1 /*-------------------------------------------------------------------------
4 * Routines copied from PostgreSQL core distribution.
6 * The main purpose of this files is having access to static functions in core.
7 * Another purpose is tweaking functions behavior by replacing part of them by
8 * macro definitions. See at the end of pg_hint_plan.c for details. Anyway,
9 * this file *must* contain required functions without making any change.
11 * This file contains the following functions from corresponding files.
13 * src/backend/optimizer/path/allpaths.c
16 * set_plain_rel_pathlist()
17 * add_paths_to_append_rel()
18 * try_partitionwise_join()
21 * standard_join_search(): This funcion is not static. The reason for
22 * including this function is make_rels_by_clause_joins. In order to
23 * avoid generating apparently unwanted join combination, we decided to
24 * change the behavior of make_join_rel, which is called under this
27 * src/backend/optimizer/path/joinrels.c
30 * join_search_one_level(): We have to modify this to call my definition of
31 * make_rels_by_clause_joins.
34 * make_rels_by_clause_joins()
35 * make_rels_by_clauseless_joins()
37 * has_join_restriction()
39 * restriction_is_constant_false()
40 * update_child_rel_info()
41 * build_child_join_sjinfo()
44 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
45 * Portions Copyright (c) 1994, Regents of the University of California
47 *-------------------------------------------------------------------------
50 static void populate_joinrel_with_paths(PlannerInfo *root, RelOptInfo *rel1,
51 RelOptInfo *rel2, RelOptInfo *joinrel,
52 SpecialJoinInfo *sjinfo, List *restrictlist);
55 * set_plain_rel_pathlist
56 * Build access paths for a plain relation (no subquery, no inheritance)
59 set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
61 Relids required_outer;
64 * We don't support pushing join clauses into the quals of a seqscan, but
65 * it could still have required parameterization due to LATERAL refs in
68 required_outer = rel->lateral_relids;
70 /* Consider sequential scan */
71 add_path(rel, create_seqscan_path(root, rel, required_outer, 0));
73 /* If appropriate, consider parallel sequential scan */
74 if (rel->consider_parallel && required_outer == NULL)
75 create_plain_partial_paths(root, rel);
77 /* Consider index scans */
78 create_index_paths(root, rel);
80 /* Consider TID scans */
81 create_tidscan_paths(root, rel);
86 * set_append_rel_pathlist
87 * Build access paths for an "append relation"
90 set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
91 Index rti, RangeTblEntry *rte)
93 int parentRTindex = rti;
94 List *live_childrels = NIL;
98 * Generate access paths for each member relation, and remember the
101 foreach(l, root->append_rel_list)
103 AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
105 RangeTblEntry *childRTE;
106 RelOptInfo *childrel;
108 /* append_rel_list contains all append rels; ignore others */
109 if (appinfo->parent_relid != parentRTindex)
112 /* Re-locate the child RTE and RelOptInfo */
113 childRTindex = appinfo->child_relid;
114 childRTE = root->simple_rte_array[childRTindex];
115 childrel = root->simple_rel_array[childRTindex];
118 * If set_append_rel_size() decided the parent appendrel was
119 * parallel-unsafe at some point after visiting this child rel, we
120 * need to propagate the unsafety marking down to the child, so that
121 * we don't generate useless partial paths for it.
123 if (!rel->consider_parallel)
124 childrel->consider_parallel = false;
127 * Compute the child's access paths.
129 set_rel_pathlist(root, childrel, childRTindex, childRTE);
132 * If child is dummy, ignore it.
134 if (IS_DUMMY_REL(childrel))
137 /* Bubble up childrel's partitioned children. */
138 if (rel->part_scheme)
139 rel->partitioned_child_rels =
140 list_concat(rel->partitioned_child_rels,
141 list_copy(childrel->partitioned_child_rels));
144 * Child is live, so add it to the live_childrels list for use below.
146 live_childrels = lappend(live_childrels, childrel);
149 /* Add paths to the append relation. */
150 add_paths_to_append_rel(root, rel, live_childrels);
155 * standard_join_search
156 * Find possible joinpaths for a query by successively finding ways
157 * to join component relations into join relations.
159 * 'levels_needed' is the number of iterations needed, ie, the number of
160 * independent jointree items in the query. This is > 1.
162 * 'initial_rels' is a list of RelOptInfo nodes for each independent
163 * jointree item. These are the components to be joined together.
164 * Note that levels_needed == list_length(initial_rels).
166 * Returns the final level of join relations, i.e., the relation that is
167 * the result of joining all the original relations together.
168 * At least one implementation path must be provided for this relation and
169 * all required sub-relations.
171 * To support loadable plugins that modify planner behavior by changing the
172 * join searching algorithm, we provide a hook variable that lets a plugin
173 * replace or supplement this function. Any such hook must return the same
174 * final join relation as the standard code would, but it might have a
175 * different set of implementation paths attached, and only the sub-joinrels
176 * needed for these paths need have been instantiated.
178 * Note to plugin authors: the functions invoked during standard_join_search()
179 * modify root->join_rel_list and root->join_rel_hash. If you want to do more
180 * than one join-order search, you'll probably need to save and restore the
181 * original states of those data structures. See geqo_eval() for an example.
184 standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
190 * This function cannot be invoked recursively within any one planning
191 * problem, so join_rel_level[] can't be in use already.
193 Assert(root->join_rel_level == NULL);
196 * We employ a simple "dynamic programming" algorithm: we first find all
197 * ways to build joins of two jointree items, then all ways to build joins
198 * of three items (from two-item joins and single items), then four-item
199 * joins, and so on until we have considered all ways to join all the
200 * items into one rel.
202 * root->join_rel_level[j] is a list of all the j-item rels. Initially we
203 * set root->join_rel_level[1] to represent all the single-jointree-item
206 root->join_rel_level = (List **) palloc0((levels_needed + 1) * sizeof(List *));
208 root->join_rel_level[1] = initial_rels;
210 for (lev = 2; lev <= levels_needed; lev++)
215 * Determine all possible pairs of relations to be joined at this
216 * level, and build paths for making each one from every available
217 * pair of lower-level relations.
219 join_search_one_level(root, lev);
222 * Run generate_partitionwise_join_paths() and generate_gather_paths()
223 * for each just-processed joinrel. We could not do this earlier
224 * because both regular and partial paths can get added to a
225 * particular joinrel at multiple times within join_search_one_level.
227 * After that, we're done creating paths for the joinrel, so run
230 foreach(lc, root->join_rel_level[lev])
232 rel = (RelOptInfo *) lfirst(lc);
234 /* Create paths for partitionwise joins. */
235 generate_partitionwise_join_paths(root, rel);
238 * Except for the topmost scan/join rel, consider gathering
239 * partial paths. We'll do the same for the topmost scan/join rel
240 * once we know the final targetlist (see grouping_planner).
242 if (lev < levels_needed)
243 generate_gather_paths(root, rel, false);
245 /* Find and save the cheapest paths for this rel */
248 #ifdef OPTIMIZER_DEBUG
249 debug_print_rel(root, rel);
255 * We should have a single rel at the final level.
257 if (root->join_rel_level[levels_needed] == NIL)
258 elog(ERROR, "failed to build any %d-way joins", levels_needed);
259 Assert(list_length(root->join_rel_level[levels_needed]) == 1);
261 rel = (RelOptInfo *) linitial(root->join_rel_level[levels_needed]);
263 root->join_rel_level = NULL;
269 * create_plain_partial_paths
270 * Build partial access paths for parallel scan of a plain relation
273 create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel)
275 int parallel_workers;
277 parallel_workers = compute_parallel_worker(rel, rel->pages, -1,
278 max_parallel_workers_per_gather);
280 /* If any limit was set to zero, the user doesn't want a parallel scan. */
281 if (parallel_workers <= 0)
284 /* Add an unordered partial path based on a parallel sequential scan. */
285 add_partial_path(rel, create_seqscan_path(root, rel, NULL, parallel_workers));
290 * join_search_one_level
291 * Consider ways to produce join relations containing exactly 'level'
292 * jointree items. (This is one step of the dynamic-programming method
293 * embodied in standard_join_search.) Join rel nodes for each feasible
294 * combination of lower-level rels are created and returned in a list.
295 * Implementation paths are created for each such joinrel, too.
297 * level: level of rels we want to make this time
298 * root->join_rel_level[j], 1 <= j < level, is a list of rels containing j items
300 * The result is returned in root->join_rel_level[level].
303 join_search_one_level(PlannerInfo *root, int level)
305 List **joinrels = root->join_rel_level;
309 Assert(joinrels[level] == NIL);
311 /* Set join_cur_level so that new joinrels are added to proper list */
312 root->join_cur_level = level;
315 * First, consider left-sided and right-sided plans, in which rels of
316 * exactly level-1 member relations are joined against initial relations.
317 * We prefer to join using join clauses, but if we find a rel of level-1
318 * members that has no join clauses, we will generate Cartesian-product
319 * joins against all initial rels not already contained in it.
321 foreach(r, joinrels[level - 1])
323 RelOptInfo *old_rel = (RelOptInfo *) lfirst(r);
325 if (old_rel->joininfo != NIL || old_rel->has_eclass_joins ||
326 has_join_restriction(root, old_rel))
329 * There are join clauses or join order restrictions relevant to
330 * this rel, so consider joins between this rel and (only) those
331 * initial rels it is linked to by a clause or restriction.
333 * At level 2 this condition is symmetric, so there is no need to
334 * look at initial rels before this one in the list; we already
335 * considered such joins when we were at the earlier rel. (The
336 * mirror-image joins are handled automatically by make_join_rel.)
337 * In later passes (level > 2), we join rels of the previous level
338 * to each initial rel they don't already include but have a join
339 * clause or restriction with.
341 ListCell *other_rels;
343 if (level == 2) /* consider remaining initial rels */
344 other_rels = lnext(r);
345 else /* consider all initial rels */
346 other_rels = list_head(joinrels[1]);
348 make_rels_by_clause_joins(root,
355 * Oops, we have a relation that is not joined to any other
356 * relation, either directly or by join-order restrictions.
357 * Cartesian product time.
359 * We consider a cartesian product with each not-already-included
360 * initial rel, whether it has other join clauses or not. At
361 * level 2, if there are two or more clauseless initial rels, we
362 * will redundantly consider joining them in both directions; but
363 * such cases aren't common enough to justify adding complexity to
364 * avoid the duplicated effort.
366 make_rels_by_clauseless_joins(root,
368 list_head(joinrels[1]));
373 * Now, consider "bushy plans" in which relations of k initial rels are
374 * joined to relations of level-k initial rels, for 2 <= k <= level-2.
376 * We only consider bushy-plan joins for pairs of rels where there is a
377 * suitable join clause (or join order restriction), in order to avoid
378 * unreasonable growth of planning time.
382 int other_level = level - k;
385 * Since make_join_rel(x, y) handles both x,y and y,x cases, we only
386 * need to go as far as the halfway point.
391 foreach(r, joinrels[k])
393 RelOptInfo *old_rel = (RelOptInfo *) lfirst(r);
394 ListCell *other_rels;
398 * We can ignore relations without join clauses here, unless they
399 * participate in join-order restrictions --- then we might have
400 * to force a bushy join plan.
402 if (old_rel->joininfo == NIL && !old_rel->has_eclass_joins &&
403 !has_join_restriction(root, old_rel))
406 if (k == other_level)
407 other_rels = lnext(r); /* only consider remaining rels */
409 other_rels = list_head(joinrels[other_level]);
411 for_each_cell(r2, other_rels)
413 RelOptInfo *new_rel = (RelOptInfo *) lfirst(r2);
415 if (!bms_overlap(old_rel->relids, new_rel->relids))
418 * OK, we can build a rel of the right level from this
419 * pair of rels. Do so if there is at least one relevant
420 * join clause or join order restriction.
422 if (have_relevant_joinclause(root, old_rel, new_rel) ||
423 have_join_order_restriction(root, old_rel, new_rel))
425 (void) make_join_rel(root, old_rel, new_rel);
433 * Last-ditch effort: if we failed to find any usable joins so far, force
434 * a set of cartesian-product joins to be generated. This handles the
435 * special case where all the available rels have join clauses but we
436 * cannot use any of those clauses yet. This can only happen when we are
437 * considering a join sub-problem (a sub-joinlist) and all the rels in the
438 * sub-problem have only join clauses with rels outside the sub-problem.
441 * SELECT ... FROM a INNER JOIN b ON TRUE, c, d, ...
442 * WHERE a.w = c.x and b.y = d.z;
444 * If the "a INNER JOIN b" sub-problem does not get flattened into the
445 * upper level, we must be willing to make a cartesian join of a and b;
446 * but the code above will not have done so, because it thought that both
447 * a and b have joinclauses. We consider only left-sided and right-sided
448 * cartesian joins in this case (no bushy).
451 if (joinrels[level] == NIL)
454 * This loop is just like the first one, except we always call
455 * make_rels_by_clauseless_joins().
457 foreach(r, joinrels[level - 1])
459 RelOptInfo *old_rel = (RelOptInfo *) lfirst(r);
461 make_rels_by_clauseless_joins(root,
463 list_head(joinrels[1]));
467 * When special joins are involved, there may be no legal way
468 * to make an N-way join for some values of N. For example consider
470 * SELECT ... FROM t1 WHERE
471 * x IN (SELECT ... FROM t2,t3 WHERE ...) AND
472 * y IN (SELECT ... FROM t4,t5 WHERE ...)
474 * We will flatten this query to a 5-way join problem, but there are
475 * no 4-way joins that join_is_legal() will consider legal. We have
476 * to accept failure at level 4 and go on to discover a workable
477 * bushy plan at level 5.
479 * However, if there are no special joins and no lateral references
480 * then join_is_legal() should never fail, and so the following sanity
484 if (joinrels[level] == NIL &&
485 root->join_info_list == NIL &&
486 !root->hasLateralRTEs)
487 elog(ERROR, "failed to build any %d-way joins", level);
493 * make_rels_by_clause_joins
494 * Build joins between the given relation 'old_rel' and other relations
495 * that participate in join clauses that 'old_rel' also participates in
496 * (or participate in join-order restrictions with it).
497 * The join rels are returned in root->join_rel_level[join_cur_level].
499 * Note: at levels above 2 we will generate the same joined relation in
500 * multiple ways --- for example (a join b) join c is the same RelOptInfo as
501 * (b join c) join a, though the second case will add a different set of Paths
502 * to it. This is the reason for using the join_rel_level mechanism, which
503 * automatically ensures that each new joinrel is only added to the list once.
505 * 'old_rel' is the relation entry for the relation to be joined
506 * 'other_rels': the first cell in a linked list containing the other
507 * rels to be considered for joining
509 * Currently, this is only used with initial rels in other_rels, but it
510 * will work for joining to joinrels too.
513 make_rels_by_clause_joins(PlannerInfo *root,
515 ListCell *other_rels)
519 for_each_cell(l, other_rels)
521 RelOptInfo *other_rel = (RelOptInfo *) lfirst(l);
523 if (!bms_overlap(old_rel->relids, other_rel->relids) &&
524 (have_relevant_joinclause(root, old_rel, other_rel) ||
525 have_join_order_restriction(root, old_rel, other_rel)))
527 (void) make_join_rel(root, old_rel, other_rel);
534 * make_rels_by_clauseless_joins
535 * Given a relation 'old_rel' and a list of other relations
536 * 'other_rels', create a join relation between 'old_rel' and each
537 * member of 'other_rels' that isn't already included in 'old_rel'.
538 * The join rels are returned in root->join_rel_level[join_cur_level].
540 * 'old_rel' is the relation entry for the relation to be joined
541 * 'other_rels': the first cell of a linked list containing the
542 * other rels to be considered for joining
544 * Currently, this is only used with initial rels in other_rels, but it would
545 * work for joining to joinrels too.
548 make_rels_by_clauseless_joins(PlannerInfo *root,
550 ListCell *other_rels)
554 for_each_cell(l, other_rels)
556 RelOptInfo *other_rel = (RelOptInfo *) lfirst(l);
558 if (!bms_overlap(other_rel->relids, old_rel->relids))
560 (void) make_join_rel(root, old_rel, other_rel);
568 * Determine whether a proposed join is legal given the query's
569 * join order constraints; and if it is, determine the join type.
571 * Caller must supply not only the two rels, but the union of their relids.
572 * (We could simplify the API by computing joinrelids locally, but this
573 * would be redundant work in the normal path through make_join_rel.)
575 * On success, *sjinfo_p is set to NULL if this is to be a plain inner join,
576 * else it's set to point to the associated SpecialJoinInfo node. Also,
577 * *reversed_p is set true if the given relations need to be swapped to
578 * match the SpecialJoinInfo node.
581 join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
583 SpecialJoinInfo **sjinfo_p, bool *reversed_p)
585 SpecialJoinInfo *match_sjinfo;
588 bool must_be_leftjoin;
592 * Ensure output params are set on failure return. This is just to
593 * suppress uninitialized-variable warnings from overly anal compilers.
599 * If we have any special joins, the proposed join might be illegal; and
600 * in any case we have to determine its join type. Scan the join info
601 * list for matches and conflicts.
605 unique_ified = false;
606 must_be_leftjoin = false;
608 foreach(l, root->join_info_list)
610 SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
613 * This special join is not relevant unless its RHS overlaps the
614 * proposed join. (Check this first as a fast path for dismissing
615 * most irrelevant SJs quickly.)
617 if (!bms_overlap(sjinfo->min_righthand, joinrelids))
621 * Also, not relevant if proposed join is fully contained within RHS
622 * (ie, we're still building up the RHS).
624 if (bms_is_subset(joinrelids, sjinfo->min_righthand))
628 * Also, not relevant if SJ is already done within either input.
630 if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
631 bms_is_subset(sjinfo->min_righthand, rel1->relids))
633 if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
634 bms_is_subset(sjinfo->min_righthand, rel2->relids))
638 * If it's a semijoin and we already joined the RHS to any other rels
639 * within either input, then we must have unique-ified the RHS at that
640 * point (see below). Therefore the semijoin is no longer relevant in
643 if (sjinfo->jointype == JOIN_SEMI)
645 if (bms_is_subset(sjinfo->syn_righthand, rel1->relids) &&
646 !bms_equal(sjinfo->syn_righthand, rel1->relids))
648 if (bms_is_subset(sjinfo->syn_righthand, rel2->relids) &&
649 !bms_equal(sjinfo->syn_righthand, rel2->relids))
654 * If one input contains min_lefthand and the other contains
655 * min_righthand, then we can perform the SJ at this join.
657 * Reject if we get matches to more than one SJ; that implies we're
658 * considering something that's not really valid.
660 if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
661 bms_is_subset(sjinfo->min_righthand, rel2->relids))
664 return false; /* invalid join path */
665 match_sjinfo = sjinfo;
668 else if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
669 bms_is_subset(sjinfo->min_righthand, rel1->relids))
672 return false; /* invalid join path */
673 match_sjinfo = sjinfo;
676 else if (sjinfo->jointype == JOIN_SEMI &&
677 bms_equal(sjinfo->syn_righthand, rel2->relids) &&
678 create_unique_path(root, rel2, rel2->cheapest_total_path,
682 * For a semijoin, we can join the RHS to anything else by
683 * unique-ifying the RHS (if the RHS can be unique-ified).
684 * We will only get here if we have the full RHS but less
685 * than min_lefthand on the LHS.
687 * The reason to consider such a join path is exemplified by
688 * SELECT ... FROM a,b WHERE (a.x,b.y) IN (SELECT c1,c2 FROM c)
689 * If we insist on doing this as a semijoin we will first have
690 * to form the cartesian product of A*B. But if we unique-ify
691 * C then the semijoin becomes a plain innerjoin and we can join
692 * in any order, eg C to A and then to B. When C is much smaller
693 * than A and B this can be a huge win. So we allow C to be
694 * joined to just A or just B here, and then make_join_rel has
695 * to handle the case properly.
697 * Note that actually we'll allow unique-ified C to be joined to
698 * some other relation D here, too. That is legal, if usually not
699 * very sane, and this routine is only concerned with legality not
700 * with whether the join is good strategy.
704 return false; /* invalid join path */
705 match_sjinfo = sjinfo;
709 else if (sjinfo->jointype == JOIN_SEMI &&
710 bms_equal(sjinfo->syn_righthand, rel1->relids) &&
711 create_unique_path(root, rel1, rel1->cheapest_total_path,
714 /* Reversed semijoin case */
716 return false; /* invalid join path */
717 match_sjinfo = sjinfo;
724 * Otherwise, the proposed join overlaps the RHS but isn't a valid
725 * implementation of this SJ. But don't panic quite yet: the RHS
726 * violation might have occurred previously, in one or both input
727 * relations, in which case we must have previously decided that
728 * it was OK to commute some other SJ with this one. If we need
729 * to perform this join to finish building up the RHS, rejecting
730 * it could lead to not finding any plan at all. (This can occur
731 * because of the heuristics elsewhere in this file that postpone
732 * clauseless joins: we might not consider doing a clauseless join
733 * within the RHS until after we've performed other, validly
734 * commutable SJs with one or both sides of the clauseless join.)
735 * This consideration boils down to the rule that if both inputs
736 * overlap the RHS, we can allow the join --- they are either
737 * fully within the RHS, or represent previously-allowed joins to
740 if (bms_overlap(rel1->relids, sjinfo->min_righthand) &&
741 bms_overlap(rel2->relids, sjinfo->min_righthand))
742 continue; /* assume valid previous violation of RHS */
745 * The proposed join could still be legal, but only if we're
746 * allowed to associate it into the RHS of this SJ. That means
747 * this SJ must be a LEFT join (not SEMI or ANTI, and certainly
748 * not FULL) and the proposed join must not overlap the LHS.
750 if (sjinfo->jointype != JOIN_LEFT ||
751 bms_overlap(joinrelids, sjinfo->min_lefthand))
752 return false; /* invalid join path */
755 * To be valid, the proposed join must be a LEFT join; otherwise
756 * it can't associate into this SJ's RHS. But we may not yet have
757 * found the SpecialJoinInfo matching the proposed join, so we
758 * can't test that yet. Remember the requirement for later.
760 must_be_leftjoin = true;
765 * Fail if violated any SJ's RHS and didn't match to a LEFT SJ: the
766 * proposed join can't associate into an SJ's RHS.
768 * Also, fail if the proposed join's predicate isn't strict; we're
769 * essentially checking to see if we can apply outer-join identity 3, and
770 * that's a requirement. (This check may be redundant with checks in
771 * make_outerjoininfo, but I'm not quite sure, and it's cheap to test.)
773 if (must_be_leftjoin &&
774 (match_sjinfo == NULL ||
775 match_sjinfo->jointype != JOIN_LEFT ||
776 !match_sjinfo->lhs_strict))
777 return false; /* invalid join path */
780 * We also have to check for constraints imposed by LATERAL references.
782 if (root->hasLateralRTEs)
786 Relids join_lateral_rels;
789 * The proposed rels could each contain lateral references to the
790 * other, in which case the join is impossible. If there are lateral
791 * references in just one direction, then the join has to be done with
792 * a nestloop with the lateral referencer on the inside. If the join
793 * matches an SJ that cannot be implemented by such a nestloop, the
794 * join is impossible.
796 * Also, if the lateral reference is only indirect, we should reject
797 * the join; whatever rel(s) the reference chain goes through must be
800 * Another case that might keep us from building a valid plan is the
801 * implementation restriction described by have_dangerous_phv().
803 lateral_fwd = bms_overlap(rel1->relids, rel2->lateral_relids);
804 lateral_rev = bms_overlap(rel2->relids, rel1->lateral_relids);
805 if (lateral_fwd && lateral_rev)
806 return false; /* have lateral refs in both directions */
809 /* has to be implemented as nestloop with rel1 on left */
813 match_sjinfo->jointype == JOIN_FULL))
814 return false; /* not implementable as nestloop */
815 /* check there is a direct reference from rel2 to rel1 */
816 if (!bms_overlap(rel1->relids, rel2->direct_lateral_relids))
817 return false; /* only indirect refs, so reject */
818 /* check we won't have a dangerous PHV */
819 if (have_dangerous_phv(root, rel1->relids, rel2->lateral_relids))
820 return false; /* might be unable to handle required PHV */
822 else if (lateral_rev)
824 /* has to be implemented as nestloop with rel2 on left */
828 match_sjinfo->jointype == JOIN_FULL))
829 return false; /* not implementable as nestloop */
830 /* check there is a direct reference from rel1 to rel2 */
831 if (!bms_overlap(rel2->relids, rel1->direct_lateral_relids))
832 return false; /* only indirect refs, so reject */
833 /* check we won't have a dangerous PHV */
834 if (have_dangerous_phv(root, rel2->relids, rel1->lateral_relids))
835 return false; /* might be unable to handle required PHV */
839 * LATERAL references could also cause problems later on if we accept
840 * this join: if the join's minimum parameterization includes any rels
841 * that would have to be on the inside of an outer join with this join
842 * rel, then it's never going to be possible to build the complete
843 * query using this join. We should reject this join not only because
844 * it'll save work, but because if we don't, the clauseless-join
845 * heuristics might think that legality of this join means that some
846 * other join rel need not be formed, and that could lead to failure
847 * to find any plan at all. We have to consider not only rels that
848 * are directly on the inner side of an OJ with the joinrel, but also
849 * ones that are indirectly so, so search to find all such rels.
851 join_lateral_rels = min_join_parameterization(root, joinrelids,
853 if (join_lateral_rels)
855 Relids join_plus_rhs = bms_copy(joinrelids);
861 foreach(l, root->join_info_list)
863 SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
865 if (bms_overlap(sjinfo->min_lefthand, join_plus_rhs) &&
866 !bms_is_subset(sjinfo->min_righthand, join_plus_rhs))
868 join_plus_rhs = bms_add_members(join_plus_rhs,
869 sjinfo->min_righthand);
872 /* full joins constrain both sides symmetrically */
873 if (sjinfo->jointype == JOIN_FULL &&
874 bms_overlap(sjinfo->min_righthand, join_plus_rhs) &&
875 !bms_is_subset(sjinfo->min_lefthand, join_plus_rhs))
877 join_plus_rhs = bms_add_members(join_plus_rhs,
878 sjinfo->min_lefthand);
883 if (bms_overlap(join_plus_rhs, join_lateral_rels))
884 return false; /* will not be able to join to some RHS rel */
888 /* Otherwise, it's a valid join */
889 *sjinfo_p = match_sjinfo;
890 *reversed_p = reversed;
896 * has_join_restriction
897 * Detect whether the specified relation has join-order restrictions,
898 * due to being inside an outer join or an IN (sub-SELECT),
899 * or participating in any LATERAL references or multi-rel PHVs.
901 * Essentially, this tests whether have_join_order_restriction() could
902 * succeed with this rel and some other one. It's OK if we sometimes
903 * say "true" incorrectly. (Therefore, we don't bother with the relatively
904 * expensive has_legal_joinclause test.)
907 has_join_restriction(PlannerInfo *root, RelOptInfo *rel)
911 if (rel->lateral_relids != NULL || rel->lateral_referencers != NULL)
914 foreach(l, root->placeholder_list)
916 PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
918 if (bms_is_subset(rel->relids, phinfo->ph_eval_at) &&
919 !bms_equal(rel->relids, phinfo->ph_eval_at))
923 foreach(l, root->join_info_list)
925 SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
927 /* ignore full joins --- other mechanisms preserve their ordering */
928 if (sjinfo->jointype == JOIN_FULL)
931 /* ignore if SJ is already contained in rel */
932 if (bms_is_subset(sjinfo->min_lefthand, rel->relids) &&
933 bms_is_subset(sjinfo->min_righthand, rel->relids))
936 /* restricted if it overlaps LHS or RHS, but doesn't contain SJ */
937 if (bms_overlap(sjinfo->min_lefthand, rel->relids) ||
938 bms_overlap(sjinfo->min_righthand, rel->relids))
947 * is_dummy_rel --- has relation been proven empty?
950 is_dummy_rel(RelOptInfo *rel)
952 return IS_DUMMY_REL(rel);
956 * Mark a relation as proven empty.
958 * During GEQO planning, this can get invoked more than once on the same
959 * baserel struct, so it's worth checking to see if the rel is already marked
962 * Also, when called during GEQO join planning, we are in a short-lived
963 * memory context. We must make sure that the dummy path attached to a
964 * baserel survives the GEQO cycle, else the baserel is trashed for future
965 * GEQO cycles. On the other hand, when we are marking a joinrel during GEQO,
966 * we don't want the dummy path to clutter the main planning context. Upshot
967 * is that the best solution is to explicitly make the dummy path in the same
968 * context the given RelOptInfo is in.
971 mark_dummy_rel(RelOptInfo *rel)
973 MemoryContext oldcontext;
975 /* Already marked? */
976 if (is_dummy_rel(rel))
979 /* No, so choose correct context to make the dummy path in */
980 oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rel));
982 /* Set dummy size estimate */
985 /* Evict any previously chosen paths */
987 rel->partial_pathlist = NIL;
989 /* Set up the dummy path */
990 add_path(rel, (Path *) create_append_path(NULL, rel, NIL, NIL, NULL,
993 /* Set or update cheapest_total_path and related fields */
996 MemoryContextSwitchTo(oldcontext);
1001 * restriction_is_constant_false --- is a restrictlist just FALSE?
1003 * In cases where a qual is provably constant FALSE, eval_const_expressions
1004 * will generally have thrown away anything that's ANDed with it. In outer
1005 * join situations this will leave us computing cartesian products only to
1006 * decide there's no match for an outer row, which is pretty stupid. So,
1007 * we need to detect the case.
1009 * If only_pushed_down is true, then consider only quals that are pushed-down
1010 * from the point of view of the joinrel.
1013 restriction_is_constant_false(List *restrictlist,
1014 RelOptInfo *joinrel,
1015 bool only_pushed_down)
1020 * Despite the above comment, the restriction list we see here might
1021 * possibly have other members besides the FALSE constant, since other
1022 * quals could get "pushed down" to the outer join level. So we check
1023 * each member of the list.
1025 foreach(lc, restrictlist)
1027 RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
1029 if (only_pushed_down && !RINFO_IS_PUSHED_DOWN(rinfo, joinrel->relids))
1032 if (rinfo->clause && IsA(rinfo->clause, Const))
1034 Const *con = (Const *) rinfo->clause;
1036 /* constant NULL is as good as constant FALSE for our purposes */
1037 if (con->constisnull)
1039 if (!DatumGetBool(con->constvalue))
1048 * Set up tlist expressions for the childrel, and add EC members referencing
1052 update_child_rel_info(PlannerInfo *root,
1053 RelOptInfo *rel, RelOptInfo *childrel)
1055 AppendRelInfo *appinfo = root->append_rel_array[childrel->relid];
1057 /* Make child tlist expressions */
1058 childrel->reltarget->exprs = (List *)
1059 adjust_appendrel_attrs(root,
1060 (Node *) rel->reltarget->exprs,
1063 /* Make child entries in the EquivalenceClass as well */
1064 if (rel->has_eclass_joins || has_useful_pathkeys(root, rel))
1065 add_child_rel_equivalences(root, appinfo, rel, childrel);
1066 childrel->has_eclass_joins = rel->has_eclass_joins;
1070 * Construct the SpecialJoinInfo for a child-join by translating
1071 * SpecialJoinInfo for the join between parents. left_relids and right_relids
1072 * are the relids of left and right side of the join respectively.
1074 static SpecialJoinInfo *
1075 build_child_join_sjinfo(PlannerInfo *root, SpecialJoinInfo *parent_sjinfo,
1076 Relids left_relids, Relids right_relids)
1078 SpecialJoinInfo *sjinfo = makeNode(SpecialJoinInfo);
1079 AppendRelInfo **left_appinfos;
1081 AppendRelInfo **right_appinfos;
1082 int right_nappinfos;
1084 memcpy(sjinfo, parent_sjinfo, sizeof(SpecialJoinInfo));
1085 left_appinfos = find_appinfos_by_relids(root, left_relids,
1087 right_appinfos = find_appinfos_by_relids(root, right_relids,
1090 sjinfo->min_lefthand = adjust_child_relids(sjinfo->min_lefthand,
1091 left_nappinfos, left_appinfos);
1092 sjinfo->min_righthand = adjust_child_relids(sjinfo->min_righthand,
1095 sjinfo->syn_lefthand = adjust_child_relids(sjinfo->syn_lefthand,
1096 left_nappinfos, left_appinfos);
1097 sjinfo->syn_righthand = adjust_child_relids(sjinfo->syn_righthand,
1100 sjinfo->semi_rhs_exprs = (List *) adjust_appendrel_attrs(root,
1101 (Node *) sjinfo->semi_rhs_exprs,
1105 pfree(left_appinfos);
1106 pfree(right_appinfos);
1112 * Assess whether join between given two partitioned relations can be broken
1113 * down into joins between matching partitions; a technique called
1114 * "partitionwise join"
1116 * Partitionwise join is possible when a. Joining relations have same
1117 * partitioning scheme b. There exists an equi-join between the partition keys
1118 * of the two relations.
1120 * Partitionwise join is planned as follows (details: optimizer/README.)
1122 * 1. Create the RelOptInfos for joins between matching partitions i.e
1123 * child-joins and add paths to them.
1125 * 2. Construct Append or MergeAppend paths across the set of child joins.
1126 * This second phase is implemented by generate_partitionwise_join_paths().
1128 * The RelOptInfo, SpecialJoinInfo and restrictlist for each child join are
1129 * obtained by translating the respective parent join structures.
1132 try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
1133 RelOptInfo *joinrel, SpecialJoinInfo *parent_sjinfo,
1134 List *parent_restrictlist)
1136 bool rel1_is_simple = IS_SIMPLE_REL(rel1);
1137 bool rel2_is_simple = IS_SIMPLE_REL(rel2);
1141 /* Guard against stack overflow due to overly deep partition hierarchy. */
1142 check_stack_depth();
1144 /* Nothing to do, if the join relation is not partitioned. */
1145 if (!IS_PARTITIONED_REL(joinrel))
1148 /* The join relation should have consider_partitionwise_join set. */
1149 Assert(joinrel->consider_partitionwise_join);
1152 * Since this join relation is partitioned, all the base relations
1153 * participating in this join must be partitioned and so are all the
1154 * intermediate join relations.
1156 Assert(IS_PARTITIONED_REL(rel1) && IS_PARTITIONED_REL(rel2));
1157 Assert(REL_HAS_ALL_PART_PROPS(rel1) && REL_HAS_ALL_PART_PROPS(rel2));
1159 /* The joining relations should have consider_partitionwise_join set. */
1160 Assert(rel1->consider_partitionwise_join &&
1161 rel2->consider_partitionwise_join);
1164 * The partition scheme of the join relation should match that of the
1165 * joining relations.
1167 Assert(joinrel->part_scheme == rel1->part_scheme &&
1168 joinrel->part_scheme == rel2->part_scheme);
1171 * Since we allow partitionwise join only when the partition bounds of the
1172 * joining relations exactly match, the partition bounds of the join
1173 * should match those of the joining relations.
1175 Assert(partition_bounds_equal(joinrel->part_scheme->partnatts,
1176 joinrel->part_scheme->parttyplen,
1177 joinrel->part_scheme->parttypbyval,
1178 joinrel->boundinfo, rel1->boundinfo));
1179 Assert(partition_bounds_equal(joinrel->part_scheme->partnatts,
1180 joinrel->part_scheme->parttyplen,
1181 joinrel->part_scheme->parttypbyval,
1182 joinrel->boundinfo, rel2->boundinfo));
1184 nparts = joinrel->nparts;
1187 * Create child-join relations for this partitioned join, if those don't
1188 * exist. Add paths to child-joins for a pair of child relations
1189 * corresponding to the given pair of parent relations.
1191 for (cnt_parts = 0; cnt_parts < nparts; cnt_parts++)
1193 RelOptInfo *child_rel1 = rel1->part_rels[cnt_parts];
1194 RelOptInfo *child_rel2 = rel2->part_rels[cnt_parts];
1195 SpecialJoinInfo *child_sjinfo;
1196 List *child_restrictlist;
1197 RelOptInfo *child_joinrel;
1198 Relids child_joinrelids;
1199 AppendRelInfo **appinfos;
1203 * If a child table has consider_partitionwise_join=false, it means
1204 * that it's a dummy relation for which we skipped setting up tlist
1205 * expressions and adding EC members in set_append_rel_size(), so do
1206 * that now for use later.
1208 if (rel1_is_simple && !child_rel1->consider_partitionwise_join)
1210 Assert(child_rel1->reloptkind == RELOPT_OTHER_MEMBER_REL);
1211 Assert(IS_DUMMY_REL(child_rel1));
1212 update_child_rel_info(root, rel1, child_rel1);
1213 child_rel1->consider_partitionwise_join = true;
1215 if (rel2_is_simple && !child_rel2->consider_partitionwise_join)
1217 Assert(child_rel2->reloptkind == RELOPT_OTHER_MEMBER_REL);
1218 Assert(IS_DUMMY_REL(child_rel2));
1219 update_child_rel_info(root, rel2, child_rel2);
1220 child_rel2->consider_partitionwise_join = true;
1223 /* We should never try to join two overlapping sets of rels. */
1224 Assert(!bms_overlap(child_rel1->relids, child_rel2->relids));
1225 child_joinrelids = bms_union(child_rel1->relids, child_rel2->relids);
1226 appinfos = find_appinfos_by_relids(root, child_joinrelids, &nappinfos);
1229 * Construct SpecialJoinInfo from parent join relations's
1232 child_sjinfo = build_child_join_sjinfo(root, parent_sjinfo,
1234 child_rel2->relids);
1237 * Construct restrictions applicable to the child join from those
1238 * applicable to the parent join.
1240 child_restrictlist =
1241 (List *) adjust_appendrel_attrs(root,
1242 (Node *) parent_restrictlist,
1243 nappinfos, appinfos);
1246 child_joinrel = joinrel->part_rels[cnt_parts];
1249 child_joinrel = build_child_join_rel(root, child_rel1, child_rel2,
1250 joinrel, child_restrictlist,
1252 child_sjinfo->jointype);
1253 joinrel->part_rels[cnt_parts] = child_joinrel;
1256 Assert(bms_equal(child_joinrel->relids, child_joinrelids));
1258 populate_joinrel_with_paths(root, child_rel1, child_rel2,
1259 child_joinrel, child_sjinfo,
1260 child_restrictlist);