to equate all of these to
1841 * each other as well as to at least one old member (if any).
1842 *
1843 * XXX as in generate_base_implied_equalities_no_const, we could be a lot
1844 * smarter here to avoid unnecessary failures in cross-type situations.
1845 * For now, use the same left-to-right method used there.
1846 */
1848 {
1851 RestrictInfo *rinfo;
1853
1854 /* For now, arbitrarily take the first old_member as the one to use */
1857
1859 {
1861
1863 {
1865
1867 prev_em->em_datatype,
1868 cur_em->em_datatype);
1870 {
1871 /* failed... */
1874 }
1875 /* do NOT set parent_ec, this qual is not redundant! */
1878 NULL);
1879
1880 result = lappend(result, rinfo);
1881 }
1883 }
1884 }
1885
1886 return result;
1887}
1888
1889/*
1890 * generate_join_implied_equalities cleanup after failure
1891 *
1892 * Return any original RestrictInfos that are enforceable at this join.
1893 *
1894 * In the case of a child inner relation, we have to translate the
1895 * original RestrictInfos from parent to child Vars.
1896 */
1899 EquivalenceClass *ec,
1901 Relids outer_relids,
1904{
1907
1909 {
1912
1917 }
1918
1919 /*
1920 * If we have to translate, just brute-force apply adjust_appendrel_attrs
1921 * to all the RestrictInfos at once. This will result in returning
1922 * RestrictInfos that are not included in EC's derived clauses, but there
1923 * shouldn't be any duplication, and it's a sufficiently narrow corner
1924 * case that we shouldn't sweat too much over it anyway.
1925 *
1926 * Since inner_rel might be an indirect descendant of the baserel
1927 * mentioned in the ec_sources clauses, we have to be prepared to apply
1928 * multiple levels of Var translation.
1929 */
1932 (Node *) result,
1933 inner_rel,
1934 inner_rel->top_parent);
1935
1936 return result;
1937}
1938
1939
1940/*
1941 * select_equality_operator
1942 * Select a suitable equality operator for comparing two EC members
1943 *
1944 * Returns InvalidOid if no operator can be found for this datatype combination
1945 */
1948{
1950
1952 {
1954 Oid opno;
1955
1958 continue;
1959 /* If no barrier quals in query, don't worry about leaky operators */
1961 return opno;
1962 /* Otherwise, insist that selected operators be leakproof */
1964 return opno;
1965 }
1967}
1968
1969
1970/*
1971 * create_join_clause
1972 * Find or make a RestrictInfo comparing the two given EC members
1973 * with the given operator (or, possibly, its commutator, because
1974 * the ordering of the operands in the result is not guaranteed).
1975 *
1976 * parent_ec is either equal to ec (if the clause is a potentially-redundant
1977 * join clause) or NULL (if not). We have to treat this as part of the
1978 * match requirements --- it's possible that a clause comparing the same two
1979 * EMs is a join clause in one join path and a restriction clause in another.
1980 */
1986 EquivalenceClass *parent_ec)
1987{
1988 RestrictInfo *rinfo;
1990 MemoryContext oldcontext;
1991
1993 if (rinfo)
1994 return rinfo;
1995
1996 /*
1997 * Not there, so build it, in planner context so we can re-use it. (Not
1998 * important in normal planning, but definitely so in GEQO.)
1999 */
2001
2002 /*
2003 * If either EM is a child, recursively create the corresponding
2004 * parent-to-parent clause, so that we can duplicate its rinfo_serial.
2005 */
2007 {
2010
2013 parent_ec);
2014 }
2015
2017 opno,
2018 ec->ec_collation,
2019 leftem->em_expr,
2020 rightem->em_expr,
2022 rightem->em_relids),
2023 ec->ec_min_security);
2024
2025 /*
2026 * If either EM is a child, force the clause's clause_relids to include
2027 * the relid(s) of the child rel. In normal cases it would already, but
2028 * not if we are considering appendrel child relations with pseudoconstant
2029 * translated variables (i.e., UNION ALL sub-selects with constant output
2030 * items). We must do this so that join_clause_is_movable_into() will
2031 * think that the clause should be evaluated at the correct place.
2032 */
2034 rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
2035 leftem->em_relids);
2037 rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
2038 rightem->em_relids);
2039
2040 /* If it's a child clause, copy the parent's rinfo_serial */
2043
2044 /* Mark the clause as redundant, or not */
2045 rinfo->parent_ec = parent_ec;
2046
2047 /*
2048 * We know the correct values for left_ec/right_ec, ie this particular EC,
2049 * so we can just set them directly instead of forcing another lookup.
2050 */
2051 rinfo->left_ec = ec;
2052 rinfo->right_ec = ec;
2053
2054 /* Mark it as usable with these EMs */
2055 rinfo->left_em = leftem;
2056 rinfo->right_em = rightem;
2057 /* and save it for possible re-use */
2058 ec_add_derived_clause(ec, rinfo);
2059
2060 MemoryContextSwitchTo(oldcontext);
2061
2062 return rinfo;
2063}
2064
2065
2066/*
2067 * reconsider_outer_join_clauses
2068 * Re-examine any outer-join clauses that were set aside by
2069 * distribute_qual_to_rels(), and see if we can derive any
2070 * EquivalenceClasses from them. Then, if they were not made
2071 * redundant, push them out into the regular join-clause lists.
2072 *
2073 * When we have mergejoinable clauses A = B that are outer-join clauses,
2074 * we can't blindly combine them with other clauses A = C to deduce B = C,
2075 * since in fact the "equality" A = B won't necessarily hold above the
2076 * outer join (one of the variables might be NULL instead). Nonetheless
2077 * there are cases where we can add qual clauses using transitivity.
2078 *
2079 * One case that we look for here is an outer-join clause OUTERVAR = INNERVAR
2080 * for which there is also an equivalence clause OUTERVAR = CONSTANT.
2081 * It is safe and useful to push a clause INNERVAR = CONSTANT into the
2082 * evaluation of the inner (nullable) relation, because any inner rows not
2083 * meeting this condition will not contribute to the outer-join result anyway.
2084 * (Any outer rows they could join to will be eliminated by the pushed-down
2085 * equivalence clause.)
2086 *
2087 * Note that the above rule does not work for full outer joins; nor is it
2088 * very interesting to consider cases where the generated equivalence clause
2089 * would involve relations outside the outer join, since such clauses couldn't
2090 * be pushed into the inner side's scan anyway. So the restriction to
2091 * outervar = pseudoconstant is not really giving up anything.
2092 *
2093 * For full-join cases, we can only do something useful if it's a FULL JOIN
2094 * USING and a merged column has an equivalence MERGEDVAR = CONSTANT.
2095 * By the time it gets here, the merged column will look like
2096 * COALESCE(LEFTVAR, RIGHTVAR)
2097 * and we will have a full-join clause LEFTVAR = RIGHTVAR that we can match
2098 * the COALESCE expression to. In this situation we can push LEFTVAR = CONSTANT
2099 * and RIGHTVAR = CONSTANT into the input relations, since any rows not
2100 * meeting these conditions cannot contribute to the join result.
2101 *
2102 * Again, there isn't any traction to be gained by trying to deal with
2103 * clauses comparing a mergedvar to a non-pseudoconstant. So we can make
2104 * use of the EquivalenceClasses to search for matching variables that were
2105 * equivalenced to constants. The interesting outer-join clauses were
2106 * accumulated for us by distribute_qual_to_rels.
2107 *
2108 * When we find one of these cases, we implement the changes we want by
2109 * generating a new equivalence clause INNERVAR = CONSTANT (or LEFTVAR, etc)
2110 * and pushing it into the EquivalenceClass structures. This is because we
2111 * may already know that INNERVAR is equivalenced to some other var(s), and
2112 * we'd like the constant to propagate to them too. Note that it would be
2113 * unsafe to merge any existing EC for INNERVAR with the OUTERVAR's EC ---
2114 * that could result in propagating constant restrictions from
2115 * INNERVAR to OUTERVAR, which would be very wrong.
2116 *
2117 * It's possible that the INNERVAR is also an OUTERVAR for some other
2118 * outer-join clause, in which case the process can be repeated. So we repeat
2119 * looping over the lists of clauses until no further deductions can be made.
2120 * Whenever we do make a deduction, we remove the generating clause from the
2121 * lists, since we don't want to make the same deduction twice.
2122 *
2123 * If we don't find any match for a set-aside outer join clause, we must
2124 * throw it back into the regular joinclause processing by passing it to
2125 * distribute_restrictinfo_to_rels(). If we do generate a derived clause,
2126 * however, the outer-join clause is redundant. We must still put some
2127 * clause into the regular processing, because otherwise the join will be
2128 * seen as a clauseless join and avoided during join order searching.
2129 * We handle this by generating a constant-TRUE clause that is marked with
2130 * the same required_relids etc as the removed outer-join clause, thus
2131 * making it a join clause between the correct relations.
2132 */
2133void
2135{
2136 bool found;
2137 ListCell *cell;
2138
2139 /* Outer loop repeats until we find no more deductions */
2140 do
2141 {
2142 found = false;
2143
2144 /* Process the LEFT JOIN clauses */
2146 {
2148
2150 {
2152
2153 found = true;
2154 /* remove it from the list */
2155 root->left_join_clauses =
2157 /* throw back a dummy replacement clause (see notes above) */
2160 rinfo->is_pushed_down,
2161 rinfo->has_clone,
2162 rinfo->is_clone,
2163 false, /* pseudoconstant */
2164 0, /* security_level */
2165 rinfo->required_relids,
2166 rinfo->incompatible_relids,
2167 rinfo->outer_relids);
2169 }
2170 }
2171
2172 /* Process the RIGHT JOIN clauses */
2174 {
2176
2178 {
2180
2181 found = true;
2182 /* remove it from the list */
2183 root->right_join_clauses =
2185 /* throw back a dummy replacement clause (see notes above) */
2188 rinfo->is_pushed_down,
2189 rinfo->has_clone,
2190 rinfo->is_clone,
2191 false, /* pseudoconstant */
2192 0, /* security_level */
2193 rinfo->required_relids,
2194 rinfo->incompatible_relids,
2195 rinfo->outer_relids);
2197 }
2198 }
2199
2200 /* Process the FULL JOIN clauses */
2202 {
2204
2206 {
2208
2209 found = true;
2210 /* remove it from the list */
2211 root->full_join_clauses =
2213 /* throw back a dummy replacement clause (see notes above) */
2216 rinfo->is_pushed_down,
2217 rinfo->has_clone,
2218 rinfo->is_clone,
2219 false, /* pseudoconstant */
2220 0, /* security_level */
2221 rinfo->required_relids,
2222 rinfo->incompatible_relids,
2223 rinfo->outer_relids);
2225 }
2226 }
2227 } while (found);
2228
2229 /* Now, any remaining clauses have to be thrown back */
2231 {
2233
2235 }
2237 {
2239
2241 }
2243 {
2245
2247 }
2248}
2249
2250/*
2251 * reconsider_outer_join_clauses for a single LEFT/RIGHT JOIN clause
2252 *
2253 * Returns true if we were able to propagate a constant through the clause.
2254 */
2255static bool
2258{
2262 *innervar;
2263 Oid opno,
2264 collation,
2265 left_type,
2266 right_type,
2267 inner_datatype;
2270
2274
2275 /* Extract needed info from the clause */
2278 {
2282 inner_relids = rinfo->right_relids;
2283 }
2284 else
2285 {
2289 inner_relids = rinfo->left_relids;
2290 }
2291
2292 /* Scan EquivalenceClasses for a match to outervar */
2294 {
2296 bool match;
2298
2299 /* We don't expect any children yet */
2301
2302 /* Ignore EC unless it contains pseudoconstants */
2304 continue;
2305 /* Never match to a volatile EC */
2307 continue;
2308 /* It has to match the outer-join clause as to semantics, too */
2310 continue;
2312 continue;
2313 /* Does it contain a match to outervar? */
2314 match = false;
2316 {
2318
2319 /* Child members should not exist in ec_members */
2322 {
2323 match = true;
2324 break;
2325 }
2326 }
2327 if (!match)
2328 continue; /* no match, so ignore this EC */
2329
2330 /*
2331 * Yes it does! Try to generate a clause INNERVAR = CONSTANT for each
2332 * CONSTANT in the EC. Note that we must succeed with at least one
2333 * constant before we can decide to throw away the outer-join clause.
2334 */
2335 match = false;
2337 {
2341 JoinDomain *jdomain;
2342
2344 continue; /* ignore non-const members */
2346 inner_datatype,
2347 cur_em->em_datatype);
2349 continue; /* can't generate equality */
2351 eq_op,
2352 cur_ec->ec_collation,
2353 innervar,
2354 cur_em->em_expr,
2356 cur_ec->ec_min_security);
2357 /* This equality holds within the OJ's child JoinDomain */
2360 match = true;
2361 }
2362
2363 /*
2364 * If we were able to equate INNERVAR to any constant, report success.
2365 * Otherwise, fall out of the search loop, since we know the OUTERVAR
2366 * appears in at most one EC.
2367 */
2368 if (match)
2369 return true;
2370 else
2371 break;
2372 }
2373
2374 return false; /* failed to make any deduction */
2375}
2376
2377/*
2378 * reconsider_outer_join_clauses for a single FULL JOIN clause
2379 *
2380 * Returns true if we were able to propagate a constant through the clause.
2381 */
2382static bool
2384{
2390 Oid opno,
2391 collation,
2392 left_type,
2393 right_type;
2395 right_relids;
2397
2398 /* Extract needed info from the clause */
2405 left_relids = rinfo->left_relids;
2406 right_relids = rinfo->right_relids;
2407
2409 {
2412 bool match;
2417
2418 /* We don't expect any children yet */
2420
2421 /* Ignore EC unless it contains pseudoconstants */
2423 continue;
2424 /* Never match to a volatile EC */
2426 continue;
2427 /* It has to match the outer-join clause as to semantics, too */
2429 continue;
2431 continue;
2432
2433 /*
2434 * Does it contain a COALESCE(leftvar, rightvar) construct?
2435 *
2436 * We can assume the COALESCE() inputs are in the same order as the
2437 * join clause, since both were automatically generated in the cases
2438 * we care about.
2439 *
2440 * XXX currently this may fail to match in cross-type cases because
2441 * the COALESCE will contain typecast operations while the join clause
2442 * may not (if there is a cross-type mergejoin operator available for
2443 * the two column types). Is it OK to strip implicit coercions from
2444 * the COALESCE arguments?
2445 */
2446 match = false;
2448 {
2450
2451 /* Child members should not exist in ec_members */
2454 {
2458
2460 continue;
2463
2464 /*
2465 * The COALESCE arguments will be marked as possibly nulled by
2466 * the full join, while we wish to generate clauses that apply
2467 * to the join's inputs. So we must strip the join from the
2468 * nullingrels fields of cfirst/csecond before comparing them
2469 * to leftvar/rightvar. (Perhaps with a less hokey
2470 * representation for FULL JOIN USING output columns, this
2471 * wouldn't be needed?)
2472 */
2475
2477 {
2479 match = true;
2480 break;
2481 }
2482 }
2483 }
2484 if (!match)
2485 continue; /* no match, so ignore this EC */
2486
2487 /*
2488 * Yes it does! Try to generate clauses LEFTVAR = CONSTANT and
2489 * RIGHTVAR = CONSTANT for each CONSTANT in the EC. Note that we must
2490 * succeed with at least one constant for each var before we can
2491 * decide to throw away the outer-join clause.
2492 */
2495 {
2499 JoinDomain *jdomain;
2500
2502 continue; /* ignore non-const members */
2504 left_type,
2505 cur_em->em_datatype);
2507 {
2509 eq_op,
2510 cur_ec->ec_collation,
2511 leftvar,
2512 cur_em->em_expr,
2514 cur_ec->ec_min_security);
2515 /* This equality holds within the lefthand child JoinDomain */
2519 }
2521 right_type,
2522 cur_em->em_datatype);
2524 {
2526 eq_op,
2527 cur_ec->ec_collation,
2528 rightvar,
2529 cur_em->em_expr,
2531 cur_ec->ec_min_security);
2532 /* This equality holds within the righthand child JoinDomain */
2536 }
2537 }
2538
2539 /*
2540 * If we were able to equate both vars to constants, we're done, and
2541 * we can throw away the full-join clause as redundant. Moreover, we
2542 * can remove the COALESCE entry from the EC, since the added
2543 * restrictions ensure it will always have the expected value. (We
2544 * don't bother trying to update ec_relids or ec_sources.)
2545 */
2547 {
2549 return true;
2550 }
2551
2552 /*
2553 * Otherwise, fall out of the search loop, since we know the COALESCE
2554 * appears in at most one EC (XXX might stop being true if we allow
2555 * stripping of coercions above?)
2556 */
2557 break;
2558 }
2559
2560 return false; /* failed to make any deduction */
2561}
2562
2563/*
2564 * rebuild_eclass_attr_needed
2565 * Put back attr_needed bits for Vars/PHVs needed for join eclasses.
2566 *
2567 * This is used to rebuild attr_needed/ph_needed sets after removal of a
2568 * useless outer join. It should match what
2569 * generate_base_implied_equalities_no_const did, except that we call
2570 * add_vars_to_attr_needed not add_vars_to_targetlist.
2571 */
2572void
2574{
2576
2578 {
2580
2581 /*
2582 * We don't expect any EC child members to exist at this point. Ensure
2583 * that's the case, otherwise, we might be getting asked to do
2584 * something this function hasn't been coded for.
2585 */
2587
2588 /* Need do anything only for a multi-member, no-const EC. */
2590 {
2592
2594 {
2597 PVC_RECURSE_AGGREGATES |
2598 PVC_RECURSE_WINDOWFUNCS |
2599 PVC_INCLUDE_PLACEHOLDERS);
2600
2603 }
2604 }
2605 }
2606}
2607
2608/*
2609 * find_join_domain
2610 * Find the highest JoinDomain enclosed within the given relid set.
2611 *
2612 * (We could avoid this search at the cost of complicating APIs elsewhere,
2613 * which doesn't seem worth it.)
2614 */
2617{
2619
2621 {
2623
2625 return jdomain;
2626 }
2629}
2630
2631
2632/*
2633 * exprs_known_equal
2634 * Detect whether two expressions are known equal due to equivalence
2635 * relationships.
2636 *
2637 * If opfamily is given, the expressions must be known equal per the semantics
2638 * of that opfamily (note it has to be a btree opfamily, since those are the
2639 * only opfamilies equivclass.c deals with). If opfamily is InvalidOid, we'll
2640 * return true if they're equal according to any opfamily, which is fuzzy but
2641 * OK for estimation purposes.
2642 *
2643 * Note: does not bother to check for "equal(item1, item2)"; caller must
2644 * check that case if it's possible to pass identical items.
2645 */
2646bool
2648{
2650
2652 {
2657
2658 /* Never match to a volatile EC */
2660 continue;
2661
2662 /*
2663 * It's okay to consider ec_broken ECs here. Brokenness just means we
2664 * couldn't derive all the implied clauses we'd have liked to; it does
2665 * not invalidate our knowledge that the members are equal.
2666 */
2667
2668 /* Ignore if this EC doesn't use specified opfamily */
2671 continue;
2672
2673 /* Ignore children here */
2675 {
2677
2678 /* Child members should not exist in ec_members */
2684 /* Exit as soon as equality is proven */
2686 return true;
2687 }
2688 }
2689 return false;
2690}
2691
2692
2693/*
2694 * match_eclasses_to_foreign_key_col
2695 * See whether a foreign key column match is proven by any eclass.
2696 *
2697 * If the referenced and referencing Vars of the fkey's colno'th column are
2698 * known equal due to any eclass, return that eclass; otherwise return NULL.
2699 * (In principle there might be more than one matching eclass if multiple
2700 * collations are involved, but since collation doesn't matter for equality,
2701 * we ignore that fine point here.) This is much like exprs_known_equal,
2702 * except for the format of the input.
2703 *
2704 * On success, we also set fkinfo->eclass[colno] to the matching eclass,
2705 * and set fkinfo->fk_eclass_member[colno] to the eclass member for the
2706 * referencing Var.
2707 */
2708EquivalenceClass *
2711 int colno)
2712{
2723
2724 /* Consider only eclasses mentioning both relations */
2729 rel2->eclass_indexes);
2730
2731 i = -1;
2733 {
2735 i);
2739
2740 /* Never match to a volatile EC */
2742 continue;
2743
2744 /*
2745 * It's okay to consider "broken" ECs here, see exprs_known_equal.
2746 * Ignore children here.
2747 */
2749 {
2751 Var *var;
2752
2753 /* Child members should not exist in ec_members */
2755
2756 /* EM must be a Var, possibly with RelabelType */
2761 continue;
2762
2763 /* Match? */
2768
2769 /* Have we found both PK and FK column in this EC? */
2771 {
2772 /*
2773 * Succeed if eqop matches EC's opfamilies. We could test
2774 * this before scanning the members, but it's probably cheaper
2775 * to test for member matches first.
2776 */
2780 {
2781 fkinfo->eclass[colno] = ec;
2783 return ec;
2784 }
2785 /* Otherwise, done with this EC, move on to the next */
2786 break;
2787 }
2788 }
2789 }
2791}
2792
2793/*
2794 * find_derived_clause_for_ec_member
2795 * Search for a previously-derived clause mentioning the given EM.
2796 *
2797 * The eclass should be an ec_has_const EC, of which the EM is a non-const
2798 * member. This should ensure there is just one derived clause mentioning
2799 * the EM (and equating it to a constant).
2800 * Returns NULL if no such clause can be found.
2801 */
2802RestrictInfo *
2804 EquivalenceClass *ec,
2806{
2809
2811}
2812
2813
2814/*
2815 * add_child_rel_equivalences
2816 * Search for EC members that reference the root parent of child_rel, and
2817 * add transformed members referencing the child_rel.
2818 *
2819 * Note that this function won't be called at all unless we have at least some
2820 * reason to believe that the EC members it generates will be useful.
2821 *
2822 * parent_rel and child_rel could be derived from appinfo, but since the
2823 * caller has already computed them, we might as well just pass them in.
2824 *
2825 * The passed-in AppendRelInfo is not used when the parent_rel is not a
2826 * top-level baserel, since it shows the mapping from the parent_rel but
2827 * we need to translate EC expressions that refer to the top-level parent.
2828 * Using it is faster than using adjust_appendrel_attrs_multilevel(), though,
2829 * so we prefer it when we can.
2830 */
2831void
2836{
2840
2841 /*
2842 * EC merging should be complete already, so we can use the parent rel's
2843 * eclass_indexes to avoid searching all of root->eq_classes.
2844 */
2847
2848 i = -1;
2850 {
2852
2853 /*
2854 * If this EC contains a volatile expression, then generating child
2855 * EMs would be downright dangerous, so skip it. We rely on a
2856 * volatile EC having only one EM.
2857 */
2859 continue;
2860
2861 /* Sanity check eclass_indexes only contain ECs for parent_rel */
2863
2865 {
2867 continue; /* ignore consts here */
2868
2869 /* Child members should not exist in ec_members */
2871
2872 /*
2873 * Consider only members that reference and can be computed at
2874 * child's topmost parent rel. In particular we want to exclude
2875 * parent-rel Vars that have nonempty varnullingrels. Translating
2876 * those might fail, if the transformed expression wouldn't be a
2877 * simple Var; and in any case it wouldn't produce a member that
2878 * has any use in creating plans for the child rel.
2879 */
2882 {
2883 /* OK, generate transformed child version */
2886
2888 {
2889 /* Simple single-level transformation */
2893 1, &appinfo);
2894 }
2895 else
2896 {
2897 /* Must do multi-level transformation */
2901 child_rel,
2902 child_rel->top_parent);
2903 }
2904
2905 /*
2906 * Transform em_relids to match. Note we do *not* do
2907 * pull_varnos(child_expr) here, as for example the
2908 * transformation might have substituted a constant, but we
2909 * don't want the child member to be marked as constant.
2910 */
2912 top_parent_relids);
2914
2916 cur_ec,
2917 i,
2918 child_expr,
2919 new_relids,
2920 cur_em->em_jdomain,
2921 cur_em,
2922 cur_em->em_datatype,
2923 child_rel->relid);
2924 }
2925 }
2926 }
2927}
2928
2929/*
2930 * add_child_join_rel_equivalences
2931 * Like add_child_rel_equivalences(), but for joinrels
2932 *
2933 * Here we find the ECs relevant to the top parent joinrel and add transformed
2934 * member expressions that refer to this child joinrel.
2935 *
2936 * Note that this function won't be called at all unless we have at least some
2937 * reason to believe that the EC members it generates will be useful.
2938 */
2939void
2944{
2948 MemoryContext oldcontext;
2950
2952
2953 /* We need consider only ECs that mention the parent joinrel */
2955
2956 /*
2957 * If we're being called during GEQO join planning, we still have to
2958 * create any new EC members in the main planner context, to avoid having
2959 * a corrupt EC data structure after the GEQO context is reset. This is
2960 * problematic since we'll leak memory across repeated GEQO cycles. For
2961 * now, though, bloat is better than crash. If it becomes a real issue
2962 * we'll have to do something to avoid generating duplicate EC members.
2963 */
2965
2966 i = -1;
2968 {
2970
2971 /*
2972 * If this EC contains a volatile expression, then generating child
2973 * EMs would be downright dangerous, so skip it. We rely on a
2974 * volatile EC having only one EM.
2975 */
2977 continue;
2978
2979 /* Sanity check on get_eclass_indexes_for_relids result */
2981
2983 {
2985 continue; /* ignore consts here */
2986
2987 /* Child members should not exist in ec_members */
2989
2990 /*
2991 * We may ignore expressions that reference a single baserel,
2992 * because add_child_rel_equivalences should have handled them.
2993 */
2995 continue;
2996
2997 /* Does this member reference child's topmost parent rel? */
2999 {
3000 /* Yes, generate transformed child version */
3003
3005 {
3006 /* Simple single-level transformation */
3010 nappinfos, appinfos);
3011 }
3012 else
3013 {
3014 /* Must do multi-level transformation */
3019 child_joinrel,
3020 child_joinrel->top_parent);
3021 }
3022
3023 /*
3024 * Transform em_relids to match. Note we do *not* do
3025 * pull_varnos(child_expr) here, as for example the
3026 * transformation might have substituted a constant, but we
3027 * don't want the child member to be marked as constant.
3028 */
3030 top_parent_relids);
3032
3033 /*
3034 * Add new child member to the EquivalenceClass. Because this
3035 * is a RELOPT_OTHER_JOINREL which has multiple component
3036 * relids, there is no ideal place to store these members in
3037 * the class. Ordinarily, child members are stored in the
3038 * ec_childmembers[] array element corresponding to their
3039 * relid, however, here we have multiple component relids, so
3040 * there's no single ec_childmembers[] array element to store
3041 * this member. So that we still correctly find this member
3042 * in loops iterating over an EquivalenceMemberIterator, we
3043 * opt to store the member in the ec_childmembers array in
3044 * only the first component relid slot of the array. This
3045 * allows the member to be found, providing callers of
3046 * setup_eclass_member_iterator() specify all the component
3047 * relids for the RELOPT_OTHER_JOINREL, which they do. If we
3048 * opted to store the member in each ec_childmembers[] element
3049 * for all the component relids, then that would just result
3050 * in eclass_member_iterator_next() finding the member
3051 * multiple times, which is a waste of effort.
3052 */
3054 cur_ec,
3055 -1,
3056 child_expr,
3057 new_relids,
3058 cur_em->em_jdomain,
3059 cur_em,
3060 cur_em->em_datatype,
3062 }
3063 }
3064 }
3065
3066 MemoryContextSwitchTo(oldcontext);
3067}
3068
3069/*
3070 * add_setop_child_rel_equivalences
3071 * Add equivalence members for each non-resjunk target in 'child_tlist'
3072 * to the EquivalenceClass in the corresponding setop_pathkey's pk_eclass.
3073 *
3074 * 'root' is the PlannerInfo belonging to the top-level set operation.
3075 * 'child_rel' is the RelOptInfo of the child relation we're adding
3076 * EquivalenceMembers for.
3077 * 'child_tlist' is the target list for the setop child relation. The target
3078 * list expressions are what we add as EquivalenceMembers.
3079 * 'setop_pathkeys' is a list of PathKeys which must contain an entry for each
3080 * non-resjunk target in 'child_tlist'.
3081 */
3082void
3085{
3088
3090 {
3094
3096 continue;
3097
3100
3103
3104 /*
3105 * We can safely pass the parent member as the first member in the
3106 * ec_members list as this is added first in generate_union_paths,
3107 * likewise, the JoinDomain can be that of the initial member of the
3108 * Pathkey's EquivalenceClass. We pass -1 for ec_index since we
3109 * maintain the eclass_indexes for the child_rel after the loop.
3110 */
3112 pk->pk_eclass,
3113 -1,
3114 tle->expr,
3115 child_rel->relids,
3116 parent_em->em_jdomain,
3117 parent_em,
3119 child_rel->relid);
3120
3122 }
3123
3124 /*
3125 * transformSetOperationStmt() ensures that the targetlist never contains
3126 * any resjunk columns, so all eclasses that exist in 'root' must have
3127 * received a new member in the loop above. Add them to the child_rel's
3128 * eclass_indexes.
3129 */
3132}
3133
3134/*
3135 * setup_eclass_member_iterator
3136 * Setup an EquivalenceMemberIterator 'it' to iterate over all parent
3137 * EquivalenceMembers and child members belonging to the given 'ec'.
3138 *
3139 * This iterator returns:
3140 * - All parent members stored directly in ec_members for 'ec', and;
3141 * - Any child member added to the given ec by add_child_eq_member() where
3142 * the child_relid specified in the add_child_eq_member() call is a member
3143 * of the 'child_relids' parameter.
3144 *
3145 * Note:
3146 * The given 'child_relids' must remain allocated and not be changed for the
3147 * lifetime of the iterator.
3148 *
3149 * Parameters:
3150 * 'it' is a pointer to the iterator to set up. Normally stack allocated.
3151 * 'ec' is the EquivalenceClass from which to iterate members for.
3152 * 'child_relids' is the relids to return child members for.
3153 */
3154void
3157{
3158 it->ec = ec;
3159 /* no need to set this if the class has no child members array set */
3161 it->current_relid = -1;
3164}
3165
3166/*
3167 * eclass_member_iterator_next
3168 * Get the next EquivalenceMember from the EquivalenceMemberIterator 'it',
3169 * as setup by setup_eclass_member_iterator(). NULL is returned if there
3170 * are no members left, after which callers must not call
3171 * eclass_member_iterator_next() again for the given iterator.
3172 */
3173EquivalenceMember *
3175{
3177 {
3179 {
3181
3182 nextcell:
3186 }
3187
3188 /* Search for the next list to return members from */
3190 {
3191 /*
3192 * Be paranoid in case we're given relids above what we've sized
3193 * the ec_childmembers array to.
3194 */
3197
3199
3200 /* If there are members in this list, use it. */
3202 {
3203 /* point current_cell to the head of this list */
3206 }
3207 }
3209 }
3210
3212}
3213
3214/*
3215 * generate_implied_equalities_for_column
3216 * Create EC-derived joinclauses usable with a specific column.
3217 *
3218 * This is used by indxpath.c to extract potentially indexable joinclauses
3219 * from ECs, and can be used by foreign data wrappers for similar purposes.
3220 * We assume that only expressions in Vars of a single table are of interest,
3221 * but the caller provides a callback function to identify exactly which
3222 * such expressions it would like to know about.
3223 *
3224 * We assume that any given table/index column could appear in only one EC.
3225 * (This should be true in all but the most pathological cases, and if it
3226 * isn't, we stop on the first match anyway.) Therefore, what we return
3227 * is a redundant list of clauses equating the table/index column to each of
3228 * the other-relation values it is known to be equal to. Any one of
3229 * these clauses can be used to create a parameterized path, and there
3230 * is no value in using more than one. (But it *is* worthwhile to create
3231 * a separate parameterized path for each one, since that leads to different
3232 * join orders.)
3233 *
3234 * The caller can pass a Relids set of rels we aren't interested in joining
3235 * to, so as to save the work of creating useless clauses.
3236 */
3237List *
3239 RelOptInfo *rel,
3241 void *callback_arg,
3243{
3248
3249 /* Should be OK to rely on eclass_indexes */
3251
3252 /* Indexes are available only on base or "other" member relations. */
3254
3255 /* If it's a child rel, we'll need to know what its parent(s) are */
3258 else
3260
3261 i = -1;
3263 {
3268
3269 /* Sanity check eclass_indexes only contain ECs for rel */
3271
3272 /*
3273 * Won't generate joinclauses if const or single-member (the latter
3274 * test covers the volatile case too)
3275 */
3277 continue;
3278
3279 /*
3280 * Scan members, looking for a match to the target column. Note that
3281 * child EC members are considered, but only when they belong to the
3282 * target relation. (Unlike regular members, the same expression
3283 * could be a child member of more than one EC. Therefore, it's
3284 * potentially order-dependent which EC a child relation's target
3285 * column gets matched to. This is annoying but it only happens in
3286 * corner cases, so for now we live with just reporting the first
3287 * match. See also get_eclass_for_sort_expr.)
3288 */
3291 {
3294 break;
3295 }
3296
3298 continue;
3299
3300 /*
3301 * Found our match. Scan the other EC members and attempt to generate
3302 * joinclauses. Ignore children here.
3303 */
3305 {
3308 RestrictInfo *rinfo;
3309
3310 /* Child members should not exist in ec_members */
3312
3313 /* Make sure it'll be a join to a different rel */
3316 continue;
3317
3318 /* Forget it if caller doesn't want joins to this rel */
3320 continue;
3321
3322 /*
3323 * Also, if this is a child rel, avoid generating a useless join
3324 * to its parent rel(s).
3325 */
3328 continue;
3329
3331 cur_em->em_datatype,
3332 other_em->em_datatype);
3334 continue;
3335
3336 /* set parent_ec to mark as redundant with other joinclauses */
3339 cur_ec);
3340
3341 result = lappend(result, rinfo);
3342 }
3343
3344 /*
3345 * If somehow we failed to create any join clauses, we might as well
3346 * keep scanning the ECs for another match. But if we did make any,
3347 * we're done, because we don't want to return non-redundant clauses.
3348 */
3349 if (result)
3350 break;
3351 }
3352
3353 return result;
3354}
3355
3356/*
3357 * have_relevant_eclass_joinclause
3358 * Detect whether there is an EquivalenceClass that could produce
3359 * a joinclause involving the two given relations.
3360 *
3361 * This is essentially a very cut-down version of
3362 * generate_join_implied_equalities(). Note it's OK to occasionally say "yes"
3363 * incorrectly. Hence we don't bother with details like whether the lack of a
3364 * cross-type operator might prevent the clause from actually being generated.
3365 * False negatives are not always fatal either: they will discourage, but not
3366 * completely prevent, investigation of particular join pathways.
3367 */
3368bool
3371{
3374
3375 /*
3376 * Examine only eclasses mentioning both rel1 and rel2.
3377 *
3378 * Note that we do not consider the possibility of an eclass generating
3379 * "join" clauses that mention just one of the rels plus an outer join
3380 * that could be formed from them. Although such clauses must be
3381 * correctly enforced when we form the outer join, they don't seem like
3382 * sufficient reason to prioritize this join over other ones. The join
3383 * ordering rules will force the join to be made when necessary.
3384 */
3386 rel2->relids);
3387
3388 i = -1;
3390 {
3392 i);
3393
3394 /*
3395 * Sanity check that get_common_eclass_indexes gave only ECs
3396 * containing both rels.
3397 */
3400
3401 /*
3402 * Won't generate joinclauses if single-member (this test covers the
3403 * volatile case too)
3404 */
3406 continue;
3407
3408 /*
3409 * We do not need to examine the individual members of the EC, because
3410 * all that we care about is whether each rel overlaps the relids of
3411 * at least one member, and get_common_eclass_indexes() and the single
3412 * member check above are sufficient to prove that. (As with
3413 * have_relevant_joinclause(), it is not necessary that the EC be able
3414 * to form a joinclause relating exactly the two given rels, only that
3415 * it be able to form a joinclause mentioning both, and this will
3416 * surely be true if both of them overlap ec_relids.)
3417 *
3418 * Note we don't test ec_broken; if we did, we'd need a separate code
3419 * path to look through ec_sources. Checking the membership anyway is
3420 * OK as a possibly-overoptimistic heuristic.
3421 *
3422 * We don't test ec_has_const either, even though a const eclass won't
3423 * generate real join clauses. This is because if we had "WHERE a.x =
3424 * b.y and a.x = 42", it is worth considering a join between a and b,
3425 * since the join result is likely to be small even though it'll end
3426 * up being an unqualified nestloop.
3427 */
3428
3429 return true;
3430 }
3431
3432 return false;
3433}
3434
3435
3436/*
3437 * has_relevant_eclass_joinclause
3438 * Detect whether there is an EquivalenceClass that could produce
3439 * a joinclause involving the given relation and anything else.
3440 *
3441 * This is the same as have_relevant_eclass_joinclause with the other rel
3442 * implicitly defined as "everything else in the query".
3443 */
3444bool
3446{
3449
3450 /* Examine only eclasses mentioning rel1 */
3452
3453 i = -1;
3455 {
3457 i);
3458
3459 /*
3460 * Won't generate joinclauses if single-member (this test covers the
3461 * volatile case too)
3462 */
3464 continue;
3465
3466 /*
3467 * Per the comment in have_relevant_eclass_joinclause, it's sufficient
3468 * to find an EC that mentions both this rel and some other rel.
3469 */
3471 return true;
3472 }
3473
3474 return false;
3475}
3476
3477
3478/*
3479 * eclass_useful_for_merging
3480 * Detect whether the EC could produce any mergejoinable join clauses
3481 * against the specified relation.
3482 *
3483 * This is just a heuristic test and doesn't have to be exact; it's better
3484 * to say "yes" incorrectly than "no". Hence we don't bother with details
3485 * like whether the lack of a cross-type operator might prevent the clause
3486 * from actually being generated.
3487 */
3488bool
3491 RelOptInfo *rel)
3492{
3493 Relids relids;
3495
3497
3498 /*
3499 * Won't generate joinclauses if const or single-member (the latter test
3500 * covers the volatile case too)
3501 */
3503 return false;
3504
3505 /*
3506 * Note we don't test ec_broken; if we did, we'd need a separate code path
3507 * to look through ec_sources. Checking the members anyway is OK as a
3508 * possibly-overoptimistic heuristic.
3509 */
3510
3511 /* If specified rel is a child, we must consider the topmost parent rel */
3513 {
3515 relids = rel->top_parent_relids;
3516 }
3517 else
3518 relids = rel->relids;
3519
3520 /* If rel already includes all members of eclass, no point in searching */
3522 return false;
3523
3524 /*
3525 * To join, we need a member not in the given rel. Ignore children here.
3526 */
3528 {
3530
3531 /* Child members should not exist in ec_members */
3533
3535 return true;
3536 }
3537
3538 return false;
3539}
3540
3541
3542/*
3543 * is_redundant_derived_clause
3544 * Test whether rinfo is derived from same EC as any clause in clauselist;
3545 * if so, it can be presumed to represent a condition that's redundant
3546 * with that member of the list.
3547 */
3548bool
3550{
3551 EquivalenceClass *parent_ec = rinfo->parent_ec;
3553
3554 /* Fail if it's not a potentially-redundant clause from some EC */
3556 return false;
3557
3559 {
3561
3563 return true;
3564 }
3565
3566 return false;
3567}
3568
3569/*
3570 * is_redundant_with_indexclauses
3571 * Test whether rinfo is redundant with any clause in the IndexClause
3572 * list. Here, for convenience, we test both simple identity and
3573 * whether it is derived from the same EC as any member of the list.
3574 */
3575bool
3577{
3578 EquivalenceClass *parent_ec = rinfo->parent_ec;
3580
3582 {
3585
3586 /* If indexclause is lossy, it won't enforce the condition exactly */
3588 continue;
3589
3590 /* Match if it's same clause (pointer equality should be enough) */
3592 return true;
3593 /* Match if derived from same EC */
3595 return true;
3596
3597 /*
3598 * No need to look at the derived clauses in iclause->indexquals; they
3599 * couldn't match if the parent clause didn't.
3600 */
3601 }
3602
3603 return false;
3604}
3605
3606/*
3607 * get_eclass_indexes_for_relids
3608 * Build and return a Bitmapset containing the indexes into root's
3609 * eq_classes list for all eclasses that mention any of these relids
3610 */
3613{
3616
3617 /* Should be OK to rely on eclass_indexes */
3619
3621 {
3623
3624 /* ignore the RTE_GROUP RTE */
3626 continue;
3627
3629 {
3631 continue;
3632 }
3633
3635 }
3637}
3638
3639/*
3640 * get_common_eclass_indexes
3641 * Build and return a Bitmapset containing the indexes into root's
3642 * eq_classes list for all eclasses that mention rels in both
3643 * relids1 and relids2.
3644 */
3647{
3650 int relid;
3651
3653
3654 /*
3655 * We can get away with just using the relation's eclass_indexes directly
3656 * when relids2 is a singleton set.
3657 */
3660 else
3662
3663 /* Calculate and return the common EC indexes, recycling the left input. */
3665}
3666
3667/*
3668 * ec_build_derives_hash
3669 * Construct the auxiliary hash table for derived clause lookups.
3670 */
3671static void
3673{
3675
3676 /*
3677 * Create the hash table.
3678 *
3679 * We pass list_length(ec->ec_derives_list) as the initial size.
3680 * Simplehash will divide this by the fillfactor (typically 0.9) and round
3681 * up to the next power of two, so this will usually give us at least 64
3682 * buckets around the threshold. That avoids immediate resizing without
3683 * hardcoding a specific size.
3684 */
3687 NULL);
3688
3690 ec_add_clause_to_derives_hash(ec, rinfo);
3691}
3692
3693/*
3694 * ec_add_derived_clause
3695 * Add a clause to the set of derived clauses for the given
3696 * EquivalenceClass. Always appends to ec_derives_list; also adds
3697 * to ec_derives_hash if it exists.
3698 *
3699 * Also asserts expected invariants of derived clauses.
3700 */
3703{
3704 /*
3705 * Constant, if present, is always placed on the RHS; see
3706 * generate_base_implied_equalities_const(). LHS is never a constant.
3707 */
3708 Assert(!clause->left_em->em_is_const);
3709
3710 /*
3711 * Clauses containing a constant are never considered redundant, so
3712 * parent_ec is not set.
3713 */
3714 Assert(!clause->parent_ec || !clause->right_em->em_is_const);
3715
3716 ec->ec_derives_list = lappend(ec->ec_derives_list, clause);
3717 if (ec->ec_derives_hash)
3718 ec_add_clause_to_derives_hash(ec, clause);
3719}
3720
3721/*
3722 * ec_add_derived_clauses
3723 * Add a list of clauses to the set of clauses derived from the given
3724 * EquivalenceClass; adding to the list and hash table if needed.
3725 *
3726 * This function is similar to ec_add_derived_clause() but optimized for adding
3727 * multiple clauses at a time to the ec_derives_list. The assertions from
3728 * ec_add_derived_clause() are not repeated here, as the input clauses are
3729 * assumed to have already been validated.
3730 */
3731static void
3733{
3737 ec_add_clause_to_derives_hash(ec, rinfo);
3738}
3739
3740/*
3741 * fill_ec_derives_key
3742 * Compute a canonical key for ec_derives_hash lookup or insertion.
3743 *
3744 * Derived clauses are looked up using a pair of EquivalenceMembers and a
3745 * parent EquivalenceClass. To avoid storing or searching for both EM orderings,
3746 * we canonicalize the key:
3747 *
3748 * - For clauses involving two non-constant EMs, em1 is set to the EM with lower
3749 * memory address and em2 is set to the other one.
3750 * - For clauses involving a constant EM, the caller must pass the non-constant
3751 * EM as leftem and NULL as rightem; we then set em1 = NULL and em2 = leftem.
3752 */
3753static inline void
3757 EquivalenceClass *parent_ec)
3758{
3760
3762 {
3765 }
3767 {
3770 }
3771 else
3772 {
3775 }
3776 key->parent_ec = parent_ec;
3777}
3778
3779/*
3780 * ec_add_clause_to_derives_hash
3781 * Add a derived clause to ec_derives_hash in the given EquivalenceClass.
3782 *
3783 * Each clause is associated with a canonicalized key. For constant-containing
3784 * clauses, only the non-constant EM is used for lookup; see comments in
3785 * fill_ec_derives_key().
3786 */
3787static void
3789{
3791 ECDerivesEntry *entry;
3792 bool found;
3793
3794 /*
3795 * Constants are always placed on the RHS; see
3796 * generate_base_implied_equalities_const().
3797 */
3798 Assert(!rinfo->left_em->em_is_const);
3799
3800 /*
3801 * Clauses containing a constant are never considered redundant, so
3802 * parent_ec is not set.
3803 */
3804 Assert(!rinfo->parent_ec || !rinfo->right_em->em_is_const);
3805
3806 /*
3807 * See fill_ec_derives_key() for details: we use a canonicalized key to
3808 * avoid storing both EM orderings. For constant EMs, only the
3809 * non-constant EM is included in the key.
3810 */
3811 fill_ec_derives_key(&key,
3812 rinfo->left_em,
3814 rinfo->parent_ec);
3816 Assert(!found);
3817 entry->rinfo = rinfo;
3818}
3819
3820/*
3821 * ec_clear_derived_clauses
3822 * Reset ec_derives_list and ec_derives_hash.
3823 *
3824 * We destroy the hash table explicitly, since it may consume significant
3825 * space. The list holds the same set of entries and can become equally large
3826 * when thousands of partitions are involved, so we free it as well -- even
3827 * though we do not typically free lists.
3828 */
3829void
3831{
3834
3836 {
3839 }
3840}
3841
3842/*
3843 * ec_search_clause_for_ems
3844 * Search for an existing RestrictInfo that equates the given pair
3845 * of EquivalenceMembers, either from ec_sources or ec_derives.
3846 *
3847 * Returns a clause with matching operands in either given order or commuted
3848 * order. We used to require matching operator OIDs, but dropped that since any
3849 * semantically different operator here would indicate a broken operator family.
3850 *
3851 * Returns NULL if no matching clause is found.
3852 */
3856 EquivalenceClass *parent_ec)
3857{
3858 /* Check original source clauses */
3860 {
3862 rinfo->right_em == rightem &&
3863 rinfo->parent_ec == parent_ec)
3864 return rinfo;
3866 rinfo->right_em == leftem &&
3867 rinfo->parent_ec == parent_ec)
3868 return rinfo;
3869 }
3870
3871 /* Not found in ec_sources; search derived clauses */
3873 parent_ec);
3874}
3875
3876/*
3877 * ec_search_derived_clause_for_ems
3878 * Search for an existing derived clause between two EquivalenceMembers.
3879 *
3880 * If the number of derived clauses exceeds a threshold, switch to hash table
3881 * lookup; otherwise, scan ec_derives_list linearly.
3882 *
3883 * Clauses involving constants are looked up by passing the non-constant EM
3884 * as leftem and setting rightem to NULL. In that case, we expect to find a
3885 * clause with a constant on the RHS.
3886 *
3887 * While searching the list, we compare each given EM with both sides of each
3888 * clause. But for hash table lookups, we construct a canonicalized key and
3889 * perform a single lookup.
3890 */
3895 EquivalenceClass *parent_ec)
3896{
3897 /* Switch to using hash lookup when list grows "too long". */
3901
3902 /* Perform hash table lookup if available */
3904 {
3906 RestrictInfo *rinfo;
3907 ECDerivesEntry *entry;
3908
3911 if (entry)
3912 {
3913 rinfo = entry->rinfo;
3914 Assert(rinfo);
3916 return rinfo;
3917 }
3918 }
3919 else
3920 {
3921 /* Fallback to linear search over ec_derives_list */
3923 {
3924 /* Handle special case: lookup by non-const EM alone */
3926 rinfo->left_em == leftem)
3927 {
3928 Assert(rinfo->right_em->em_is_const);
3929 return rinfo;
3930 }
3932 rinfo->right_em == rightem &&
3933 rinfo->parent_ec == parent_ec)
3934 return rinfo;
3936 rinfo->right_em == leftem &&
3937 rinfo->parent_ec == parent_ec)
3938 return rinfo;
3939 }
3940 }
3941
3943}
Node * adjust_appendrel_attrs(PlannerInfo *root, Node *node, int nappinfos, AppendRelInfo **appinfos)
Definition appendinfo.c:200
Node * adjust_appendrel_attrs_multilevel(PlannerInfo *root, Node *node, RelOptInfo *childrel, RelOptInfo *parentrel)
Definition appendinfo.c:592
Bitmapset * bms_difference(const Bitmapset *a, const Bitmapset *b)
Definition bitmapset.c:346
Bitmapset * bms_int_members(Bitmapset *a, const Bitmapset *b)
Definition bitmapset.c:1108
Bitmapset * bms_intersect(const Bitmapset *a, const Bitmapset *b)
Definition bitmapset.c:292
Bitmapset * bms_add_range(Bitmapset *a, int lower, int upper)
Definition bitmapset.c:1018
Bitmapset * bms_add_members(Bitmapset *a, const Bitmapset *b)
Definition bitmapset.c:916
bool bms_get_singleton_member(const Bitmapset *a, int *member)
Definition bitmapset.c:714
void rebuild_eclass_attr_needed(PlannerInfo *root)
Definition equivclass.c:2573
EquivalenceClass * get_eclass_for_sort_expr(PlannerInfo *root, Expr *expr, List *opfamilies, Oid opcintype, Oid collation, Index sortref, Relids rel, bool create_it)
Definition equivclass.c:736
void add_child_rel_equivalences(PlannerInfo *root, AppendRelInfo *appinfo, RelOptInfo *parent_rel, RelOptInfo *child_rel)
Definition equivclass.c:2832
bool is_redundant_with_indexclauses(RestrictInfo *rinfo, List *indexclauses)
Definition equivclass.c:3576
void generate_base_implied_equalities(PlannerInfo *root)
Definition equivclass.c:1187
bool exprs_known_equal(PlannerInfo *root, Node *item1, Node *item2, Oid opfamily)
Definition equivclass.c:2647
static List * generate_join_implied_equalities_normal(PlannerInfo *root, EquivalenceClass *ec, Relids join_relids, Relids outer_relids, Relids inner_relids)
Definition equivclass.c:1720
static RestrictInfo * ec_search_derived_clause_for_ems(PlannerInfo *root, EquivalenceClass *ec, EquivalenceMember *leftem, EquivalenceMember *rightem, EquivalenceClass *parent_ec)
Definition equivclass.c:3892
static void ec_build_derives_hash(PlannerInfo *root, EquivalenceClass *ec)
Definition equivclass.c:3672
Expr * canonicalize_ec_expression(Expr *expr, Oid req_type, Oid req_collation)
Definition equivclass.c:545
EquivalenceMember * find_ec_member_matching_expr(EquivalenceClass *ec, Expr *expr, Relids relids)
Definition equivclass.c:916
static void ec_add_clause_to_derives_hash(EquivalenceClass *ec, RestrictInfo *rinfo)
Definition equivclass.c:3788
static JoinDomain * find_join_domain(PlannerInfo *root, Relids relids)
Definition equivclass.c:2616
bool relation_can_be_sorted_early(PlannerInfo *root, RelOptInfo *rel, EquivalenceClass *ec, bool require_parallel_safe)
Definition equivclass.c:1076
void setup_eclass_member_iterator(EquivalenceMemberIterator *it, EquivalenceClass *ec, Relids child_relids)
Definition equivclass.c:3155
static void generate_base_implied_equalities_broken(PlannerInfo *root, EquivalenceClass *ec)
Definition equivclass.c:1486
void ec_clear_derived_clauses(EquivalenceClass *ec)
Definition equivclass.c:3830
static void ec_add_derived_clause(EquivalenceClass *ec, RestrictInfo *clause)
Definition equivclass.c:3702
bool process_equivalence(PlannerInfo *root, RestrictInfo **p_restrictinfo, JoinDomain *jdomain)
Definition equivclass.c:179
List * generate_implied_equalities_for_column(PlannerInfo *root, RelOptInfo *rel, ec_matches_callback_type callback, void *callback_arg, Relids prohibited_rels)
Definition equivclass.c:3238
static EquivalenceMember * add_child_eq_member(PlannerInfo *root, EquivalenceClass *ec, int ec_index, Expr *expr, Relids relids, JoinDomain *jdomain, EquivalenceMember *parent_em, Oid datatype, Index child_relid)
Definition equivclass.c:661
EquivalenceMember * eclass_member_iterator_next(EquivalenceMemberIterator *it)
Definition equivclass.c:3174
bool have_relevant_eclass_joinclause(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
Definition equivclass.c:3369
EquivalenceMember * find_computable_ec_member(PlannerInfo *root, EquivalenceClass *ec, List *exprs, Relids relids, bool require_parallel_safe)
Definition equivclass.c:991
static Bitmapset * get_common_eclass_indexes(PlannerInfo *root, Relids relids1, Relids relids2)
Definition equivclass.c:3646
List * generate_join_implied_equalities_for_ecs(PlannerInfo *root, List *eclasses, Relids join_relids, Relids outer_relids, RelOptInfo *inner_rel)
Definition equivclass.c:1649
void add_setop_child_rel_equivalences(PlannerInfo *root, RelOptInfo *child_rel, List *child_tlist, List *setop_pathkeys)
Definition equivclass.c:3083
static void fill_ec_derives_key(ECDerivesKey *key, EquivalenceMember *leftem, EquivalenceMember *rightem, EquivalenceClass *parent_ec)
Definition equivclass.c:3754
void reconsider_outer_join_clauses(PlannerInfo *root)
Definition equivclass.c:2134
bool eclass_useful_for_merging(PlannerInfo *root, EquivalenceClass *eclass, RelOptInfo *rel)
Definition equivclass.c:3489
void add_child_join_rel_equivalences(PlannerInfo *root, int nappinfos, AppendRelInfo **appinfos, RelOptInfo *parent_joinrel, RelOptInfo *child_joinrel)
Definition equivclass.c:2940
static RestrictInfo * create_join_clause(PlannerInfo *root, EquivalenceClass *ec, Oid opno, EquivalenceMember *leftem, EquivalenceMember *rightem, EquivalenceClass *parent_ec)
Definition equivclass.c:1982
static void ec_add_derived_clauses(EquivalenceClass *ec, List *clauses)
Definition equivclass.c:3732
static Bitmapset * get_eclass_indexes_for_relids(PlannerInfo *root, Relids relids)
Definition equivclass.c:3612
bool is_redundant_derived_clause(RestrictInfo *rinfo, List *clauselist)
Definition equivclass.c:3549
RestrictInfo * find_derived_clause_for_ec_member(PlannerInfo *root, EquivalenceClass *ec, EquivalenceMember *em)
Definition equivclass.c:2803
static RestrictInfo * ec_search_clause_for_ems(PlannerInfo *root, EquivalenceClass *ec, EquivalenceMember *leftem, EquivalenceMember *rightem, EquivalenceClass *parent_ec)
Definition equivclass.c:3854
static void generate_base_implied_equalities_no_const(PlannerInfo *root, EquivalenceClass *ec)
Definition equivclass.c:1370
static void generate_base_implied_equalities_const(PlannerInfo *root, EquivalenceClass *ec)
Definition equivclass.c:1271
static Oid select_equality_operator(EquivalenceClass *ec, Oid lefttype, Oid righttype)
Definition equivclass.c:1947
EquivalenceClass * match_eclasses_to_foreign_key_col(PlannerInfo *root, ForeignKeyOptInfo *fkinfo, int colno)
Definition equivclass.c:2709
static EquivalenceMember * make_eq_member(EquivalenceClass *ec, Expr *expr, Relids relids, JoinDomain *jdomain, EquivalenceMember *parent, Oid datatype)
Definition equivclass.c:592
static bool reconsider_outer_join_clause(PlannerInfo *root, OuterJoinClauseInfo *ojcinfo, bool outer_on_left)
Definition equivclass.c:2256
List * generate_join_implied_equalities(PlannerInfo *root, Relids join_relids, Relids outer_relids, RelOptInfo *inner_rel, SpecialJoinInfo *sjinfo)
Definition equivclass.c:1549
static EquivalenceMember * add_eq_member(EquivalenceClass *ec, Expr *expr, Relids relids, JoinDomain *jdomain, Oid datatype)
Definition equivclass.c:628
bool has_relevant_eclass_joinclause(PlannerInfo *root, RelOptInfo *rel1)
Definition equivclass.c:3445
static bool reconsider_full_join_clause(PlannerInfo *root, OuterJoinClauseInfo *ojcinfo)
Definition equivclass.c:2383
static List * generate_join_implied_equalities_broken(PlannerInfo *root, EquivalenceClass *ec, Relids nominal_join_relids, Relids outer_relids, Relids nominal_inner_relids, RelOptInfo *inner_rel)
Definition equivclass.c:1898
void distribute_restrictinfo_to_rels(PlannerInfo *root, RestrictInfo *restrictinfo)
Definition initsplan.c:3558
RestrictInfo * build_implied_join_equality(PlannerInfo *root, Oid opno, Oid collation, Expr *item1, Expr *item2, Relids qualscope, Index security_level)
Definition initsplan.c:3787
void add_vars_to_targetlist(PlannerInfo *root, List *vars, Relids where_needed)
Definition initsplan.c:289
RestrictInfo * process_implied_equality(PlannerInfo *root, Oid opno, Oid collation, Expr *item1, Expr *item2, Relids qualscope, Index security_level, bool both_const)
Definition initsplan.c:3643
void add_vars_to_attr_needed(PlannerInfo *root, List *vars, Relids where_needed)
Definition initsplan.c:360
Relids add_outer_joins_to_relids(PlannerInfo *root, Relids input_relids, SpecialJoinInfo *sjinfo, List **pushed_down_joins)
Definition joinrels.c:800
Oid get_opfamily_member_for_cmptype(Oid opfamily, Oid lefttype, Oid righttype, CompareType cmptype)
Definition lsyscache.c:197
void op_input_types(Oid opno, Oid *lefttype, Oid *righttype)
Definition lsyscache.c:1508
Node * applyRelabelType(Node *arg, Oid rtype, int32 rtypmod, Oid rcollid, CoercionForm rformat, int rlocation, bool overwrite_ok)
Definition nodeFuncs.c:636
static MemoryContext MemoryContextSwitchTo(MemoryContext context)
Definition palloc.h:124
bool(* ec_matches_callback_type)(PlannerInfo *root, RelOptInfo *rel, EquivalenceClass *ec, EquivalenceMember *em, void *arg)
Definition paths.h:129
Relids find_childrel_parents(PlannerInfo *root, RelOptInfo *rel)
Definition relnode.c:1657
RestrictInfo * make_restrictinfo(PlannerInfo *root, Expr *clause, bool is_pushed_down, bool has_clone, bool is_clone, bool pseudoconstant, Index security_level, Relids required_relids, Relids incompatible_relids, Relids outer_relids)
Definition restrictinfo.c:52
Node * remove_nulling_relids(Node *node, const Bitmapset *removable_relids, const Bitmapset *except_relids)
Definition rewriteManip.c:1328
Definition pathnodes.h:3259
Definition bitmapset.h:50
Definition primnodes.h:1510
Definition primnodes.h:324
Definition equivclass.c:117
Definition equivclass.c:109
Definition pathnodes.h:1634
Definition pathnodes.h:1760
Definition pathnodes.h:1695
Definition primnodes.h:189
Definition pathnodes.h:1441
Definition pathnodes.h:2080
Definition pathnodes.h:1542
Definition pg_list.h:54
Definition memnodes.h:118
Definition nodes.h:135
Definition primnodes.h:1981
Definition primnodes.h:846
Definition pathnodes.h:3220
Definition pathnodes.h:1787
Definition pathnodes.h:1852
Definition pathnodes.h:297
Definition pathnodes.h:992
Definition primnodes.h:1215
Definition pathnodes.h:2864
Definition pathnodes.h:3191
Definition primnodes.h:2236
Definition primnodes.h:262
Definition regcomp.c:282
static void callback(struct sockaddr *addr, struct sockaddr *mask, void *unused)
Definition test_ifaddrs.c:46
Definition pg_list.h:46
◆ SH_HASH_KEY
| #define SH_HASH_KEY | ( | tb, | |
| key | |||
| ) | hash_bytes((const unsigned char *) &(key), sizeof(ECDerivesKey)) |
Definition at line 130 of file equivclass.c.
◆ SH_KEY
| #define SH_KEY key |
Definition at line 129 of file equivclass.c.
◆ SH_KEY_TYPE
| #define SH_KEY_TYPE ECDerivesKey |
Definition at line 128 of file equivclass.c.
◆ SH_PREFIX
Definition at line 126 of file equivclass.c.
◆ SH_SCOPE
Definition at line 134 of file equivclass.c.
Function Documentation
◆ add_child_eq_member()
|
static |
Definition at line 661 of file equivclass.c.
665{
667
669
670 /*
671 * Allocate the array to store child members; an array of Lists indexed by
672 * relid, or expand the existing one, if necessary.
673 */
675 {
678 else
680 ec->ec_childmembers_size,
681 root->simple_rel_array_size);
682
684 }
685
687
688 /* add member to the ec_childmembers List for the given child_relid */
690
691 /* Record this EC index for the child rel */
693 {
695
698 }
699
701}
References Assert, bms_add_member(), EquivalenceClass::ec_childmembers, EquivalenceClass::ec_childmembers_size, RelOptInfo::eclass_indexes, fb(), lappend(), make_eq_member(), palloc0_array, repalloc0_array, root, and unlikely.
Referenced by add_child_join_rel_equivalences(), add_child_rel_equivalences(), and add_setop_child_rel_equivalences().
◆ add_child_join_rel_equivalences()
| void add_child_join_rel_equivalences | ( | PlannerInfo * | root, |
| int | nappinfos, | ||
| AppendRelInfo ** | appinfos, | ||
| RelOptInfo * | parent_joinrel, | ||
| RelOptInfo * | child_joinrel | ||
| ) |
Definition at line 2940 of file equivclass.c.
2944{
2948 MemoryContext oldcontext;
2950
2952
2953 /* We need consider only ECs that mention the parent joinrel */
2955
2956 /*
2957 * If we're being called during GEQO join planning, we still have to
2958 * create any new EC members in the main planner context, to avoid having
2959 * a corrupt EC data structure after the GEQO context is reset. This is
2960 * problematic since we'll leak memory across repeated GEQO cycles. For
2961 * now, though, bloat is better than crash. If it becomes a real issue
2962 * we'll have to do something to avoid generating duplicate EC members.
2963 */
2965
2966 i = -1;
2968 {
2970
2971 /*
2972 * If this EC contains a volatile expression, then generating child
2973 * EMs would be downright dangerous, so skip it. We rely on a
2974 * volatile EC having only one EM.
2975 */
2977 continue;
2978
2979 /* Sanity check on get_eclass_indexes_for_relids result */
2981
2983 {
2985 continue; /* ignore consts here */
2986
2987 /* Child members should not exist in ec_members */
2989
2990 /*
2991 * We may ignore expressions that reference a single baserel,
2992 * because add_child_rel_equivalences should have handled them.
2993 */
2995 continue;
2996
2997 /* Does this member reference child's topmost parent rel? */
2999 {
3000 /* Yes, generate transformed child version */
3003
3005 {
3006 /* Simple single-level transformation */
3010 nappinfos, appinfos);
3011 }
3012 else
3013 {
3014 /* Must do multi-level transformation */
3019 child_joinrel,
3020 child_joinrel->top_parent);
3021 }
3022
3023 /*
3024 * Transform em_relids to match. Note we do *not* do
3025 * pull_varnos(child_expr) here, as for example the
3026 * transformation might have substituted a constant, but we
3027 * don't want the child member to be marked as constant.
3028 */
3030 top_parent_relids);
3032
3033 /*
3034 * Add new child member to the EquivalenceClass. Because this
3035 * is a RELOPT_OTHER_JOINREL which has multiple component
3036 * relids, there is no ideal place to store these members in
3037 * the class. Ordinarily, child members are stored in the
3038 * ec_childmembers[] array element corresponding to their
3039 * relid, however, here we have multiple component relids, so
3040 * there's no single ec_childmembers[] array element to store
3041 * this member. So that we still correctly find this member
3042 * in loops iterating over an EquivalenceMemberIterator, we
3043 * opt to store the member in the ec_childmembers array in
3044 * only the first component relid slot of the array. This
3045 * allows the member to be found, providing callers of
3046 * setup_eclass_member_iterator() specify all the component
3047 * relids for the RELOPT_OTHER_JOINREL, which they do. If we
3048 * opted to store the member in each ec_childmembers[] element
3049 * for all the component relids, then that would just result
3050 * in eclass_member_iterator_next() finding the member
3051 * multiple times, which is a waste of effort.
3052 */
3054 cur_ec,
3055 -1,
3056 child_expr,
3057 new_relids,
3058 cur_em->em_jdomain,
3059 cur_em,
3060 cur_em->em_datatype,
3062 }
3063 }
3064 }
3065
3066 MemoryContextSwitchTo(oldcontext);
3067}
References add_child_eq_member(), adjust_appendrel_attrs(), adjust_appendrel_attrs_multilevel(), Assert, bms_add_members(), bms_difference(), bms_membership(), BMS_MULTIPLE, bms_next_member(), bms_overlap(), fb(), foreach_node, get_eclass_indexes_for_relids(), i, IS_JOIN_REL, list_nth(), MemoryContextSwitchTo(), RELOPT_JOINREL, RELOPT_OTHER_JOINREL, and root.
Referenced by build_child_join_rel().
◆ add_child_rel_equivalences()
| void add_child_rel_equivalences | ( | PlannerInfo * | root, |
| AppendRelInfo * | appinfo, | ||
| RelOptInfo * | parent_rel, | ||
| RelOptInfo * | child_rel | ||
| ) |
Definition at line 2832 of file equivclass.c.
2836{
2840
2841 /*
2842 * EC merging should be complete already, so we can use the parent rel's
2843 * eclass_indexes to avoid searching all of root->eq_classes.
2844 */
2847
2848 i = -1;
2850 {
2852
2853 /*
2854 * If this EC contains a volatile expression, then generating child
2855 * EMs would be downright dangerous, so skip it. We rely on a
2856 * volatile EC having only one EM.
2857 */
2859 continue;
2860
2861 /* Sanity check eclass_indexes only contain ECs for parent_rel */
2863
2865 {
2867 continue; /* ignore consts here */
2868
2869 /* Child members should not exist in ec_members */
2871
2872 /*
2873 * Consider only members that reference and can be computed at
2874 * child's topmost parent rel. In particular we want to exclude
2875 * parent-rel Vars that have nonempty varnullingrels. Translating
2876 * those might fail, if the transformed expression wouldn't be a
2877 * simple Var; and in any case it wouldn't produce a member that
2878 * has any use in creating plans for the child rel.
2879 */
2882 {
2883 /* OK, generate transformed child version */
2886
2888 {
2889 /* Simple single-level transformation */
2893 1, &appinfo);
2894 }
2895 else
2896 {
2897 /* Must do multi-level transformation */
2901 child_rel,
2902 child_rel->top_parent);
2903 }
2904
2905 /*
2906 * Transform em_relids to match. Note we do *not* do
2907 * pull_varnos(child_expr) here, as for example the
2908 * transformation might have substituted a constant, but we
2909 * don't want the child member to be marked as constant.
2910 */
2912 top_parent_relids);
2914
2916 cur_ec,
2917 i,
2918 child_expr,
2919 new_relids,
2920 cur_em->em_jdomain,
2921 cur_em,
2922 cur_em->em_datatype,
2923 child_rel->relid);
2924 }
2925 }
2926 }
2927}
References add_child_eq_member(), adjust_appendrel_attrs(), adjust_appendrel_attrs_multilevel(), Assert, bms_add_members(), bms_difference(), bms_is_empty, bms_is_subset(), bms_next_member(), fb(), foreach_node, i, IS_SIMPLE_REL, list_nth(), RELOPT_BASEREL, and root.
Referenced by set_append_rel_size().
◆ add_eq_member()
|
static |
Definition at line 628 of file equivclass.c.
630{
632 NULL, datatype);
633
634 /* add to the members list */
636
637 /* record the relids for parent members */
639
641}
References bms_add_members(), EquivalenceClass::ec_members, EquivalenceClass::ec_relids, fb(), lappend(), and make_eq_member().
Referenced by get_eclass_for_sort_expr(), and process_equivalence().
◆ add_setop_child_rel_equivalences()
| void add_setop_child_rel_equivalences | ( | PlannerInfo * | root, |
| RelOptInfo * | child_rel, | ||
| List * | child_tlist, | ||
| List * | setop_pathkeys | ||
| ) |
Definition at line 3083 of file equivclass.c.
3085{
3088
3090 {
3094
3096 continue;
3097
3100
3103
3104 /*
3105 * We can safely pass the parent member as the first member in the
3106 * ec_members list as this is added first in generate_union_paths,
3107 * likewise, the JoinDomain can be that of the initial member of the
3108 * Pathkey's EquivalenceClass. We pass -1 for ec_index since we
3109 * maintain the eclass_indexes for the child_rel after the loop.
3110 */
3112 pk->pk_eclass,
3113 -1,
3114 tle->expr,
3115 child_rel->relids,
3116 parent_em->em_jdomain,
3117 parent_em,
3119 child_rel->relid);
3120
3122 }
3123
3124 /*
3125 * transformSetOperationStmt() ensures that the targetlist never contains
3126 * any resjunk columns, so all eclasses that exist in 'root' must have
3127 * received a new member in the loop above. Add them to the child_rel's
3128 * eclass_indexes.
3129 */
3132}
References add_child_eq_member(), bms_add_range(), elog, ERROR, exprType(), fb(), lfirst_node, linitial, list_head(), list_length(), lnext(), and root.
Referenced by build_setop_child_paths().
◆ canonicalize_ec_expression()
Definition at line 545 of file equivclass.c.
546{
548
549 /*
550 * For a polymorphic-input-type opclass, just keep the same exposed type.
551 * RECORD opclasses work like polymorphic-type ones for this purpose.
552 */
555
556 /*
557 * No work if the expression exposes the right type/collation already.
558 */
561 {
562 /*
563 * If we have to change the type of the expression, set typmod to -1,
564 * since the new type may not have the same typmod interpretation.
565 * When we only have to change collation, preserve the exposed typmod.
566 */
568
570 req_typmod = -1;
571 else
573
574 /*
575 * Use applyRelabelType so that we preserve const-flatness. This is
576 * important since eval_const_expressions has already been applied.
577 */
581 }
582
583 return expr;
584}
References applyRelabelType(), COERCE_IMPLICIT_CAST, exprCollation(), exprType(), exprTypmod(), and fb().
Referenced by convert_subquery_pathkeys(), get_eclass_for_sort_expr(), and process_equivalence().
◆ create_join_clause()
|
static |
Definition at line 1982 of file equivclass.c.
1987{
1988 RestrictInfo *rinfo;
1990 MemoryContext oldcontext;
1991
1993 if (rinfo)
1994 return rinfo;
1995
1996 /*
1997 * Not there, so build it, in planner context so we can re-use it. (Not
1998 * important in normal planning, but definitely so in GEQO.)
1999 */
2001
2002 /*
2003 * If either EM is a child, recursively create the corresponding
2004 * parent-to-parent clause, so that we can duplicate its rinfo_serial.
2005 */
2007 {
2010
2013 parent_ec);
2014 }
2015
2017 opno,
2018 ec->ec_collation,
2019 leftem->em_expr,
2020 rightem->em_expr,
2022 rightem->em_relids),
2023 ec->ec_min_security);
2024
2025 /*
2026 * If either EM is a child, force the clause's clause_relids to include
2027 * the relid(s) of the child rel. In normal cases it would already, but
2028 * not if we are considering appendrel child relations with pseudoconstant
2029 * translated variables (i.e., UNION ALL sub-selects with constant output
2030 * items). We must do this so that join_clause_is_movable_into() will
2031 * think that the clause should be evaluated at the correct place.
2032 */
2034 rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
2035 leftem->em_relids);
2037 rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
2038 rightem->em_relids);
2039
2040 /* If it's a child clause, copy the parent's rinfo_serial */
2043
2044 /* Mark the clause as redundant, or not */
2045 rinfo->parent_ec = parent_ec;
2046
2047 /*
2048 * We know the correct values for left_ec/right_ec, ie this particular EC,
2049 * so we can just set them directly instead of forcing another lookup.
2050 */
2051 rinfo->left_ec = ec;
2052 rinfo->right_ec = ec;
2053
2054 /* Mark it as usable with these EMs */
2055 rinfo->left_em = leftem;
2056 rinfo->right_em = rightem;
2057 /* and save it for possible re-use */
2058 ec_add_derived_clause(ec, rinfo);
2059
2060 MemoryContextSwitchTo(oldcontext);
2061
2062 return rinfo;
2063}
References bms_add_members(), bms_union(), build_implied_join_equality(), create_join_clause(), ec_add_derived_clause(), EquivalenceClass::ec_collation, EquivalenceClass::ec_min_security, ec_search_clause_for_ems(), fb(), MemoryContextSwitchTo(), RestrictInfo::rinfo_serial, and root.
Referenced by create_join_clause(), generate_implied_equalities_for_column(), and generate_join_implied_equalities_normal().
◆ ec_add_clause_to_derives_hash()
|
static |
Definition at line 3788 of file equivclass.c.
3789{
3791 ECDerivesEntry *entry;
3792 bool found;
3793
3794 /*
3795 * Constants are always placed on the RHS; see
3796 * generate_base_implied_equalities_const().
3797 */
3798 Assert(!rinfo->left_em->em_is_const);
3799
3800 /*
3801 * Clauses containing a constant are never considered redundant, so
3802 * parent_ec is not set.
3803 */
3804 Assert(!rinfo->parent_ec || !rinfo->right_em->em_is_const);
3805
3806 /*
3807 * See fill_ec_derives_key() for details: we use a canonicalized key to
3808 * avoid storing both EM orderings. For constant EMs, only the
3809 * non-constant EM is included in the key.
3810 */
3811 fill_ec_derives_key(&key,
3812 rinfo->left_em,
3814 rinfo->parent_ec);
3816 Assert(!found);
3817 entry->rinfo = rinfo;
3818}
References Assert, EquivalenceClass::ec_derives_hash, fb(), fill_ec_derives_key(), and ECDerivesEntry::rinfo.
Referenced by ec_add_derived_clause(), ec_add_derived_clauses(), and ec_build_derives_hash().
◆ ec_add_derived_clause()
|
static |
Definition at line 3702 of file equivclass.c.
3703{
3704 /*
3705 * Constant, if present, is always placed on the RHS; see
3706 * generate_base_implied_equalities_const(). LHS is never a constant.
3707 */
3708 Assert(!clause->left_em->em_is_const);
3709
3710 /*
3711 * Clauses containing a constant are never considered redundant, so
3712 * parent_ec is not set.
3713 */
3714 Assert(!clause->parent_ec || !clause->right_em->em_is_const);
3715
3718 ec_add_clause_to_derives_hash(ec, clause);
3719}
References Assert, ec_add_clause_to_derives_hash(), EquivalenceClass::ec_derives_hash, EquivalenceClass::ec_derives_list, and lappend().
Referenced by create_join_clause(), and generate_base_implied_equalities_const().
◆ ec_add_derived_clauses()
|
static |
Definition at line 3732 of file equivclass.c.
References ec_add_clause_to_derives_hash(), EquivalenceClass::ec_derives_hash, EquivalenceClass::ec_derives_list, foreach_node, and list_concat().
Referenced by process_equivalence().
◆ ec_build_derives_hash()
|
static |
Definition at line 3672 of file equivclass.c.
3673{
3675
3676 /*
3677 * Create the hash table.
3678 *
3679 * We pass list_length(ec->ec_derives_list) as the initial size.
3680 * Simplehash will divide this by the fillfactor (typically 0.9) and round
3681 * up to the next power of two, so this will usually give us at least 64
3682 * buckets around the threshold. That avoids immediate resizing without
3683 * hardcoding a specific size.
3684 */
3687 NULL);
3688
3690 ec_add_clause_to_derives_hash(ec, rinfo);
3691}
References Assert, ec_add_clause_to_derives_hash(), EquivalenceClass::ec_derives_hash, EquivalenceClass::ec_derives_list, fb(), foreach_node, list_length(), and root.
Referenced by ec_search_derived_clause_for_ems().
◆ ec_clear_derived_clauses()
| void ec_clear_derived_clauses | ( | EquivalenceClass * | ec | ) |
Definition at line 3830 of file equivclass.c.
3831{
3834
3836 {
3839 }
3840}
References EquivalenceClass::ec_derives_hash, EquivalenceClass::ec_derives_list, fb(), list_free(), and NIL.
Referenced by process_equivalence(), remove_rel_from_eclass(), and update_eclasses().
◆ ec_search_clause_for_ems()
|
static |
Definition at line 3854 of file equivclass.c.
3857{
3858 /* Check original source clauses */
3860 {
3862 rinfo->right_em == rightem &&
3863 rinfo->parent_ec == parent_ec)
3864 return rinfo;
3866 rinfo->right_em == leftem &&
3867 rinfo->parent_ec == parent_ec)
3868 return rinfo;
3869 }
3870
3871 /* Not found in ec_sources; search derived clauses */
3873 parent_ec);
3874}
References ec_search_derived_clause_for_ems(), EquivalenceClass::ec_sources, fb(), foreach_node, and root.
Referenced by create_join_clause().
◆ ec_search_derived_clause_for_ems()
|
static |
Definition at line 3892 of file equivclass.c.
3896{
3897 /* Switch to using hash lookup when list grows "too long". */
3901
3902 /* Perform hash table lookup if available */
3904 {
3906 RestrictInfo *rinfo;
3907 ECDerivesEntry *entry;
3908
3911 if (entry)
3912 {
3913 rinfo = entry->rinfo;
3914 Assert(rinfo);
3916 return rinfo;
3917 }
3918 }
3919 else
3920 {
3921 /* Fallback to linear search over ec_derives_list */
3923 {
3924 /* Handle special case: lookup by non-const EM alone */
3926 rinfo->left_em == leftem)
3927 {
3928 Assert(rinfo->right_em->em_is_const);
3929 return rinfo;
3930 }
3932 rinfo->right_em == rightem &&
3933 rinfo->parent_ec == parent_ec)
3934 return rinfo;
3936 rinfo->right_em == leftem &&
3937 rinfo->parent_ec == parent_ec)
3938 return rinfo;
3939 }
3940 }
3941
3943}
References Assert, ec_build_derives_hash(), EquivalenceClass::ec_derives_hash, EC_DERIVES_HASH_THRESHOLD, EquivalenceClass::ec_derives_list, fb(), fill_ec_derives_key(), foreach_node, list_length(), ECDerivesEntry::rinfo, and root.
Referenced by ec_search_clause_for_ems(), and find_derived_clause_for_ec_member().
◆ eclass_member_iterator_next()
| EquivalenceMember * eclass_member_iterator_next | ( | EquivalenceMemberIterator * | it | ) |
Definition at line 3174 of file equivclass.c.
3175{
3177 {
3179 {
3181
3182 nextcell:
3186 }
3187
3188 /* Search for the next list to return members from */
3190 {
3191 /*
3192 * Be paranoid in case we're given relids above what we've sized
3193 * the ec_childmembers array to.
3194 */
3197
3199
3200 /* If there are members in this list, use it. */
3202 {
3203 /* point current_cell to the head of this list */
3206 }
3207 }
3209 }
3210
3212}
References bms_next_member(), fb(), lfirst_node, list_head(), lnext(), and NIL.
Referenced by find_computable_ec_member(), find_ec_member_matching_expr(), find_em_for_rel(), generate_implied_equalities_for_column(), generate_join_implied_equalities_normal(), get_eclass_for_sort_expr(), and match_pathkeys_to_index().
◆ eclass_useful_for_merging()
| bool eclass_useful_for_merging | ( | PlannerInfo * | root, |
| EquivalenceClass * | eclass, | ||
| RelOptInfo * | rel | ||
| ) |
Definition at line 3489 of file equivclass.c.
3492{
3493 Relids relids;
3495
3497
3498 /*
3499 * Won't generate joinclauses if const or single-member (the latter test
3500 * covers the volatile case too)
3501 */
3503 return false;
3504
3505 /*
3506 * Note we don't test ec_broken; if we did, we'd need a separate code path
3507 * to look through ec_sources. Checking the members anyway is OK as a
3508 * possibly-overoptimistic heuristic.
3509 */
3510
3511 /* If specified rel is a child, we must consider the topmost parent rel */
3513 {
3515 relids = rel->top_parent_relids;
3516 }
3517 else
3518 relids = rel->relids;
3519
3520 /* If rel already includes all members of eclass, no point in searching */
3522 return false;
3523
3524 /*
3525 * To join, we need a member not in the given rel. Ignore children here.
3526 */
3528 {
3530
3531 /* Child members should not exist in ec_members */
3533
3535 return true;
3536 }
3537
3538 return false;
3539}
References Assert, bms_is_empty, bms_is_subset(), bms_overlap(), eclass(), fb(), IS_OTHER_REL, lfirst, list_length(), RelOptInfo::relids, and RelOptInfo::top_parent_relids.
Referenced by get_useful_ecs_for_relation(), and pathkeys_useful_for_merging().
◆ exprs_known_equal()
| bool exprs_known_equal | ( | PlannerInfo * | root, |
| Node * | item1, | ||
| Node * | item2, | ||
| Oid | opfamily | ||
| ) |
Definition at line 2647 of file equivclass.c.
2648{
2650
2652 {
2657
2658 /* Never match to a volatile EC */
2660 continue;
2661
2662 /*
2663 * It's okay to consider ec_broken ECs here. Brokenness just means we
2664 * couldn't derive all the implied clauses we'd have liked to; it does
2665 * not invalidate our knowledge that the members are equal.
2666 */
2667
2668 /* Ignore if this EC doesn't use specified opfamily */
2671 continue;
2672
2673 /* Ignore children here */
2675 {
2677
2678 /* Child members should not exist in ec_members */
2684 /* Exit as soon as equality is proven */
2686 return true;
2687 }
2688 }
2689 return false;
2690}
References Assert, EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_members, EquivalenceClass::ec_opfamilies, equal(), fb(), lfirst, list_member_oid(), OidIsValid, and root.
Referenced by add_unique_group_var(), and have_partkey_equi_join().
◆ fill_ec_derives_key()
|
inlinestatic |
Definition at line 3754 of file equivclass.c.
3758{
3760
3762 {
3765 }
3767 {
3770 }
3771 else
3772 {
3775 }
3776 key->parent_ec = parent_ec;
3777}
Referenced by ec_add_clause_to_derives_hash(), and ec_search_derived_clause_for_ems().
◆ find_computable_ec_member()
| EquivalenceMember * find_computable_ec_member | ( | PlannerInfo * | root, |
| EquivalenceClass * | ec, | ||
| List * | exprs, | ||
| Relids | relids, | ||
| bool | require_parallel_safe | ||
| ) |
Definition at line 991 of file equivclass.c.
996{
1000
1001 /*
1002 * Pull out the Vars and quasi-Vars present in "exprs". In the typical
1003 * non-appendrel case, this is just another representation of the same
1004 * list. However, it does remove the distinction between the case of a
1005 * list of plain expressions and a list of TargetEntrys.
1006 */
1008 PVC_INCLUDE_AGGREGATES |
1009 PVC_INCLUDE_WINDOWFUNCS |
1010 PVC_INCLUDE_PLACEHOLDERS);
1011
1014 {
1017
1018 /*
1019 * We shouldn't be trying to sort by an equivalence class that
1020 * contains a constant, so no need to consider such cases any further.
1021 */
1023 continue;
1024
1025 /*
1026 * Ignore child members unless they belong to the requested rel.
1027 */
1030 continue;
1031
1032 /*
1033 * Match if all Vars and quasi-Vars are present in "exprs".
1034 */
1036 PVC_INCLUDE_AGGREGATES |
1037 PVC_INCLUDE_WINDOWFUNCS |
1038 PVC_INCLUDE_PLACEHOLDERS);
1040 {
1042 break;
1043 }
1046 continue; /* we hit a non-available Var */
1047
1048 /*
1049 * If requested, reject expressions that are not parallel-safe. We
1050 * check this last because it's a rather expensive test.
1051 */
1054 continue;
1055
1057 }
1058
1060}
References bms_is_subset(), eclass_member_iterator_next(), fb(), is_parallel_safe(), lfirst, list_free(), list_member(), pull_var_clause(), PVC_INCLUDE_AGGREGATES, PVC_INCLUDE_PLACEHOLDERS, PVC_INCLUDE_WINDOWFUNCS, root, and setup_eclass_member_iterator().
Referenced by prepare_sort_from_pathkeys(), and relation_can_be_sorted_early().
◆ find_derived_clause_for_ec_member()
| RestrictInfo * find_derived_clause_for_ec_member | ( | PlannerInfo * | root, |
| EquivalenceClass * | ec, | ||
| EquivalenceMember * | em | ||
| ) |
Definition at line 2803 of file equivclass.c.
2806{
2809
2811}
References Assert, EquivalenceClass::ec_has_const, ec_search_derived_clause_for_ems(), fb(), and root.
Referenced by get_foreign_key_join_selectivity().
◆ find_ec_member_matching_expr()
| EquivalenceMember * find_ec_member_matching_expr | ( | EquivalenceClass * | ec, |
| Expr * | expr, | ||
| Relids | relids | ||
| ) |
Definition at line 916 of file equivclass.c.
919{
922
923 /* We ignore binary-compatible relabeling on both ends */
925 expr = ((RelabelType *) expr)->arg;
926
929 {
931
932 /*
933 * We shouldn't be trying to sort by an equivalence class that
934 * contains a constant, so no need to consider such cases any further.
935 */
937 continue;
938
939 /*
940 * Ignore child members unless they belong to the requested rel.
941 */
944 continue;
945
946 /*
947 * Match if same expression (after stripping relabel).
948 */
952
955 }
956
958}
References bms_is_subset(), eclass_member_iterator_next(), equal(), fb(), IsA, and setup_eclass_member_iterator().
Referenced by make_unique_from_pathkeys(), prepare_sort_from_pathkeys(), and relation_can_be_sorted_early().
◆ find_join_domain()
|
static |
Definition at line 2616 of file equivclass.c.
2617{
2619
2621 {
2623
2625 return jdomain;
2626 }
2629}
References bms_is_subset(), elog, ERROR, fb(), JoinDomain::jd_relids, lfirst, and root.
Referenced by reconsider_full_join_clause(), and reconsider_outer_join_clause().
◆ generate_base_implied_equalities()
| void generate_base_implied_equalities | ( | PlannerInfo * | root | ) |
Definition at line 1187 of file equivclass.c.
1188{
1191
1192 /*
1193 * At this point, we're done absorbing knowledge of equivalences in the
1194 * query, so no further EC merging should happen, and ECs remaining in the
1195 * eq_classes list can be considered canonical. (But note that it's still
1196 * possible for new single-member ECs to be added through
1197 * get_eclass_for_sort_expr().)
1198 */
1200
1201 ec_index = 0;
1203 {
1207
1210
1211 /*
1212 * Generate implied equalities that are restriction clauses.
1213 * Single-member ECs won't generate any deductions, either here or at
1214 * the join level.
1215 */
1217 {
1220 else
1222
1223 /* Recover if we failed to generate required derived clauses */
1226
1227 /* Detect whether this EC might generate join clauses */
1228 can_generate_joinclause =
1230 }
1231
1232 /*
1233 * Mark the base rels cited in each eclass (which should all exist by
1234 * now) with the eq_classes indexes of all eclasses mentioning them.
1235 * This will let us avoid searching in subsequent lookups. While
1236 * we're at it, we can mark base rels that have pending eclass joins;
1237 * this is a cheap version of has_relevant_eclass_joinclause().
1238 */
1239 i = -1;
1241 {
1243
1244 /* ignore the RTE_GROUP RTE */
1246 continue;
1247
1249 {
1251 continue;
1252 }
1253
1255
1257 ec_index);
1258
1261 }
1262
1263 ec_index++;
1264 }
1265}
References Assert, bms_add_member(), bms_is_member(), bms_membership(), BMS_MULTIPLE, bms_next_member(), EquivalenceClass::ec_broken, EquivalenceClass::ec_has_const, EquivalenceClass::ec_members, EquivalenceClass::ec_merged, EquivalenceClass::ec_relids, RelOptInfo::eclass_indexes, fb(), generate_base_implied_equalities_broken(), generate_base_implied_equalities_const(), generate_base_implied_equalities_no_const(), RelOptInfo::has_eclass_joins, i, lfirst, list_length(), RELOPT_BASEREL, RelOptInfo::reloptkind, and root.
Referenced by query_planner().
◆ generate_base_implied_equalities_broken()
|
static |
Definition at line 1486 of file equivclass.c.
1488{
1490
1492 {
1494
1498 }
1499}
References bms_membership(), BMS_MULTIPLE, distribute_restrictinfo_to_rels(), EquivalenceClass::ec_has_const, EquivalenceClass::ec_sources, fb(), lfirst, and root.
Referenced by generate_base_implied_equalities().
◆ generate_base_implied_equalities_const()
|
static |
Definition at line 1271 of file equivclass.c.
1273{
1276
1277 /*
1278 * In the trivial case where we just had one "var = const" clause, push
1279 * the original clause back into the main planner machinery. There is
1280 * nothing to be gained by doing it differently, and we save the effort to
1281 * re-build and re-analyze an equality clause that will be exactly
1282 * equivalent to the old one.
1283 */
1286 {
1288
1290 return;
1291 }
1292
1293 /* We don't expect any children yet */
1295
1296 /*
1297 * Find the constant member to use. We prefer an actual constant to
1298 * pseudo-constants (such as Params), because the constraint exclusion
1299 * machinery might be able to exclude relations on the basis of generated
1300 * "var = const" equalities, but "var = param" won't work for that.
1301 */
1303 {
1305
1307 {
1310 break;
1311 }
1312 }
1314
1315 /* Generate a derived equality against each other member */
1317 {
1320 RestrictInfo *rinfo;
1321
1322 /* Child members should not exist in ec_members */
1325 continue;
1327 cur_em->em_datatype,
1328 const_em->em_datatype);
1330 {
1331 /* failed... */
1333 break;
1334 }
1335
1336 /*
1337 * We use the constant's em_jdomain as qualscope, so that if the
1338 * generated clause is variable-free (i.e, both EMs are consts) it
1339 * will be enforced at the join domain level.
1340 */
1343 const_em->em_jdomain->jd_relids,
1344 ec->ec_min_security,
1345 cur_em->em_is_const);
1346
1347 /*
1348 * If the clause didn't degenerate to a constant, fill in the correct
1349 * markings for a mergejoinable clause, and save it as a derived
1350 * clause. (We will not re-use such clauses directly, but selectivity
1351 * estimation may consult those later. Note that this use of derived
1352 * clauses does not overlap with its use for join clauses, since we
1353 * never generate join clauses from an ec_has_const eclass.)
1354 */
1355 if (rinfo && rinfo->mergeopfamilies)
1356 {
1357 /* it's not redundant, so don't set parent_ec */
1358 rinfo->left_ec = rinfo->right_ec = ec;
1359 rinfo->left_em = cur_em;
1360 rinfo->right_em = const_em;
1361 ec_add_derived_clause(ec, rinfo);
1362 }
1363 }
1364}
References Assert, distribute_restrictinfo_to_rels(), ec_add_derived_clause(), EquivalenceClass::ec_broken, EquivalenceClass::ec_childmembers, EquivalenceClass::ec_collation, EquivalenceClass::ec_members, EquivalenceClass::ec_min_security, EquivalenceClass::ec_sources, fb(), IsA, lfirst, linitial, list_length(), OidIsValid, process_implied_equality(), root, and select_equality_operator().
Referenced by generate_base_implied_equalities().
◆ generate_base_implied_equalities_no_const()
|
static |
Definition at line 1370 of file equivclass.c.
1372{
1375
1376 /*
1377 * We scan the EC members once and track the last-seen member for each
1378 * base relation. When we see another member of the same base relation,
1379 * we generate "prev_em = cur_em". This results in the minimum number of
1380 * derived clauses, but it's possible that it will fail when a different
1381 * ordering would succeed. XXX FIXME: use a UNION-FIND algorithm similar
1382 * to the way we build merged ECs. (Use a list-of-lists for each rel.)
1383 */
1386
1387 /* We don't expect any children yet */
1389
1391 {
1393 int relid;
1394
1395 /* Child members should not exist in ec_members */
1397
1399 continue;
1401
1403 {
1406 RestrictInfo *rinfo;
1407
1409 prev_em->em_datatype,
1410 cur_em->em_datatype);
1412 {
1413 /* failed... */
1415 break;
1416 }
1417
1418 /*
1419 * The expressions aren't constants, so the passed qualscope will
1420 * never be used to place the generated clause. We just need to
1421 * be sure it covers both expressions, which em_relids should do.
1422 */
1425 cur_em->em_relids,
1426 ec->ec_min_security,
1427 false);
1428
1429 /*
1430 * If the clause didn't degenerate to a constant, fill in the
1431 * correct markings for a mergejoinable clause. We don't record
1432 * it as a derived clause, since we don't currently need to
1433 * re-find such clauses, and don't want to clutter the
1434 * derived-clause set with non-join clauses.
1435 */
1436 if (rinfo && rinfo->mergeopfamilies)
1437 {
1438 /* it's not redundant, so don't set parent_ec */
1439 rinfo->left_ec = rinfo->right_ec = ec;
1440 rinfo->left_em = prev_em;
1441 rinfo->right_em = cur_em;
1442 }
1443 }
1445 }
1446
1448
1449 /*
1450 * We also have to make sure that all the Vars used in the member clauses
1451 * will be available at any join node we might try to reference them at.
1452 * For the moment we force all the Vars to be available at all join nodes
1453 * for this eclass. Perhaps this could be improved by doing some
1454 * pre-analysis of which members we prefer to join, but it's no worse than
1455 * what happened in the pre-8.3 code. (Note: rebuild_eclass_attr_needed
1456 * needs to match this code.)
1457 */
1459 {
1462 PVC_RECURSE_AGGREGATES |
1463 PVC_RECURSE_WINDOWFUNCS |
1464 PVC_INCLUDE_PLACEHOLDERS);
1465
1468 }
1469}
References add_vars_to_targetlist(), Assert, bms_get_singleton_member(), EquivalenceClass::ec_broken, EquivalenceClass::ec_childmembers, EquivalenceClass::ec_collation, EquivalenceClass::ec_members, EquivalenceClass::ec_min_security, EquivalenceClass::ec_relids, fb(), lfirst, list_free(), OidIsValid, palloc0(), pfree(), process_implied_equality(), pull_var_clause(), PVC_INCLUDE_PLACEHOLDERS, PVC_RECURSE_AGGREGATES, PVC_RECURSE_WINDOWFUNCS, root, and select_equality_operator().
Referenced by generate_base_implied_equalities().
◆ generate_implied_equalities_for_column()
| List * generate_implied_equalities_for_column | ( | PlannerInfo * | root, |
| RelOptInfo * | rel, | ||
| ec_matches_callback_type | callback, | ||
| void * | callback_arg, | ||
| Relids | prohibited_rels | ||
| ) |
Definition at line 3238 of file equivclass.c.
3243{
3248
3249 /* Should be OK to rely on eclass_indexes */
3251
3252 /* Indexes are available only on base or "other" member relations. */
3254
3255 /* If it's a child rel, we'll need to know what its parent(s) are */
3258 else
3260
3261 i = -1;
3263 {
3268
3269 /* Sanity check eclass_indexes only contain ECs for rel */
3271
3272 /*
3273 * Won't generate joinclauses if const or single-member (the latter
3274 * test covers the volatile case too)
3275 */
3277 continue;
3278
3279 /*
3280 * Scan members, looking for a match to the target column. Note that
3281 * child EC members are considered, but only when they belong to the
3282 * target relation. (Unlike regular members, the same expression
3283 * could be a child member of more than one EC. Therefore, it's
3284 * potentially order-dependent which EC a child relation's target
3285 * column gets matched to. This is annoying but it only happens in
3286 * corner cases, so for now we live with just reporting the first
3287 * match. See also get_eclass_for_sort_expr.)
3288 */
3291 {
3294 break;
3295 }
3296
3298 continue;
3299
3300 /*
3301 * Found our match. Scan the other EC members and attempt to generate
3302 * joinclauses. Ignore children here.
3303 */
3305 {
3308 RestrictInfo *rinfo;
3309
3310 /* Child members should not exist in ec_members */
3312
3313 /* Make sure it'll be a join to a different rel */
3316 continue;
3317
3318 /* Forget it if caller doesn't want joins to this rel */
3320 continue;
3321
3322 /*
3323 * Also, if this is a child rel, avoid generating a useless join
3324 * to its parent rel(s).
3325 */
3328 continue;
3329
3331 cur_em->em_datatype,
3332 other_em->em_datatype);
3334 continue;
3335
3336 /* set parent_ec to mark as redundant with other joinclauses */
3339 cur_ec);
3340
3341 result = lappend(result, rinfo);
3342 }
3343
3344 /*
3345 * If somehow we failed to create any join clauses, we might as well
3346 * keep scanning the ECs for another match. But if we did make any,
3347 * we're done, because we don't want to return non-redundant clauses.
3348 */
3349 if (result)
3350 break;
3351 }
3352
3353 return result;
3354}
References Assert, bms_equal(), bms_is_subset(), bms_next_member(), bms_overlap(), callback(), create_join_clause(), RelOptInfo::eclass_indexes, eclass_member_iterator_next(), fb(), find_childrel_parents(), i, IS_SIMPLE_REL, lappend(), lfirst, list_length(), list_nth(), NIL, OidIsValid, RelOptInfo::relids, RELOPT_OTHER_MEMBER_REL, RelOptInfo::reloptkind, root, select_equality_operator(), and setup_eclass_member_iterator().
Referenced by create_tidscan_paths(), match_eclass_clauses_to_index(), and postgresGetForeignPaths().
◆ generate_join_implied_equalities()
| List * generate_join_implied_equalities | ( | PlannerInfo * | root, |
| Relids | join_relids, | ||
| Relids | outer_relids, | ||
| RelOptInfo * | inner_rel, | ||
| SpecialJoinInfo * | sjinfo | ||
| ) |
Definition at line 1549 of file equivclass.c.
1554{
1561
1562 /* If inner rel is a child, extra setup work is needed */
1564 {
1566
1567 /* Fetch relid set for the topmost parent rel */
1569 /* ECs will be marked with the parent's relid, not the child's */
1572 nominal_join_relids,
1573 sjinfo,
1574 NULL);
1575 }
1576 else
1577 {
1579 nominal_join_relids = join_relids;
1580 }
1581
1582 /*
1583 * Examine all potentially-relevant eclasses.
1584 *
1585 * If we are considering an outer join, we must include "join" clauses
1586 * that mention either input rel plus the outer join's relid; these
1587 * represent post-join filter clauses that have to be applied at this
1588 * join. We don't have infrastructure that would let us identify such
1589 * eclasses cheaply, so just fall back to considering all eclasses
1590 * mentioning anything in nominal_join_relids.
1591 *
1592 * At inner joins, we can be smarter: only consider eclasses mentioning
1593 * both input rels.
1594 */
1597 else
1599 outer_relids);
1600
1601 i = -1;
1603 {
1606
1607 /* ECs containing consts do not need any further enforcement */
1609 continue;
1610
1611 /* Single-member ECs won't generate any deductions */
1613 continue;
1614
1615 /* Sanity check that this eclass overlaps the join */
1617
1620 ec,
1621 join_relids,
1622 outer_relids,
1623 inner_relids);
1624
1625 /* Recover if we failed to generate required derived clauses */
1628 ec,
1629 nominal_join_relids,
1630 outer_relids,
1631 nominal_inner_relids,
1632 inner_rel);
1633
1635 }
1636
1637 return result;
1638}
References add_outer_joins_to_relids(), Assert, bms_is_empty, bms_next_member(), bms_overlap(), bms_union(), EquivalenceClass::ec_broken, EquivalenceClass::ec_has_const, EquivalenceClass::ec_members, EquivalenceClass::ec_relids, fb(), generate_join_implied_equalities_broken(), generate_join_implied_equalities_normal(), get_common_eclass_indexes(), get_eclass_indexes_for_relids(), i, IS_OTHER_REL, list_concat(), list_length(), list_nth(), NIL, SpecialJoinInfo::ojrelid, and root.
Referenced by build_joinrel_restrictlist(), check_index_predicates(), get_baserel_parampathinfo(), get_joinrel_parampathinfo(), reduce_unique_semijoins(), and remove_self_joins_one_group().
◆ generate_join_implied_equalities_broken()
|
static |
Definition at line 1898 of file equivclass.c.
1904{
1907
1909 {
1912
1917 }
1918
1919 /*
1920 * If we have to translate, just brute-force apply adjust_appendrel_attrs
1921 * to all the RestrictInfos at once. This will result in returning
1922 * RestrictInfos that are not included in EC's derived clauses, but there
1923 * shouldn't be any duplication, and it's a sufficiently narrow corner
1924 * case that we shouldn't sweat too much over it anyway.
1925 *
1926 * Since inner_rel might be an indirect descendant of the baserel
1927 * mentioned in the ec_sources clauses, we have to be prepared to apply
1928 * multiple levels of Var translation.
1929 */
1932 (Node *) result,
1933 inner_rel,
1934 inner_rel->top_parent);
1935
1936 return result;
1937}
References adjust_appendrel_attrs_multilevel(), bms_is_subset(), EquivalenceClass::ec_sources, fb(), IS_OTHER_REL, lappend(), lfirst, NIL, and root.
Referenced by generate_join_implied_equalities(), and generate_join_implied_equalities_for_ecs().
◆ generate_join_implied_equalities_for_ecs()
| List * generate_join_implied_equalities_for_ecs | ( | PlannerInfo * | root, |
| List * | eclasses, | ||
| Relids | join_relids, | ||
| Relids | outer_relids, | ||
| RelOptInfo * | inner_rel | ||
| ) |
Definition at line 1649 of file equivclass.c.
1654{
1660
1661 /* If inner rel is a child, extra setup work is needed */
1663 {
1665
1666 /* Fetch relid set for the topmost parent rel */
1668 /* ECs will be marked with the parent's relid, not the child's */
1670 }
1671 else
1672 {
1674 nominal_join_relids = join_relids;
1675 }
1676
1678 {
1681
1682 /* ECs containing consts do not need any further enforcement */
1684 continue;
1685
1686 /* Single-member ECs won't generate any deductions */
1688 continue;
1689
1690 /* We can quickly ignore any that don't overlap the join, too */
1692 continue;
1693
1696 ec,
1697 join_relids,
1698 outer_relids,
1699 inner_relids);
1700
1701 /* Recover if we failed to generate required derived clauses */
1704 ec,
1705 nominal_join_relids,
1706 outer_relids,
1707 nominal_inner_relids,
1708 inner_rel);
1709
1711 }
1712
1713 return result;
1714}
References Assert, bms_is_empty, bms_overlap(), bms_union(), EquivalenceClass::ec_broken, EquivalenceClass::ec_has_const, EquivalenceClass::ec_members, EquivalenceClass::ec_relids, fb(), generate_join_implied_equalities_broken(), generate_join_implied_equalities_normal(), IS_OTHER_REL, lfirst, list_concat(), list_length(), NIL, and root.
Referenced by get_joinrel_parampathinfo().
◆ generate_join_implied_equalities_normal()
|
static |
Definition at line 1720 of file equivclass.c.
1725{
1732
1733 /*
1734 * First, scan the EC to identify member values that are computable at the
1735 * outer rel, at the inner rel, or at this relation but not in either
1736 * input rel. The outer-rel members should already be enforced equal,
1737 * likewise for the inner-rel members. We'll need to create clauses to
1738 * enforce that any newly computable members are all equal to each other
1739 * as well as to at least one input member, plus enforce at least one
1740 * outer-rel member equal to at least one inner-rel member.
1741 */
1744 {
1745 /*
1746 * We don't need to check explicitly for child EC members. This test
1747 * against join_relids will cause them to be ignored except when
1748 * considering a child inner rel, which is what we want.
1749 */
1751 continue; /* not computable yet, or wrong child */
1752
1757 else
1759 }
1760
1761 /*
1762 * First, select the joinclause if needed. We can equate any one outer
1763 * member to any one inner member, but we have to find a datatype
1764 * combination for which an opfamily member operator exists. If we have
1765 * choices, we prefer simple Var members (possibly with RelabelType) since
1766 * these are (a) cheapest to compute at runtime and (b) most likely to
1767 * have useful statistics. Also, prefer operators that are also
1768 * hashjoinable.
1769 */
1771 {
1776 RestrictInfo *rinfo;
1778
1780 {
1783
1785 {
1789
1791 outer_em->em_datatype,
1792 inner_em->em_datatype);
1794 continue;
1795 score = 0;
1799 score++;
1803 score++;
1806 score++;
1808 {
1814 break; /* no need to look further */
1815 }
1816 }
1818 break; /* no need to look further */
1819 }
1821 {
1822 /* failed... */
1825 }
1826
1827 /*
1828 * Create clause, setting parent_ec to mark it as redundant with other
1829 * joinclauses
1830 */
1833 ec);
1834
1835 result = lappend(result, rinfo);
1836 }
1837
1838 /*
1839 * Now deal with building restrictions for any expressions that involve
1840 * Vars from both sides of the join. We have to equate all of these to
1841 * each other as well as to at least one old member (if any).
1842 *
1843 * XXX as in generate_base_implied_equalities_no_const, we could be a lot
1844 * smarter here to avoid unnecessary failures in cross-type situations.
1845 * For now, use the same left-to-right method used there.
1846 */
1848 {
1851 RestrictInfo *rinfo;
1853
1854 /* For now, arbitrarily take the first old_member as the one to use */
1857
1859 {
1861
1863 {
1865
1867 prev_em->em_datatype,
1868 cur_em->em_datatype);
1870 {
1871 /* failed... */
1874 }
1875 /* do NOT set parent_ec, this qual is not redundant! */
1878 NULL);
1879
1880 result = lappend(result, rinfo);
1881 }
1883 }
1884 }
1885
1886 return result;
1887}
References bms_is_subset(), create_join_clause(), EquivalenceClass::ec_broken, eclass_member_iterator_next(), exprType(), fb(), InvalidOid, IsA, lappend(), lfirst, linitial, list_concat(), NIL, OidIsValid, op_hashjoinable(), root, select_equality_operator(), and setup_eclass_member_iterator().
Referenced by generate_join_implied_equalities(), and generate_join_implied_equalities_for_ecs().
◆ get_common_eclass_indexes()
|
static |
Definition at line 3646 of file equivclass.c.
3647{
3650 int relid;
3651
3653
3654 /*
3655 * We can get away with just using the relation's eclass_indexes directly
3656 * when relids2 is a singleton set.
3657 */
3660 else
3662
3663 /* Calculate and return the common EC indexes, recycling the left input. */
3665}
References bms_get_singleton_member(), bms_int_members(), fb(), get_eclass_indexes_for_relids(), and root.
Referenced by generate_join_implied_equalities(), and have_relevant_eclass_joinclause().
◆ get_eclass_for_sort_expr()
| EquivalenceClass * get_eclass_for_sort_expr | ( | PlannerInfo * | root, |
| Expr * | expr, | ||
| List * | opfamilies, | ||
| Oid | opcintype, | ||
| Oid | collation, | ||
| Index | sortref, | ||
| Relids | rel, | ||
| bool | create_it | ||
| ) |
Definition at line 736 of file equivclass.c.
744{
745 JoinDomain *jdomain;
750 MemoryContext oldcontext;
751
752 /*
753 * Ensure the expression exposes the correct type and collation.
754 */
755 expr = canonicalize_ec_expression(expr, opcintype, collation);
756
757 /*
758 * Since SortGroupClause nodes are top-level expressions (GROUP BY, ORDER
759 * BY, etc), they can be presumed to belong to the top JoinDomain.
760 */
762
763 /*
764 * Scan through the existing EquivalenceClasses for a match
765 */
767 {
771
772 /*
773 * Never match to a volatile EC, except when we are looking at another
774 * reference to the same volatile SortGroupClause.
775 */
778 continue;
779
781 continue;
783 continue;
784
787 {
788 /*
789 * Ignore child members unless they match the request.
790 */
793 continue;
794
795 /*
796 * Match constants only within the same JoinDomain (see
797 * optimizer/README).
798 */
800 continue;
801
805 }
806 }
807
808 /* No match; does caller want a NULL result? */
811
812 /*
813 * OK, build a new single-member EC
814 *
815 * Here, we must be sure that we construct the EC in the right context.
816 */
818
821 newec->ec_collation = collation;
822 newec->ec_childmembers_size = 0;
834 newec->ec_max_security = 0;
836
839
840 /*
841 * Get the precise set of relids appearing in the expression.
842 */
844
846 jdomain, opcintype);
847
848 /*
849 * add_eq_member doesn't check for volatile functions, set-returning
850 * functions, aggregates, or window functions, but such could appear in
851 * sort expressions; so we have to check whether its const-marking was
852 * correct.
853 */
855 {
860 {
863 }
864 }
865
867
868 /*
869 * If EC merging is already complete, we have to mop up by adding the new
870 * EC to the eclass_indexes of the relation(s) mentioned in it.
871 */
873 {
876
878 {
880
881 /* ignore the RTE_GROUP RTE */
883 continue;
884
886 {
888 continue;
889 }
890
892
894 ec_index);
895 }
896 }
897
898 MemoryContextSwitchTo(oldcontext);
899
901}
References add_eq_member(), Assert, bms_add_member(), bms_equal(), bms_is_member(), bms_next_member(), canonicalize_ec_expression(), contain_agg_clause(), contain_volatile_functions(), contain_window_function(), copyObject, RelOptInfo::eclass_indexes, eclass_member_iterator_next(), elog, equal(), ERROR, expression_returns_set(), fb(), i, lappend(), lfirst, linitial_node, list_copy(), list_length(), makeNode, MemoryContextSwitchTo(), NIL, pull_varnos(), RELOPT_BASEREL, RelOptInfo::reloptkind, root, and setup_eclass_member_iterator().
Referenced by convert_subquery_pathkeys(), get_eclass_for_sortgroupclause(), initialize_mergeclause_eclasses(), and make_pathkey_from_sortinfo().
◆ get_eclass_indexes_for_relids()
|
static |
Definition at line 3612 of file equivclass.c.
3613{
3616
3617 /* Should be OK to rely on eclass_indexes */
3619
3621 {
3623
3624 /* ignore the RTE_GROUP RTE */
3626 continue;
3627
3629 {
3631 continue;
3632 }
3633
3635 }
3637}
References Assert, bms_add_members(), bms_is_member(), bms_next_member(), RelOptInfo::eclass_indexes, fb(), i, and root.
Referenced by add_child_join_rel_equivalences(), generate_join_implied_equalities(), get_common_eclass_indexes(), and has_relevant_eclass_joinclause().
◆ has_relevant_eclass_joinclause()
| bool has_relevant_eclass_joinclause | ( | PlannerInfo * | root, |
| RelOptInfo * | rel1 | ||
| ) |
Definition at line 3445 of file equivclass.c.
3446{
3449
3450 /* Examine only eclasses mentioning rel1 */
3452
3453 i = -1;
3455 {
3457 i);
3458
3459 /*
3460 * Won't generate joinclauses if single-member (this test covers the
3461 * volatile case too)
3462 */
3464 continue;
3465
3466 /*
3467 * Per the comment in have_relevant_eclass_joinclause, it's sufficient
3468 * to find an EC that mentions both this rel and some other rel.
3469 */
3471 return true;
3472 }
3473
3474 return false;
3475}
References bms_is_subset(), bms_next_member(), EquivalenceClass::ec_members, EquivalenceClass::ec_relids, fb(), get_eclass_indexes_for_relids(), i, list_length(), list_nth(), and root.
Referenced by build_join_rel().
◆ have_relevant_eclass_joinclause()
| bool have_relevant_eclass_joinclause | ( | PlannerInfo * | root, |
| RelOptInfo * | rel1, | ||
| RelOptInfo * | rel2 | ||
| ) |
Definition at line 3369 of file equivclass.c.
3371{
3374
3375 /*
3376 * Examine only eclasses mentioning both rel1 and rel2.
3377 *
3378 * Note that we do not consider the possibility of an eclass generating
3379 * "join" clauses that mention just one of the rels plus an outer join
3380 * that could be formed from them. Although such clauses must be
3381 * correctly enforced when we form the outer join, they don't seem like
3382 * sufficient reason to prioritize this join over other ones. The join
3383 * ordering rules will force the join to be made when necessary.
3384 */
3386 rel2->relids);
3387
3388 i = -1;
3390 {
3392 i);
3393
3394 /*
3395 * Sanity check that get_common_eclass_indexes gave only ECs
3396 * containing both rels.
3397 */
3400
3401 /*
3402 * Won't generate joinclauses if single-member (this test covers the
3403 * volatile case too)
3404 */
3406 continue;
3407
3408 /*
3409 * We do not need to examine the individual members of the EC, because
3410 * all that we care about is whether each rel overlaps the relids of
3411 * at least one member, and get_common_eclass_indexes() and the single
3412 * member check above are sufficient to prove that. (As with
3413 * have_relevant_joinclause(), it is not necessary that the EC be able
3414 * to form a joinclause relating exactly the two given rels, only that
3415 * it be able to form a joinclause mentioning both, and this will
3416 * surely be true if both of them overlap ec_relids.)
3417 *
3418 * Note we don't test ec_broken; if we did, we'd need a separate code
3419 * path to look through ec_sources. Checking the membership anyway is
3420 * OK as a possibly-overoptimistic heuristic.
3421 *
3422 * We don't test ec_has_const either, even though a const eclass won't
3423 * generate real join clauses. This is because if we had "WHERE a.x =
3424 * b.y and a.x = 42", it is worth considering a join between a and b,
3425 * since the join result is likely to be small even though it'll end
3426 * up being an unqualified nestloop.
3427 */
3428
3429 return true;
3430 }
3431
3432 return false;
3433}
References Assert, bms_next_member(), bms_overlap(), EquivalenceClass::ec_members, EquivalenceClass::ec_relids, fb(), get_common_eclass_indexes(), i, list_length(), list_nth(), and root.
Referenced by have_relevant_joinclause().
◆ is_redundant_derived_clause()
| bool is_redundant_derived_clause | ( | RestrictInfo * | rinfo, |
| List * | clauselist | ||
| ) |
Definition at line 3549 of file equivclass.c.
3550{
3551 EquivalenceClass *parent_ec = rinfo->parent_ec;
3553
3554 /* Fail if it's not a potentially-redundant clause from some EC */
3556 return false;
3557
3559 {
3561
3563 return true;
3564 }
3565
3566 return false;
3567}
Referenced by create_tidscan_plan().
◆ is_redundant_with_indexclauses()
| bool is_redundant_with_indexclauses | ( | RestrictInfo * | rinfo, |
| List * | indexclauses | ||
| ) |
Definition at line 3576 of file equivclass.c.
3577{
3578 EquivalenceClass *parent_ec = rinfo->parent_ec;
3580
3582 {
3585
3586 /* If indexclause is lossy, it won't enforce the condition exactly */
3588 continue;
3589
3590 /* Match if it's same clause (pointer equality should be enough) */
3592 return true;
3593 /* Match if derived from same EC */
3595 return true;
3596
3597 /*
3598 * No need to look at the derived clauses in iclause->indexquals; they
3599 * couldn't match if the parent clause didn't.
3600 */
3601 }
3602
3603 return false;
3604}
References fb(), and lfirst_node.
Referenced by create_indexscan_plan(), extract_nonindex_conditions(), and has_indexed_join_quals().
◆ make_eq_member()
|
static |
Definition at line 592 of file equivclass.c.
594{
596
597 em->em_expr = expr;
598 em->em_relids = relids;
601 em->em_datatype = datatype;
602 em->em_jdomain = jdomain;
603 em->em_parent = parent;
604
606 {
607 /*
608 * No Vars, assume it's a pseudoconstant. This is correct for entries
609 * generated from process_equivalence(), because a WHERE clause can't
610 * contain aggregates or SRFs, and non-volatility was checked before
611 * process_equivalence() ever got called. But
612 * get_eclass_for_sort_expr() has to work harder. We put the tests
613 * there not here to save cycles in the equivalence case.
614 */
615 Assert(!parent);
618 /* it can't affect ec_relids */
619 }
620
622}
References Assert, bms_is_empty, EquivalenceClass::ec_has_const, fb(), and makeNode.
Referenced by add_child_eq_member(), and add_eq_member().
◆ match_eclasses_to_foreign_key_col()
| EquivalenceClass * match_eclasses_to_foreign_key_col | ( | PlannerInfo * | root, |
| ForeignKeyOptInfo * | fkinfo, | ||
| int | colno | ||
| ) |
Definition at line 2709 of file equivclass.c.
2712{
2723
2724 /* Consider only eclasses mentioning both relations */
2729 rel2->eclass_indexes);
2730
2731 i = -1;
2733 {
2735 i);
2739
2740 /* Never match to a volatile EC */
2742 continue;
2743
2744 /*
2745 * It's okay to consider "broken" ECs here, see exprs_known_equal.
2746 * Ignore children here.
2747 */
2749 {
2751 Var *var;
2752
2753 /* Child members should not exist in ec_members */
2755
2756 /* EM must be a Var, possibly with RelabelType */
2761 continue;
2762
2763 /* Match? */
2768
2769 /* Have we found both PK and FK column in this EC? */
2771 {
2772 /*
2773 * Succeed if eqop matches EC's opfamilies. We could test
2774 * this before scanning the members, but it's probably cheaper
2775 * to test for member matches first.
2776 */
2780 {
2781 fkinfo->eclass[colno] = ec;
2783 return ec;
2784 }
2785 /* Otherwise, done with this EC, move on to the next */
2786 break;
2787 }
2788 }
2789 }
2791}
References arg, Assert, bms_intersect(), bms_next_member(), EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_members, EquivalenceClass::ec_opfamilies, equal(), fb(), get_mergejoin_opfamilies(), i, IS_SIMPLE_REL, IsA, lfirst, list_nth(), NIL, root, Var::varattno, and Var::varno.
Referenced by match_foreign_keys_to_quals().
◆ process_equivalence()
| bool process_equivalence | ( | PlannerInfo * | root, |
| RestrictInfo ** | p_restrictinfo, | ||
| JoinDomain * | jdomain | ||
| ) |
Definition at line 179 of file equivclass.c.
182{
185 Oid opno,
186 collation,
187 item1_type,
188 item2_type;
192 item2_relids;
195 *ec2;
196 EquivalenceMember *em1,
197 *em2;
200
201 /* Should not already be marked as having generated an eclass */
204
205 /* Reject if it is potentially postponable by security considerations */
207 return false;
208
209 /* Extract info from given clause */
211 opno = ((OpExpr *) clause)->opno;
212 collation = ((OpExpr *) clause)->inputcollid;
217
218 /*
219 * Ensure both input expressions expose the desired collation (their types
220 * should be OK already); see comments for canonicalize_ec_expression.
221 */
224 collation);
227 collation);
228
229 /*
230 * Clauses of the form X=X cannot be translated into EquivalenceClasses.
231 * We'd either end up with a single-entry EC, losing the knowledge that
232 * the clause was present at all, or else make an EC with duplicate
233 * entries, causing other issues.
234 */
236 {
237 /*
238 * If the operator is strict, then the clause can be treated as just
239 * "X IS NOT NULL". (Since we know we are considering a top-level
240 * qual, we can ignore the difference between FALSE and NULL results.)
241 * It's worth making the conversion because we'll typically get a much
242 * better selectivity estimate than we would for X=X.
243 *
244 * If the operator is not strict, we can't be sure what it will do
245 * with NULLs, so don't attempt to optimize it.
246 */
249 {
251
255 ntest->location = -1;
256
257 *p_restrictinfo =
260 restrictinfo->is_pushed_down,
261 restrictinfo->has_clone,
262 restrictinfo->is_clone,
263 restrictinfo->pseudoconstant,
264 restrictinfo->security_level,
265 NULL,
266 restrictinfo->incompatible_relids,
267 restrictinfo->outer_relids);
268 }
269 return false;
270 }
271
272 /*
273 * We use the declared input types of the operator, not exprType() of the
274 * inputs, as the nominal datatypes for opfamily lookup. This presumes
275 * that btree operators are always registered with amoplefttype and
276 * amoprighttype equal to their declared input types. We will need this
277 * info anyway to build EquivalenceMember nodes, and by extracting it now
278 * we can use type comparisons to short-circuit some equal() tests.
279 */
281
283
284 /*
285 * Sweep through the existing EquivalenceClasses looking for matches to
286 * item1 and item2. These are the possible outcomes:
287 *
288 * 1. We find both in the same EC. The equivalence is already known, so
289 * there's nothing to do.
290 *
291 * 2. We find both in different ECs. Merge the two ECs together.
292 *
293 * 3. We find just one. Add the other to its EC.
294 *
295 * 4. We find neither. Make a new, two-entry EC.
296 *
297 * Note: since all ECs are built through this process or the similar
298 * search in get_eclass_for_sort_expr(), it's impossible that we'd match
299 * an item in more than one existing nonvolatile EC. So it's okay to stop
300 * at the first match.
301 */
303 em1 = em2 = NULL;
304 ec2_idx = -1;
306 {
309
310 /* Never match to a volatile EC */
312 continue;
313
314 /*
315 * The collation has to match; check this first since it's cheaper
316 * than the opfamily comparison.
317 */
319 continue;
320
321 /*
322 * A "match" requires matching sets of btree opfamilies. Use of
323 * equal() for this test has implications discussed in the comments
324 * for get_mergejoin_opfamilies().
325 */
327 continue;
328
329 /* We don't expect any children yet */
331
333 {
335
336 /* Child members should not exist in ec_members */
338
339 /*
340 * Match constants only within the same JoinDomain (see
341 * optimizer/README).
342 */
344 continue;
345
349 {
351 em1 = cur_em;
353 break;
354 }
355
359 {
362 em2 = cur_em;
364 break;
365 }
366 }
367
369 break;
370 }
371
372 /* Sweep finished, what did we find? */
373
375 {
376 /* If case 1, nothing to do, except add to sources */
378 {
381 restrictinfo->security_level);
383 restrictinfo->security_level);
384 /* mark the RI as associated with this eclass */
387 /* mark the RI as usable with this pair of EMs */
388 restrictinfo->left_em = em1;
389 restrictinfo->right_em = em2;
390 return true;
391 }
392
393 /*
394 * Case 2: need to merge ec1 and ec2. This should never happen after
395 * the ECs have reached canonical state; otherwise, pathkeys could be
396 * rendered non-canonical by the merge, and relation eclass indexes
397 * would get broken by removal of an eq_classes list entry.
398 */
401
402 /*
403 * We add ec2's items to ec1, then set ec2's ec_merged link to point
404 * to ec1 and remove ec2 from the eq_classes list. We cannot simply
405 * delete ec2 because that could leave dangling pointers in existing
406 * PathKeys. We leave it behind with a link so that the merged EC can
407 * be found.
408 */
411
412 /*
413 * Appends ec2's derived clauses to ec1->ec_derives_list and adds them
414 * to ec1->ec_derives_hash if present.
415 */
419 /* can't need to set has_volatile */
421 ec2->ec_min_security);
423 ec2->ec_max_security);
426 /* just to avoid debugging confusion w/ dangling pointers: */
433 restrictinfo->security_level);
435 restrictinfo->security_level);
436 /* mark the RI as associated with this eclass */
439 /* mark the RI as usable with this pair of EMs */
440 restrictinfo->left_em = em1;
441 restrictinfo->right_em = em2;
442 }
444 {
445 /* Case 3: add item2 to ec1 */
447 jdomain, item2_type);
450 restrictinfo->security_level);
452 restrictinfo->security_level);
453 /* mark the RI as associated with this eclass */
456 /* mark the RI as usable with this pair of EMs */
457 restrictinfo->left_em = em1;
458 restrictinfo->right_em = em2;
459 }
461 {
462 /* Case 3: add item1 to ec2 */
464 jdomain, item1_type);
467 restrictinfo->security_level);
469 restrictinfo->security_level);
470 /* mark the RI as associated with this eclass */
473 /* mark the RI as usable with this pair of EMs */
474 restrictinfo->left_em = em1;
475 restrictinfo->right_em = em2;
476 }
477 else
478 {
479 /* Case 4: make a new, two-entry EC */
481
483 ec->ec_collation = collation;
484 ec->ec_childmembers_size = 0;
494 ec->ec_sortref = 0;
499 jdomain, item1_type);
501 jdomain, item2_type);
502
504
505 /* mark the RI as associated with this eclass */
506 restrictinfo->left_ec = ec;
507 restrictinfo->right_ec = ec;
508 /* mark the RI as usable with this pair of EMs */
509 restrictinfo->left_em = em1;
510 restrictinfo->right_em = em2;
511 }
512
513 return true;
514}
References add_eq_member(), Assert, bms_join(), canonicalize_ec_expression(), ec_add_derived_clauses(), EquivalenceClass::ec_broken, EquivalenceClass::ec_childmembers, EquivalenceClass::ec_childmembers_size, ec_clear_derived_clauses(), EquivalenceClass::ec_collation, EquivalenceClass::ec_derives_hash, EquivalenceClass::ec_derives_list, EquivalenceClass::ec_has_const, EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_max_security, EquivalenceClass::ec_members, EquivalenceClass::ec_merged, EquivalenceClass::ec_min_security, EquivalenceClass::ec_opfamilies, EquivalenceClass::ec_relids, EquivalenceClass::ec_sortref, EquivalenceClass::ec_sources, elog, equal(), ERROR, exprType(), fb(), foreach_current_index, func_strict(), get_leftop(), get_rightop(), IS_NOT_NULL, is_opclause(), lappend(), lfirst, list_concat(), list_delete_nth_cell(), list_make1, make_restrictinfo(), makeNode, Max, Min, NIL, op_input_types(), root, and set_opfuncid().
Referenced by distribute_qual_to_rels(), reconsider_full_join_clause(), and reconsider_outer_join_clause().
◆ rebuild_eclass_attr_needed()
| void rebuild_eclass_attr_needed | ( | PlannerInfo * | root | ) |
Definition at line 2573 of file equivclass.c.
2574{
2576
2578 {
2580
2581 /*
2582 * We don't expect any EC child members to exist at this point. Ensure
2583 * that's the case, otherwise, we might be getting asked to do
2584 * something this function hasn't been coded for.
2585 */
2587
2588 /* Need do anything only for a multi-member, no-const EC. */
2590 {
2592
2594 {
2597 PVC_RECURSE_AGGREGATES |
2598 PVC_RECURSE_WINDOWFUNCS |
2599 PVC_INCLUDE_PLACEHOLDERS);
2600
2603 }
2604 }
2605 }
2606}
References add_vars_to_attr_needed(), Assert, EquivalenceClass::ec_childmembers, EquivalenceClass::ec_has_const, EquivalenceClass::ec_members, EquivalenceClass::ec_relids, fb(), lfirst, list_free(), list_length(), pull_var_clause(), PVC_INCLUDE_PLACEHOLDERS, PVC_RECURSE_AGGREGATES, PVC_RECURSE_WINDOWFUNCS, and root.
Referenced by remove_leftjoinrel_from_query(), and remove_self_join_rel().
◆ reconsider_full_join_clause()
|
static |
Definition at line 2383 of file equivclass.c.
2384{
2390 Oid opno,
2391 collation,
2392 left_type,
2393 right_type;
2395 right_relids;
2397
2398 /* Extract needed info from the clause */
2405 left_relids = rinfo->left_relids;
2406 right_relids = rinfo->right_relids;
2407
2409 {
2412 bool match;
2417
2418 /* We don't expect any children yet */
2420
2421 /* Ignore EC unless it contains pseudoconstants */
2423 continue;
2424 /* Never match to a volatile EC */
2426 continue;
2427 /* It has to match the outer-join clause as to semantics, too */
2429 continue;
2431 continue;
2432
2433 /*
2434 * Does it contain a COALESCE(leftvar, rightvar) construct?
2435 *
2436 * We can assume the COALESCE() inputs are in the same order as the
2437 * join clause, since both were automatically generated in the cases
2438 * we care about.
2439 *
2440 * XXX currently this may fail to match in cross-type cases because
2441 * the COALESCE will contain typecast operations while the join clause
2442 * may not (if there is a cross-type mergejoin operator available for
2443 * the two column types). Is it OK to strip implicit coercions from
2444 * the COALESCE arguments?
2445 */
2446 match = false;
2448 {
2450
2451 /* Child members should not exist in ec_members */
2454 {
2458
2460 continue;
2463
2464 /*
2465 * The COALESCE arguments will be marked as possibly nulled by
2466 * the full join, while we wish to generate clauses that apply
2467 * to the join's inputs. So we must strip the join from the
2468 * nullingrels fields of cfirst/csecond before comparing them
2469 * to leftvar/rightvar. (Perhaps with a less hokey
2470 * representation for FULL JOIN USING output columns, this
2471 * wouldn't be needed?)
2472 */
2475
2477 {
2479 match = true;
2480 break;
2481 }
2482 }
2483 }
2484 if (!match)
2485 continue; /* no match, so ignore this EC */
2486
2487 /*
2488 * Yes it does! Try to generate clauses LEFTVAR = CONSTANT and
2489 * RIGHTVAR = CONSTANT for each CONSTANT in the EC. Note that we must
2490 * succeed with at least one constant for each var before we can
2491 * decide to throw away the outer-join clause.
2492 */
2495 {
2499 JoinDomain *jdomain;
2500
2502 continue; /* ignore non-const members */
2504 left_type,
2505 cur_em->em_datatype);
2507 {
2509 eq_op,
2510 cur_ec->ec_collation,
2511 leftvar,
2512 cur_em->em_expr,
2514 cur_ec->ec_min_security);
2515 /* This equality holds within the lefthand child JoinDomain */
2519 }
2521 right_type,
2522 cur_em->em_datatype);
2524 {
2526 eq_op,
2527 cur_ec->ec_collation,
2528 rightvar,
2529 cur_em->em_expr,
2531 cur_ec->ec_min_security);
2532 /* This equality holds within the righthand child JoinDomain */
2536 }
2537 }
2538
2539 /*
2540 * If we were able to equate both vars to constants, we're done, and
2541 * we can throw away the full-join clause as redundant. Moreover, we
2542 * can remove the COALESCE entry from the EC, since the added
2543 * restrictions ensure it will always have the expected value. (We
2544 * don't bother trying to update ec_relids or ec_sources.)
2545 */
2547 {
2549 return true;
2550 }
2551
2552 /*
2553 * Otherwise, fall out of the search loop, since we know the COALESCE
2554 * appears in at most one EC (XXX might stop being true if we allow
2555 * stripping of coercions above?)
2556 */
2557 break;
2558 }
2559
2560 return false; /* failed to make any deduction */
2561}
References CoalesceExpr::args, Assert, bms_copy(), bms_make_singleton(), build_implied_join_equality(), RestrictInfo::clause, equal(), fb(), find_join_domain(), foreach_current_index, get_leftop(), get_rightop(), is_opclause(), IsA, lfirst, linitial, list_delete_nth_cell(), list_length(), lsecond, OidIsValid, SpecialJoinInfo::ojrelid, op_input_types(), process_equivalence(), remove_nulling_relids(), root, select_equality_operator(), SpecialJoinInfo::syn_lefthand, and SpecialJoinInfo::syn_righthand.
Referenced by reconsider_outer_join_clauses().
◆ reconsider_outer_join_clause()
|
static |
Definition at line 2256 of file equivclass.c.
2258{
2262 *innervar;
2263 Oid opno,
2264 collation,
2265 left_type,
2266 right_type,
2267 inner_datatype;
2270
2274
2275 /* Extract needed info from the clause */
2278 {
2282 inner_relids = rinfo->right_relids;
2283 }
2284 else
2285 {
2289 inner_relids = rinfo->left_relids;
2290 }
2291
2292 /* Scan EquivalenceClasses for a match to outervar */
2294 {
2296 bool match;
2298
2299 /* We don't expect any children yet */
2301
2302 /* Ignore EC unless it contains pseudoconstants */
2304 continue;
2305 /* Never match to a volatile EC */
2307 continue;
2308 /* It has to match the outer-join clause as to semantics, too */
2310 continue;
2312 continue;
2313 /* Does it contain a match to outervar? */
2314 match = false;
2316 {
2318
2319 /* Child members should not exist in ec_members */
2322 {
2323 match = true;
2324 break;
2325 }
2326 }
2327 if (!match)
2328 continue; /* no match, so ignore this EC */
2329
2330 /*
2331 * Yes it does! Try to generate a clause INNERVAR = CONSTANT for each
2332 * CONSTANT in the EC. Note that we must succeed with at least one
2333 * constant before we can decide to throw away the outer-join clause.
2334 */
2335 match = false;
2337 {
2341 JoinDomain *jdomain;
2342
2344 continue; /* ignore non-const members */
2346 inner_datatype,
2347 cur_em->em_datatype);
2349 continue; /* can't generate equality */
2351 eq_op,
2352 cur_ec->ec_collation,
2353 innervar,
2354 cur_em->em_expr,
2356 cur_ec->ec_min_security);
2357 /* This equality holds within the OJ's child JoinDomain */
2360 match = true;
2361 }
2362
2363 /*
2364 * If we were able to equate INNERVAR to any constant, report success.
2365 * Otherwise, fall out of the search loop, since we know the OUTERVAR
2366 * appears in at most one EC.
2367 */
2368 if (match)
2369 return true;
2370 else
2371 break;
2372 }
2373
2374 return false; /* failed to make any deduction */
2375}
References Assert, bms_copy(), build_implied_join_equality(), RestrictInfo::clause, equal(), fb(), find_join_domain(), get_leftop(), get_rightop(), is_opclause(), lfirst, OidIsValid, op_input_types(), process_equivalence(), root, select_equality_operator(), and SpecialJoinInfo::syn_righthand.
Referenced by reconsider_outer_join_clauses().
◆ reconsider_outer_join_clauses()
| void reconsider_outer_join_clauses | ( | PlannerInfo * | root | ) |
Definition at line 2134 of file equivclass.c.
2135{
2136 bool found;
2137 ListCell *cell;
2138
2139 /* Outer loop repeats until we find no more deductions */
2140 do
2141 {
2142 found = false;
2143
2144 /* Process the LEFT JOIN clauses */
2146 {
2148
2150 {
2152
2153 found = true;
2154 /* remove it from the list */
2155 root->left_join_clauses =
2157 /* throw back a dummy replacement clause (see notes above) */
2160 rinfo->is_pushed_down,
2161 rinfo->has_clone,
2162 rinfo->is_clone,
2163 false, /* pseudoconstant */
2164 0, /* security_level */
2165 rinfo->required_relids,
2166 rinfo->incompatible_relids,
2167 rinfo->outer_relids);
2169 }
2170 }
2171
2172 /* Process the RIGHT JOIN clauses */
2174 {
2176
2178 {
2180
2181 found = true;
2182 /* remove it from the list */
2183 root->right_join_clauses =
2185 /* throw back a dummy replacement clause (see notes above) */
2188 rinfo->is_pushed_down,
2189 rinfo->has_clone,
2190 rinfo->is_clone,
2191 false, /* pseudoconstant */
2192 0, /* security_level */
2193 rinfo->required_relids,
2194 rinfo->incompatible_relids,
2195 rinfo->outer_relids);
2197 }
2198 }
2199
2200 /* Process the FULL JOIN clauses */
2202 {
2204
2206 {
2208
2209 found = true;
2210 /* remove it from the list */
2211 root->full_join_clauses =
2213 /* throw back a dummy replacement clause (see notes above) */
2216 rinfo->is_pushed_down,
2217 rinfo->has_clone,
2218 rinfo->is_clone,
2219 false, /* pseudoconstant */
2220 0, /* security_level */
2221 rinfo->required_relids,
2222 rinfo->incompatible_relids,
2223 rinfo->outer_relids);
2225 }
2226 }
2227 } while (found);
2228
2229 /* Now, any remaining clauses have to be thrown back */
2231 {
2233
2235 }
2237 {
2239
2241 }
2243 {
2245
2247 }
2248}
References distribute_restrictinfo_to_rels(), fb(), foreach_delete_current, RestrictInfo::has_clone, RestrictInfo::incompatible_relids, RestrictInfo::is_clone, RestrictInfo::is_pushed_down, lfirst, make_restrictinfo(), makeBoolConst(), RestrictInfo::outer_relids, reconsider_full_join_clause(), reconsider_outer_join_clause(), RestrictInfo::required_relids, and root.
Referenced by query_planner().
◆ relation_can_be_sorted_early()
| bool relation_can_be_sorted_early | ( | PlannerInfo * | root, |
| RelOptInfo * | rel, | ||
| EquivalenceClass * | ec, | ||
| bool | require_parallel_safe | ||
| ) |
Definition at line 1076 of file equivclass.c.
1078{
1082
1083 /*
1084 * Reject volatile ECs immediately; such sorts must always be postponed.
1085 */
1087 return false;
1088
1089 /*
1090 * Try to find an EM directly matching some reltarget member.
1091 */
1093 {
1095
1098 continue;
1099
1100 /*
1101 * Reject expressions involving set-returning functions, as those
1102 * can't be computed early either. (Note: this test and the following
1103 * one are effectively checking properties of targetexpr, so there's
1104 * no point in asking whether some other EC member would be better.)
1105 */
1107 continue;
1108
1109 /*
1110 * If requested, reject expressions that are not parallel-safe. We
1111 * check this last because it's a rather expensive test.
1112 */
1115 continue;
1116
1117 return true;
1118 }
1119
1120 /*
1121 * Try to find an expression computable from the reltarget.
1122 */
1124 require_parallel_safe);
1126 return false;
1127
1128 /*
1129 * Reject expressions involving set-returning functions, as those can't be
1130 * computed early either. (There's no point in looking for another EC
1131 * member in this case; since SRFs can't appear in WHERE, they cannot
1132 * belong to multi-member ECs.)
1133 */
1135 return false;
1136
1137 return true;
1138}
References EquivalenceClass::ec_has_volatile, expression_returns_set(), PathTarget::exprs, fb(), find_computable_ec_member(), find_ec_member_matching_expr(), is_parallel_safe(), lfirst, RelOptInfo::relids, RelOptInfo::reltarget, and root.
Referenced by get_useful_pathkeys_for_relation().
◆ select_equality_operator()
|
static |
Definition at line 1947 of file equivclass.c.
1948{
1950
1952 {
1954 Oid opno;
1955
1958 continue;
1959 /* If no barrier quals in query, don't worry about leaky operators */
1961 return opno;
1962 /* Otherwise, insist that selected operators be leakproof */
1964 return opno;
1965 }
1967}
References COMPARE_EQ, EquivalenceClass::ec_max_security, EquivalenceClass::ec_opfamilies, fb(), get_func_leakproof(), get_opcode(), get_opfamily_member_for_cmptype(), InvalidOid, lfirst_oid, and OidIsValid.
Referenced by generate_base_implied_equalities_const(), generate_base_implied_equalities_no_const(), generate_implied_equalities_for_column(), generate_join_implied_equalities_normal(), reconsider_full_join_clause(), and reconsider_outer_join_clause().
◆ setup_eclass_member_iterator()
| void setup_eclass_member_iterator | ( | EquivalenceMemberIterator * | it, |
| EquivalenceClass * | ec, | ||
| Relids | child_relids | ||
| ) |
Definition at line 3155 of file equivclass.c.
3157{
3158 it->ec = ec;
3159 /* no need to set this if the class has no child members array set */
3161 it->current_relid = -1;
3164}
References EquivalenceClass::ec_childmembers, EquivalenceClass::ec_members, fb(), and list_head().
Referenced by find_computable_ec_member(), find_ec_member_matching_expr(), find_em_for_rel(), generate_implied_equalities_for_column(), generate_join_implied_equalities_normal(), get_eclass_for_sort_expr(), and match_pathkeys_to_index().
