Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * joinpath.c
4 : * Routines to find all possible paths for processing a set of joins
5 : *
6 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/optimizer/path/joinpath.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : #include "postgres.h"
16 :
17 : #include <math.h>
18 :
19 : #include "executor/executor.h"
20 : #include "foreign/fdwapi.h"
21 : #include "nodes/nodeFuncs.h"
22 : #include "optimizer/cost.h"
23 : #include "optimizer/optimizer.h"
24 : #include "optimizer/pathnode.h"
25 : #include "optimizer/paths.h"
26 : #include "optimizer/placeholder.h"
27 : #include "optimizer/planmain.h"
28 : #include "optimizer/restrictinfo.h"
29 : #include "utils/lsyscache.h"
30 : #include "utils/typcache.h"
31 :
32 : /* Hook for plugins to get control in add_paths_to_joinrel() */
33 : set_join_pathlist_hook_type set_join_pathlist_hook = NULL;
34 :
35 : /*
36 : * Paths parameterized by a parent rel can be considered to be parameterized
37 : * by any of its children, when we are performing partitionwise joins. These
38 : * macros simplify checking for such cases. Beware multiple eval of args.
39 : */
40 : #define PATH_PARAM_BY_PARENT(path, rel) \
41 : ((path)->param_info && bms_overlap(PATH_REQ_OUTER(path), \
42 : (rel)->top_parent_relids))
43 : #define PATH_PARAM_BY_REL_SELF(path, rel) \
44 : ((path)->param_info && bms_overlap(PATH_REQ_OUTER(path), (rel)->relids))
45 :
46 : #define PATH_PARAM_BY_REL(path, rel) \
47 : (PATH_PARAM_BY_REL_SELF(path, rel) || PATH_PARAM_BY_PARENT(path, rel))
48 :
49 : static void try_partial_mergejoin_path(PlannerInfo *root,
50 : RelOptInfo *joinrel,
51 : Path *outer_path,
52 : Path *inner_path,
53 : List *pathkeys,
54 : List *mergeclauses,
55 : List *outersortkeys,
56 : List *innersortkeys,
57 : JoinType jointype,
58 : JoinPathExtraData *extra);
59 : static void sort_inner_and_outer(PlannerInfo *root, RelOptInfo *joinrel,
60 : RelOptInfo *outerrel, RelOptInfo *innerrel,
61 : JoinType jointype, JoinPathExtraData *extra);
62 : static void match_unsorted_outer(PlannerInfo *root, RelOptInfo *joinrel,
63 : RelOptInfo *outerrel, RelOptInfo *innerrel,
64 : JoinType jointype, JoinPathExtraData *extra);
65 : static void consider_parallel_nestloop(PlannerInfo *root,
66 : RelOptInfo *joinrel,
67 : RelOptInfo *outerrel,
68 : RelOptInfo *innerrel,
69 : JoinType jointype,
70 : JoinPathExtraData *extra);
71 : static void consider_parallel_mergejoin(PlannerInfo *root,
72 : RelOptInfo *joinrel,
73 : RelOptInfo *outerrel,
74 : RelOptInfo *innerrel,
75 : JoinType jointype,
76 : JoinPathExtraData *extra,
77 : Path *inner_cheapest_total);
78 : static void hash_inner_and_outer(PlannerInfo *root, RelOptInfo *joinrel,
79 : RelOptInfo *outerrel, RelOptInfo *innerrel,
80 : JoinType jointype, JoinPathExtraData *extra);
81 : static List *select_mergejoin_clauses(PlannerInfo *root,
82 : RelOptInfo *joinrel,
83 : RelOptInfo *outerrel,
84 : RelOptInfo *innerrel,
85 : List *restrictlist,
86 : JoinType jointype,
87 : bool *mergejoin_allowed);
88 : static void generate_mergejoin_paths(PlannerInfo *root,
89 : RelOptInfo *joinrel,
90 : RelOptInfo *innerrel,
91 : Path *outerpath,
92 : JoinType jointype,
93 : JoinPathExtraData *extra,
94 : bool useallclauses,
95 : Path *inner_cheapest_total,
96 : List *merge_pathkeys,
97 : bool is_partial);
98 :
99 :
100 : /*
101 : * add_paths_to_joinrel
102 : * Given a join relation and two component rels from which it can be made,
103 : * consider all possible paths that use the two component rels as outer
104 : * and inner rel respectively. Add these paths to the join rel's pathlist
105 : * if they survive comparison with other paths (and remove any existing
106 : * paths that are dominated by these paths).
107 : *
108 : * Modifies the pathlist field of the joinrel node to contain the best
109 : * paths found so far.
110 : *
111 : * jointype is not necessarily the same as sjinfo->jointype; it might be
112 : * "flipped around" if we are considering joining the rels in the opposite
113 : * direction from what's indicated in sjinfo.
114 : *
115 : * Also, this routine and others in this module accept the special JoinTypes
116 : * JOIN_UNIQUE_OUTER and JOIN_UNIQUE_INNER to indicate that we should
117 : * unique-ify the outer or inner relation and then apply a regular inner
118 : * join. These values are not allowed to propagate outside this module,
119 : * however. Path cost estimation code may need to recognize that it's
120 : * dealing with such a case --- the combination of nominal jointype INNER
121 : * with sjinfo->jointype == JOIN_SEMI indicates that.
122 : */
123 : void
124 684456 : add_paths_to_joinrel(PlannerInfo *root,
125 : RelOptInfo *joinrel,
126 : RelOptInfo *outerrel,
127 : RelOptInfo *innerrel,
128 : JoinType jointype,
129 : SpecialJoinInfo *sjinfo,
130 : List *restrictlist)
131 : {
132 : JoinPathExtraData extra;
133 684456 : bool mergejoin_allowed = true;
134 : ListCell *lc;
135 : Relids joinrelids;
136 :
137 : /*
138 : * PlannerInfo doesn't contain the SpecialJoinInfos created for joins
139 : * between child relations, even if there is a SpecialJoinInfo node for
140 : * the join between the topmost parents. So, while calculating Relids set
141 : * representing the restriction, consider relids of topmost parent of
142 : * partitions.
143 : */
144 684456 : if (joinrel->reloptkind == RELOPT_OTHER_JOINREL)
145 11704 : joinrelids = joinrel->top_parent_relids;
146 : else
147 672752 : joinrelids = joinrel->relids;
148 :
149 684456 : extra.restrictlist = restrictlist;
150 684456 : extra.mergeclause_list = NIL;
151 684456 : extra.sjinfo = sjinfo;
152 684456 : extra.param_source_rels = NULL;
153 :
154 : /*
155 : * See if the inner relation is provably unique for this outer rel.
156 : *
157 : * We have some special cases: for JOIN_SEMI and JOIN_ANTI, it doesn't
158 : * matter since the executor can make the equivalent optimization anyway;
159 : * we need not expend planner cycles on proofs. For JOIN_UNIQUE_INNER, we
160 : * must be considering a semijoin whose inner side is not provably unique
161 : * (else reduce_unique_semijoins would've simplified it), so there's no
162 : * point in calling innerrel_is_unique. However, if the LHS covers all of
163 : * the semijoin's min_lefthand, then it's appropriate to set inner_unique
164 : * because the path produced by create_unique_path will be unique relative
165 : * to the LHS. (If we have an LHS that's only part of the min_lefthand,
166 : * that is *not* true.) For JOIN_UNIQUE_OUTER, pass JOIN_INNER to avoid
167 : * letting that value escape this module.
168 : */
169 684456 : switch (jointype)
170 : {
171 12766 : case JOIN_SEMI:
172 : case JOIN_ANTI:
173 :
174 : /*
175 : * XXX it may be worth proving this to allow a Memoize to be
176 : * considered for Nested Loop Semi/Anti Joins.
177 : */
178 12766 : extra.inner_unique = false; /* well, unproven */
179 12766 : break;
180 7522 : case JOIN_UNIQUE_INNER:
181 15044 : extra.inner_unique = bms_is_subset(sjinfo->min_lefthand,
182 7522 : outerrel->relids);
183 7522 : break;
184 7522 : case JOIN_UNIQUE_OUTER:
185 7522 : extra.inner_unique = innerrel_is_unique(root,
186 : joinrel->relids,
187 : outerrel->relids,
188 : innerrel,
189 : JOIN_INNER,
190 : restrictlist,
191 : false);
192 7522 : break;
193 656646 : default:
194 656646 : extra.inner_unique = innerrel_is_unique(root,
195 : joinrel->relids,
196 : outerrel->relids,
197 : innerrel,
198 : jointype,
199 : restrictlist,
200 : false);
201 656646 : break;
202 : }
203 :
204 : /*
205 : * Find potential mergejoin clauses. We can skip this if we are not
206 : * interested in doing a mergejoin. However, mergejoin may be our only
207 : * way of implementing a full outer join, so override enable_mergejoin if
208 : * it's a full join.
209 : */
210 684456 : if (enable_mergejoin || jointype == JOIN_FULL)
211 680884 : extra.mergeclause_list = select_mergejoin_clauses(root,
212 : joinrel,
213 : outerrel,
214 : innerrel,
215 : restrictlist,
216 : jointype,
217 : &mergejoin_allowed);
218 :
219 : /*
220 : * If it's SEMI, ANTI, or inner_unique join, compute correction factors
221 : * for cost estimation. These will be the same for all paths.
222 : */
223 684456 : if (jointype == JOIN_SEMI || jointype == JOIN_ANTI || extra.inner_unique)
224 214156 : compute_semi_anti_join_factors(root, joinrel, outerrel, innerrel,
225 : jointype, sjinfo, restrictlist,
226 : &extra.semifactors);
227 :
228 : /*
229 : * Decide whether it's sensible to generate parameterized paths for this
230 : * joinrel, and if so, which relations such paths should require. There
231 : * is usually no need to create a parameterized result path unless there
232 : * is a join order restriction that prevents joining one of our input rels
233 : * directly to the parameter source rel instead of joining to the other
234 : * input rel. (But see allow_star_schema_join().) This restriction
235 : * reduces the number of parameterized paths we have to deal with at
236 : * higher join levels, without compromising the quality of the resulting
237 : * plan. We express the restriction as a Relids set that must overlap the
238 : * parameterization of any proposed join path. Note: param_source_rels
239 : * should contain only baserels, not OJ relids, so starting from
240 : * all_baserels not all_query_rels is correct.
241 : */
242 1437136 : foreach(lc, root->join_info_list)
243 : {
244 752680 : SpecialJoinInfo *sjinfo2 = (SpecialJoinInfo *) lfirst(lc);
245 :
246 : /*
247 : * SJ is relevant to this join if we have some part of its RHS
248 : * (possibly not all of it), and haven't yet joined to its LHS. (This
249 : * test is pretty simplistic, but should be sufficient considering the
250 : * join has already been proven legal.) If the SJ is relevant, it
251 : * presents constraints for joining to anything not in its RHS.
252 : */
253 752680 : if (bms_overlap(joinrelids, sjinfo2->min_righthand) &&
254 498684 : !bms_overlap(joinrelids, sjinfo2->min_lefthand))
255 21124 : extra.param_source_rels = bms_join(extra.param_source_rels,
256 21124 : bms_difference(root->all_baserels,
257 21124 : sjinfo2->min_righthand));
258 :
259 : /* full joins constrain both sides symmetrically */
260 757584 : if (sjinfo2->jointype == JOIN_FULL &&
261 4904 : bms_overlap(joinrelids, sjinfo2->min_lefthand) &&
262 4848 : !bms_overlap(joinrelids, sjinfo2->min_righthand))
263 672 : extra.param_source_rels = bms_join(extra.param_source_rels,
264 672 : bms_difference(root->all_baserels,
265 672 : sjinfo2->min_lefthand));
266 : }
267 :
268 : /*
269 : * However, when a LATERAL subquery is involved, there will simply not be
270 : * any paths for the joinrel that aren't parameterized by whatever the
271 : * subquery is parameterized by, unless its parameterization is resolved
272 : * within the joinrel. So we might as well allow additional dependencies
273 : * on whatever residual lateral dependencies the joinrel will have.
274 : */
275 1368912 : extra.param_source_rels = bms_add_members(extra.param_source_rels,
276 684456 : joinrel->lateral_relids);
277 :
278 : /*
279 : * 1. Consider mergejoin paths where both relations must be explicitly
280 : * sorted. Skip this if we can't mergejoin.
281 : */
282 684456 : if (mergejoin_allowed)
283 667254 : sort_inner_and_outer(root, joinrel, outerrel, innerrel,
284 : jointype, &extra);
285 :
286 : /*
287 : * 2. Consider paths where the outer relation need not be explicitly
288 : * sorted. This includes both nestloops and mergejoins where the outer
289 : * path is already ordered. Again, skip this if we can't mergejoin.
290 : * (That's okay because we know that nestloop can't handle
291 : * right/right-anti/right-semi/full joins at all, so it wouldn't work in
292 : * the prohibited cases either.)
293 : */
294 684456 : if (mergejoin_allowed)
295 667254 : match_unsorted_outer(root, joinrel, outerrel, innerrel,
296 : jointype, &extra);
297 :
298 : #ifdef NOT_USED
299 :
300 : /*
301 : * 3. Consider paths where the inner relation need not be explicitly
302 : * sorted. This includes mergejoins only (nestloops were already built in
303 : * match_unsorted_outer).
304 : *
305 : * Diked out as redundant 2/13/2000 -- tgl. There isn't any really
306 : * significant difference between the inner and outer side of a mergejoin,
307 : * so match_unsorted_inner creates no paths that aren't equivalent to
308 : * those made by match_unsorted_outer when add_paths_to_joinrel() is
309 : * invoked with the two rels given in the other order.
310 : */
311 : if (mergejoin_allowed)
312 : match_unsorted_inner(root, joinrel, outerrel, innerrel,
313 : jointype, &extra);
314 : #endif
315 :
316 : /*
317 : * 4. Consider paths where both outer and inner relations must be hashed
318 : * before being joined. As above, disregard enable_hashjoin for full
319 : * joins, because there may be no other alternative.
320 : */
321 684456 : if (enable_hashjoin || jointype == JOIN_FULL)
322 679268 : hash_inner_and_outer(root, joinrel, outerrel, innerrel,
323 : jointype, &extra);
324 :
325 : /*
326 : * 5. If inner and outer relations are foreign tables (or joins) belonging
327 : * to the same server and assigned to the same user to check access
328 : * permissions as, give the FDW a chance to push down joins.
329 : */
330 684456 : if (joinrel->fdwroutine &&
331 2660 : joinrel->fdwroutine->GetForeignJoinPaths)
332 2656 : joinrel->fdwroutine->GetForeignJoinPaths(root, joinrel,
333 : outerrel, innerrel,
334 : jointype, &extra);
335 :
336 : /*
337 : * 6. Finally, give extensions a chance to manipulate the path list. They
338 : * could add new paths (such as CustomPaths) by calling add_path(), or
339 : * add_partial_path() if parallel aware. They could also delete or modify
340 : * paths added by the core code.
341 : */
342 684456 : if (set_join_pathlist_hook)
343 0 : set_join_pathlist_hook(root, joinrel, outerrel, innerrel,
344 : jointype, &extra);
345 684456 : }
346 :
347 : /*
348 : * We override the param_source_rels heuristic to accept nestloop paths in
349 : * which the outer rel satisfies some but not all of the inner path's
350 : * parameterization. This is necessary to get good plans for star-schema
351 : * scenarios, in which a parameterized path for a large table may require
352 : * parameters from multiple small tables that will not get joined directly to
353 : * each other. We can handle that by stacking nestloops that have the small
354 : * tables on the outside; but this breaks the rule the param_source_rels
355 : * heuristic is based on, namely that parameters should not be passed down
356 : * across joins unless there's a join-order-constraint-based reason to do so.
357 : * So we ignore the param_source_rels restriction when this case applies.
358 : *
359 : * allow_star_schema_join() returns true if the param_source_rels restriction
360 : * should be overridden, ie, it's okay to perform this join.
361 : */
362 : static inline bool
363 308858 : allow_star_schema_join(PlannerInfo *root,
364 : Relids outerrelids,
365 : Relids inner_paramrels)
366 : {
367 : /*
368 : * It's a star-schema case if the outer rel provides some but not all of
369 : * the inner rel's parameterization.
370 : */
371 360328 : return (bms_overlap(inner_paramrels, outerrelids) &&
372 51470 : bms_nonempty_difference(inner_paramrels, outerrelids));
373 : }
374 :
375 : /*
376 : * If the parameterization is only partly satisfied by the outer rel,
377 : * the unsatisfied part can't include any outer-join relids that could
378 : * null rels of the satisfied part. That would imply that we're trying
379 : * to use a clause involving a Var with nonempty varnullingrels at
380 : * a join level where that value isn't yet computable.
381 : *
382 : * In practice, this test never finds a problem because earlier join order
383 : * restrictions prevent us from attempting a join that would cause a problem.
384 : * (That's unsurprising, because the code worked before we ever added
385 : * outer-join relids to expression relids.) It still seems worth checking
386 : * as a backstop, but we only do so in assert-enabled builds.
387 : */
388 : #ifdef USE_ASSERT_CHECKING
389 : static inline bool
390 : have_unsafe_outer_join_ref(PlannerInfo *root,
391 : Relids outerrelids,
392 : Relids inner_paramrels)
393 : {
394 : bool result = false;
395 : Relids unsatisfied = bms_difference(inner_paramrels, outerrelids);
396 : Relids satisfied = bms_intersect(inner_paramrels, outerrelids);
397 :
398 : if (bms_overlap(unsatisfied, root->outer_join_rels))
399 : {
400 : ListCell *lc;
401 :
402 : foreach(lc, root->join_info_list)
403 : {
404 : SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
405 :
406 : if (!bms_is_member(sjinfo->ojrelid, unsatisfied))
407 : continue; /* not relevant */
408 : if (bms_overlap(satisfied, sjinfo->min_righthand) ||
409 : (sjinfo->jointype == JOIN_FULL &&
410 : bms_overlap(satisfied, sjinfo->min_lefthand)))
411 : {
412 : result = true; /* doesn't work */
413 : break;
414 : }
415 : }
416 : }
417 :
418 : /* Waste no memory when we reject a path here */
419 : bms_free(unsatisfied);
420 : bms_free(satisfied);
421 :
422 : return result;
423 : }
424 : #endif /* USE_ASSERT_CHECKING */
425 :
426 : /*
427 : * paraminfo_get_equal_hashops
428 : * Determine if the clauses in param_info and innerrel's lateral vars
429 : * can be hashed.
430 : * Returns true if hashing is possible, otherwise false.
431 : *
432 : * Additionally, on success we collect the outer expressions and the
433 : * appropriate equality operators for each hashable parameter to innerrel.
434 : * These are returned in parallel lists in *param_exprs and *operators.
435 : * We also set *binary_mode to indicate whether strict binary matching is
436 : * required.
437 : */
438 : static bool
439 393248 : paraminfo_get_equal_hashops(PlannerInfo *root, ParamPathInfo *param_info,
440 : RelOptInfo *outerrel, RelOptInfo *innerrel,
441 : List *ph_lateral_vars, List **param_exprs,
442 : List **operators, bool *binary_mode)
443 :
444 : {
445 : List *lateral_vars;
446 : ListCell *lc;
447 :
448 393248 : *param_exprs = NIL;
449 393248 : *operators = NIL;
450 393248 : *binary_mode = false;
451 :
452 : /* Add join clauses from param_info to the hash key */
453 393248 : if (param_info != NULL)
454 : {
455 393248 : List *clauses = param_info->ppi_clauses;
456 :
457 742942 : foreach(lc, clauses)
458 : {
459 430370 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
460 : OpExpr *opexpr;
461 : Node *expr;
462 : Oid hasheqoperator;
463 :
464 430370 : opexpr = (OpExpr *) rinfo->clause;
465 :
466 : /*
467 : * Bail if the rinfo is not compatible. We need a join OpExpr
468 : * with 2 args.
469 : */
470 430370 : if (!IsA(opexpr, OpExpr) || list_length(opexpr->args) != 2 ||
471 408100 : !clause_sides_match_join(rinfo, outerrel->relids,
472 : innerrel->relids))
473 : {
474 80520 : list_free(*operators);
475 80520 : list_free(*param_exprs);
476 80676 : return false;
477 : }
478 :
479 349850 : if (rinfo->outer_is_left)
480 : {
481 203742 : expr = (Node *) linitial(opexpr->args);
482 203742 : hasheqoperator = rinfo->left_hasheqoperator;
483 : }
484 : else
485 : {
486 146108 : expr = (Node *) lsecond(opexpr->args);
487 146108 : hasheqoperator = rinfo->right_hasheqoperator;
488 : }
489 :
490 : /* can't do memoize if we can't hash the outer type */
491 349850 : if (!OidIsValid(hasheqoperator))
492 : {
493 156 : list_free(*operators);
494 156 : list_free(*param_exprs);
495 156 : return false;
496 : }
497 :
498 : /*
499 : * 'expr' may already exist as a parameter from a previous item in
500 : * ppi_clauses. No need to include it again, however we'd better
501 : * ensure we do switch into binary mode if required. See below.
502 : */
503 349694 : if (!list_member(*param_exprs, expr))
504 : {
505 349688 : *operators = lappend_oid(*operators, hasheqoperator);
506 349688 : *param_exprs = lappend(*param_exprs, expr);
507 : }
508 :
509 : /*
510 : * When the join operator is not hashable then it's possible that
511 : * the operator will be able to distinguish something that the
512 : * hash equality operator could not. For example with floating
513 : * point types -0.0 and +0.0 are classed as equal by the hash
514 : * function and equality function, but some other operator may be
515 : * able to tell those values apart. This means that we must put
516 : * memoize into binary comparison mode so that it does bit-by-bit
517 : * comparisons rather than a "logical" comparison as it would
518 : * using the hash equality operator.
519 : */
520 349694 : if (!OidIsValid(rinfo->hashjoinoperator))
521 1194 : *binary_mode = true;
522 : }
523 : }
524 :
525 : /* Now add any lateral vars to the cache key too */
526 312572 : lateral_vars = list_concat(ph_lateral_vars, innerrel->lateral_vars);
527 316870 : foreach(lc, lateral_vars)
528 : {
529 4496 : Node *expr = (Node *) lfirst(lc);
530 : TypeCacheEntry *typentry;
531 :
532 : /* Reject if there are any volatile functions in lateral vars */
533 4496 : if (contain_volatile_functions(expr))
534 : {
535 0 : list_free(*operators);
536 0 : list_free(*param_exprs);
537 198 : return false;
538 : }
539 :
540 4496 : typentry = lookup_type_cache(exprType(expr),
541 : TYPECACHE_HASH_PROC | TYPECACHE_EQ_OPR);
542 :
543 : /* can't use memoize without a valid hash proc and equals operator */
544 4496 : if (!OidIsValid(typentry->hash_proc) || !OidIsValid(typentry->eq_opr))
545 : {
546 198 : list_free(*operators);
547 198 : list_free(*param_exprs);
548 198 : return false;
549 : }
550 :
551 : /*
552 : * 'expr' may already exist as a parameter from the ppi_clauses. No
553 : * need to include it again, however we'd better ensure we do switch
554 : * into binary mode.
555 : */
556 4298 : if (!list_member(*param_exprs, expr))
557 : {
558 3848 : *operators = lappend_oid(*operators, typentry->eq_opr);
559 3848 : *param_exprs = lappend(*param_exprs, expr);
560 : }
561 :
562 : /*
563 : * We must go into binary mode as we don't have too much of an idea of
564 : * how these lateral Vars are being used. See comment above when we
565 : * set *binary_mode for the non-lateral Var case. This could be
566 : * relaxed a bit if we had the RestrictInfos and knew the operators
567 : * being used, however for cases like Vars that are arguments to
568 : * functions we must operate in binary mode as we don't have
569 : * visibility into what the function is doing with the Vars.
570 : */
571 4298 : *binary_mode = true;
572 : }
573 :
574 : /* We're okay to use memoize */
575 312374 : return true;
576 : }
577 :
578 : /*
579 : * extract_lateral_vars_from_PHVs
580 : * Extract lateral references within PlaceHolderVars that are due to be
581 : * evaluated at 'innerrelids'.
582 : */
583 : static List *
584 1296020 : extract_lateral_vars_from_PHVs(PlannerInfo *root, Relids innerrelids)
585 : {
586 1296020 : List *ph_lateral_vars = NIL;
587 : ListCell *lc;
588 :
589 : /* Nothing would be found if the query contains no LATERAL RTEs */
590 1296020 : if (!root->hasLateralRTEs)
591 1277622 : return NIL;
592 :
593 : /*
594 : * No need to consider PHVs that are due to be evaluated at joinrels,
595 : * since we do not add Memoize nodes on top of joinrel paths.
596 : */
597 18398 : if (bms_membership(innerrelids) == BMS_MULTIPLE)
598 5538 : return NIL;
599 :
600 15124 : foreach(lc, root->placeholder_list)
601 : {
602 2264 : PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc);
603 : List *vars;
604 : ListCell *cell;
605 :
606 : /* PHV is uninteresting if no lateral refs */
607 2264 : if (phinfo->ph_lateral == NULL)
608 1038 : continue;
609 :
610 : /* PHV is uninteresting if not due to be evaluated at innerrelids */
611 1226 : if (!bms_equal(phinfo->ph_eval_at, innerrelids))
612 982 : continue;
613 :
614 : /*
615 : * If the PHV does not reference any rels in innerrelids, use its
616 : * contained expression as a cache key rather than extracting the
617 : * Vars/PHVs from it and using those. This can be beneficial in cases
618 : * where the expression results in fewer distinct values to cache
619 : * tuples for.
620 : */
621 244 : if (!bms_overlap(pull_varnos(root, (Node *) phinfo->ph_var->phexpr),
622 : innerrelids))
623 : {
624 232 : ph_lateral_vars = lappend(ph_lateral_vars, phinfo->ph_var->phexpr);
625 232 : continue;
626 : }
627 :
628 : /* Fetch Vars and PHVs of lateral references within PlaceHolderVars */
629 12 : vars = pull_vars_of_level((Node *) phinfo->ph_var->phexpr, 0);
630 36 : foreach(cell, vars)
631 : {
632 24 : Node *node = (Node *) lfirst(cell);
633 :
634 24 : if (IsA(node, Var))
635 : {
636 12 : Var *var = (Var *) node;
637 :
638 : Assert(var->varlevelsup == 0);
639 :
640 12 : if (bms_is_member(var->varno, phinfo->ph_lateral))
641 0 : ph_lateral_vars = lappend(ph_lateral_vars, node);
642 : }
643 12 : else if (IsA(node, PlaceHolderVar))
644 : {
645 12 : PlaceHolderVar *phv = (PlaceHolderVar *) node;
646 :
647 : Assert(phv->phlevelsup == 0);
648 :
649 12 : if (bms_is_subset(find_placeholder_info(root, phv)->ph_eval_at,
650 12 : phinfo->ph_lateral))
651 12 : ph_lateral_vars = lappend(ph_lateral_vars, node);
652 : }
653 : else
654 : Assert(false);
655 : }
656 :
657 12 : list_free(vars);
658 : }
659 :
660 12860 : return ph_lateral_vars;
661 : }
662 :
663 : /*
664 : * get_memoize_path
665 : * If possible, make and return a Memoize path atop of 'inner_path'.
666 : * Otherwise return NULL.
667 : *
668 : * Note that currently we do not add Memoize nodes on top of join relation
669 : * paths. This is because the ParamPathInfos for join relation paths do not
670 : * maintain ppi_clauses, as the set of relevant clauses varies depending on how
671 : * the join is formed. In addition, joinrels do not maintain lateral_vars. So
672 : * we do not have a way to extract cache keys from joinrels.
673 : */
674 : static Path *
675 1821940 : get_memoize_path(PlannerInfo *root, RelOptInfo *innerrel,
676 : RelOptInfo *outerrel, Path *inner_path,
677 : Path *outer_path, JoinType jointype,
678 : JoinPathExtraData *extra)
679 : {
680 : List *param_exprs;
681 : List *hash_operators;
682 : ListCell *lc;
683 : bool binary_mode;
684 : List *ph_lateral_vars;
685 :
686 : /* Obviously not if it's disabled */
687 1821940 : if (!enable_memoize)
688 388 : return NULL;
689 :
690 : /*
691 : * We can safely not bother with all this unless we expect to perform more
692 : * than one inner scan. The first scan is always going to be a cache
693 : * miss. This would likely fail later anyway based on costs, so this is
694 : * really just to save some wasted effort.
695 : */
696 1821552 : if (outer_path->parent->rows < 2)
697 525532 : return NULL;
698 :
699 : /*
700 : * Extract lateral Vars/PHVs within PlaceHolderVars that are due to be
701 : * evaluated at innerrel. These lateral Vars/PHVs could be used as
702 : * memoize cache keys.
703 : */
704 1296020 : ph_lateral_vars = extract_lateral_vars_from_PHVs(root, innerrel->relids);
705 :
706 : /*
707 : * We can only have a memoize node when there's some kind of cache key,
708 : * either parameterized path clauses or lateral Vars. No cache key sounds
709 : * more like something a Materialize node might be more useful for.
710 : */
711 1296020 : if ((inner_path->param_info == NULL ||
712 545292 : inner_path->param_info->ppi_clauses == NIL) &&
713 771888 : innerrel->lateral_vars == NIL &&
714 : ph_lateral_vars == NIL)
715 768810 : return NULL;
716 :
717 : /*
718 : * Currently we don't do this for SEMI and ANTI joins unless they're
719 : * marked as inner_unique. This is because nested loop SEMI/ANTI joins
720 : * don't scan the inner node to completion, which will mean memoize cannot
721 : * mark the cache entry as complete.
722 : *
723 : * XXX Currently we don't attempt to mark SEMI/ANTI joins as inner_unique
724 : * = true. Should we? See add_paths_to_joinrel()
725 : */
726 527210 : if (!extra->inner_unique && (jointype == JOIN_SEMI ||
727 : jointype == JOIN_ANTI))
728 10436 : return NULL;
729 :
730 : /*
731 : * Memoize normally marks cache entries as complete when it runs out of
732 : * tuples to read from its subplan. However, with unique joins, Nested
733 : * Loop will skip to the next outer tuple after finding the first matching
734 : * inner tuple. This means that we may not read the inner side of the
735 : * join to completion which leaves no opportunity to mark the cache entry
736 : * as complete. To work around that, when the join is unique we
737 : * automatically mark cache entries as complete after fetching the first
738 : * tuple. This works when the entire join condition is parameterized.
739 : * Otherwise, when the parameterization is only a subset of the join
740 : * condition, we can't be sure which part of it causes the join to be
741 : * unique. This means there are no guarantees that only 1 tuple will be
742 : * read. We cannot mark the cache entry as complete after reading the
743 : * first tuple without that guarantee. This means the scope of Memoize
744 : * node's usefulness is limited to only outer rows that have no join
745 : * partner as this is the only case where Nested Loop would exhaust the
746 : * inner scan of a unique join. Since the scope is limited to that, we
747 : * just don't bother making a memoize path in this case.
748 : *
749 : * Lateral vars needn't be considered here as they're not considered when
750 : * determining if the join is unique.
751 : */
752 516774 : if (extra->inner_unique)
753 : {
754 : Bitmapset *ppi_serials;
755 :
756 317288 : if (inner_path->param_info == NULL)
757 0 : return NULL;
758 :
759 317288 : ppi_serials = inner_path->param_info->ppi_serials;
760 :
761 750726 : foreach_node(RestrictInfo, rinfo, extra->restrictlist)
762 : {
763 363174 : if (!bms_is_member(rinfo->rinfo_serial, ppi_serials))
764 123512 : return NULL;
765 : }
766 : }
767 :
768 : /*
769 : * We can't use a memoize node if there are volatile functions in the
770 : * inner rel's target list or restrict list. A cache hit could reduce the
771 : * number of calls to these functions.
772 : */
773 393262 : if (contain_volatile_functions((Node *) innerrel->reltarget))
774 0 : return NULL;
775 :
776 661536 : foreach(lc, innerrel->baserestrictinfo)
777 : {
778 268286 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
779 :
780 268286 : if (contain_volatile_functions((Node *) rinfo))
781 12 : return NULL;
782 : }
783 :
784 : /*
785 : * Also check the parameterized path restrictinfos for volatile functions.
786 : * Indexed functions must be immutable so shouldn't have any volatile
787 : * functions, however, with a lateral join the inner scan may not be an
788 : * index scan.
789 : */
790 393250 : if (inner_path->param_info != NULL)
791 : {
792 854634 : foreach(lc, inner_path->param_info->ppi_clauses)
793 : {
794 461386 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
795 :
796 461386 : if (contain_volatile_functions((Node *) rinfo))
797 2 : return NULL;
798 : }
799 : }
800 :
801 : /* Check if we have hash ops for each parameter to the path */
802 393248 : if (paraminfo_get_equal_hashops(root,
803 : inner_path->param_info,
804 393248 : outerrel->top_parent ?
805 : outerrel->top_parent : outerrel,
806 : innerrel,
807 : ph_lateral_vars,
808 : ¶m_exprs,
809 : &hash_operators,
810 : &binary_mode))
811 : {
812 312374 : return (Path *) create_memoize_path(root,
813 : innerrel,
814 : inner_path,
815 : param_exprs,
816 : hash_operators,
817 312374 : extra->inner_unique,
818 : binary_mode,
819 : outer_path->rows);
820 : }
821 :
822 80874 : return NULL;
823 : }
824 :
825 : /*
826 : * try_nestloop_path
827 : * Consider a nestloop join path; if it appears useful, push it into
828 : * the joinrel's pathlist via add_path().
829 : */
830 : static void
831 3144878 : try_nestloop_path(PlannerInfo *root,
832 : RelOptInfo *joinrel,
833 : Path *outer_path,
834 : Path *inner_path,
835 : List *pathkeys,
836 : JoinType jointype,
837 : JoinPathExtraData *extra)
838 : {
839 : Relids required_outer;
840 : JoinCostWorkspace workspace;
841 3144878 : RelOptInfo *innerrel = inner_path->parent;
842 3144878 : RelOptInfo *outerrel = outer_path->parent;
843 : Relids innerrelids;
844 : Relids outerrelids;
845 3144878 : Relids inner_paramrels = PATH_REQ_OUTER(inner_path);
846 3144878 : Relids outer_paramrels = PATH_REQ_OUTER(outer_path);
847 :
848 : /*
849 : * If we are forming an outer join at this join, it's nonsensical to use
850 : * an input path that uses the outer join as part of its parameterization.
851 : * (This can happen despite our join order restrictions, since those apply
852 : * to what is in an input relation not what its parameters are.)
853 : */
854 3862800 : if (extra->sjinfo->ojrelid != 0 &&
855 1435844 : (bms_is_member(extra->sjinfo->ojrelid, inner_paramrels) ||
856 717922 : bms_is_member(extra->sjinfo->ojrelid, outer_paramrels)))
857 308670 : return;
858 :
859 : /*
860 : * Any parameterization of the input paths refers to topmost parents of
861 : * the relevant relations, because reparameterize_path_by_child() hasn't
862 : * been called yet. So we must consider topmost parents of the relations
863 : * being joined, too, while determining parameterization of the result and
864 : * checking for disallowed parameterization cases.
865 : */
866 3144758 : if (innerrel->top_parent_relids)
867 37036 : innerrelids = innerrel->top_parent_relids;
868 : else
869 3107722 : innerrelids = innerrel->relids;
870 :
871 3144758 : if (outerrel->top_parent_relids)
872 37036 : outerrelids = outerrel->top_parent_relids;
873 : else
874 3107722 : outerrelids = outerrel->relids;
875 :
876 : /*
877 : * Check to see if proposed path is still parameterized, and reject if the
878 : * parameterization wouldn't be sensible --- unless allow_star_schema_join
879 : * says to allow it anyway. Also, we must reject if have_dangerous_phv
880 : * doesn't like the look of it, which could only happen if the nestloop is
881 : * still parameterized.
882 : */
883 3144758 : required_outer = calc_nestloop_required_outer(outerrelids, outer_paramrels,
884 : innerrelids, inner_paramrels);
885 3144758 : if (required_outer &&
886 341700 : ((!bms_overlap(required_outer, extra->param_source_rels) &&
887 342104 : !allow_star_schema_join(root, outerrelids, inner_paramrels)) ||
888 33246 : have_dangerous_phv(root, outerrelids, inner_paramrels)))
889 : {
890 : /* Waste no memory when we reject a path here */
891 308550 : bms_free(required_outer);
892 308550 : return;
893 : }
894 :
895 : /* If we got past that, we shouldn't have any unsafe outer-join refs */
896 : Assert(!have_unsafe_outer_join_ref(root, outerrelids, inner_paramrels));
897 :
898 : /*
899 : * If the inner path is parameterized, it is parameterized by the topmost
900 : * parent of the outer rel, not the outer rel itself. We will need to
901 : * translate the parameterization, if this path is chosen, during
902 : * create_plan(). Here we just check whether we will be able to perform
903 : * the translation, and if not avoid creating a nestloop path.
904 : */
905 2836208 : if (PATH_PARAM_BY_PARENT(inner_path, outer_path->parent) &&
906 12112 : !path_is_reparameterizable_by_child(inner_path, outer_path->parent))
907 : {
908 0 : bms_free(required_outer);
909 0 : return;
910 : }
911 :
912 : /*
913 : * Do a precheck to quickly eliminate obviously-inferior paths. We
914 : * calculate a cheap lower bound on the path's cost and then use
915 : * add_path_precheck() to see if the path is clearly going to be dominated
916 : * by some existing path for the joinrel. If not, do the full pushup with
917 : * creating a fully valid path structure and submitting it to add_path().
918 : * The latter two steps are expensive enough to make this two-phase
919 : * methodology worthwhile.
920 : */
921 2836208 : initial_cost_nestloop(root, &workspace, jointype,
922 : outer_path, inner_path, extra);
923 :
924 2836208 : if (add_path_precheck(joinrel, workspace.disabled_nodes,
925 : workspace.startup_cost, workspace.total_cost,
926 : pathkeys, required_outer))
927 : {
928 1377330 : add_path(joinrel, (Path *)
929 1377330 : create_nestloop_path(root,
930 : joinrel,
931 : jointype,
932 : &workspace,
933 : extra,
934 : outer_path,
935 : inner_path,
936 : extra->restrictlist,
937 : pathkeys,
938 : required_outer));
939 : }
940 : else
941 : {
942 : /* Waste no memory when we reject a path here */
943 1458878 : bms_free(required_outer);
944 : }
945 : }
946 :
947 : /*
948 : * try_partial_nestloop_path
949 : * Consider a partial nestloop join path; if it appears useful, push it into
950 : * the joinrel's partial_pathlist via add_partial_path().
951 : */
952 : static void
953 42260 : try_partial_nestloop_path(PlannerInfo *root,
954 : RelOptInfo *joinrel,
955 : Path *outer_path,
956 : Path *inner_path,
957 : List *pathkeys,
958 : JoinType jointype,
959 : JoinPathExtraData *extra)
960 : {
961 : JoinCostWorkspace workspace;
962 :
963 : /*
964 : * If the inner path is parameterized, the parameterization must be fully
965 : * satisfied by the proposed outer path. Parameterized partial paths are
966 : * not supported. The caller should already have verified that no lateral
967 : * rels are required here.
968 : */
969 : Assert(bms_is_empty(joinrel->lateral_relids));
970 : Assert(bms_is_empty(PATH_REQ_OUTER(outer_path)));
971 42260 : if (inner_path->param_info != NULL)
972 : {
973 14844 : Relids inner_paramrels = inner_path->param_info->ppi_req_outer;
974 14844 : RelOptInfo *outerrel = outer_path->parent;
975 : Relids outerrelids;
976 :
977 : /*
978 : * The inner and outer paths are parameterized, if at all, by the top
979 : * level parents, not the child relations, so we must use those relids
980 : * for our parameterization tests.
981 : */
982 14844 : if (outerrel->top_parent_relids)
983 11016 : outerrelids = outerrel->top_parent_relids;
984 : else
985 3828 : outerrelids = outerrel->relids;
986 :
987 14844 : if (!bms_is_subset(inner_paramrels, outerrelids))
988 29612 : return;
989 : }
990 :
991 : /*
992 : * If the inner path is parameterized, it is parameterized by the topmost
993 : * parent of the outer rel, not the outer rel itself. We will need to
994 : * translate the parameterization, if this path is chosen, during
995 : * create_plan(). Here we just check whether we will be able to perform
996 : * the translation, and if not avoid creating a nestloop path.
997 : */
998 41006 : if (PATH_PARAM_BY_PARENT(inner_path, outer_path->parent) &&
999 10116 : !path_is_reparameterizable_by_child(inner_path, outer_path->parent))
1000 0 : return;
1001 :
1002 : /*
1003 : * Before creating a path, get a quick lower bound on what it is likely to
1004 : * cost. Bail out right away if it looks terrible.
1005 : */
1006 41006 : initial_cost_nestloop(root, &workspace, jointype,
1007 : outer_path, inner_path, extra);
1008 41006 : if (!add_partial_path_precheck(joinrel, workspace.disabled_nodes,
1009 : workspace.total_cost, pathkeys))
1010 28358 : return;
1011 :
1012 : /* Might be good enough to be worth trying, so let's try it. */
1013 12648 : add_partial_path(joinrel, (Path *)
1014 12648 : create_nestloop_path(root,
1015 : joinrel,
1016 : jointype,
1017 : &workspace,
1018 : extra,
1019 : outer_path,
1020 : inner_path,
1021 : extra->restrictlist,
1022 : pathkeys,
1023 : NULL));
1024 : }
1025 :
1026 : /*
1027 : * try_mergejoin_path
1028 : * Consider a merge join path; if it appears useful, push it into
1029 : * the joinrel's pathlist via add_path().
1030 : */
1031 : static void
1032 1301364 : try_mergejoin_path(PlannerInfo *root,
1033 : RelOptInfo *joinrel,
1034 : Path *outer_path,
1035 : Path *inner_path,
1036 : List *pathkeys,
1037 : List *mergeclauses,
1038 : List *outersortkeys,
1039 : List *innersortkeys,
1040 : JoinType jointype,
1041 : JoinPathExtraData *extra,
1042 : bool is_partial)
1043 : {
1044 : Relids required_outer;
1045 : JoinCostWorkspace workspace;
1046 :
1047 1301364 : if (is_partial)
1048 : {
1049 6862 : try_partial_mergejoin_path(root,
1050 : joinrel,
1051 : outer_path,
1052 : inner_path,
1053 : pathkeys,
1054 : mergeclauses,
1055 : outersortkeys,
1056 : innersortkeys,
1057 : jointype,
1058 : extra);
1059 50688 : return;
1060 : }
1061 :
1062 : /*
1063 : * If we are forming an outer join at this join, it's nonsensical to use
1064 : * an input path that uses the outer join as part of its parameterization.
1065 : * (This can happen despite our join order restrictions, since those apply
1066 : * to what is in an input relation not what its parameters are.)
1067 : */
1068 1692112 : if (extra->sjinfo->ojrelid != 0 &&
1069 795220 : (bms_is_member(extra->sjinfo->ojrelid, PATH_REQ_OUTER(inner_path)) ||
1070 397610 : bms_is_member(extra->sjinfo->ojrelid, PATH_REQ_OUTER(outer_path))))
1071 12 : return;
1072 :
1073 : /*
1074 : * Check to see if proposed path is still parameterized, and reject if the
1075 : * parameterization wouldn't be sensible.
1076 : */
1077 1294490 : required_outer = calc_non_nestloop_required_outer(outer_path,
1078 : inner_path);
1079 1294490 : if (required_outer &&
1080 46246 : !bms_overlap(required_outer, extra->param_source_rels))
1081 : {
1082 : /* Waste no memory when we reject a path here */
1083 43814 : bms_free(required_outer);
1084 43814 : return;
1085 : }
1086 :
1087 : /*
1088 : * If the given paths are already well enough ordered, we can skip doing
1089 : * an explicit sort.
1090 : */
1091 1859564 : if (outersortkeys &&
1092 608888 : pathkeys_contained_in(outersortkeys, outer_path->pathkeys))
1093 22764 : outersortkeys = NIL;
1094 2257926 : if (innersortkeys &&
1095 1007250 : pathkeys_contained_in(innersortkeys, inner_path->pathkeys))
1096 41322 : innersortkeys = NIL;
1097 :
1098 : /*
1099 : * See comments in try_nestloop_path().
1100 : */
1101 1250676 : initial_cost_mergejoin(root, &workspace, jointype, mergeclauses,
1102 : outer_path, inner_path,
1103 : outersortkeys, innersortkeys,
1104 : extra);
1105 :
1106 1250676 : if (add_path_precheck(joinrel, workspace.disabled_nodes,
1107 : workspace.startup_cost, workspace.total_cost,
1108 : pathkeys, required_outer))
1109 : {
1110 318620 : add_path(joinrel, (Path *)
1111 318620 : create_mergejoin_path(root,
1112 : joinrel,
1113 : jointype,
1114 : &workspace,
1115 : extra,
1116 : outer_path,
1117 : inner_path,
1118 : extra->restrictlist,
1119 : pathkeys,
1120 : required_outer,
1121 : mergeclauses,
1122 : outersortkeys,
1123 : innersortkeys));
1124 : }
1125 : else
1126 : {
1127 : /* Waste no memory when we reject a path here */
1128 932056 : bms_free(required_outer);
1129 : }
1130 : }
1131 :
1132 : /*
1133 : * try_partial_mergejoin_path
1134 : * Consider a partial merge join path; if it appears useful, push it into
1135 : * the joinrel's pathlist via add_partial_path().
1136 : */
1137 : static void
1138 20056 : try_partial_mergejoin_path(PlannerInfo *root,
1139 : RelOptInfo *joinrel,
1140 : Path *outer_path,
1141 : Path *inner_path,
1142 : List *pathkeys,
1143 : List *mergeclauses,
1144 : List *outersortkeys,
1145 : List *innersortkeys,
1146 : JoinType jointype,
1147 : JoinPathExtraData *extra)
1148 : {
1149 : JoinCostWorkspace workspace;
1150 :
1151 : /*
1152 : * See comments in try_partial_hashjoin_path().
1153 : */
1154 : Assert(bms_is_empty(joinrel->lateral_relids));
1155 : Assert(bms_is_empty(PATH_REQ_OUTER(outer_path)));
1156 20056 : if (!bms_is_empty(PATH_REQ_OUTER(inner_path)))
1157 10624 : return;
1158 :
1159 : /*
1160 : * If the given paths are already well enough ordered, we can skip doing
1161 : * an explicit sort.
1162 : */
1163 33250 : if (outersortkeys &&
1164 13194 : pathkeys_contained_in(outersortkeys, outer_path->pathkeys))
1165 168 : outersortkeys = NIL;
1166 37278 : if (innersortkeys &&
1167 17222 : pathkeys_contained_in(innersortkeys, inner_path->pathkeys))
1168 252 : innersortkeys = NIL;
1169 :
1170 : /*
1171 : * See comments in try_partial_nestloop_path().
1172 : */
1173 20056 : initial_cost_mergejoin(root, &workspace, jointype, mergeclauses,
1174 : outer_path, inner_path,
1175 : outersortkeys, innersortkeys,
1176 : extra);
1177 :
1178 20056 : if (!add_partial_path_precheck(joinrel, workspace.disabled_nodes,
1179 : workspace.total_cost, pathkeys))
1180 10624 : return;
1181 :
1182 : /* Might be good enough to be worth trying, so let's try it. */
1183 9432 : add_partial_path(joinrel, (Path *)
1184 9432 : create_mergejoin_path(root,
1185 : joinrel,
1186 : jointype,
1187 : &workspace,
1188 : extra,
1189 : outer_path,
1190 : inner_path,
1191 : extra->restrictlist,
1192 : pathkeys,
1193 : NULL,
1194 : mergeclauses,
1195 : outersortkeys,
1196 : innersortkeys));
1197 : }
1198 :
1199 : /*
1200 : * try_hashjoin_path
1201 : * Consider a hash join path; if it appears useful, push it into
1202 : * the joinrel's pathlist via add_path().
1203 : */
1204 : static void
1205 783996 : try_hashjoin_path(PlannerInfo *root,
1206 : RelOptInfo *joinrel,
1207 : Path *outer_path,
1208 : Path *inner_path,
1209 : List *hashclauses,
1210 : JoinType jointype,
1211 : JoinPathExtraData *extra)
1212 : {
1213 : Relids required_outer;
1214 : JoinCostWorkspace workspace;
1215 :
1216 : /*
1217 : * If we are forming an outer join at this join, it's nonsensical to use
1218 : * an input path that uses the outer join as part of its parameterization.
1219 : * (This can happen despite our join order restrictions, since those apply
1220 : * to what is in an input relation not what its parameters are.)
1221 : */
1222 1049812 : if (extra->sjinfo->ojrelid != 0 &&
1223 531602 : (bms_is_member(extra->sjinfo->ojrelid, PATH_REQ_OUTER(inner_path)) ||
1224 265786 : bms_is_member(extra->sjinfo->ojrelid, PATH_REQ_OUTER(outer_path))))
1225 122724 : return;
1226 :
1227 : /*
1228 : * Check to see if proposed path is still parameterized, and reject if the
1229 : * parameterization wouldn't be sensible.
1230 : */
1231 783936 : required_outer = calc_non_nestloop_required_outer(outer_path,
1232 : inner_path);
1233 783936 : if (required_outer &&
1234 135550 : !bms_overlap(required_outer, extra->param_source_rels))
1235 : {
1236 : /* Waste no memory when we reject a path here */
1237 122664 : bms_free(required_outer);
1238 122664 : return;
1239 : }
1240 :
1241 : /*
1242 : * See comments in try_nestloop_path(). Also note that hashjoin paths
1243 : * never have any output pathkeys, per comments in create_hashjoin_path.
1244 : */
1245 661272 : initial_cost_hashjoin(root, &workspace, jointype, hashclauses,
1246 : outer_path, inner_path, extra, false);
1247 :
1248 661272 : if (add_path_precheck(joinrel, workspace.disabled_nodes,
1249 : workspace.startup_cost, workspace.total_cost,
1250 : NIL, required_outer))
1251 : {
1252 283524 : add_path(joinrel, (Path *)
1253 283524 : create_hashjoin_path(root,
1254 : joinrel,
1255 : jointype,
1256 : &workspace,
1257 : extra,
1258 : outer_path,
1259 : inner_path,
1260 : false, /* parallel_hash */
1261 : extra->restrictlist,
1262 : required_outer,
1263 : hashclauses));
1264 : }
1265 : else
1266 : {
1267 : /* Waste no memory when we reject a path here */
1268 377748 : bms_free(required_outer);
1269 : }
1270 : }
1271 :
1272 : /*
1273 : * try_partial_hashjoin_path
1274 : * Consider a partial hashjoin join path; if it appears useful, push it into
1275 : * the joinrel's partial_pathlist via add_partial_path().
1276 : * The outer side is partial. If parallel_hash is true, then the inner path
1277 : * must be partial and will be run in parallel to create one or more shared
1278 : * hash tables; otherwise the inner path must be complete and a copy of it
1279 : * is run in every process to create separate identical private hash tables.
1280 : */
1281 : static void
1282 21868 : try_partial_hashjoin_path(PlannerInfo *root,
1283 : RelOptInfo *joinrel,
1284 : Path *outer_path,
1285 : Path *inner_path,
1286 : List *hashclauses,
1287 : JoinType jointype,
1288 : JoinPathExtraData *extra,
1289 : bool parallel_hash)
1290 : {
1291 : JoinCostWorkspace workspace;
1292 :
1293 : /*
1294 : * If the inner path is parameterized, we can't use a partial hashjoin.
1295 : * Parameterized partial paths are not supported. The caller should
1296 : * already have verified that no lateral rels are required here.
1297 : */
1298 : Assert(bms_is_empty(joinrel->lateral_relids));
1299 : Assert(bms_is_empty(PATH_REQ_OUTER(outer_path)));
1300 21868 : if (!bms_is_empty(PATH_REQ_OUTER(inner_path)))
1301 10528 : return;
1302 :
1303 : /*
1304 : * Before creating a path, get a quick lower bound on what it is likely to
1305 : * cost. Bail out right away if it looks terrible.
1306 : */
1307 21868 : initial_cost_hashjoin(root, &workspace, jointype, hashclauses,
1308 : outer_path, inner_path, extra, parallel_hash);
1309 21868 : if (!add_partial_path_precheck(joinrel, workspace.disabled_nodes,
1310 : workspace.total_cost, NIL))
1311 10528 : return;
1312 :
1313 : /* Might be good enough to be worth trying, so let's try it. */
1314 11340 : add_partial_path(joinrel, (Path *)
1315 11340 : create_hashjoin_path(root,
1316 : joinrel,
1317 : jointype,
1318 : &workspace,
1319 : extra,
1320 : outer_path,
1321 : inner_path,
1322 : parallel_hash,
1323 : extra->restrictlist,
1324 : NULL,
1325 : hashclauses));
1326 : }
1327 :
1328 : /*
1329 : * sort_inner_and_outer
1330 : * Create mergejoin join paths by explicitly sorting both the outer and
1331 : * inner join relations on each available merge ordering.
1332 : *
1333 : * 'joinrel' is the join relation
1334 : * 'outerrel' is the outer join relation
1335 : * 'innerrel' is the inner join relation
1336 : * 'jointype' is the type of join to do
1337 : * 'extra' contains additional input values
1338 : */
1339 : static void
1340 667254 : sort_inner_and_outer(PlannerInfo *root,
1341 : RelOptInfo *joinrel,
1342 : RelOptInfo *outerrel,
1343 : RelOptInfo *innerrel,
1344 : JoinType jointype,
1345 : JoinPathExtraData *extra)
1346 : {
1347 667254 : JoinType save_jointype = jointype;
1348 : Path *outer_path;
1349 : Path *inner_path;
1350 667254 : Path *cheapest_partial_outer = NULL;
1351 667254 : Path *cheapest_safe_inner = NULL;
1352 : List *all_pathkeys;
1353 : ListCell *l;
1354 :
1355 : /* Nothing to do if there are no available mergejoin clauses */
1356 667254 : if (extra->mergeclause_list == NIL)
1357 117208 : return;
1358 :
1359 : /*
1360 : * We only consider the cheapest-total-cost input paths, since we are
1361 : * assuming here that a sort is required. We will consider
1362 : * cheapest-startup-cost input paths later, and only if they don't need a
1363 : * sort.
1364 : *
1365 : * This function intentionally does not consider parameterized input
1366 : * paths, except when the cheapest-total is parameterized. If we did so,
1367 : * we'd have a combinatorial explosion of mergejoin paths of dubious
1368 : * value. This interacts with decisions elsewhere that also discriminate
1369 : * against mergejoins with parameterized inputs; see comments in
1370 : * src/backend/optimizer/README.
1371 : */
1372 550046 : outer_path = outerrel->cheapest_total_path;
1373 550046 : inner_path = innerrel->cheapest_total_path;
1374 :
1375 : /*
1376 : * If either cheapest-total path is parameterized by the other rel, we
1377 : * can't use a mergejoin. (There's no use looking for alternative input
1378 : * paths, since these should already be the least-parameterized available
1379 : * paths.)
1380 : */
1381 550046 : if (PATH_PARAM_BY_REL(outer_path, innerrel) ||
1382 549310 : PATH_PARAM_BY_REL(inner_path, outerrel))
1383 1496 : return;
1384 :
1385 : /*
1386 : * If unique-ification is requested, do it and then handle as a plain
1387 : * inner join.
1388 : */
1389 548550 : if (jointype == JOIN_UNIQUE_OUTER)
1390 : {
1391 5740 : outer_path = (Path *) create_unique_path(root, outerrel,
1392 : outer_path, extra->sjinfo);
1393 : Assert(outer_path);
1394 5740 : jointype = JOIN_INNER;
1395 : }
1396 542810 : else if (jointype == JOIN_UNIQUE_INNER)
1397 : {
1398 5740 : inner_path = (Path *) create_unique_path(root, innerrel,
1399 : inner_path, extra->sjinfo);
1400 : Assert(inner_path);
1401 5740 : jointype = JOIN_INNER;
1402 : }
1403 :
1404 : /*
1405 : * If the joinrel is parallel-safe, we may be able to consider a partial
1406 : * merge join. However, we can't handle JOIN_UNIQUE_OUTER, because the
1407 : * outer path will be partial, and therefore we won't be able to properly
1408 : * guarantee uniqueness. Similarly, we can't handle JOIN_FULL, JOIN_RIGHT
1409 : * and JOIN_RIGHT_ANTI, because they can produce false null extended rows.
1410 : * Also, the resulting path must not be parameterized.
1411 : */
1412 548550 : if (joinrel->consider_parallel &&
1413 485758 : save_jointype != JOIN_UNIQUE_OUTER &&
1414 483390 : save_jointype != JOIN_FULL &&
1415 399056 : save_jointype != JOIN_RIGHT &&
1416 397396 : save_jointype != JOIN_RIGHT_ANTI &&
1417 397396 : outerrel->partial_pathlist != NIL &&
1418 9610 : bms_is_empty(joinrel->lateral_relids))
1419 : {
1420 9610 : cheapest_partial_outer = (Path *) linitial(outerrel->partial_pathlist);
1421 :
1422 9610 : if (inner_path->parallel_safe)
1423 9514 : cheapest_safe_inner = inner_path;
1424 96 : else if (save_jointype != JOIN_UNIQUE_INNER)
1425 : cheapest_safe_inner =
1426 90 : get_cheapest_parallel_safe_total_inner(innerrel->pathlist);
1427 : }
1428 :
1429 : /*
1430 : * Each possible ordering of the available mergejoin clauses will generate
1431 : * a differently-sorted result path at essentially the same cost. We have
1432 : * no basis for choosing one over another at this level of joining, but
1433 : * some sort orders may be more useful than others for higher-level
1434 : * mergejoins, so it's worth considering multiple orderings.
1435 : *
1436 : * Actually, it's not quite true that every mergeclause ordering will
1437 : * generate a different path order, because some of the clauses may be
1438 : * partially redundant (refer to the same EquivalenceClasses). Therefore,
1439 : * what we do is convert the mergeclause list to a list of canonical
1440 : * pathkeys, and then consider different orderings of the pathkeys.
1441 : *
1442 : * Generating a path for *every* permutation of the pathkeys doesn't seem
1443 : * like a winning strategy; the cost in planning time is too high. For
1444 : * now, we generate one path for each pathkey, listing that pathkey first
1445 : * and the rest in random order. This should allow at least a one-clause
1446 : * mergejoin without re-sorting against any other possible mergejoin
1447 : * partner path. But if we've not guessed the right ordering of secondary
1448 : * keys, we may end up evaluating clauses as qpquals when they could have
1449 : * been done as mergeclauses. (In practice, it's rare that there's more
1450 : * than two or three mergeclauses, so expending a huge amount of thought
1451 : * on that is probably not worth it.)
1452 : *
1453 : * The pathkey order returned by select_outer_pathkeys_for_merge() has
1454 : * some heuristics behind it (see that function), so be sure to try it
1455 : * exactly as-is as well as making variants.
1456 : */
1457 548550 : all_pathkeys = select_outer_pathkeys_for_merge(root,
1458 : extra->mergeclause_list,
1459 : joinrel);
1460 :
1461 1157438 : foreach(l, all_pathkeys)
1462 : {
1463 608888 : PathKey *front_pathkey = (PathKey *) lfirst(l);
1464 : List *cur_mergeclauses;
1465 : List *outerkeys;
1466 : List *innerkeys;
1467 : List *merge_pathkeys;
1468 :
1469 : /* Make a pathkey list with this guy first */
1470 608888 : if (l != list_head(all_pathkeys))
1471 60338 : outerkeys = lcons(front_pathkey,
1472 : list_delete_nth_cell(list_copy(all_pathkeys),
1473 : foreach_current_index(l)));
1474 : else
1475 548550 : outerkeys = all_pathkeys; /* no work at first one... */
1476 :
1477 : /* Sort the mergeclauses into the corresponding ordering */
1478 : cur_mergeclauses =
1479 608888 : find_mergeclauses_for_outer_pathkeys(root,
1480 : outerkeys,
1481 : extra->mergeclause_list);
1482 :
1483 : /* Should have used them all... */
1484 : Assert(list_length(cur_mergeclauses) == list_length(extra->mergeclause_list));
1485 :
1486 : /* Build sort pathkeys for the inner side */
1487 608888 : innerkeys = make_inner_pathkeys_for_merge(root,
1488 : cur_mergeclauses,
1489 : outerkeys);
1490 :
1491 : /* Build pathkeys representing output sort order */
1492 608888 : merge_pathkeys = build_join_pathkeys(root, joinrel, jointype,
1493 : outerkeys);
1494 :
1495 : /*
1496 : * And now we can make the path.
1497 : *
1498 : * Note: it's possible that the cheapest paths will already be sorted
1499 : * properly. try_mergejoin_path will detect that case and suppress an
1500 : * explicit sort step, so we needn't do so here.
1501 : */
1502 608888 : try_mergejoin_path(root,
1503 : joinrel,
1504 : outer_path,
1505 : inner_path,
1506 : merge_pathkeys,
1507 : cur_mergeclauses,
1508 : outerkeys,
1509 : innerkeys,
1510 : jointype,
1511 : extra,
1512 : false);
1513 :
1514 : /*
1515 : * If we have partial outer and parallel safe inner path then try
1516 : * partial mergejoin path.
1517 : */
1518 608888 : if (cheapest_partial_outer && cheapest_safe_inner)
1519 13194 : try_partial_mergejoin_path(root,
1520 : joinrel,
1521 : cheapest_partial_outer,
1522 : cheapest_safe_inner,
1523 : merge_pathkeys,
1524 : cur_mergeclauses,
1525 : outerkeys,
1526 : innerkeys,
1527 : jointype,
1528 : extra);
1529 : }
1530 : }
1531 :
1532 : /*
1533 : * generate_mergejoin_paths
1534 : * Creates possible mergejoin paths for input outerpath.
1535 : *
1536 : * We generate mergejoins if mergejoin clauses are available. We have
1537 : * two ways to generate the inner path for a mergejoin: sort the cheapest
1538 : * inner path, or use an inner path that is already suitably ordered for the
1539 : * merge. If we have several mergeclauses, it could be that there is no inner
1540 : * path (or only a very expensive one) for the full list of mergeclauses, but
1541 : * better paths exist if we truncate the mergeclause list (thereby discarding
1542 : * some sort key requirements). So, we consider truncations of the
1543 : * mergeclause list as well as the full list. (Ideally we'd consider all
1544 : * subsets of the mergeclause list, but that seems way too expensive.)
1545 : */
1546 : static void
1547 1290656 : generate_mergejoin_paths(PlannerInfo *root,
1548 : RelOptInfo *joinrel,
1549 : RelOptInfo *innerrel,
1550 : Path *outerpath,
1551 : JoinType jointype,
1552 : JoinPathExtraData *extra,
1553 : bool useallclauses,
1554 : Path *inner_cheapest_total,
1555 : List *merge_pathkeys,
1556 : bool is_partial)
1557 : {
1558 : List *mergeclauses;
1559 : List *innersortkeys;
1560 : List *trialsortkeys;
1561 : Path *cheapest_startup_inner;
1562 : Path *cheapest_total_inner;
1563 1290656 : JoinType save_jointype = jointype;
1564 : int num_sortkeys;
1565 : int sortkeycnt;
1566 :
1567 1290656 : if (jointype == JOIN_UNIQUE_OUTER || jointype == JOIN_UNIQUE_INNER)
1568 15472 : jointype = JOIN_INNER;
1569 :
1570 : /* Look for useful mergeclauses (if any) */
1571 : mergeclauses =
1572 1290656 : find_mergeclauses_for_outer_pathkeys(root,
1573 : outerpath->pathkeys,
1574 : extra->mergeclause_list);
1575 :
1576 : /*
1577 : * Done with this outer path if no chance for a mergejoin.
1578 : *
1579 : * Special corner case: for "x FULL JOIN y ON true", there will be no join
1580 : * clauses at all. Ordinarily we'd generate a clauseless nestloop path,
1581 : * but since mergejoin is our only join type that supports FULL JOIN
1582 : * without any join clauses, it's necessary to generate a clauseless
1583 : * mergejoin path instead.
1584 : */
1585 1290656 : if (mergeclauses == NIL)
1586 : {
1587 852684 : if (jointype == JOIN_FULL)
1588 : /* okay to try for mergejoin */ ;
1589 : else
1590 849300 : return;
1591 : }
1592 532358 : if (useallclauses &&
1593 91002 : list_length(mergeclauses) != list_length(extra->mergeclause_list))
1594 14252 : return;
1595 :
1596 : /* Compute the required ordering of the inner path */
1597 427104 : innersortkeys = make_inner_pathkeys_for_merge(root,
1598 : mergeclauses,
1599 : outerpath->pathkeys);
1600 :
1601 : /*
1602 : * Generate a mergejoin on the basis of sorting the cheapest inner. Since
1603 : * a sort will be needed, only cheapest total cost matters. (But
1604 : * try_mergejoin_path will do the right thing if inner_cheapest_total is
1605 : * already correctly sorted.)
1606 : */
1607 427104 : try_mergejoin_path(root,
1608 : joinrel,
1609 : outerpath,
1610 : inner_cheapest_total,
1611 : merge_pathkeys,
1612 : mergeclauses,
1613 : NIL,
1614 : innersortkeys,
1615 : jointype,
1616 : extra,
1617 : is_partial);
1618 :
1619 : /* Can't do anything else if inner path needs to be unique'd */
1620 427104 : if (save_jointype == JOIN_UNIQUE_INNER)
1621 2140 : return;
1622 :
1623 : /*
1624 : * Look for presorted inner paths that satisfy the innersortkey list ---
1625 : * or any truncation thereof, if we are allowed to build a mergejoin using
1626 : * a subset of the merge clauses. Here, we consider both cheap startup
1627 : * cost and cheap total cost.
1628 : *
1629 : * Currently we do not consider parameterized inner paths here. This
1630 : * interacts with decisions elsewhere that also discriminate against
1631 : * mergejoins with parameterized inputs; see comments in
1632 : * src/backend/optimizer/README.
1633 : *
1634 : * As we shorten the sortkey list, we should consider only paths that are
1635 : * strictly cheaper than (in particular, not the same as) any path found
1636 : * in an earlier iteration. Otherwise we'd be intentionally using fewer
1637 : * merge keys than a given path allows (treating the rest as plain
1638 : * joinquals), which is unlikely to be a good idea. Also, eliminating
1639 : * paths here on the basis of compare_path_costs is a lot cheaper than
1640 : * building the mergejoin path only to throw it away.
1641 : *
1642 : * If inner_cheapest_total is well enough sorted to have not required a
1643 : * sort in the path made above, we shouldn't make a duplicate path with
1644 : * it, either. We handle that case with the same logic that handles the
1645 : * previous consideration, by initializing the variables that track
1646 : * cheapest-so-far properly. Note that we do NOT reject
1647 : * inner_cheapest_total if we find it matches some shorter set of
1648 : * pathkeys. That case corresponds to using fewer mergekeys to avoid
1649 : * sorting inner_cheapest_total, whereas we did sort it above, so the
1650 : * plans being considered are different.
1651 : */
1652 424964 : if (pathkeys_contained_in(innersortkeys,
1653 : inner_cheapest_total->pathkeys))
1654 : {
1655 : /* inner_cheapest_total didn't require a sort */
1656 20188 : cheapest_startup_inner = inner_cheapest_total;
1657 20188 : cheapest_total_inner = inner_cheapest_total;
1658 : }
1659 : else
1660 : {
1661 : /* it did require a sort, at least for the full set of keys */
1662 404776 : cheapest_startup_inner = NULL;
1663 404776 : cheapest_total_inner = NULL;
1664 : }
1665 424964 : num_sortkeys = list_length(innersortkeys);
1666 424964 : if (num_sortkeys > 1 && !useallclauses)
1667 17518 : trialsortkeys = list_copy(innersortkeys); /* need modifiable copy */
1668 : else
1669 407446 : trialsortkeys = innersortkeys; /* won't really truncate */
1670 :
1671 790832 : for (sortkeycnt = num_sortkeys; sortkeycnt > 0; sortkeycnt--)
1672 : {
1673 : Path *innerpath;
1674 442474 : List *newclauses = NIL;
1675 :
1676 : /*
1677 : * Look for an inner path ordered well enough for the first
1678 : * 'sortkeycnt' innersortkeys. NB: trialsortkeys list is modified
1679 : * destructively, which is why we made a copy...
1680 : */
1681 442474 : trialsortkeys = list_truncate(trialsortkeys, sortkeycnt);
1682 442474 : innerpath = get_cheapest_path_for_pathkeys(innerrel->pathlist,
1683 : trialsortkeys,
1684 : NULL,
1685 : TOTAL_COST,
1686 : is_partial);
1687 442474 : if (innerpath != NULL &&
1688 32812 : (cheapest_total_inner == NULL ||
1689 32812 : compare_path_costs(innerpath, cheapest_total_inner,
1690 : TOTAL_COST) < 0))
1691 : {
1692 : /* Found a cheap (or even-cheaper) sorted path */
1693 : /* Select the right mergeclauses, if we didn't already */
1694 262890 : if (sortkeycnt < num_sortkeys)
1695 : {
1696 : newclauses =
1697 6274 : trim_mergeclauses_for_inner_pathkeys(root,
1698 : mergeclauses,
1699 : trialsortkeys);
1700 : Assert(newclauses != NIL);
1701 : }
1702 : else
1703 256616 : newclauses = mergeclauses;
1704 262890 : try_mergejoin_path(root,
1705 : joinrel,
1706 : outerpath,
1707 : innerpath,
1708 : merge_pathkeys,
1709 : newclauses,
1710 : NIL,
1711 : NIL,
1712 : jointype,
1713 : extra,
1714 : is_partial);
1715 262890 : cheapest_total_inner = innerpath;
1716 : }
1717 : /* Same on the basis of cheapest startup cost ... */
1718 442474 : innerpath = get_cheapest_path_for_pathkeys(innerrel->pathlist,
1719 : trialsortkeys,
1720 : NULL,
1721 : STARTUP_COST,
1722 : is_partial);
1723 442474 : if (innerpath != NULL &&
1724 32812 : (cheapest_startup_inner == NULL ||
1725 32812 : compare_path_costs(innerpath, cheapest_startup_inner,
1726 : STARTUP_COST) < 0))
1727 : {
1728 : /* Found a cheap (or even-cheaper) sorted path */
1729 259936 : if (innerpath != cheapest_total_inner)
1730 : {
1731 : /*
1732 : * Avoid rebuilding clause list if we already made one; saves
1733 : * memory in big join trees...
1734 : */
1735 2482 : if (newclauses == NIL)
1736 : {
1737 68 : if (sortkeycnt < num_sortkeys)
1738 : {
1739 : newclauses =
1740 4 : trim_mergeclauses_for_inner_pathkeys(root,
1741 : mergeclauses,
1742 : trialsortkeys);
1743 : Assert(newclauses != NIL);
1744 : }
1745 : else
1746 64 : newclauses = mergeclauses;
1747 : }
1748 2482 : try_mergejoin_path(root,
1749 : joinrel,
1750 : outerpath,
1751 : innerpath,
1752 : merge_pathkeys,
1753 : newclauses,
1754 : NIL,
1755 : NIL,
1756 : jointype,
1757 : extra,
1758 : is_partial);
1759 : }
1760 259936 : cheapest_startup_inner = innerpath;
1761 : }
1762 :
1763 : /*
1764 : * Don't consider truncated sortkeys if we need all clauses.
1765 : */
1766 442474 : if (useallclauses)
1767 76606 : break;
1768 : }
1769 : }
1770 :
1771 : /*
1772 : * match_unsorted_outer
1773 : * Creates possible join paths for processing a single join relation
1774 : * 'joinrel' by employing either iterative substitution or
1775 : * mergejoining on each of its possible outer paths (considering
1776 : * only outer paths that are already ordered well enough for merging).
1777 : *
1778 : * We always generate a nestloop path for each available outer path.
1779 : * In fact we may generate as many as five: one on the cheapest-total-cost
1780 : * inner path, one on the same with materialization, one on the
1781 : * cheapest-startup-cost inner path (if different), one on the
1782 : * cheapest-total inner-indexscan path (if any), and one on the
1783 : * cheapest-startup inner-indexscan path (if different).
1784 : *
1785 : * We also consider mergejoins if mergejoin clauses are available. See
1786 : * detailed comments in generate_mergejoin_paths.
1787 : *
1788 : * 'joinrel' is the join relation
1789 : * 'outerrel' is the outer join relation
1790 : * 'innerrel' is the inner join relation
1791 : * 'jointype' is the type of join to do
1792 : * 'extra' contains additional input values
1793 : */
1794 : static void
1795 667254 : match_unsorted_outer(PlannerInfo *root,
1796 : RelOptInfo *joinrel,
1797 : RelOptInfo *outerrel,
1798 : RelOptInfo *innerrel,
1799 : JoinType jointype,
1800 : JoinPathExtraData *extra)
1801 : {
1802 667254 : JoinType save_jointype = jointype;
1803 : bool nestjoinOK;
1804 : bool useallclauses;
1805 667254 : Path *inner_cheapest_total = innerrel->cheapest_total_path;
1806 667254 : Path *matpath = NULL;
1807 : ListCell *lc1;
1808 :
1809 : /*
1810 : * For now we do not support RIGHT_SEMI join in mergejoin or nestloop
1811 : * join.
1812 : */
1813 667254 : if (jointype == JOIN_RIGHT_SEMI)
1814 102 : return;
1815 :
1816 : /*
1817 : * Nestloop only supports inner, left, semi, and anti joins. Also, if we
1818 : * are doing a right, right-anti or full mergejoin, we must use *all* the
1819 : * mergeclauses as join clauses, else we will not have a valid plan.
1820 : * (Although these two flags are currently inverses, keep them separate
1821 : * for clarity and possible future changes.)
1822 : */
1823 667152 : switch (jointype)
1824 : {
1825 553500 : case JOIN_INNER:
1826 : case JOIN_LEFT:
1827 : case JOIN_SEMI:
1828 : case JOIN_ANTI:
1829 553500 : nestjoinOK = true;
1830 553500 : useallclauses = false;
1831 553500 : break;
1832 98608 : case JOIN_RIGHT:
1833 : case JOIN_RIGHT_ANTI:
1834 : case JOIN_FULL:
1835 98608 : nestjoinOK = false;
1836 98608 : useallclauses = true;
1837 98608 : break;
1838 15044 : case JOIN_UNIQUE_OUTER:
1839 : case JOIN_UNIQUE_INNER:
1840 15044 : jointype = JOIN_INNER;
1841 15044 : nestjoinOK = true;
1842 15044 : useallclauses = false;
1843 15044 : break;
1844 0 : default:
1845 0 : elog(ERROR, "unrecognized join type: %d",
1846 : (int) jointype);
1847 : nestjoinOK = false; /* keep compiler quiet */
1848 : useallclauses = false;
1849 : break;
1850 : }
1851 :
1852 : /*
1853 : * If inner_cheapest_total is parameterized by the outer rel, ignore it;
1854 : * we will consider it below as a member of cheapest_parameterized_paths,
1855 : * but the other possibilities considered in this routine aren't usable.
1856 : */
1857 667152 : if (PATH_PARAM_BY_REL(inner_cheapest_total, outerrel))
1858 11510 : inner_cheapest_total = NULL;
1859 :
1860 : /*
1861 : * If we need to unique-ify the inner path, we will consider only the
1862 : * cheapest-total inner.
1863 : */
1864 667152 : if (save_jointype == JOIN_UNIQUE_INNER)
1865 : {
1866 : /* No way to do this with an inner path parameterized by outer rel */
1867 7522 : if (inner_cheapest_total == NULL)
1868 24 : return;
1869 : inner_cheapest_total = (Path *)
1870 7498 : create_unique_path(root, innerrel, inner_cheapest_total, extra->sjinfo);
1871 : Assert(inner_cheapest_total);
1872 : }
1873 659630 : else if (nestjoinOK)
1874 : {
1875 : /*
1876 : * Consider materializing the cheapest inner path, unless
1877 : * enable_material is off or the path in question materializes its
1878 : * output anyway.
1879 : */
1880 561022 : if (enable_material && inner_cheapest_total != NULL &&
1881 549066 : !ExecMaterializesOutput(inner_cheapest_total->pathtype))
1882 : matpath = (Path *)
1883 520446 : create_material_path(innerrel, inner_cheapest_total);
1884 : }
1885 :
1886 2220880 : foreach(lc1, outerrel->pathlist)
1887 : {
1888 1553752 : Path *outerpath = (Path *) lfirst(lc1);
1889 : List *merge_pathkeys;
1890 :
1891 : /*
1892 : * We cannot use an outer path that is parameterized by the inner rel.
1893 : */
1894 1553752 : if (PATH_PARAM_BY_REL(outerpath, innerrel))
1895 256400 : continue;
1896 :
1897 : /*
1898 : * If we need to unique-ify the outer path, it's pointless to consider
1899 : * any but the cheapest outer. (XXX we don't consider parameterized
1900 : * outers, nor inners, for unique-ified cases. Should we?)
1901 : */
1902 1297352 : if (save_jointype == JOIN_UNIQUE_OUTER)
1903 : {
1904 8808 : if (outerpath != outerrel->cheapest_total_path)
1905 1310 : continue;
1906 7498 : outerpath = (Path *) create_unique_path(root, outerrel,
1907 : outerpath, extra->sjinfo);
1908 : Assert(outerpath);
1909 : }
1910 :
1911 : /*
1912 : * The result will have this sort order (even if it is implemented as
1913 : * a nestloop, and even if some of the mergeclauses are implemented by
1914 : * qpquals rather than as true mergeclauses):
1915 : */
1916 1296042 : merge_pathkeys = build_join_pathkeys(root, joinrel, jointype,
1917 : outerpath->pathkeys);
1918 :
1919 1296042 : if (save_jointype == JOIN_UNIQUE_INNER)
1920 : {
1921 : /*
1922 : * Consider nestloop join, but only with the unique-ified cheapest
1923 : * inner path
1924 : */
1925 14488 : try_nestloop_path(root,
1926 : joinrel,
1927 : outerpath,
1928 : inner_cheapest_total,
1929 : merge_pathkeys,
1930 : jointype,
1931 : extra);
1932 : }
1933 1281554 : else if (nestjoinOK)
1934 : {
1935 : /*
1936 : * Consider nestloop joins using this outer path and various
1937 : * available paths for the inner relation. We consider the
1938 : * cheapest-total paths for each available parameterization of the
1939 : * inner relation, including the unparameterized case.
1940 : */
1941 : ListCell *lc2;
1942 :
1943 2894098 : foreach(lc2, innerrel->cheapest_parameterized_paths)
1944 : {
1945 1798638 : Path *innerpath = (Path *) lfirst(lc2);
1946 : Path *mpath;
1947 :
1948 1798638 : try_nestloop_path(root,
1949 : joinrel,
1950 : outerpath,
1951 : innerpath,
1952 : merge_pathkeys,
1953 : jointype,
1954 : extra);
1955 :
1956 : /*
1957 : * Try generating a memoize path and see if that makes the
1958 : * nested loop any cheaper.
1959 : */
1960 1798638 : mpath = get_memoize_path(root, innerrel, outerrel,
1961 : innerpath, outerpath, jointype,
1962 : extra);
1963 1798638 : if (mpath != NULL)
1964 306576 : try_nestloop_path(root,
1965 : joinrel,
1966 : outerpath,
1967 : mpath,
1968 : merge_pathkeys,
1969 : jointype,
1970 : extra);
1971 : }
1972 :
1973 : /* Also consider materialized form of the cheapest inner path */
1974 1095460 : if (matpath != NULL)
1975 1025176 : try_nestloop_path(root,
1976 : joinrel,
1977 : outerpath,
1978 : matpath,
1979 : merge_pathkeys,
1980 : jointype,
1981 : extra);
1982 : }
1983 :
1984 : /* Can't do anything else if outer path needs to be unique'd */
1985 1296042 : if (save_jointype == JOIN_UNIQUE_OUTER)
1986 7498 : continue;
1987 :
1988 : /* Can't do anything else if inner rel is parameterized by outer */
1989 1288544 : if (inner_cheapest_total == NULL)
1990 12528 : continue;
1991 :
1992 : /* Generate merge join paths */
1993 1276016 : generate_mergejoin_paths(root, joinrel, innerrel, outerpath,
1994 : save_jointype, extra, useallclauses,
1995 : inner_cheapest_total, merge_pathkeys,
1996 : false);
1997 : }
1998 :
1999 : /*
2000 : * Consider partial nestloop and mergejoin plan if outerrel has any
2001 : * partial path and the joinrel is parallel-safe. However, we can't
2002 : * handle JOIN_UNIQUE_OUTER, because the outer path will be partial, and
2003 : * therefore we won't be able to properly guarantee uniqueness. Nor can
2004 : * we handle joins needing lateral rels, since partial paths must not be
2005 : * parameterized. Similarly, we can't handle JOIN_FULL, JOIN_RIGHT and
2006 : * JOIN_RIGHT_ANTI, because they can produce false null extended rows.
2007 : */
2008 667128 : if (joinrel->consider_parallel &&
2009 562170 : save_jointype != JOIN_UNIQUE_OUTER &&
2010 559682 : save_jointype != JOIN_FULL &&
2011 473712 : save_jointype != JOIN_RIGHT &&
2012 472046 : save_jointype != JOIN_RIGHT_ANTI &&
2013 472046 : outerrel->partial_pathlist != NIL &&
2014 11244 : bms_is_empty(joinrel->lateral_relids))
2015 : {
2016 11244 : if (nestjoinOK)
2017 11244 : consider_parallel_nestloop(root, joinrel, outerrel, innerrel,
2018 : save_jointype, extra);
2019 :
2020 : /*
2021 : * If inner_cheapest_total is NULL or non parallel-safe then find the
2022 : * cheapest total parallel safe path. If doing JOIN_UNIQUE_INNER, we
2023 : * can't use any alternative inner path.
2024 : */
2025 11244 : if (inner_cheapest_total == NULL ||
2026 10836 : !inner_cheapest_total->parallel_safe)
2027 : {
2028 780 : if (save_jointype == JOIN_UNIQUE_INNER)
2029 6 : return;
2030 :
2031 774 : inner_cheapest_total = get_cheapest_parallel_safe_total_inner(innerrel->pathlist);
2032 : }
2033 :
2034 11238 : if (inner_cheapest_total)
2035 10824 : consider_parallel_mergejoin(root, joinrel, outerrel, innerrel,
2036 : save_jointype, extra,
2037 : inner_cheapest_total);
2038 : }
2039 : }
2040 :
2041 : /*
2042 : * consider_parallel_mergejoin
2043 : * Try to build partial paths for a joinrel by joining a partial path
2044 : * for the outer relation to a complete path for the inner relation.
2045 : *
2046 : * 'joinrel' is the join relation
2047 : * 'outerrel' is the outer join relation
2048 : * 'innerrel' is the inner join relation
2049 : * 'jointype' is the type of join to do
2050 : * 'extra' contains additional input values
2051 : * 'inner_cheapest_total' cheapest total path for innerrel
2052 : */
2053 : static void
2054 10824 : consider_parallel_mergejoin(PlannerInfo *root,
2055 : RelOptInfo *joinrel,
2056 : RelOptInfo *outerrel,
2057 : RelOptInfo *innerrel,
2058 : JoinType jointype,
2059 : JoinPathExtraData *extra,
2060 : Path *inner_cheapest_total)
2061 : {
2062 : ListCell *lc1;
2063 :
2064 : /* generate merge join path for each partial outer path */
2065 25464 : foreach(lc1, outerrel->partial_pathlist)
2066 : {
2067 14640 : Path *outerpath = (Path *) lfirst(lc1);
2068 : List *merge_pathkeys;
2069 :
2070 : /*
2071 : * Figure out what useful ordering any paths we create will have.
2072 : */
2073 14640 : merge_pathkeys = build_join_pathkeys(root, joinrel, jointype,
2074 : outerpath->pathkeys);
2075 :
2076 14640 : generate_mergejoin_paths(root, joinrel, innerrel, outerpath, jointype,
2077 : extra, false, inner_cheapest_total,
2078 : merge_pathkeys, true);
2079 : }
2080 10824 : }
2081 :
2082 : /*
2083 : * consider_parallel_nestloop
2084 : * Try to build partial paths for a joinrel by joining a partial path for the
2085 : * outer relation to a complete path for the inner relation.
2086 : *
2087 : * 'joinrel' is the join relation
2088 : * 'outerrel' is the outer join relation
2089 : * 'innerrel' is the inner join relation
2090 : * 'jointype' is the type of join to do
2091 : * 'extra' contains additional input values
2092 : */
2093 : static void
2094 11244 : consider_parallel_nestloop(PlannerInfo *root,
2095 : RelOptInfo *joinrel,
2096 : RelOptInfo *outerrel,
2097 : RelOptInfo *innerrel,
2098 : JoinType jointype,
2099 : JoinPathExtraData *extra)
2100 : {
2101 11244 : JoinType save_jointype = jointype;
2102 11244 : Path *inner_cheapest_total = innerrel->cheapest_total_path;
2103 11244 : Path *matpath = NULL;
2104 : ListCell *lc1;
2105 :
2106 11244 : if (jointype == JOIN_UNIQUE_INNER)
2107 642 : jointype = JOIN_INNER;
2108 :
2109 : /*
2110 : * Consider materializing the cheapest inner path, unless: 1) we're doing
2111 : * JOIN_UNIQUE_INNER, because in this case we have to unique-ify the
2112 : * cheapest inner path, 2) enable_material is off, 3) the cheapest inner
2113 : * path is not parallel-safe, 4) the cheapest inner path is parameterized
2114 : * by the outer rel, or 5) the cheapest inner path materializes its output
2115 : * anyway.
2116 : */
2117 11244 : if (save_jointype != JOIN_UNIQUE_INNER &&
2118 10394 : enable_material && inner_cheapest_total->parallel_safe &&
2119 10202 : !PATH_PARAM_BY_REL(inner_cheapest_total, outerrel) &&
2120 9812 : !ExecMaterializesOutput(inner_cheapest_total->pathtype))
2121 : {
2122 : matpath = (Path *)
2123 9716 : create_material_path(innerrel, inner_cheapest_total);
2124 : Assert(matpath->parallel_safe);
2125 : }
2126 :
2127 26442 : foreach(lc1, outerrel->partial_pathlist)
2128 : {
2129 15198 : Path *outerpath = (Path *) lfirst(lc1);
2130 : List *pathkeys;
2131 : ListCell *lc2;
2132 :
2133 : /* Figure out what useful ordering any paths we create will have. */
2134 15198 : pathkeys = build_join_pathkeys(root, joinrel, jointype,
2135 : outerpath->pathkeys);
2136 :
2137 : /*
2138 : * Try the cheapest parameterized paths; only those which will produce
2139 : * an unparameterized path when joined to this outerrel will survive
2140 : * try_partial_nestloop_path. The cheapest unparameterized path is
2141 : * also in this list.
2142 : */
2143 40072 : foreach(lc2, innerrel->cheapest_parameterized_paths)
2144 : {
2145 24874 : Path *innerpath = (Path *) lfirst(lc2);
2146 : Path *mpath;
2147 :
2148 : /* Can't join to an inner path that is not parallel-safe */
2149 24874 : if (!innerpath->parallel_safe)
2150 426 : continue;
2151 :
2152 : /*
2153 : * If we're doing JOIN_UNIQUE_INNER, we can only use the inner's
2154 : * cheapest_total_path, and we have to unique-ify it. (We might
2155 : * be able to relax this to allow other safe, unparameterized
2156 : * inner paths, but right now create_unique_path is not on board
2157 : * with that.)
2158 : */
2159 24448 : if (save_jointype == JOIN_UNIQUE_INNER)
2160 : {
2161 2130 : if (innerpath != innerrel->cheapest_total_path)
2162 1146 : continue;
2163 984 : innerpath = (Path *) create_unique_path(root, innerrel,
2164 : innerpath,
2165 : extra->sjinfo);
2166 : Assert(innerpath);
2167 : }
2168 :
2169 23302 : try_partial_nestloop_path(root, joinrel, outerpath, innerpath,
2170 : pathkeys, jointype, extra);
2171 :
2172 : /*
2173 : * Try generating a memoize path and see if that makes the nested
2174 : * loop any cheaper.
2175 : */
2176 23302 : mpath = get_memoize_path(root, innerrel, outerrel,
2177 : innerpath, outerpath, jointype,
2178 : extra);
2179 23302 : if (mpath != NULL)
2180 5798 : try_partial_nestloop_path(root, joinrel, outerpath, mpath,
2181 : pathkeys, jointype, extra);
2182 : }
2183 :
2184 : /* Also consider materialized form of the cheapest inner path */
2185 15198 : if (matpath != NULL)
2186 13160 : try_partial_nestloop_path(root, joinrel, outerpath, matpath,
2187 : pathkeys, jointype, extra);
2188 : }
2189 11244 : }
2190 :
2191 : /*
2192 : * hash_inner_and_outer
2193 : * Create hashjoin join paths by explicitly hashing both the outer and
2194 : * inner keys of each available hash clause.
2195 : *
2196 : * 'joinrel' is the join relation
2197 : * 'outerrel' is the outer join relation
2198 : * 'innerrel' is the inner join relation
2199 : * 'jointype' is the type of join to do
2200 : * 'extra' contains additional input values
2201 : */
2202 : static void
2203 679268 : hash_inner_and_outer(PlannerInfo *root,
2204 : RelOptInfo *joinrel,
2205 : RelOptInfo *outerrel,
2206 : RelOptInfo *innerrel,
2207 : JoinType jointype,
2208 : JoinPathExtraData *extra)
2209 : {
2210 679268 : JoinType save_jointype = jointype;
2211 679268 : bool isouterjoin = IS_OUTER_JOIN(jointype);
2212 : List *hashclauses;
2213 : ListCell *l;
2214 :
2215 : /*
2216 : * We need to build only one hashclauses list for any given pair of outer
2217 : * and inner relations; all of the hashable clauses will be used as keys.
2218 : *
2219 : * Scan the join's restrictinfo list to find hashjoinable clauses that are
2220 : * usable with this pair of sub-relations.
2221 : */
2222 679268 : hashclauses = NIL;
2223 1423824 : foreach(l, extra->restrictlist)
2224 : {
2225 744556 : RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(l);
2226 :
2227 : /*
2228 : * If processing an outer join, only use its own join clauses for
2229 : * hashing. For inner joins we need not be so picky.
2230 : */
2231 744556 : if (isouterjoin && RINFO_IS_PUSHED_DOWN(restrictinfo, joinrel->relids))
2232 11736 : continue;
2233 :
2234 732820 : if (!restrictinfo->can_join ||
2235 646316 : restrictinfo->hashjoinoperator == InvalidOid)
2236 108512 : continue; /* not hashjoinable */
2237 :
2238 : /*
2239 : * Check if clause has the form "outer op inner" or "inner op outer".
2240 : */
2241 624308 : if (!clause_sides_match_join(restrictinfo, outerrel->relids,
2242 : innerrel->relids))
2243 144 : continue; /* no good for these input relations */
2244 :
2245 : /*
2246 : * If clause has the form "inner op outer", check if its operator has
2247 : * valid commutator. This is necessary because hashclauses in this
2248 : * form will get commuted in createplan.c to put the outer var on the
2249 : * left (see get_switched_clauses). This probably shouldn't ever
2250 : * fail, since hashable operators ought to have commutators, but be
2251 : * paranoid.
2252 : *
2253 : * The clause being hashjoinable indicates that it's an OpExpr.
2254 : */
2255 936246 : if (!restrictinfo->outer_is_left &&
2256 312082 : !OidIsValid(get_commutator(castNode(OpExpr, restrictinfo->clause)->opno)))
2257 6 : continue;
2258 :
2259 624158 : hashclauses = lappend(hashclauses, restrictinfo);
2260 : }
2261 :
2262 : /* If we found any usable hashclauses, make paths */
2263 679268 : if (hashclauses)
2264 : {
2265 : /*
2266 : * We consider both the cheapest-total-cost and cheapest-startup-cost
2267 : * outer paths. There's no need to consider any but the
2268 : * cheapest-total-cost inner path, however.
2269 : */
2270 563002 : Path *cheapest_startup_outer = outerrel->cheapest_startup_path;
2271 563002 : Path *cheapest_total_outer = outerrel->cheapest_total_path;
2272 563002 : Path *cheapest_total_inner = innerrel->cheapest_total_path;
2273 :
2274 : /*
2275 : * If either cheapest-total path is parameterized by the other rel, we
2276 : * can't use a hashjoin. (There's no use looking for alternative
2277 : * input paths, since these should already be the least-parameterized
2278 : * available paths.)
2279 : */
2280 563002 : if (PATH_PARAM_BY_REL(cheapest_total_outer, innerrel) ||
2281 562266 : PATH_PARAM_BY_REL(cheapest_total_inner, outerrel))
2282 1472 : return;
2283 :
2284 : /* Unique-ify if need be; we ignore parameterized possibilities */
2285 561530 : if (jointype == JOIN_UNIQUE_OUTER)
2286 : {
2287 : cheapest_total_outer = (Path *)
2288 5638 : create_unique_path(root, outerrel,
2289 : cheapest_total_outer, extra->sjinfo);
2290 : Assert(cheapest_total_outer);
2291 5638 : jointype = JOIN_INNER;
2292 5638 : try_hashjoin_path(root,
2293 : joinrel,
2294 : cheapest_total_outer,
2295 : cheapest_total_inner,
2296 : hashclauses,
2297 : jointype,
2298 : extra);
2299 : /* no possibility of cheap startup here */
2300 : }
2301 555892 : else if (jointype == JOIN_UNIQUE_INNER)
2302 : {
2303 : cheapest_total_inner = (Path *)
2304 5638 : create_unique_path(root, innerrel,
2305 : cheapest_total_inner, extra->sjinfo);
2306 : Assert(cheapest_total_inner);
2307 5638 : jointype = JOIN_INNER;
2308 5638 : try_hashjoin_path(root,
2309 : joinrel,
2310 : cheapest_total_outer,
2311 : cheapest_total_inner,
2312 : hashclauses,
2313 : jointype,
2314 : extra);
2315 5638 : if (cheapest_startup_outer != NULL &&
2316 : cheapest_startup_outer != cheapest_total_outer)
2317 352 : try_hashjoin_path(root,
2318 : joinrel,
2319 : cheapest_startup_outer,
2320 : cheapest_total_inner,
2321 : hashclauses,
2322 : jointype,
2323 : extra);
2324 : }
2325 : else
2326 : {
2327 : /*
2328 : * For other jointypes, we consider the cheapest startup outer
2329 : * together with the cheapest total inner, and then consider
2330 : * pairings of cheapest-total paths including parameterized ones.
2331 : * There is no use in generating parameterized paths on the basis
2332 : * of possibly cheap startup cost, so this is sufficient.
2333 : */
2334 : ListCell *lc1;
2335 : ListCell *lc2;
2336 :
2337 550254 : if (cheapest_startup_outer != NULL)
2338 549654 : try_hashjoin_path(root,
2339 : joinrel,
2340 : cheapest_startup_outer,
2341 : cheapest_total_inner,
2342 : hashclauses,
2343 : jointype,
2344 : extra);
2345 :
2346 1408828 : foreach(lc1, outerrel->cheapest_parameterized_paths)
2347 : {
2348 858574 : Path *outerpath = (Path *) lfirst(lc1);
2349 :
2350 : /*
2351 : * We cannot use an outer path that is parameterized by the
2352 : * inner rel.
2353 : */
2354 858574 : if (PATH_PARAM_BY_REL(outerpath, innerrel))
2355 249698 : continue;
2356 :
2357 1577532 : foreach(lc2, innerrel->cheapest_parameterized_paths)
2358 : {
2359 968656 : Path *innerpath = (Path *) lfirst(lc2);
2360 :
2361 : /*
2362 : * We cannot use an inner path that is parameterized by
2363 : * the outer rel, either.
2364 : */
2365 968656 : if (PATH_PARAM_BY_REL(innerpath, outerrel))
2366 283838 : continue;
2367 :
2368 684818 : if (outerpath == cheapest_startup_outer &&
2369 : innerpath == cheapest_total_inner)
2370 462104 : continue; /* already tried it */
2371 :
2372 222714 : try_hashjoin_path(root,
2373 : joinrel,
2374 : outerpath,
2375 : innerpath,
2376 : hashclauses,
2377 : jointype,
2378 : extra);
2379 : }
2380 : }
2381 : }
2382 :
2383 : /*
2384 : * If the joinrel is parallel-safe, we may be able to consider a
2385 : * partial hash join. However, we can't handle JOIN_UNIQUE_OUTER,
2386 : * because the outer path will be partial, and therefore we won't be
2387 : * able to properly guarantee uniqueness. Also, the resulting path
2388 : * must not be parameterized.
2389 : */
2390 561530 : if (joinrel->consider_parallel &&
2391 498378 : save_jointype != JOIN_UNIQUE_OUTER &&
2392 498378 : outerrel->partial_pathlist != NIL &&
2393 17042 : bms_is_empty(joinrel->lateral_relids))
2394 : {
2395 : Path *cheapest_partial_outer;
2396 17042 : Path *cheapest_partial_inner = NULL;
2397 17042 : Path *cheapest_safe_inner = NULL;
2398 :
2399 17042 : cheapest_partial_outer =
2400 17042 : (Path *) linitial(outerrel->partial_pathlist);
2401 :
2402 : /*
2403 : * Can we use a partial inner plan too, so that we can build a
2404 : * shared hash table in parallel? We can't handle
2405 : * JOIN_UNIQUE_INNER because we can't guarantee uniqueness.
2406 : */
2407 17042 : if (innerrel->partial_pathlist != NIL &&
2408 12828 : save_jointype != JOIN_UNIQUE_INNER &&
2409 : enable_parallel_hash)
2410 : {
2411 12552 : cheapest_partial_inner =
2412 12552 : (Path *) linitial(innerrel->partial_pathlist);
2413 12552 : try_partial_hashjoin_path(root, joinrel,
2414 : cheapest_partial_outer,
2415 : cheapest_partial_inner,
2416 : hashclauses, jointype, extra,
2417 : true /* parallel_hash */ );
2418 : }
2419 :
2420 : /*
2421 : * Normally, given that the joinrel is parallel-safe, the cheapest
2422 : * total inner path will also be parallel-safe, but if not, we'll
2423 : * have to search for the cheapest safe, unparameterized inner
2424 : * path. If doing JOIN_UNIQUE_INNER, we can't use any alternative
2425 : * inner path. If full, right, right-semi or right-anti join, we
2426 : * can't use parallelism (building the hash table in each backend)
2427 : * because no one process has all the match bits.
2428 : */
2429 17042 : if (save_jointype == JOIN_FULL ||
2430 13226 : save_jointype == JOIN_RIGHT ||
2431 9658 : save_jointype == JOIN_RIGHT_SEMI ||
2432 : save_jointype == JOIN_RIGHT_ANTI)
2433 7714 : cheapest_safe_inner = NULL;
2434 9328 : else if (cheapest_total_inner->parallel_safe)
2435 9100 : cheapest_safe_inner = cheapest_total_inner;
2436 228 : else if (save_jointype != JOIN_UNIQUE_INNER)
2437 : cheapest_safe_inner =
2438 222 : get_cheapest_parallel_safe_total_inner(innerrel->pathlist);
2439 :
2440 17042 : if (cheapest_safe_inner != NULL)
2441 9316 : try_partial_hashjoin_path(root, joinrel,
2442 : cheapest_partial_outer,
2443 : cheapest_safe_inner,
2444 : hashclauses, jointype, extra,
2445 : false /* parallel_hash */ );
2446 : }
2447 : }
2448 : }
2449 :
2450 : /*
2451 : * select_mergejoin_clauses
2452 : * Select mergejoin clauses that are usable for a particular join.
2453 : * Returns a list of RestrictInfo nodes for those clauses.
2454 : *
2455 : * *mergejoin_allowed is normally set to true, but it is set to false if
2456 : * this is a right-semi join, or this is a right/right-anti/full join and
2457 : * there are nonmergejoinable join clauses. The executor's mergejoin
2458 : * machinery cannot handle such cases, so we have to avoid generating a
2459 : * mergejoin plan. (Note that this flag does NOT consider whether there are
2460 : * actually any mergejoinable clauses. This is correct because in some
2461 : * cases we need to build a clauseless mergejoin. Simply returning NIL is
2462 : * therefore not enough to distinguish safe from unsafe cases.)
2463 : *
2464 : * We also mark each selected RestrictInfo to show which side is currently
2465 : * being considered as outer. These are transient markings that are only
2466 : * good for the duration of the current add_paths_to_joinrel() call!
2467 : *
2468 : * We examine each restrictinfo clause known for the join to see
2469 : * if it is mergejoinable and involves vars from the two sub-relations
2470 : * currently of interest.
2471 : */
2472 : static List *
2473 680884 : select_mergejoin_clauses(PlannerInfo *root,
2474 : RelOptInfo *joinrel,
2475 : RelOptInfo *outerrel,
2476 : RelOptInfo *innerrel,
2477 : List *restrictlist,
2478 : JoinType jointype,
2479 : bool *mergejoin_allowed)
2480 : {
2481 680884 : List *result_list = NIL;
2482 680884 : bool isouterjoin = IS_OUTER_JOIN(jointype);
2483 680884 : bool have_nonmergeable_joinclause = false;
2484 : ListCell *l;
2485 :
2486 : /*
2487 : * For now we do not support RIGHT_SEMI join in mergejoin: the benefit of
2488 : * swapping inputs tends to be small here.
2489 : */
2490 680884 : if (jointype == JOIN_RIGHT_SEMI)
2491 : {
2492 7212 : *mergejoin_allowed = false;
2493 7212 : return NIL;
2494 : }
2495 :
2496 1413876 : foreach(l, restrictlist)
2497 : {
2498 740204 : RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(l);
2499 :
2500 : /*
2501 : * If processing an outer join, only use its own join clauses in the
2502 : * merge. For inner joins we can use pushed-down clauses too. (Note:
2503 : * we don't set have_nonmergeable_joinclause here because pushed-down
2504 : * clauses will become otherquals not joinquals.)
2505 : */
2506 740204 : if (isouterjoin && RINFO_IS_PUSHED_DOWN(restrictinfo, joinrel->relids))
2507 11760 : continue;
2508 :
2509 : /* Check that clause is a mergeable operator clause */
2510 728444 : if (!restrictinfo->can_join ||
2511 641958 : restrictinfo->mergeopfamilies == NIL)
2512 : {
2513 : /*
2514 : * The executor can handle extra joinquals that are constants, but
2515 : * not anything else, when doing right/right-anti/full merge join.
2516 : * (The reason to support constants is so we can do FULL JOIN ON
2517 : * FALSE.)
2518 : */
2519 107208 : if (!restrictinfo->clause || !IsA(restrictinfo->clause, Const))
2520 96816 : have_nonmergeable_joinclause = true;
2521 107208 : continue; /* not mergejoinable */
2522 : }
2523 :
2524 : /*
2525 : * Check if clause has the form "outer op inner" or "inner op outer".
2526 : */
2527 621236 : if (!clause_sides_match_join(restrictinfo, outerrel->relids,
2528 : innerrel->relids))
2529 : {
2530 768 : have_nonmergeable_joinclause = true;
2531 768 : continue; /* no good for these input relations */
2532 : }
2533 :
2534 : /*
2535 : * If clause has the form "inner op outer", check if its operator has
2536 : * valid commutator. This is necessary because mergejoin clauses in
2537 : * this form will get commuted in createplan.c to put the outer var on
2538 : * the left (see get_switched_clauses). This probably shouldn't ever
2539 : * fail, since mergejoinable operators ought to have commutators, but
2540 : * be paranoid.
2541 : *
2542 : * The clause being mergejoinable indicates that it's an OpExpr.
2543 : */
2544 927900 : if (!restrictinfo->outer_is_left &&
2545 307432 : !OidIsValid(get_commutator(castNode(OpExpr, restrictinfo->clause)->opno)))
2546 : {
2547 36 : have_nonmergeable_joinclause = true;
2548 36 : continue;
2549 : }
2550 :
2551 : /*
2552 : * Insist that each side have a non-redundant eclass. This
2553 : * restriction is needed because various bits of the planner expect
2554 : * that each clause in a merge be associable with some pathkey in a
2555 : * canonical pathkey list, but redundant eclasses can't appear in
2556 : * canonical sort orderings. (XXX it might be worth relaxing this,
2557 : * but not enough time to address it for 8.3.)
2558 : */
2559 620432 : update_mergeclause_eclasses(root, restrictinfo);
2560 :
2561 620432 : if (EC_MUST_BE_REDUNDANT(restrictinfo->left_ec) ||
2562 620384 : EC_MUST_BE_REDUNDANT(restrictinfo->right_ec))
2563 : {
2564 128 : have_nonmergeable_joinclause = true;
2565 128 : continue; /* can't handle redundant eclasses */
2566 : }
2567 :
2568 620304 : result_list = lappend(result_list, restrictinfo);
2569 : }
2570 :
2571 : /*
2572 : * Report whether mergejoin is allowed (see comment at top of function).
2573 : */
2574 673672 : switch (jointype)
2575 : {
2576 108388 : case JOIN_RIGHT:
2577 : case JOIN_RIGHT_ANTI:
2578 : case JOIN_FULL:
2579 108388 : *mergejoin_allowed = !have_nonmergeable_joinclause;
2580 108388 : break;
2581 565284 : default:
2582 565284 : *mergejoin_allowed = true;
2583 565284 : break;
2584 : }
2585 :
2586 673672 : return result_list;
2587 : }
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