Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * analyzejoins.c
4 : * Routines for simplifying joins after initial query analysis
5 : *
6 : * While we do a great deal of join simplification in prep/prepjointree.c,
7 : * certain optimizations cannot be performed at that stage for lack of
8 : * detailed information about the query. The routines here are invoked
9 : * after initsplan.c has done its work, and can do additional join removal
10 : * and simplification steps based on the information extracted. The penalty
11 : * is that we have to work harder to clean up after ourselves when we modify
12 : * the query, since the derived data structures have to be updated too.
13 : *
14 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
15 : * Portions Copyright (c) 1994, Regents of the University of California
16 : *
17 : *
18 : * IDENTIFICATION
19 : * src/backend/optimizer/plan/analyzejoins.c
20 : *
21 : *-------------------------------------------------------------------------
22 : */
23 : #include "postgres.h"
24 :
25 : #include "catalog/pg_class.h"
26 : #include "nodes/nodeFuncs.h"
27 : #include "optimizer/joininfo.h"
28 : #include "optimizer/optimizer.h"
29 : #include "optimizer/pathnode.h"
30 : #include "optimizer/paths.h"
31 : #include "optimizer/placeholder.h"
32 : #include "optimizer/planmain.h"
33 : #include "optimizer/restrictinfo.h"
34 : #include "rewrite/rewriteManip.h"
35 : #include "utils/lsyscache.h"
36 :
37 : /*
38 : * Utility structure. A sorting procedure is needed to simplify the search
39 : * of SJE-candidate baserels referencing the same database relation. Having
40 : * collected all baserels from the query jointree, the planner sorts them
41 : * according to the reloid value, groups them with the next pass and attempts
42 : * to remove self-joins.
43 : *
44 : * Preliminary sorting prevents quadratic behavior that can be harmful in the
45 : * case of numerous joins.
46 : */
47 : typedef struct
48 : {
49 : int relid;
50 : Oid reloid;
51 : } SelfJoinCandidate;
52 :
53 : bool enable_self_join_elimination;
54 :
55 : /* local functions */
56 : static bool join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo);
57 : static void remove_leftjoinrel_from_query(PlannerInfo *root, int relid,
58 : SpecialJoinInfo *sjinfo);
59 : static void remove_rel_from_restrictinfo(RestrictInfo *rinfo,
60 : int relid, int ojrelid);
61 : static void remove_rel_from_eclass(EquivalenceClass *ec,
62 : SpecialJoinInfo *sjinfo,
63 : int relid, int subst);
64 : static List *remove_rel_from_joinlist(List *joinlist, int relid, int *nremoved);
65 : static bool rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel);
66 : static bool rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel,
67 : List *clause_list, List **extra_clauses);
68 : static Oid distinct_col_search(int colno, List *colnos, List *opids);
69 : static bool is_innerrel_unique_for(PlannerInfo *root,
70 : Relids joinrelids,
71 : Relids outerrelids,
72 : RelOptInfo *innerrel,
73 : JoinType jointype,
74 : List *restrictlist,
75 : List **extra_clauses);
76 : static int self_join_candidates_cmp(const void *a, const void *b);
77 :
78 :
79 : /*
80 : * remove_useless_joins
81 : * Check for relations that don't actually need to be joined at all,
82 : * and remove them from the query.
83 : *
84 : * We are passed the current joinlist and return the updated list. Other
85 : * data structures that have to be updated are accessible via "root".
86 : */
87 : List *
88 324872 : remove_useless_joins(PlannerInfo *root, List *joinlist)
89 : {
90 : ListCell *lc;
91 :
92 : /*
93 : * We are only interested in relations that are left-joined to, so we can
94 : * scan the join_info_list to find them easily.
95 : */
96 324872 : restart:
97 364070 : foreach(lc, root->join_info_list)
98 : {
99 49438 : SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
100 : int innerrelid;
101 : int nremoved;
102 :
103 : /* Skip if not removable */
104 49438 : if (!join_is_removable(root, sjinfo))
105 39198 : continue;
106 :
107 : /*
108 : * Currently, join_is_removable can only succeed when the sjinfo's
109 : * righthand is a single baserel. Remove that rel from the query and
110 : * joinlist.
111 : */
112 10240 : innerrelid = bms_singleton_member(sjinfo->min_righthand);
113 :
114 10240 : remove_leftjoinrel_from_query(root, innerrelid, sjinfo);
115 :
116 : /* We verify that exactly one reference gets removed from joinlist */
117 10240 : nremoved = 0;
118 10240 : joinlist = remove_rel_from_joinlist(joinlist, innerrelid, &nremoved);
119 10240 : if (nremoved != 1)
120 0 : elog(ERROR, "failed to find relation %d in joinlist", innerrelid);
121 :
122 : /*
123 : * We can delete this SpecialJoinInfo from the list too, since it's no
124 : * longer of interest. (Since we'll restart the foreach loop
125 : * immediately, we don't bother with foreach_delete_current.)
126 : */
127 10240 : root->join_info_list = list_delete_cell(root->join_info_list, lc);
128 :
129 : /*
130 : * Restart the scan. This is necessary to ensure we find all
131 : * removable joins independently of ordering of the join_info_list
132 : * (note that removal of attr_needed bits may make a join appear
133 : * removable that did not before).
134 : */
135 10240 : goto restart;
136 : }
137 :
138 314632 : return joinlist;
139 : }
140 :
141 : /*
142 : * join_is_removable
143 : * Check whether we need not perform this special join at all, because
144 : * it will just duplicate its left input.
145 : *
146 : * This is true for a left join for which the join condition cannot match
147 : * more than one inner-side row. (There are other possibly interesting
148 : * cases, but we don't have the infrastructure to prove them.) We also
149 : * have to check that the inner side doesn't generate any variables needed
150 : * above the join.
151 : */
152 : static bool
153 49438 : join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo)
154 : {
155 : int innerrelid;
156 : RelOptInfo *innerrel;
157 : Relids inputrelids;
158 : Relids joinrelids;
159 49438 : List *clause_list = NIL;
160 : ListCell *l;
161 : int attroff;
162 :
163 : /*
164 : * Must be a left join to a single baserel, else we aren't going to be
165 : * able to do anything with it.
166 : */
167 49438 : if (sjinfo->jointype != JOIN_LEFT)
168 7068 : return false;
169 :
170 42370 : if (!bms_get_singleton_member(sjinfo->min_righthand, &innerrelid))
171 1296 : return false;
172 :
173 : /*
174 : * Never try to eliminate a left join to the query result rel. Although
175 : * the case is syntactically impossible in standard SQL, MERGE will build
176 : * a join tree that looks exactly like that.
177 : */
178 41074 : if (innerrelid == root->parse->resultRelation)
179 746 : return false;
180 :
181 40328 : innerrel = find_base_rel(root, innerrelid);
182 :
183 : /*
184 : * Before we go to the effort of checking whether any innerrel variables
185 : * are needed above the join, make a quick check to eliminate cases in
186 : * which we will surely be unable to prove uniqueness of the innerrel.
187 : */
188 40328 : if (!rel_supports_distinctness(root, innerrel))
189 3010 : return false;
190 :
191 : /* Compute the relid set for the join we are considering */
192 37318 : inputrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
193 : Assert(sjinfo->ojrelid != 0);
194 37318 : joinrelids = bms_copy(inputrelids);
195 37318 : joinrelids = bms_add_member(joinrelids, sjinfo->ojrelid);
196 :
197 : /*
198 : * We can't remove the join if any inner-rel attributes are used above the
199 : * join. Here, "above" the join includes pushed-down conditions, so we
200 : * should reject if attr_needed includes the OJ's own relid; therefore,
201 : * compare to inputrelids not joinrelids.
202 : *
203 : * As a micro-optimization, it seems better to start with max_attr and
204 : * count down rather than starting with min_attr and counting up, on the
205 : * theory that the system attributes are somewhat less likely to be wanted
206 : * and should be tested last.
207 : */
208 337324 : for (attroff = innerrel->max_attr - innerrel->min_attr;
209 : attroff >= 0;
210 300006 : attroff--)
211 : {
212 326922 : if (!bms_is_subset(innerrel->attr_needed[attroff], inputrelids))
213 26916 : return false;
214 : }
215 :
216 : /*
217 : * Similarly check that the inner rel isn't needed by any PlaceHolderVars
218 : * that will be used above the join. The PHV case is a little bit more
219 : * complicated, because PHVs may have been assigned a ph_eval_at location
220 : * that includes the innerrel, yet their contained expression might not
221 : * actually reference the innerrel (it could be just a constant, for
222 : * instance). If such a PHV is due to be evaluated above the join then it
223 : * needn't prevent join removal.
224 : */
225 10594 : foreach(l, root->placeholder_list)
226 : {
227 228 : PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
228 :
229 228 : if (bms_overlap(phinfo->ph_lateral, innerrel->relids))
230 36 : return false; /* it references innerrel laterally */
231 228 : if (!bms_overlap(phinfo->ph_eval_at, innerrel->relids))
232 54 : continue; /* it definitely doesn't reference innerrel */
233 174 : if (bms_is_subset(phinfo->ph_needed, inputrelids))
234 6 : continue; /* PHV is not used above the join */
235 168 : if (!bms_is_member(sjinfo->ojrelid, phinfo->ph_eval_at))
236 30 : return false; /* it has to be evaluated below the join */
237 :
238 : /*
239 : * We need to be sure there will still be a place to evaluate the PHV
240 : * if we remove the join, ie that ph_eval_at wouldn't become empty.
241 : */
242 138 : if (!bms_overlap(sjinfo->min_lefthand, phinfo->ph_eval_at))
243 6 : return false; /* there isn't any other place to eval PHV */
244 : /* Check contained expression last, since this is a bit expensive */
245 132 : if (bms_overlap(pull_varnos(root, (Node *) phinfo->ph_var->phexpr),
246 132 : innerrel->relids))
247 0 : return false; /* contained expression references innerrel */
248 : }
249 :
250 : /*
251 : * Search for mergejoinable clauses that constrain the inner rel against
252 : * either the outer rel or a pseudoconstant. If an operator is
253 : * mergejoinable then it behaves like equality for some btree opclass, so
254 : * it's what we want. The mergejoinability test also eliminates clauses
255 : * containing volatile functions, which we couldn't depend on.
256 : */
257 21066 : foreach(l, innerrel->joininfo)
258 : {
259 10700 : RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(l);
260 :
261 : /*
262 : * If the current join commutes with some other outer join(s) via
263 : * outer join identity 3, there will be multiple clones of its join
264 : * clauses in the joininfo list. We want to consider only the
265 : * has_clone form of such clauses. Processing more than one form
266 : * would be wasteful, and also some of the others would confuse the
267 : * RINFO_IS_PUSHED_DOWN test below.
268 : */
269 10700 : if (restrictinfo->is_clone)
270 124 : continue; /* ignore it */
271 :
272 : /*
273 : * If it's not a join clause for this outer join, we can't use it.
274 : * Note that if the clause is pushed-down, then it is logically from
275 : * above the outer join, even if it references no other rels (it might
276 : * be from WHERE, for example).
277 : */
278 10576 : if (RINFO_IS_PUSHED_DOWN(restrictinfo, joinrelids))
279 120 : continue; /* ignore; not useful here */
280 :
281 : /* Ignore if it's not a mergejoinable clause */
282 10456 : if (!restrictinfo->can_join ||
283 10386 : restrictinfo->mergeopfamilies == NIL)
284 70 : continue; /* not mergejoinable */
285 :
286 : /*
287 : * Check if the clause has the form "outer op inner" or "inner op
288 : * outer", and if so mark which side is inner.
289 : */
290 10386 : if (!clause_sides_match_join(restrictinfo, sjinfo->min_lefthand,
291 : innerrel->relids))
292 6 : continue; /* no good for these input relations */
293 :
294 : /* OK, add to list */
295 10380 : clause_list = lappend(clause_list, restrictinfo);
296 : }
297 :
298 : /*
299 : * Now that we have the relevant equality join clauses, try to prove the
300 : * innerrel distinct.
301 : */
302 10366 : if (rel_is_distinct_for(root, innerrel, clause_list, NULL))
303 10240 : return true;
304 :
305 : /*
306 : * Some day it would be nice to check for other methods of establishing
307 : * distinctness.
308 : */
309 126 : return false;
310 : }
311 :
312 :
313 : /*
314 : * Remove the target rel->relid and references to the target join from the
315 : * planner's data structures, having determined that there is no need
316 : * to include them in the query. Optionally replace them with subst if subst
317 : * is non-negative.
318 : *
319 : * This function updates only parts needed for both left-join removal and
320 : * self-join removal.
321 : */
322 : static void
323 10828 : remove_rel_from_query(PlannerInfo *root, RelOptInfo *rel,
324 : int subst, SpecialJoinInfo *sjinfo,
325 : Relids joinrelids)
326 : {
327 10828 : int relid = rel->relid;
328 : Index rti;
329 : ListCell *l;
330 :
331 : /*
332 : * Update all_baserels and related relid sets.
333 : */
334 10828 : root->all_baserels = adjust_relid_set(root->all_baserels, relid, subst);
335 10828 : root->all_query_rels = adjust_relid_set(root->all_query_rels, relid, subst);
336 :
337 10828 : if (sjinfo != NULL)
338 : {
339 20480 : root->outer_join_rels = bms_del_member(root->outer_join_rels,
340 10240 : sjinfo->ojrelid);
341 10240 : root->all_query_rels = bms_del_member(root->all_query_rels,
342 10240 : sjinfo->ojrelid);
343 : }
344 :
345 : /*
346 : * Likewise remove references from SpecialJoinInfo data structures.
347 : *
348 : * This is relevant in case the outer join we're deleting is nested inside
349 : * other outer joins: the upper joins' relid sets have to be adjusted. The
350 : * RHS of the target outer join will be made empty here, but that's OK
351 : * since caller will delete that SpecialJoinInfo entirely.
352 : */
353 24886 : foreach(l, root->join_info_list)
354 : {
355 14058 : SpecialJoinInfo *sjinf = (SpecialJoinInfo *) lfirst(l);
356 :
357 : /*
358 : * initsplan.c is fairly cavalier about allowing SpecialJoinInfos'
359 : * lefthand/righthand relid sets to be shared with other data
360 : * structures. Ensure that we don't modify the original relid sets.
361 : * (The commute_xxx sets are always per-SpecialJoinInfo though.)
362 : */
363 14058 : sjinf->min_lefthand = bms_copy(sjinf->min_lefthand);
364 14058 : sjinf->min_righthand = bms_copy(sjinf->min_righthand);
365 14058 : sjinf->syn_lefthand = bms_copy(sjinf->syn_lefthand);
366 14058 : sjinf->syn_righthand = bms_copy(sjinf->syn_righthand);
367 : /* Now remove relid from the sets: */
368 14058 : sjinf->min_lefthand = adjust_relid_set(sjinf->min_lefthand, relid, subst);
369 14058 : sjinf->min_righthand = adjust_relid_set(sjinf->min_righthand, relid, subst);
370 14058 : sjinf->syn_lefthand = adjust_relid_set(sjinf->syn_lefthand, relid, subst);
371 14058 : sjinf->syn_righthand = adjust_relid_set(sjinf->syn_righthand, relid, subst);
372 :
373 14058 : if (sjinfo != NULL)
374 : {
375 : Assert(subst <= 0);
376 :
377 : /* Remove sjinfo->ojrelid bits from the sets: */
378 27924 : sjinf->min_lefthand = bms_del_member(sjinf->min_lefthand,
379 13962 : sjinfo->ojrelid);
380 27924 : sjinf->min_righthand = bms_del_member(sjinf->min_righthand,
381 13962 : sjinfo->ojrelid);
382 27924 : sjinf->syn_lefthand = bms_del_member(sjinf->syn_lefthand,
383 13962 : sjinfo->ojrelid);
384 27924 : sjinf->syn_righthand = bms_del_member(sjinf->syn_righthand,
385 13962 : sjinfo->ojrelid);
386 : /* relid cannot appear in these fields, but ojrelid can: */
387 27924 : sjinf->commute_above_l = bms_del_member(sjinf->commute_above_l,
388 13962 : sjinfo->ojrelid);
389 27924 : sjinf->commute_above_r = bms_del_member(sjinf->commute_above_r,
390 13962 : sjinfo->ojrelid);
391 27924 : sjinf->commute_below_l = bms_del_member(sjinf->commute_below_l,
392 13962 : sjinfo->ojrelid);
393 13962 : sjinf->commute_below_r = bms_del_member(sjinf->commute_below_r,
394 13962 : sjinfo->ojrelid);
395 : }
396 : else
397 : {
398 : Assert(subst > 0);
399 :
400 96 : ChangeVarNodes((Node *) sjinf->semi_rhs_exprs, relid, subst, 0);
401 : }
402 : }
403 :
404 : /*
405 : * Likewise remove references from PlaceHolderVar data structures,
406 : * removing any no-longer-needed placeholders entirely.
407 : *
408 : * Removal is a bit trickier than it might seem: we can remove PHVs that
409 : * are used at the target rel and/or in the join qual, but not those that
410 : * are used at join partner rels or above the join. It's not that easy to
411 : * distinguish PHVs used at partner rels from those used in the join qual,
412 : * since they will both have ph_needed sets that are subsets of
413 : * joinrelids. However, a PHV used at a partner rel could not have the
414 : * target rel in ph_eval_at, so we check that while deciding whether to
415 : * remove or just update the PHV. There is no corresponding test in
416 : * join_is_removable because it doesn't need to distinguish those cases.
417 : */
418 11038 : foreach(l, root->placeholder_list)
419 : {
420 210 : PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
421 :
422 : Assert(sjinfo == NULL || !bms_is_member(relid, phinfo->ph_lateral));
423 246 : if (bms_is_subset(phinfo->ph_needed, joinrelids) &&
424 54 : bms_is_member(relid, phinfo->ph_eval_at) &&
425 12 : (sjinfo == NULL || !bms_is_member(sjinfo->ojrelid, phinfo->ph_eval_at)))
426 : {
427 12 : root->placeholder_list = foreach_delete_current(root->placeholder_list,
428 : l);
429 12 : root->placeholder_array[phinfo->phid] = NULL;
430 : }
431 : else
432 : {
433 198 : PlaceHolderVar *phv = phinfo->ph_var;
434 :
435 198 : phinfo->ph_eval_at = adjust_relid_set(phinfo->ph_eval_at, relid, subst);
436 198 : if (sjinfo != NULL)
437 168 : phinfo->ph_eval_at = adjust_relid_set(phinfo->ph_eval_at,
438 168 : sjinfo->ojrelid, subst);
439 : Assert(!bms_is_empty(phinfo->ph_eval_at)); /* checked previously */
440 : /* Reduce ph_needed to contain only "relation 0"; see below */
441 198 : if (bms_is_member(0, phinfo->ph_needed))
442 102 : phinfo->ph_needed = bms_make_singleton(0);
443 : else
444 96 : phinfo->ph_needed = NULL;
445 :
446 198 : phinfo->ph_lateral = adjust_relid_set(phinfo->ph_lateral, relid, subst);
447 :
448 : /*
449 : * ph_lateral might contain rels mentioned in ph_eval_at after the
450 : * replacement, remove them.
451 : */
452 198 : phinfo->ph_lateral = bms_difference(phinfo->ph_lateral, phinfo->ph_eval_at);
453 : /* ph_lateral might or might not be empty */
454 :
455 198 : phv->phrels = adjust_relid_set(phv->phrels, relid, subst);
456 198 : if (sjinfo != NULL)
457 168 : phv->phrels = adjust_relid_set(phv->phrels,
458 168 : sjinfo->ojrelid, subst);
459 : Assert(!bms_is_empty(phv->phrels));
460 :
461 198 : ChangeVarNodes((Node *) phv->phexpr, relid, subst, 0);
462 :
463 : Assert(phv->phnullingrels == NULL); /* no need to adjust */
464 : }
465 : }
466 :
467 : /*
468 : * Likewise remove references from EquivalenceClasses.
469 : */
470 57704 : foreach(l, root->eq_classes)
471 : {
472 46876 : EquivalenceClass *ec = (EquivalenceClass *) lfirst(l);
473 :
474 46876 : if (bms_is_member(relid, ec->ec_relids) ||
475 31152 : (sjinfo == NULL || bms_is_member(sjinfo->ojrelid, ec->ec_relids)))
476 15724 : remove_rel_from_eclass(ec, sjinfo, relid, subst);
477 : }
478 :
479 : /*
480 : * Finally, we must recompute per-Var attr_needed and per-PlaceHolderVar
481 : * ph_needed relid sets. These have to be known accurately, else we may
482 : * fail to remove other now-removable outer joins. And our removal of the
483 : * join clause(s) for this outer join may mean that Vars that were
484 : * formerly needed no longer are. So we have to do this honestly by
485 : * repeating the construction of those relid sets. We can cheat to one
486 : * small extent: we can avoid re-examining the targetlist and HAVING qual
487 : * by preserving "relation 0" bits from the existing relid sets. This is
488 : * safe because we'd never remove such references.
489 : *
490 : * So, start by removing all other bits from attr_needed sets and
491 : * lateral_vars lists. (We already did this above for ph_needed.)
492 : */
493 67756 : for (rti = 1; rti < root->simple_rel_array_size; rti++)
494 : {
495 56928 : RelOptInfo *otherrel = root->simple_rel_array[rti];
496 : int attroff;
497 :
498 : /* there may be empty slots corresponding to non-baserel RTEs */
499 56928 : if (otherrel == NULL)
500 27746 : continue;
501 :
502 : Assert(otherrel->relid == rti); /* sanity check on array */
503 :
504 649966 : for (attroff = otherrel->max_attr - otherrel->min_attr;
505 : attroff >= 0;
506 620784 : attroff--)
507 : {
508 620784 : if (bms_is_member(0, otherrel->attr_needed[attroff]))
509 45650 : otherrel->attr_needed[attroff] = bms_make_singleton(0);
510 : else
511 575134 : otherrel->attr_needed[attroff] = NULL;
512 : }
513 :
514 29182 : if (subst > 0)
515 1460 : ChangeVarNodes((Node *) otherrel->lateral_vars, relid, subst, 0);
516 : }
517 10828 : }
518 :
519 : /*
520 : * Remove the target relid and references to the target join from the
521 : * planner's data structures, having determined that there is no need
522 : * to include them in the query.
523 : *
524 : * We are not terribly thorough here. We only bother to update parts of
525 : * the planner's data structures that will actually be consulted later.
526 : */
527 : static void
528 10240 : remove_leftjoinrel_from_query(PlannerInfo *root, int relid,
529 : SpecialJoinInfo *sjinfo)
530 : {
531 10240 : RelOptInfo *rel = find_base_rel(root, relid);
532 10240 : int ojrelid = sjinfo->ojrelid;
533 : Relids joinrelids;
534 : Relids join_plus_commute;
535 : List *joininfos;
536 : ListCell *l;
537 :
538 : /* Compute the relid set for the join we are considering */
539 10240 : joinrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
540 : Assert(ojrelid != 0);
541 10240 : joinrelids = bms_add_member(joinrelids, ojrelid);
542 :
543 10240 : remove_rel_from_query(root, rel, -1, sjinfo, joinrelids);
544 :
545 : /*
546 : * Remove any joinquals referencing the rel from the joininfo lists.
547 : *
548 : * In some cases, a joinqual has to be put back after deleting its
549 : * reference to the target rel. This can occur for pseudoconstant and
550 : * outerjoin-delayed quals, which can get marked as requiring the rel in
551 : * order to force them to be evaluated at or above the join. We can't
552 : * just discard them, though. Only quals that logically belonged to the
553 : * outer join being discarded should be removed from the query.
554 : *
555 : * We might encounter a qual that is a clone of a deletable qual with some
556 : * outer-join relids added (see deconstruct_distribute_oj_quals). To
557 : * ensure we get rid of such clones as well, add the relids of all OJs
558 : * commutable with this one to the set we test against for
559 : * pushed-down-ness.
560 : */
561 10240 : join_plus_commute = bms_union(joinrelids,
562 10240 : sjinfo->commute_above_r);
563 10240 : join_plus_commute = bms_add_members(join_plus_commute,
564 10240 : sjinfo->commute_below_l);
565 :
566 : /*
567 : * We must make a copy of the rel's old joininfo list before starting the
568 : * loop, because otherwise remove_join_clause_from_rels would destroy the
569 : * list while we're scanning it.
570 : */
571 10240 : joininfos = list_copy(rel->joininfo);
572 20838 : foreach(l, joininfos)
573 : {
574 10598 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
575 :
576 10598 : remove_join_clause_from_rels(root, rinfo, rinfo->required_relids);
577 :
578 10598 : if (RINFO_IS_PUSHED_DOWN(rinfo, join_plus_commute))
579 : {
580 : /*
581 : * There might be references to relid or ojrelid in the
582 : * RestrictInfo's relid sets, as a consequence of PHVs having had
583 : * ph_eval_at sets that include those. We already checked above
584 : * that any such PHV is safe (and updated its ph_eval_at), so we
585 : * can just drop those references.
586 : */
587 120 : remove_rel_from_restrictinfo(rinfo, relid, ojrelid);
588 :
589 : /*
590 : * Cross-check that the clause itself does not reference the
591 : * target rel or join.
592 : */
593 : #ifdef USE_ASSERT_CHECKING
594 : {
595 : Relids clause_varnos = pull_varnos(root,
596 : (Node *) rinfo->clause);
597 :
598 : Assert(!bms_is_member(relid, clause_varnos));
599 : Assert(!bms_is_member(ojrelid, clause_varnos));
600 : }
601 : #endif
602 : /* Now throw it back into the joininfo lists */
603 120 : distribute_restrictinfo_to_rels(root, rinfo);
604 : }
605 : }
606 :
607 : /*
608 : * There may be references to the rel in root->fkey_list, but if so,
609 : * match_foreign_keys_to_quals() will get rid of them.
610 : */
611 :
612 : /*
613 : * Now remove the rel from the baserel array to prevent it from being
614 : * referenced again. (We can't do this earlier because
615 : * remove_join_clause_from_rels will touch it.)
616 : */
617 10240 : root->simple_rel_array[relid] = NULL;
618 :
619 : /* And nuke the RelOptInfo, just in case there's another access path */
620 10240 : pfree(rel);
621 :
622 : /*
623 : * Now repeat construction of attr_needed bits coming from all other
624 : * sources.
625 : */
626 10240 : rebuild_placeholder_attr_needed(root);
627 10240 : rebuild_joinclause_attr_needed(root);
628 10240 : rebuild_eclass_attr_needed(root);
629 10240 : rebuild_lateral_attr_needed(root);
630 10240 : }
631 :
632 : /*
633 : * Remove any references to relid or ojrelid from the RestrictInfo.
634 : *
635 : * We only bother to clean out bits in clause_relids and required_relids,
636 : * not nullingrel bits in contained Vars and PHVs. (This might have to be
637 : * improved sometime.) However, if the RestrictInfo contains an OR clause
638 : * we have to also clean up the sub-clauses.
639 : */
640 : static void
641 4480 : remove_rel_from_restrictinfo(RestrictInfo *rinfo, int relid, int ojrelid)
642 : {
643 : /*
644 : * initsplan.c is fairly cavalier about allowing RestrictInfos to share
645 : * relid sets with other RestrictInfos, and SpecialJoinInfos too. Make
646 : * sure this RestrictInfo has its own relid sets before we modify them.
647 : * (In present usage, clause_relids is probably not shared, but
648 : * required_relids could be; let's not assume anything.)
649 : */
650 4480 : rinfo->clause_relids = bms_copy(rinfo->clause_relids);
651 4480 : rinfo->clause_relids = bms_del_member(rinfo->clause_relids, relid);
652 4480 : rinfo->clause_relids = bms_del_member(rinfo->clause_relids, ojrelid);
653 : /* Likewise for required_relids */
654 4480 : rinfo->required_relids = bms_copy(rinfo->required_relids);
655 4480 : rinfo->required_relids = bms_del_member(rinfo->required_relids, relid);
656 4480 : rinfo->required_relids = bms_del_member(rinfo->required_relids, ojrelid);
657 :
658 : /* If it's an OR, recurse to clean up sub-clauses */
659 4480 : if (restriction_is_or_clause(rinfo))
660 : {
661 : ListCell *lc;
662 :
663 : Assert(is_orclause(rinfo->orclause));
664 18 : foreach(lc, ((BoolExpr *) rinfo->orclause)->args)
665 : {
666 12 : Node *orarg = (Node *) lfirst(lc);
667 :
668 : /* OR arguments should be ANDs or sub-RestrictInfos */
669 12 : if (is_andclause(orarg))
670 : {
671 0 : List *andargs = ((BoolExpr *) orarg)->args;
672 : ListCell *lc2;
673 :
674 0 : foreach(lc2, andargs)
675 : {
676 0 : RestrictInfo *rinfo2 = lfirst_node(RestrictInfo, lc2);
677 :
678 0 : remove_rel_from_restrictinfo(rinfo2, relid, ojrelid);
679 : }
680 : }
681 : else
682 : {
683 12 : RestrictInfo *rinfo2 = castNode(RestrictInfo, orarg);
684 :
685 12 : remove_rel_from_restrictinfo(rinfo2, relid, ojrelid);
686 : }
687 : }
688 : }
689 4480 : }
690 :
691 : /*
692 : * Remove any references to relid or sjinfo->ojrelid (if sjinfo != NULL)
693 : * from the EquivalenceClass.
694 : *
695 : * Like remove_rel_from_restrictinfo, we don't worry about cleaning out
696 : * any nullingrel bits in contained Vars and PHVs. (This might have to be
697 : * improved sometime.) We do need to fix the EC and EM relid sets to ensure
698 : * that implied join equalities will be generated at the appropriate join
699 : * level(s).
700 : */
701 : static void
702 15724 : remove_rel_from_eclass(EquivalenceClass *ec, SpecialJoinInfo *sjinfo,
703 : int relid, int subst)
704 : {
705 : ListCell *lc;
706 :
707 : /* Fix up the EC's overall relids */
708 15724 : ec->ec_relids = adjust_relid_set(ec->ec_relids, relid, subst);
709 15724 : if (sjinfo != NULL)
710 14686 : ec->ec_relids = adjust_relid_set(ec->ec_relids,
711 14686 : sjinfo->ojrelid, subst);
712 :
713 : /*
714 : * Fix up the member expressions. Any non-const member that ends with
715 : * empty em_relids must be a Var or PHV of the removed relation. We don't
716 : * need it anymore, so we can drop it.
717 : */
718 36566 : foreach(lc, ec->ec_members)
719 : {
720 20842 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
721 :
722 20842 : if (bms_is_member(relid, cur_em->em_relids) ||
723 4348 : (sjinfo != NULL && bms_is_member(sjinfo->ojrelid,
724 4348 : cur_em->em_relids)))
725 : {
726 : Assert(!cur_em->em_is_const);
727 14686 : cur_em->em_relids = adjust_relid_set(cur_em->em_relids, relid, subst);
728 14686 : if (sjinfo != NULL)
729 14686 : cur_em->em_relids = adjust_relid_set(cur_em->em_relids,
730 14686 : sjinfo->ojrelid, subst);
731 14686 : if (bms_is_empty(cur_em->em_relids))
732 14674 : ec->ec_members = foreach_delete_current(ec->ec_members, lc);
733 : }
734 : }
735 :
736 : /* Fix up the source clauses, in case we can re-use them later */
737 21110 : foreach(lc, ec->ec_sources)
738 : {
739 5386 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
740 :
741 5386 : if (sjinfo == NULL)
742 1038 : ChangeVarNodes((Node *) rinfo, relid, subst, 0);
743 : else
744 4348 : remove_rel_from_restrictinfo(rinfo, relid, sjinfo->ojrelid);
745 : }
746 :
747 : /*
748 : * Rather than expend code on fixing up any already-derived clauses, just
749 : * drop them. (At this point, any such clauses would be base restriction
750 : * clauses, which we'd not need anymore anyway.)
751 : */
752 15724 : ec->ec_derives = NIL;
753 15724 : }
754 :
755 : /*
756 : * Remove any occurrences of the target relid from a joinlist structure.
757 : *
758 : * It's easiest to build a whole new list structure, so we handle it that
759 : * way. Efficiency is not a big deal here.
760 : *
761 : * *nremoved is incremented by the number of occurrences removed (there
762 : * should be exactly one, but the caller checks that).
763 : */
764 : static List *
765 11092 : remove_rel_from_joinlist(List *joinlist, int relid, int *nremoved)
766 : {
767 11092 : List *result = NIL;
768 : ListCell *jl;
769 :
770 40538 : foreach(jl, joinlist)
771 : {
772 29446 : Node *jlnode = (Node *) lfirst(jl);
773 :
774 29446 : if (IsA(jlnode, RangeTblRef))
775 : {
776 29182 : int varno = ((RangeTblRef *) jlnode)->rtindex;
777 :
778 29182 : if (varno == relid)
779 10828 : (*nremoved)++;
780 : else
781 18354 : result = lappend(result, jlnode);
782 : }
783 264 : else if (IsA(jlnode, List))
784 : {
785 : /* Recurse to handle subproblem */
786 : List *sublist;
787 :
788 264 : sublist = remove_rel_from_joinlist((List *) jlnode,
789 : relid, nremoved);
790 : /* Avoid including empty sub-lists in the result */
791 264 : if (sublist)
792 264 : result = lappend(result, sublist);
793 : }
794 : else
795 : {
796 0 : elog(ERROR, "unrecognized joinlist node type: %d",
797 : (int) nodeTag(jlnode));
798 : }
799 : }
800 :
801 11092 : return result;
802 : }
803 :
804 :
805 : /*
806 : * reduce_unique_semijoins
807 : * Check for semijoins that can be simplified to plain inner joins
808 : * because the inner relation is provably unique for the join clauses.
809 : *
810 : * Ideally this would happen during reduce_outer_joins, but we don't have
811 : * enough information at that point.
812 : *
813 : * To perform the strength reduction when applicable, we need only delete
814 : * the semijoin's SpecialJoinInfo from root->join_info_list. (We don't
815 : * bother fixing the join type attributed to it in the query jointree,
816 : * since that won't be consulted again.)
817 : */
818 : void
819 314632 : reduce_unique_semijoins(PlannerInfo *root)
820 : {
821 : ListCell *lc;
822 :
823 : /*
824 : * Scan the join_info_list to find semijoins.
825 : */
826 353604 : foreach(lc, root->join_info_list)
827 : {
828 38972 : SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
829 : int innerrelid;
830 : RelOptInfo *innerrel;
831 : Relids joinrelids;
832 : List *restrictlist;
833 :
834 : /*
835 : * Must be a semijoin to a single baserel, else we aren't going to be
836 : * able to do anything with it.
837 : */
838 38972 : if (sjinfo->jointype != JOIN_SEMI)
839 38662 : continue;
840 :
841 2208 : if (!bms_get_singleton_member(sjinfo->min_righthand, &innerrelid))
842 164 : continue;
843 :
844 2044 : innerrel = find_base_rel(root, innerrelid);
845 :
846 : /*
847 : * Before we trouble to run generate_join_implied_equalities, make a
848 : * quick check to eliminate cases in which we will surely be unable to
849 : * prove uniqueness of the innerrel.
850 : */
851 2044 : if (!rel_supports_distinctness(root, innerrel))
852 878 : continue;
853 :
854 : /* Compute the relid set for the join we are considering */
855 1166 : joinrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
856 : Assert(sjinfo->ojrelid == 0); /* SEMI joins don't have RT indexes */
857 :
858 : /*
859 : * Since we're only considering a single-rel RHS, any join clauses it
860 : * has must be clauses linking it to the semijoin's min_lefthand. We
861 : * can also consider EC-derived join clauses.
862 : */
863 : restrictlist =
864 1166 : list_concat(generate_join_implied_equalities(root,
865 : joinrelids,
866 : sjinfo->min_lefthand,
867 : innerrel,
868 : NULL),
869 1166 : innerrel->joininfo);
870 :
871 : /* Test whether the innerrel is unique for those clauses. */
872 1166 : if (!innerrel_is_unique(root,
873 : joinrelids, sjinfo->min_lefthand, innerrel,
874 : JOIN_SEMI, restrictlist, true))
875 856 : continue;
876 :
877 : /* OK, remove the SpecialJoinInfo from the list. */
878 310 : root->join_info_list = foreach_delete_current(root->join_info_list, lc);
879 : }
880 314632 : }
881 :
882 :
883 : /*
884 : * rel_supports_distinctness
885 : * Could the relation possibly be proven distinct on some set of columns?
886 : *
887 : * This is effectively a pre-checking function for rel_is_distinct_for().
888 : * It must return true if rel_is_distinct_for() could possibly return true
889 : * with this rel, but it should not expend a lot of cycles. The idea is
890 : * that callers can avoid doing possibly-expensive processing to compute
891 : * rel_is_distinct_for()'s argument lists if the call could not possibly
892 : * succeed.
893 : */
894 : static bool
895 569176 : rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel)
896 : {
897 : /* We only know about baserels ... */
898 569176 : if (rel->reloptkind != RELOPT_BASEREL)
899 187370 : return false;
900 381806 : if (rel->rtekind == RTE_RELATION)
901 : {
902 : /*
903 : * For a plain relation, we only know how to prove uniqueness by
904 : * reference to unique indexes. Make sure there's at least one
905 : * suitable unique index. It must be immediately enforced, and not a
906 : * partial index. (Keep these conditions in sync with
907 : * relation_has_unique_index_for!)
908 : */
909 : ListCell *lc;
910 :
911 489290 : foreach(lc, rel->indexlist)
912 : {
913 439728 : IndexOptInfo *ind = (IndexOptInfo *) lfirst(lc);
914 :
915 439728 : if (ind->unique && ind->immediate && ind->indpred == NIL)
916 304882 : return true;
917 : }
918 : }
919 27362 : else if (rel->rtekind == RTE_SUBQUERY)
920 : {
921 4656 : Query *subquery = root->simple_rte_array[rel->relid]->subquery;
922 :
923 : /* Check if the subquery has any qualities that support distinctness */
924 4656 : if (query_supports_distinctness(subquery))
925 3136 : return true;
926 : }
927 : /* We have no proof rules for any other rtekinds. */
928 73788 : return false;
929 : }
930 :
931 : /*
932 : * rel_is_distinct_for
933 : * Does the relation return only distinct rows according to clause_list?
934 : *
935 : * clause_list is a list of join restriction clauses involving this rel and
936 : * some other one. Return true if no two rows emitted by this rel could
937 : * possibly join to the same row of the other rel.
938 : *
939 : * The caller must have already determined that each condition is a
940 : * mergejoinable equality with an expression in this relation on one side, and
941 : * an expression not involving this relation on the other. The transient
942 : * outer_is_left flag is used to identify which side references this relation:
943 : * left side if outer_is_left is false, right side if it is true.
944 : *
945 : * Note that the passed-in clause_list may be destructively modified! This
946 : * is OK for current uses, because the clause_list is built by the caller for
947 : * the sole purpose of passing to this function.
948 : *
949 : * (*extra_clauses) to be set to the right sides of baserestrictinfo clauses,
950 : * looking like "x = const" if distinctness is derived from such clauses, not
951 : * joininfo clauses. Pass NULL to the extra_clauses if this value is not
952 : * needed.
953 : */
954 : static bool
955 196472 : rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel, List *clause_list,
956 : List **extra_clauses)
957 : {
958 : /*
959 : * We could skip a couple of tests here if we assume all callers checked
960 : * rel_supports_distinctness first, but it doesn't seem worth taking any
961 : * risk for.
962 : */
963 196472 : if (rel->reloptkind != RELOPT_BASEREL)
964 0 : return false;
965 196472 : if (rel->rtekind == RTE_RELATION)
966 : {
967 : /*
968 : * Examine the indexes to see if we have a matching unique index.
969 : * relation_has_unique_index_ext automatically adds any usable
970 : * restriction clauses for the rel, so we needn't do that here.
971 : */
972 194338 : if (relation_has_unique_index_ext(root, rel, clause_list, NIL, NIL,
973 : extra_clauses))
974 115096 : return true;
975 : }
976 2134 : else if (rel->rtekind == RTE_SUBQUERY)
977 : {
978 2134 : Index relid = rel->relid;
979 2134 : Query *subquery = root->simple_rte_array[relid]->subquery;
980 2134 : List *colnos = NIL;
981 2134 : List *opids = NIL;
982 : ListCell *l;
983 :
984 : /*
985 : * Build the argument lists for query_is_distinct_for: a list of
986 : * output column numbers that the query needs to be distinct over, and
987 : * a list of equality operators that the output columns need to be
988 : * distinct according to.
989 : *
990 : * (XXX we are not considering restriction clauses attached to the
991 : * subquery; is that worth doing?)
992 : */
993 4232 : foreach(l, clause_list)
994 : {
995 2098 : RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
996 : Oid op;
997 : Var *var;
998 :
999 : /*
1000 : * Get the equality operator we need uniqueness according to.
1001 : * (This might be a cross-type operator and thus not exactly the
1002 : * same operator the subquery would consider; that's all right
1003 : * since query_is_distinct_for can resolve such cases.) The
1004 : * caller's mergejoinability test should have selected only
1005 : * OpExprs.
1006 : */
1007 2098 : op = castNode(OpExpr, rinfo->clause)->opno;
1008 :
1009 : /* caller identified the inner side for us */
1010 2098 : if (rinfo->outer_is_left)
1011 1760 : var = (Var *) get_rightop(rinfo->clause);
1012 : else
1013 338 : var = (Var *) get_leftop(rinfo->clause);
1014 :
1015 : /*
1016 : * We may ignore any RelabelType node above the operand. (There
1017 : * won't be more than one, since eval_const_expressions() has been
1018 : * applied already.)
1019 : */
1020 2098 : if (var && IsA(var, RelabelType))
1021 638 : var = (Var *) ((RelabelType *) var)->arg;
1022 :
1023 : /*
1024 : * If inner side isn't a Var referencing a subquery output column,
1025 : * this clause doesn't help us.
1026 : */
1027 2098 : if (!var || !IsA(var, Var) ||
1028 2086 : var->varno != relid || var->varlevelsup != 0)
1029 12 : continue;
1030 :
1031 2086 : colnos = lappend_int(colnos, var->varattno);
1032 2086 : opids = lappend_oid(opids, op);
1033 : }
1034 :
1035 2134 : if (query_is_distinct_for(subquery, colnos, opids))
1036 212 : return true;
1037 : }
1038 81164 : return false;
1039 : }
1040 :
1041 :
1042 : /*
1043 : * query_supports_distinctness - could the query possibly be proven distinct
1044 : * on some set of output columns?
1045 : *
1046 : * This is effectively a pre-checking function for query_is_distinct_for().
1047 : * It must return true if query_is_distinct_for() could possibly return true
1048 : * with this query, but it should not expend a lot of cycles. The idea is
1049 : * that callers can avoid doing possibly-expensive processing to compute
1050 : * query_is_distinct_for()'s argument lists if the call could not possibly
1051 : * succeed.
1052 : */
1053 : bool
1054 5402 : query_supports_distinctness(Query *query)
1055 : {
1056 : /* SRFs break distinctness except with DISTINCT, see below */
1057 5402 : if (query->hasTargetSRFs && query->distinctClause == NIL)
1058 1004 : return false;
1059 :
1060 : /* check for features we can prove distinctness with */
1061 4398 : if (query->distinctClause != NIL ||
1062 4254 : query->groupClause != NIL ||
1063 4066 : query->groupingSets != NIL ||
1064 4066 : query->hasAggs ||
1065 3794 : query->havingQual ||
1066 3794 : query->setOperations)
1067 3846 : return true;
1068 :
1069 552 : return false;
1070 : }
1071 :
1072 : /*
1073 : * query_is_distinct_for - does query never return duplicates of the
1074 : * specified columns?
1075 : *
1076 : * query is a not-yet-planned subquery (in current usage, it's always from
1077 : * a subquery RTE, which the planner avoids scribbling on).
1078 : *
1079 : * colnos is an integer list of output column numbers (resno's). We are
1080 : * interested in whether rows consisting of just these columns are certain
1081 : * to be distinct. "Distinctness" is defined according to whether the
1082 : * corresponding upper-level equality operators listed in opids would think
1083 : * the values are distinct. (Note: the opids entries could be cross-type
1084 : * operators, and thus not exactly the equality operators that the subquery
1085 : * would use itself. We use equality_ops_are_compatible() to check
1086 : * compatibility. That looks at opfamily membership for index AMs that have
1087 : * declared that they support consistent equality semantics within an
1088 : * opfamily, and so should give trustworthy answers for all operators that we
1089 : * might need to deal with here.)
1090 : */
1091 : bool
1092 2330 : query_is_distinct_for(Query *query, List *colnos, List *opids)
1093 : {
1094 : ListCell *l;
1095 : Oid opid;
1096 :
1097 : Assert(list_length(colnos) == list_length(opids));
1098 :
1099 : /*
1100 : * DISTINCT (including DISTINCT ON) guarantees uniqueness if all the
1101 : * columns in the DISTINCT clause appear in colnos and operator semantics
1102 : * match. This is true even if there are SRFs in the DISTINCT columns or
1103 : * elsewhere in the tlist.
1104 : */
1105 2330 : if (query->distinctClause)
1106 : {
1107 150 : foreach(l, query->distinctClause)
1108 : {
1109 120 : SortGroupClause *sgc = (SortGroupClause *) lfirst(l);
1110 120 : TargetEntry *tle = get_sortgroupclause_tle(sgc,
1111 : query->targetList);
1112 :
1113 120 : opid = distinct_col_search(tle->resno, colnos, opids);
1114 120 : if (!OidIsValid(opid) ||
1115 48 : !equality_ops_are_compatible(opid, sgc->eqop))
1116 : break; /* exit early if no match */
1117 : }
1118 102 : if (l == NULL) /* had matches for all? */
1119 30 : return true;
1120 : }
1121 :
1122 : /*
1123 : * Otherwise, a set-returning function in the query's targetlist can
1124 : * result in returning duplicate rows, despite any grouping that might
1125 : * occur before tlist evaluation. (If all tlist SRFs are within GROUP BY
1126 : * columns, it would be safe because they'd be expanded before grouping.
1127 : * But it doesn't currently seem worth the effort to check for that.)
1128 : */
1129 2300 : if (query->hasTargetSRFs)
1130 0 : return false;
1131 :
1132 : /*
1133 : * Similarly, GROUP BY without GROUPING SETS guarantees uniqueness if all
1134 : * the grouped columns appear in colnos and operator semantics match.
1135 : */
1136 2300 : if (query->groupClause && !query->groupingSets)
1137 : {
1138 234 : foreach(l, query->groupClause)
1139 : {
1140 164 : SortGroupClause *sgc = (SortGroupClause *) lfirst(l);
1141 164 : TargetEntry *tle = get_sortgroupclause_tle(sgc,
1142 : query->targetList);
1143 :
1144 164 : opid = distinct_col_search(tle->resno, colnos, opids);
1145 164 : if (!OidIsValid(opid) ||
1146 112 : !equality_ops_are_compatible(opid, sgc->eqop))
1147 : break; /* exit early if no match */
1148 : }
1149 122 : if (l == NULL) /* had matches for all? */
1150 70 : return true;
1151 : }
1152 2178 : else if (query->groupingSets)
1153 : {
1154 : /*
1155 : * If we have grouping sets with expressions, we probably don't have
1156 : * uniqueness and analysis would be hard. Punt.
1157 : */
1158 0 : if (query->groupClause)
1159 0 : return false;
1160 :
1161 : /*
1162 : * If we have no groupClause (therefore no grouping expressions), we
1163 : * might have one or many empty grouping sets. If there's just one,
1164 : * then we're returning only one row and are certainly unique. But
1165 : * otherwise, we know we're certainly not unique.
1166 : */
1167 0 : if (list_length(query->groupingSets) == 1 &&
1168 0 : ((GroupingSet *) linitial(query->groupingSets))->kind == GROUPING_SET_EMPTY)
1169 0 : return true;
1170 : else
1171 0 : return false;
1172 : }
1173 : else
1174 : {
1175 : /*
1176 : * If we have no GROUP BY, but do have aggregates or HAVING, then the
1177 : * result is at most one row so it's surely unique, for any operators.
1178 : */
1179 2178 : if (query->hasAggs || query->havingQual)
1180 100 : return true;
1181 : }
1182 :
1183 : /*
1184 : * UNION, INTERSECT, EXCEPT guarantee uniqueness of the whole output row,
1185 : * except with ALL.
1186 : */
1187 2130 : if (query->setOperations)
1188 : {
1189 2006 : SetOperationStmt *topop = castNode(SetOperationStmt, query->setOperations);
1190 :
1191 : Assert(topop->op != SETOP_NONE);
1192 :
1193 2006 : if (!topop->all)
1194 : {
1195 : ListCell *lg;
1196 :
1197 : /* We're good if all the nonjunk output columns are in colnos */
1198 72 : lg = list_head(topop->groupClauses);
1199 90 : foreach(l, query->targetList)
1200 : {
1201 78 : TargetEntry *tle = (TargetEntry *) lfirst(l);
1202 : SortGroupClause *sgc;
1203 :
1204 78 : if (tle->resjunk)
1205 0 : continue; /* ignore resjunk columns */
1206 :
1207 : /* non-resjunk columns should have grouping clauses */
1208 : Assert(lg != NULL);
1209 78 : sgc = (SortGroupClause *) lfirst(lg);
1210 78 : lg = lnext(topop->groupClauses, lg);
1211 :
1212 78 : opid = distinct_col_search(tle->resno, colnos, opids);
1213 78 : if (!OidIsValid(opid) ||
1214 18 : !equality_ops_are_compatible(opid, sgc->eqop))
1215 : break; /* exit early if no match */
1216 : }
1217 72 : if (l == NULL) /* had matches for all? */
1218 12 : return true;
1219 : }
1220 : }
1221 :
1222 : /*
1223 : * XXX Are there any other cases in which we can easily see the result
1224 : * must be distinct?
1225 : *
1226 : * If you do add more smarts to this function, be sure to update
1227 : * query_supports_distinctness() to match.
1228 : */
1229 :
1230 2118 : return false;
1231 : }
1232 :
1233 : /*
1234 : * distinct_col_search - subroutine for query_is_distinct_for
1235 : *
1236 : * If colno is in colnos, return the corresponding element of opids,
1237 : * else return InvalidOid. (Ordinarily colnos would not contain duplicates,
1238 : * but if it does, we arbitrarily select the first match.)
1239 : */
1240 : static Oid
1241 362 : distinct_col_search(int colno, List *colnos, List *opids)
1242 : {
1243 : ListCell *lc1,
1244 : *lc2;
1245 :
1246 574 : forboth(lc1, colnos, lc2, opids)
1247 : {
1248 390 : if (colno == lfirst_int(lc1))
1249 178 : return lfirst_oid(lc2);
1250 : }
1251 184 : return InvalidOid;
1252 : }
1253 :
1254 :
1255 : /*
1256 : * innerrel_is_unique
1257 : * Check if the innerrel provably contains at most one tuple matching any
1258 : * tuple from the outerrel, based on join clauses in the 'restrictlist'.
1259 : *
1260 : * We need an actual RelOptInfo for the innerrel, but it's sufficient to
1261 : * identify the outerrel by its Relids. This asymmetry supports use of this
1262 : * function before joinrels have been built. (The caller is expected to
1263 : * also supply the joinrelids, just to save recalculating that.)
1264 : *
1265 : * The proof must be made based only on clauses that will be "joinquals"
1266 : * rather than "otherquals" at execution. For an inner join there's no
1267 : * difference; but if the join is outer, we must ignore pushed-down quals,
1268 : * as those will become "otherquals". Note that this means the answer might
1269 : * vary depending on whether IS_OUTER_JOIN(jointype); since we cache the
1270 : * answer without regard to that, callers must take care not to call this
1271 : * with jointypes that would be classified differently by IS_OUTER_JOIN().
1272 : *
1273 : * The actual proof is undertaken by is_innerrel_unique_for(); this function
1274 : * is a frontend that is mainly concerned with caching the answers.
1275 : * In particular, the force_cache argument allows overriding the internal
1276 : * heuristic about whether to cache negative answers; it should be "true"
1277 : * if making an inquiry that is not part of the normal bottom-up join search
1278 : * sequence.
1279 : */
1280 : bool
1281 627934 : innerrel_is_unique(PlannerInfo *root,
1282 : Relids joinrelids,
1283 : Relids outerrelids,
1284 : RelOptInfo *innerrel,
1285 : JoinType jointype,
1286 : List *restrictlist,
1287 : bool force_cache)
1288 : {
1289 627934 : return innerrel_is_unique_ext(root, joinrelids, outerrelids, innerrel,
1290 : jointype, restrictlist, force_cache, NULL);
1291 : }
1292 :
1293 : /*
1294 : * innerrel_is_unique_ext
1295 : * Do the same as innerrel_is_unique(), but also set to (*extra_clauses)
1296 : * additional clauses from a baserestrictinfo list used to prove the
1297 : * uniqueness.
1298 : *
1299 : * A non-NULL extra_clauses indicates that we're checking for self-join and
1300 : * correspondingly dealing with filtered clauses.
1301 : */
1302 : bool
1303 629910 : innerrel_is_unique_ext(PlannerInfo *root,
1304 : Relids joinrelids,
1305 : Relids outerrelids,
1306 : RelOptInfo *innerrel,
1307 : JoinType jointype,
1308 : List *restrictlist,
1309 : bool force_cache,
1310 : List **extra_clauses)
1311 : {
1312 : MemoryContext old_context;
1313 : ListCell *lc;
1314 : UniqueRelInfo *uniqueRelInfo;
1315 629910 : List *outer_exprs = NIL;
1316 629910 : bool self_join = (extra_clauses != NULL);
1317 :
1318 : /* Certainly can't prove uniqueness when there are no joinclauses */
1319 629910 : if (restrictlist == NIL)
1320 103106 : return false;
1321 :
1322 : /*
1323 : * Make a quick check to eliminate cases in which we will surely be unable
1324 : * to prove uniqueness of the innerrel.
1325 : */
1326 526804 : if (!rel_supports_distinctness(root, innerrel))
1327 257270 : return false;
1328 :
1329 : /*
1330 : * Query the cache to see if we've managed to prove that innerrel is
1331 : * unique for any subset of this outerrel. For non-self-join search, we
1332 : * don't need an exact match, as extra outerrels can't make the innerrel
1333 : * any less unique (or more formally, the restrictlist for a join to a
1334 : * superset outerrel must be a superset of the conditions we successfully
1335 : * used before). For self-join search, we require an exact match of
1336 : * outerrels because we need extra clauses to be valid for our case. Also,
1337 : * for self-join checking we've filtered the clauses list. Thus, we can
1338 : * match only the result cached for a self-join search for another
1339 : * self-join check.
1340 : */
1341 300258 : foreach(lc, innerrel->unique_for_rels)
1342 : {
1343 113828 : uniqueRelInfo = (UniqueRelInfo *) lfirst(lc);
1344 :
1345 113828 : if ((!self_join && bms_is_subset(uniqueRelInfo->outerrelids, outerrelids)) ||
1346 68 : (self_join && bms_equal(uniqueRelInfo->outerrelids, outerrelids) &&
1347 56 : uniqueRelInfo->self_join))
1348 : {
1349 83104 : if (extra_clauses)
1350 12 : *extra_clauses = uniqueRelInfo->extra_clauses;
1351 83104 : return true; /* Success! */
1352 : }
1353 : }
1354 :
1355 : /*
1356 : * Conversely, we may have already determined that this outerrel, or some
1357 : * superset thereof, cannot prove this innerrel to be unique.
1358 : */
1359 186914 : foreach(lc, innerrel->non_unique_for_rels)
1360 : {
1361 808 : Relids unique_for_rels = (Relids) lfirst(lc);
1362 :
1363 808 : if (bms_is_subset(outerrelids, unique_for_rels))
1364 324 : return false;
1365 : }
1366 :
1367 : /* No cached information, so try to make the proof. */
1368 186106 : if (is_innerrel_unique_for(root, joinrelids, outerrelids, innerrel,
1369 : jointype, restrictlist,
1370 : self_join ? &outer_exprs : NULL))
1371 : {
1372 : /*
1373 : * Cache the positive result for future probes, being sure to keep it
1374 : * in the planner_cxt even if we are working in GEQO.
1375 : *
1376 : * Note: one might consider trying to isolate the minimal subset of
1377 : * the outerrels that proved the innerrel unique. But it's not worth
1378 : * the trouble, because the planner builds up joinrels incrementally
1379 : * and so we'll see the minimally sufficient outerrels before any
1380 : * supersets of them anyway.
1381 : */
1382 105068 : old_context = MemoryContextSwitchTo(root->planner_cxt);
1383 105068 : uniqueRelInfo = makeNode(UniqueRelInfo);
1384 105068 : uniqueRelInfo->outerrelids = bms_copy(outerrelids);
1385 105068 : uniqueRelInfo->self_join = self_join;
1386 105068 : uniqueRelInfo->extra_clauses = outer_exprs;
1387 105068 : innerrel->unique_for_rels = lappend(innerrel->unique_for_rels,
1388 : uniqueRelInfo);
1389 105068 : MemoryContextSwitchTo(old_context);
1390 :
1391 105068 : if (extra_clauses)
1392 642 : *extra_clauses = outer_exprs;
1393 105068 : return true; /* Success! */
1394 : }
1395 : else
1396 : {
1397 : /*
1398 : * None of the join conditions for outerrel proved innerrel unique, so
1399 : * we can safely reject this outerrel or any subset of it in future
1400 : * checks.
1401 : *
1402 : * However, in normal planning mode, caching this knowledge is totally
1403 : * pointless; it won't be queried again, because we build up joinrels
1404 : * from smaller to larger. It is useful in GEQO mode, where the
1405 : * knowledge can be carried across successive planning attempts; and
1406 : * it's likely to be useful when using join-search plugins, too. Hence
1407 : * cache when join_search_private is non-NULL. (Yeah, that's a hack,
1408 : * but it seems reasonable.)
1409 : *
1410 : * Also, allow callers to override that heuristic and force caching;
1411 : * that's useful for reduce_unique_semijoins, which calls here before
1412 : * the normal join search starts.
1413 : */
1414 81038 : if (force_cache || root->join_search_private)
1415 : {
1416 1180 : old_context = MemoryContextSwitchTo(root->planner_cxt);
1417 1180 : innerrel->non_unique_for_rels =
1418 1180 : lappend(innerrel->non_unique_for_rels,
1419 1180 : bms_copy(outerrelids));
1420 1180 : MemoryContextSwitchTo(old_context);
1421 : }
1422 :
1423 81038 : return false;
1424 : }
1425 : }
1426 :
1427 : /*
1428 : * is_innerrel_unique_for
1429 : * Check if the innerrel provably contains at most one tuple matching any
1430 : * tuple from the outerrel, based on join clauses in the 'restrictlist'.
1431 : */
1432 : static bool
1433 186106 : is_innerrel_unique_for(PlannerInfo *root,
1434 : Relids joinrelids,
1435 : Relids outerrelids,
1436 : RelOptInfo *innerrel,
1437 : JoinType jointype,
1438 : List *restrictlist,
1439 : List **extra_clauses)
1440 : {
1441 186106 : List *clause_list = NIL;
1442 : ListCell *lc;
1443 :
1444 : /*
1445 : * Search for mergejoinable clauses that constrain the inner rel against
1446 : * the outer rel. If an operator is mergejoinable then it behaves like
1447 : * equality for some btree opclass, so it's what we want. The
1448 : * mergejoinability test also eliminates clauses containing volatile
1449 : * functions, which we couldn't depend on.
1450 : */
1451 412052 : foreach(lc, restrictlist)
1452 : {
1453 225946 : RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(lc);
1454 :
1455 : /*
1456 : * As noted above, if it's a pushed-down clause and we're at an outer
1457 : * join, we can't use it.
1458 : */
1459 225946 : if (IS_OUTER_JOIN(jointype) &&
1460 95106 : RINFO_IS_PUSHED_DOWN(restrictinfo, joinrelids))
1461 4166 : continue;
1462 :
1463 : /* Ignore if it's not a mergejoinable clause */
1464 221780 : if (!restrictinfo->can_join ||
1465 203466 : restrictinfo->mergeopfamilies == NIL)
1466 19240 : continue; /* not mergejoinable */
1467 :
1468 : /*
1469 : * Check if the clause has the form "outer op inner" or "inner op
1470 : * outer", and if so mark which side is inner.
1471 : */
1472 202540 : if (!clause_sides_match_join(restrictinfo, outerrelids,
1473 : innerrel->relids))
1474 40 : continue; /* no good for these input relations */
1475 :
1476 : /* OK, add to the list */
1477 202500 : clause_list = lappend(clause_list, restrictinfo);
1478 : }
1479 :
1480 : /* Let rel_is_distinct_for() do the hard work */
1481 186106 : return rel_is_distinct_for(root, innerrel, clause_list, extra_clauses);
1482 : }
1483 :
1484 : /*
1485 : * Update EC members to point to the remaining relation instead of the removed
1486 : * one, removing duplicates.
1487 : *
1488 : * Restriction clauses for base relations are already distributed to
1489 : * the respective baserestrictinfo lists (see
1490 : * generate_implied_equalities_for_column). The above code has already processed
1491 : * this list and updated these clauses to reference the remaining
1492 : * relation, so that we can skip them here based on their relids.
1493 : *
1494 : * Likewise, we have already processed the join clauses that join the
1495 : * removed relation to the remaining one.
1496 : *
1497 : * Finally, there might be join clauses tying the removed relation to
1498 : * some third relation. We can't just delete the source clauses and
1499 : * regenerate them from the EC because the corresponding equality
1500 : * operators might be missing (see the handling of ec_broken).
1501 : * Therefore, we will update the references in the source clauses.
1502 : *
1503 : * Derived clauses can be generated again, so it is simpler just to
1504 : * delete them.
1505 : */
1506 : static void
1507 900 : update_eclasses(EquivalenceClass *ec, int from, int to)
1508 : {
1509 900 : List *new_members = NIL;
1510 900 : List *new_sources = NIL;
1511 :
1512 3636 : foreach_node(EquivalenceMember, em, ec->ec_members)
1513 : {
1514 1836 : bool is_redundant = false;
1515 :
1516 1836 : if (!bms_is_member(from, em->em_relids))
1517 : {
1518 918 : new_members = lappend(new_members, em);
1519 918 : continue;
1520 : }
1521 :
1522 918 : em->em_relids = adjust_relid_set(em->em_relids, from, to);
1523 918 : em->em_jdomain->jd_relids = adjust_relid_set(em->em_jdomain->jd_relids, from, to);
1524 :
1525 : /* We only process inner joins */
1526 918 : ChangeVarNodes((Node *) em->em_expr, from, to, 0);
1527 :
1528 1860 : foreach_node(EquivalenceMember, other, new_members)
1529 : {
1530 298 : if (!equal(em->em_relids, other->em_relids))
1531 24 : continue;
1532 :
1533 274 : if (equal(em->em_expr, other->em_expr))
1534 : {
1535 274 : is_redundant = true;
1536 274 : break;
1537 : }
1538 : }
1539 :
1540 918 : if (!is_redundant)
1541 644 : new_members = lappend(new_members, em);
1542 : }
1543 :
1544 900 : list_free(ec->ec_members);
1545 900 : ec->ec_members = new_members;
1546 :
1547 900 : list_free(ec->ec_derives);
1548 900 : ec->ec_derives = NULL;
1549 :
1550 : /* Update EC source expressions */
1551 2736 : foreach_node(RestrictInfo, rinfo, ec->ec_sources)
1552 : {
1553 936 : bool is_redundant = false;
1554 :
1555 936 : if (!bms_is_member(from, rinfo->required_relids))
1556 : {
1557 118 : new_sources = lappend(new_sources, rinfo);
1558 118 : continue;
1559 : }
1560 :
1561 818 : ChangeVarNodes((Node *) rinfo, from, to, 0);
1562 :
1563 : /*
1564 : * After switching the clause to the remaining relation, check it for
1565 : * redundancy with existing ones. We don't have to check for
1566 : * redundancy with derived clauses, because we've just deleted them.
1567 : */
1568 1660 : foreach_node(RestrictInfo, other, new_sources)
1569 : {
1570 36 : if (!equal(rinfo->clause_relids, other->clause_relids))
1571 24 : continue;
1572 :
1573 12 : if (equal(rinfo->clause, other->clause))
1574 : {
1575 12 : is_redundant = true;
1576 12 : break;
1577 : }
1578 : }
1579 :
1580 818 : if (!is_redundant)
1581 806 : new_sources = lappend(new_sources, rinfo);
1582 : }
1583 :
1584 900 : list_free(ec->ec_sources);
1585 900 : ec->ec_sources = new_sources;
1586 900 : ec->ec_relids = adjust_relid_set(ec->ec_relids, from, to);
1587 900 : }
1588 :
1589 : /*
1590 : * "Logically" compares two RestrictInfo's ignoring the 'rinfo_serial' field,
1591 : * which makes almost every RestrictInfo unique. This type of comparison is
1592 : * useful when removing duplicates while moving RestrictInfo's from removed
1593 : * relation to remaining relation during self-join elimination.
1594 : *
1595 : * XXX: In the future, we might remove the 'rinfo_serial' field completely and
1596 : * get rid of this function.
1597 : */
1598 : static bool
1599 506 : restrict_infos_logically_equal(RestrictInfo *a, RestrictInfo *b)
1600 : {
1601 506 : int saved_rinfo_serial = a->rinfo_serial;
1602 : bool result;
1603 :
1604 506 : a->rinfo_serial = b->rinfo_serial;
1605 506 : result = equal(a, b);
1606 506 : a->rinfo_serial = saved_rinfo_serial;
1607 :
1608 506 : return result;
1609 : }
1610 :
1611 : /*
1612 : * This function adds all non-redundant clauses to the keeping relation
1613 : * during self-join elimination. That is a contradictory operation. On the
1614 : * one hand, we reduce the length of the `restrict` lists, which can
1615 : * impact planning or executing time. Additionally, we improve the
1616 : * accuracy of cardinality estimation. On the other hand, it is one more
1617 : * place that can make planning time much longer in specific cases. It
1618 : * would have been better to avoid calling the equal() function here, but
1619 : * it's the only way to detect duplicated inequality expressions.
1620 : *
1621 : * (*keep_rinfo_list) is given by pointer because it might be altered by
1622 : * distribute_restrictinfo_to_rels().
1623 : */
1624 : static void
1625 1176 : add_non_redundant_clauses(PlannerInfo *root,
1626 : List *rinfo_candidates,
1627 : List **keep_rinfo_list,
1628 : Index removed_relid)
1629 : {
1630 3250 : foreach_node(RestrictInfo, rinfo, rinfo_candidates)
1631 : {
1632 898 : bool is_redundant = false;
1633 :
1634 : Assert(!bms_is_member(removed_relid, rinfo->required_relids));
1635 :
1636 2160 : foreach_node(RestrictInfo, src, (*keep_rinfo_list))
1637 : {
1638 518 : if (!bms_equal(src->clause_relids, rinfo->clause_relids))
1639 : /* Can't compare trivially different clauses */
1640 6 : continue;
1641 :
1642 512 : if (src == rinfo ||
1643 512 : (rinfo->parent_ec != NULL &&
1644 804 : src->parent_ec == rinfo->parent_ec) ||
1645 506 : restrict_infos_logically_equal(rinfo, src))
1646 : {
1647 154 : is_redundant = true;
1648 154 : break;
1649 : }
1650 : }
1651 898 : if (!is_redundant)
1652 744 : distribute_restrictinfo_to_rels(root, rinfo);
1653 : }
1654 1176 : }
1655 :
1656 : /*
1657 : * Remove a relation after we have proven that it participates only in an
1658 : * unneeded unique self-join.
1659 : *
1660 : * Replace any links in planner info structures.
1661 : *
1662 : * Transfer join and restriction clauses from the removed relation to the
1663 : * remaining one. We change the Vars of the clause to point to the
1664 : * remaining relation instead of the removed one. The clauses that require
1665 : * a subset of joinrelids become restriction clauses of the remaining
1666 : * relation, and others remain join clauses. We append them to
1667 : * baserestrictinfo and joininfo, respectively, trying not to introduce
1668 : * duplicates.
1669 : *
1670 : * We also have to process the 'joinclauses' list here, because it
1671 : * contains EC-derived join clauses which must become filter clauses. It
1672 : * is not enough to just correct the ECs because the EC-derived
1673 : * restrictions are generated before join removal (see
1674 : * generate_base_implied_equalities).
1675 : *
1676 : * NOTE: Remember to keep the code in sync with PlannerInfo to be sure all
1677 : * cached relids and relid bitmapsets can be correctly cleaned during the
1678 : * self-join elimination procedure.
1679 : */
1680 : static void
1681 588 : remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
1682 : RelOptInfo *toKeep, RelOptInfo *toRemove,
1683 : List *restrictlist)
1684 : {
1685 : List *joininfos;
1686 : ListCell *lc;
1687 : int i;
1688 588 : List *jinfo_candidates = NIL;
1689 588 : List *binfo_candidates = NIL;
1690 :
1691 : Assert(toKeep->relid > 0);
1692 : Assert(toRemove->relid > 0);
1693 :
1694 : /*
1695 : * Replace the index of the removing table with the keeping one. The
1696 : * technique of removing/distributing restrictinfo is used here to attach
1697 : * just appeared (for keeping relation) join clauses and avoid adding
1698 : * duplicates of those that already exist in the joininfo list.
1699 : */
1700 588 : joininfos = list_copy(toRemove->joininfo);
1701 1254 : foreach_node(RestrictInfo, rinfo, joininfos)
1702 : {
1703 78 : remove_join_clause_from_rels(root, rinfo, rinfo->required_relids);
1704 78 : ChangeVarNodes((Node *) rinfo, toRemove->relid, toKeep->relid, 0);
1705 :
1706 78 : if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
1707 60 : jinfo_candidates = lappend(jinfo_candidates, rinfo);
1708 : else
1709 18 : binfo_candidates = lappend(binfo_candidates, rinfo);
1710 : }
1711 :
1712 : /*
1713 : * Concatenate restrictlist to the list of base restrictions of the
1714 : * removing table just to simplify the replacement procedure: all of them
1715 : * weren't connected to any keeping relations and need to be added to some
1716 : * rels.
1717 : */
1718 588 : toRemove->baserestrictinfo = list_concat(toRemove->baserestrictinfo,
1719 : restrictlist);
1720 1996 : foreach_node(RestrictInfo, rinfo, toRemove->baserestrictinfo)
1721 : {
1722 820 : ChangeVarNodes((Node *) rinfo, toRemove->relid, toKeep->relid, 0);
1723 :
1724 820 : if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
1725 0 : jinfo_candidates = lappend(jinfo_candidates, rinfo);
1726 : else
1727 820 : binfo_candidates = lappend(binfo_candidates, rinfo);
1728 : }
1729 :
1730 : /*
1731 : * Now, add all non-redundant clauses to the keeping relation.
1732 : */
1733 588 : add_non_redundant_clauses(root, binfo_candidates,
1734 : &toKeep->baserestrictinfo, toRemove->relid);
1735 588 : add_non_redundant_clauses(root, jinfo_candidates,
1736 : &toKeep->joininfo, toRemove->relid);
1737 :
1738 588 : list_free(binfo_candidates);
1739 588 : list_free(jinfo_candidates);
1740 :
1741 : /*
1742 : * Arrange equivalence classes, mentioned removing a table, with the
1743 : * keeping one: varno of removing table should be replaced in members and
1744 : * sources lists. Also, remove duplicated elements if this replacement
1745 : * procedure created them.
1746 : */
1747 588 : i = -1;
1748 1488 : while ((i = bms_next_member(toRemove->eclass_indexes, i)) >= 0)
1749 : {
1750 900 : EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
1751 :
1752 900 : update_eclasses(ec, toRemove->relid, toKeep->relid);
1753 900 : toKeep->eclass_indexes = bms_add_member(toKeep->eclass_indexes, i);
1754 : }
1755 :
1756 : /*
1757 : * Transfer the targetlist and attr_needed flags.
1758 : */
1759 :
1760 2360 : foreach(lc, toRemove->reltarget->exprs)
1761 : {
1762 1772 : Node *node = lfirst(lc);
1763 :
1764 1772 : ChangeVarNodes(node, toRemove->relid, toKeep->relid, 0);
1765 1772 : if (!list_member(toKeep->reltarget->exprs, node))
1766 174 : toKeep->reltarget->exprs = lappend(toKeep->reltarget->exprs, node);
1767 : }
1768 :
1769 7470 : for (i = toKeep->min_attr; i <= toKeep->max_attr; i++)
1770 : {
1771 6882 : int attno = i - toKeep->min_attr;
1772 :
1773 13764 : toRemove->attr_needed[attno] = adjust_relid_set(toRemove->attr_needed[attno],
1774 6882 : toRemove->relid, toKeep->relid);
1775 6882 : toKeep->attr_needed[attno] = bms_add_members(toKeep->attr_needed[attno],
1776 6882 : toRemove->attr_needed[attno]);
1777 : }
1778 :
1779 : /*
1780 : * If the removed relation has a row mark, transfer it to the remaining
1781 : * one.
1782 : *
1783 : * If both rels have row marks, just keep the one corresponding to the
1784 : * remaining relation because we verified earlier that they have the same
1785 : * strength.
1786 : */
1787 588 : if (rmark)
1788 : {
1789 74 : if (kmark)
1790 : {
1791 : Assert(kmark->markType == rmark->markType);
1792 :
1793 74 : root->rowMarks = list_delete_ptr(root->rowMarks, rmark);
1794 : }
1795 : else
1796 : {
1797 : /* Shouldn't have inheritance children here. */
1798 : Assert(rmark->rti == rmark->prti);
1799 :
1800 0 : rmark->rti = rmark->prti = toKeep->relid;
1801 : }
1802 : }
1803 :
1804 : /*
1805 : * Replace varno in all the query structures, except nodes RangeTblRef
1806 : * otherwise later remove_rel_from_joinlist will yield errors.
1807 : */
1808 588 : ChangeVarNodesExtended((Node *) root->parse, toRemove->relid, toKeep->relid, 0, false);
1809 :
1810 : /* Replace links in the planner info */
1811 588 : remove_rel_from_query(root, toRemove, toKeep->relid, NULL, NULL);
1812 :
1813 : /* At last, replace varno in root targetlist and HAVING clause */
1814 588 : ChangeVarNodes((Node *) root->processed_tlist, toRemove->relid, toKeep->relid, 0);
1815 588 : ChangeVarNodes((Node *) root->processed_groupClause, toRemove->relid, toKeep->relid, 0);
1816 :
1817 588 : adjust_relid_set(root->all_result_relids, toRemove->relid, toKeep->relid);
1818 588 : adjust_relid_set(root->leaf_result_relids, toRemove->relid, toKeep->relid);
1819 :
1820 : /*
1821 : * There may be references to the rel in root->fkey_list, but if so,
1822 : * match_foreign_keys_to_quals() will get rid of them.
1823 : */
1824 :
1825 : /*
1826 : * Finally, remove the rel from the baserel array to prevent it from being
1827 : * referenced again. (We can't do this earlier because
1828 : * remove_join_clause_from_rels will touch it.)
1829 : */
1830 588 : root->simple_rel_array[toRemove->relid] = NULL;
1831 :
1832 : /* And nuke the RelOptInfo, just in case there's another access path. */
1833 588 : pfree(toRemove);
1834 :
1835 : /*
1836 : * Now repeat construction of attr_needed bits coming from all other
1837 : * sources.
1838 : */
1839 588 : rebuild_placeholder_attr_needed(root);
1840 588 : rebuild_joinclause_attr_needed(root);
1841 588 : rebuild_eclass_attr_needed(root);
1842 588 : rebuild_lateral_attr_needed(root);
1843 588 : }
1844 :
1845 : /*
1846 : * split_selfjoin_quals
1847 : * Processes 'joinquals' by building two lists: one containing the quals
1848 : * where the columns/exprs are on either side of the join match and
1849 : * another one containing the remaining quals.
1850 : *
1851 : * 'joinquals' must only contain quals for a RTE_RELATION being joined to
1852 : * itself.
1853 : */
1854 : static void
1855 1976 : split_selfjoin_quals(PlannerInfo *root, List *joinquals, List **selfjoinquals,
1856 : List **otherjoinquals, int from, int to)
1857 : {
1858 1976 : List *sjoinquals = NIL;
1859 1976 : List *ojoinquals = NIL;
1860 :
1861 6062 : foreach_node(RestrictInfo, rinfo, joinquals)
1862 : {
1863 : OpExpr *expr;
1864 : Node *leftexpr;
1865 : Node *rightexpr;
1866 :
1867 : /* In general, clause looks like F(arg1) = G(arg2) */
1868 4220 : if (!rinfo->mergeopfamilies ||
1869 4220 : bms_num_members(rinfo->clause_relids) != 2 ||
1870 4220 : bms_membership(rinfo->left_relids) != BMS_SINGLETON ||
1871 2110 : bms_membership(rinfo->right_relids) != BMS_SINGLETON)
1872 : {
1873 0 : ojoinquals = lappend(ojoinquals, rinfo);
1874 0 : continue;
1875 : }
1876 :
1877 2110 : expr = (OpExpr *) rinfo->clause;
1878 :
1879 2110 : if (!IsA(expr, OpExpr) || list_length(expr->args) != 2)
1880 : {
1881 0 : ojoinquals = lappend(ojoinquals, rinfo);
1882 0 : continue;
1883 : }
1884 :
1885 2110 : leftexpr = get_leftop(rinfo->clause);
1886 2110 : rightexpr = copyObject(get_rightop(rinfo->clause));
1887 :
1888 2110 : if (leftexpr && IsA(leftexpr, RelabelType))
1889 12 : leftexpr = (Node *) ((RelabelType *) leftexpr)->arg;
1890 2110 : if (rightexpr && IsA(rightexpr, RelabelType))
1891 6 : rightexpr = (Node *) ((RelabelType *) rightexpr)->arg;
1892 :
1893 : /*
1894 : * Quite an expensive operation, narrowing the use case. For example,
1895 : * when we have cast of the same var to different (but compatible)
1896 : * types.
1897 : */
1898 2110 : ChangeVarNodes(rightexpr, bms_singleton_member(rinfo->right_relids),
1899 2110 : bms_singleton_member(rinfo->left_relids), 0);
1900 :
1901 2110 : if (equal(leftexpr, rightexpr))
1902 1624 : sjoinquals = lappend(sjoinquals, rinfo);
1903 : else
1904 486 : ojoinquals = lappend(ojoinquals, rinfo);
1905 : }
1906 :
1907 1976 : *selfjoinquals = sjoinquals;
1908 1976 : *otherjoinquals = ojoinquals;
1909 1976 : }
1910 :
1911 : /*
1912 : * Check for a case when uniqueness is at least partly derived from a
1913 : * baserestrictinfo clause. In this case, we have a chance to return only
1914 : * one row (if such clauses on both sides of SJ are equal) or nothing (if they
1915 : * are different).
1916 : */
1917 : static bool
1918 654 : match_unique_clauses(PlannerInfo *root, RelOptInfo *outer, List *uclauses,
1919 : Index relid)
1920 : {
1921 1326 : foreach_node(RestrictInfo, rinfo, uclauses)
1922 : {
1923 : Expr *clause;
1924 : Node *iclause;
1925 : Node *c1;
1926 150 : bool matched = false;
1927 :
1928 : Assert(outer->relid > 0 && relid > 0);
1929 :
1930 : /* Only filters like f(R.x1,...,R.xN) == expr we should consider. */
1931 : Assert(bms_is_empty(rinfo->left_relids) ^
1932 : bms_is_empty(rinfo->right_relids));
1933 :
1934 150 : clause = (Expr *) copyObject(rinfo->clause);
1935 150 : ChangeVarNodes((Node *) clause, relid, outer->relid, 0);
1936 :
1937 150 : iclause = bms_is_empty(rinfo->left_relids) ? get_rightop(clause) :
1938 144 : get_leftop(clause);
1939 150 : c1 = bms_is_empty(rinfo->left_relids) ? get_leftop(clause) :
1940 144 : get_rightop(clause);
1941 :
1942 : /*
1943 : * Compare these left and right sides with the corresponding sides of
1944 : * the outer's filters. If no one is detected - return immediately.
1945 : */
1946 408 : foreach_node(RestrictInfo, orinfo, outer->baserestrictinfo)
1947 : {
1948 : Node *oclause;
1949 : Node *c2;
1950 :
1951 192 : if (orinfo->mergeopfamilies == NIL)
1952 : /* Don't consider clauses that aren't similar to 'F(X)=G(Y)' */
1953 60 : continue;
1954 :
1955 : Assert(is_opclause(orinfo->clause));
1956 :
1957 264 : oclause = bms_is_empty(orinfo->left_relids) ?
1958 132 : get_rightop(orinfo->clause) : get_leftop(orinfo->clause);
1959 264 : c2 = (bms_is_empty(orinfo->left_relids) ?
1960 132 : get_leftop(orinfo->clause) : get_rightop(orinfo->clause));
1961 :
1962 132 : if (equal(iclause, oclause) && equal(c1, c2))
1963 : {
1964 84 : matched = true;
1965 84 : break;
1966 : }
1967 : }
1968 :
1969 150 : if (!matched)
1970 66 : return false;
1971 : }
1972 :
1973 588 : return true;
1974 : }
1975 :
1976 : /*
1977 : * Find and remove unique self-joins in a group of base relations that have
1978 : * the same Oid.
1979 : *
1980 : * Returns a set of relids that were removed.
1981 : */
1982 : static Relids
1983 10788 : remove_self_joins_one_group(PlannerInfo *root, Relids relids)
1984 : {
1985 10788 : Relids result = NULL;
1986 : int k; /* Index of kept relation */
1987 10788 : int r = -1; /* Index of removed relation */
1988 :
1989 33524 : while ((r = bms_next_member(relids, r)) > 0)
1990 : {
1991 22736 : RelOptInfo *inner = root->simple_rel_array[r];
1992 :
1993 22736 : k = r;
1994 :
1995 35468 : while ((k = bms_next_member(relids, k)) > 0)
1996 : {
1997 13320 : Relids joinrelids = NULL;
1998 13320 : RelOptInfo *outer = root->simple_rel_array[k];
1999 : List *restrictlist;
2000 : List *selfjoinquals;
2001 : List *otherjoinquals;
2002 : ListCell *lc;
2003 13320 : bool jinfo_check = true;
2004 13320 : PlanRowMark *omark = NULL;
2005 13320 : PlanRowMark *imark = NULL;
2006 13320 : List *uclauses = NIL;
2007 :
2008 : /* A sanity check: the relations have the same Oid. */
2009 : Assert(root->simple_rte_array[k]->relid ==
2010 : root->simple_rte_array[r]->relid);
2011 :
2012 : /*
2013 : * It is impossible to eliminate the join of two relations if they
2014 : * belong to different rules of order. Otherwise, the planner
2015 : * can't find any variants of the correct query plan.
2016 : */
2017 16470 : foreach(lc, root->join_info_list)
2018 : {
2019 10526 : SpecialJoinInfo *info = (SpecialJoinInfo *) lfirst(lc);
2020 :
2021 21052 : if ((bms_is_member(k, info->syn_lefthand) ^
2022 14942 : bms_is_member(r, info->syn_lefthand)) ||
2023 4416 : (bms_is_member(k, info->syn_righthand) ^
2024 4416 : bms_is_member(r, info->syn_righthand)))
2025 : {
2026 7376 : jinfo_check = false;
2027 7376 : break;
2028 : }
2029 : }
2030 13320 : if (!jinfo_check)
2031 12732 : continue;
2032 :
2033 : /*
2034 : * Check Row Marks equivalence. We can't remove the join if the
2035 : * relations have row marks of different strength (e.g., one is
2036 : * locked FOR UPDATE, and another just has ROW_MARK_REFERENCE for
2037 : * EvalPlanQual rechecking).
2038 : */
2039 6152 : foreach(lc, root->rowMarks)
2040 : {
2041 380 : PlanRowMark *rowMark = (PlanRowMark *) lfirst(lc);
2042 :
2043 380 : if (rowMark->rti == k)
2044 : {
2045 : Assert(imark == NULL);
2046 172 : imark = rowMark;
2047 : }
2048 208 : else if (rowMark->rti == r)
2049 : {
2050 : Assert(omark == NULL);
2051 172 : omark = rowMark;
2052 : }
2053 :
2054 380 : if (omark && imark)
2055 172 : break;
2056 : }
2057 5944 : if (omark && imark && omark->markType != imark->markType)
2058 52 : continue;
2059 :
2060 : /*
2061 : * We only deal with base rels here, so their relids bitset
2062 : * contains only one member -- their relid.
2063 : */
2064 5892 : joinrelids = bms_add_member(joinrelids, r);
2065 5892 : joinrelids = bms_add_member(joinrelids, k);
2066 :
2067 : /*
2068 : * PHVs should not impose any constraints on removing self-joins.
2069 : */
2070 :
2071 : /*
2072 : * At this stage, joininfo lists of inner and outer can contain
2073 : * only clauses required for a superior outer join that can't
2074 : * influence this optimization. So, we can avoid to call the
2075 : * build_joinrel_restrictlist() routine.
2076 : */
2077 5892 : restrictlist = generate_join_implied_equalities(root, joinrelids,
2078 : inner->relids,
2079 : outer, NULL);
2080 5892 : if (restrictlist == NIL)
2081 3916 : continue;
2082 :
2083 : /*
2084 : * Process restrictlist to separate the self-join quals from the
2085 : * other quals. e.g., "x = x" goes to selfjoinquals and "a = b" to
2086 : * otherjoinquals.
2087 : */
2088 1976 : split_selfjoin_quals(root, restrictlist, &selfjoinquals,
2089 1976 : &otherjoinquals, inner->relid, outer->relid);
2090 :
2091 : Assert(list_length(restrictlist) ==
2092 : (list_length(selfjoinquals) + list_length(otherjoinquals)));
2093 :
2094 : /*
2095 : * To enable SJE for the only degenerate case without any self
2096 : * join clauses at all, add baserestrictinfo to this list. The
2097 : * degenerate case works only if both sides have the same clause.
2098 : * So doesn't matter which side to add.
2099 : */
2100 1976 : selfjoinquals = list_concat(selfjoinquals, outer->baserestrictinfo);
2101 :
2102 : /*
2103 : * Determine if the inner table can duplicate outer rows. We must
2104 : * bypass the unique rel cache here since we're possibly using a
2105 : * subset of join quals. We can use 'force_cache' == true when all
2106 : * join quals are self-join quals. Otherwise, we could end up
2107 : * putting false negatives in the cache.
2108 : */
2109 1976 : if (!innerrel_is_unique_ext(root, joinrelids, inner->relids,
2110 : outer, JOIN_INNER, selfjoinquals,
2111 1976 : list_length(otherjoinquals) == 0,
2112 : &uclauses))
2113 1322 : continue;
2114 :
2115 : /*
2116 : * 'uclauses' is the copy of outer->baserestrictinfo that are
2117 : * associated with an index. We proved by matching selfjoinquals
2118 : * to a unique index that the outer relation has at most one
2119 : * matching row for each inner row. Sometimes that is not enough.
2120 : * e.g. "WHERE s1.b = s2.b AND s1.a = 1 AND s2.a = 2" when the
2121 : * unique index is (a,b). Having non-empty uclauses, we must
2122 : * validate that the inner baserestrictinfo contains the same
2123 : * expressions, or we won't match the same row on each side of the
2124 : * join.
2125 : */
2126 654 : if (!match_unique_clauses(root, inner, uclauses, outer->relid))
2127 66 : continue;
2128 :
2129 : /*
2130 : * We can remove either relation, so remove the inner one in order
2131 : * to simplify this loop.
2132 : */
2133 588 : remove_self_join_rel(root, omark, imark, outer, inner, restrictlist);
2134 :
2135 588 : result = bms_add_member(result, r);
2136 :
2137 : /* We have removed the outer relation, try the next one. */
2138 588 : break;
2139 : }
2140 : }
2141 :
2142 10788 : return result;
2143 : }
2144 :
2145 : /*
2146 : * Gather indexes of base relations from the joinlist and try to eliminate self
2147 : * joins.
2148 : */
2149 : static Relids
2150 95934 : remove_self_joins_recurse(PlannerInfo *root, List *joinlist, Relids toRemove)
2151 : {
2152 : ListCell *jl;
2153 95934 : Relids relids = NULL;
2154 95934 : SelfJoinCandidate *candidates = NULL;
2155 : int i;
2156 : int j;
2157 : int numRels;
2158 :
2159 : /* Collect indexes of base relations of the join tree */
2160 320622 : foreach(jl, joinlist)
2161 : {
2162 224688 : Node *jlnode = (Node *) lfirst(jl);
2163 :
2164 224688 : if (IsA(jlnode, RangeTblRef))
2165 : {
2166 221322 : int varno = ((RangeTblRef *) jlnode)->rtindex;
2167 221322 : RangeTblEntry *rte = root->simple_rte_array[varno];
2168 :
2169 : /*
2170 : * We only consider ordinary relations as candidates to be
2171 : * removed, and these relations should not have TABLESAMPLE
2172 : * clauses specified. Removing a relation with TABLESAMPLE clause
2173 : * could potentially change the syntax of the query. Because of
2174 : * UPDATE/DELETE EPQ mechanism, currently Query->resultRelation or
2175 : * Query->mergeTargetRelation associated rel cannot be eliminated.
2176 : */
2177 221322 : if (rte->rtekind == RTE_RELATION &&
2178 194984 : rte->relkind == RELKIND_RELATION &&
2179 189802 : rte->tablesample == NULL &&
2180 189778 : varno != root->parse->resultRelation &&
2181 188006 : varno != root->parse->mergeTargetRelation)
2182 : {
2183 : Assert(!bms_is_member(varno, relids));
2184 188006 : relids = bms_add_member(relids, varno);
2185 : }
2186 : }
2187 3366 : else if (IsA(jlnode, List))
2188 : {
2189 : /* Recursively go inside the sub-joinlist */
2190 3366 : toRemove = remove_self_joins_recurse(root, (List *) jlnode,
2191 : toRemove);
2192 : }
2193 : else
2194 0 : elog(ERROR, "unrecognized joinlist node type: %d",
2195 : (int) nodeTag(jlnode));
2196 : }
2197 :
2198 95934 : numRels = bms_num_members(relids);
2199 :
2200 : /* Need at least two relations for the join */
2201 95934 : if (numRels < 2)
2202 26946 : return toRemove;
2203 :
2204 : /*
2205 : * In order to find relations with the same oid we first build an array of
2206 : * candidates and then sort it by oid.
2207 : */
2208 68988 : candidates = (SelfJoinCandidate *) palloc(sizeof(SelfJoinCandidate) *
2209 : numRels);
2210 68988 : i = -1;
2211 68988 : j = 0;
2212 238030 : while ((i = bms_next_member(relids, i)) >= 0)
2213 : {
2214 169042 : candidates[j].relid = i;
2215 169042 : candidates[j].reloid = root->simple_rte_array[i]->relid;
2216 169042 : j++;
2217 : }
2218 :
2219 68988 : qsort(candidates, numRels, sizeof(SelfJoinCandidate),
2220 : self_join_candidates_cmp);
2221 :
2222 : /*
2223 : * Iteratively form a group of relation indexes with the same oid and
2224 : * launch the routine that detects self-joins in this group and removes
2225 : * excessive range table entries.
2226 : *
2227 : * At the end of the iteration, exclude the group from the overall relids
2228 : * list. So each next iteration of the cycle will involve less and less
2229 : * value of relids.
2230 : */
2231 68988 : i = 0;
2232 238030 : for (j = 1; j < numRels + 1; j++)
2233 : {
2234 169042 : if (j == numRels || candidates[j].reloid != candidates[i].reloid)
2235 : {
2236 157166 : if (j - i >= 2)
2237 : {
2238 : /* Create a group of relation indexes with the same oid */
2239 10722 : Relids group = NULL;
2240 : Relids removed;
2241 :
2242 33320 : while (i < j)
2243 : {
2244 22598 : group = bms_add_member(group, candidates[i].relid);
2245 22598 : i++;
2246 : }
2247 10722 : relids = bms_del_members(relids, group);
2248 :
2249 : /*
2250 : * Try to remove self-joins from a group of identical entries.
2251 : * Make the next attempt iteratively - if something is deleted
2252 : * from a group, changes in clauses and equivalence classes
2253 : * can give us a chance to find more candidates.
2254 : */
2255 : do
2256 : {
2257 : Assert(!bms_overlap(group, toRemove));
2258 10788 : removed = remove_self_joins_one_group(root, group);
2259 10788 : toRemove = bms_add_members(toRemove, removed);
2260 10788 : group = bms_del_members(group, removed);
2261 564 : } while (!bms_is_empty(removed) &&
2262 10788 : bms_membership(group) == BMS_MULTIPLE);
2263 10722 : bms_free(removed);
2264 10722 : bms_free(group);
2265 : }
2266 : else
2267 : {
2268 : /* Single relation, just remove it from the set */
2269 146444 : relids = bms_del_member(relids, candidates[i].relid);
2270 146444 : i = j;
2271 : }
2272 : }
2273 : }
2274 :
2275 : Assert(bms_is_empty(relids));
2276 :
2277 68988 : return toRemove;
2278 : }
2279 :
2280 : /*
2281 : * Compare self-join candidates by their oids.
2282 : */
2283 : static int
2284 125212 : self_join_candidates_cmp(const void *a, const void *b)
2285 : {
2286 125212 : const SelfJoinCandidate *ca = (const SelfJoinCandidate *) a;
2287 125212 : const SelfJoinCandidate *cb = (const SelfJoinCandidate *) b;
2288 :
2289 125212 : if (ca->reloid != cb->reloid)
2290 113282 : return (ca->reloid < cb->reloid ? -1 : 1);
2291 : else
2292 11930 : return 0;
2293 : }
2294 :
2295 : /*
2296 : * Find and remove useless self joins.
2297 : *
2298 : * Search for joins where a relation is joined to itself. If the join clause
2299 : * for each tuple from one side of the join is proven to match the same
2300 : * physical row (or nothing) on the other side, that self-join can be
2301 : * eliminated from the query. Suitable join clauses are assumed to be in the
2302 : * form of X = X, and can be replaced with NOT NULL clauses.
2303 : *
2304 : * For the sake of simplicity, we don't apply this optimization to special
2305 : * joins. Here is a list of what we could do in some particular cases:
2306 : * 'a a1 semi join a a2': is reduced to inner by reduce_unique_semijoins,
2307 : * and then removed normally.
2308 : * 'a a1 anti join a a2': could simplify to a scan with 'outer quals AND
2309 : * (IS NULL on join columns OR NOT inner quals)'.
2310 : * 'a a1 left join a a2': could simplify to a scan like inner but without
2311 : * NOT NULL conditions on join columns.
2312 : * 'a a1 left join (a a2 join b)': can't simplify this, because join to b
2313 : * can both remove rows and introduce duplicates.
2314 : *
2315 : * To search for removable joins, we order all the relations on their Oid,
2316 : * go over each set with the same Oid, and consider each pair of relations
2317 : * in this set.
2318 : *
2319 : * To remove the join, we mark one of the participating relations as dead
2320 : * and rewrite all references to it to point to the remaining relation.
2321 : * This includes modifying RestrictInfos, EquivalenceClasses, and
2322 : * EquivalenceMembers. We also have to modify the row marks. The join clauses
2323 : * of the removed relation become either restriction or join clauses, based on
2324 : * whether they reference any relations not participating in the removed join.
2325 : *
2326 : * 'joinlist' is the top-level joinlist of the query. If it has any
2327 : * references to the removed relations, we update them to point to the
2328 : * remaining ones.
2329 : */
2330 : List *
2331 314632 : remove_useless_self_joins(PlannerInfo *root, List *joinlist)
2332 : {
2333 314632 : Relids toRemove = NULL;
2334 314632 : int relid = -1;
2335 :
2336 629264 : if (!enable_self_join_elimination || joinlist == NIL ||
2337 537564 : (list_length(joinlist) == 1 && !IsA(linitial(joinlist), List)))
2338 222064 : return joinlist;
2339 :
2340 : /*
2341 : * Merge pairs of relations participated in self-join. Remove unnecessary
2342 : * range table entries.
2343 : */
2344 92568 : toRemove = remove_self_joins_recurse(root, joinlist, toRemove);
2345 :
2346 92568 : if (unlikely(toRemove != NULL))
2347 : {
2348 : /* At the end, remove orphaned relation links */
2349 1146 : while ((relid = bms_next_member(toRemove, relid)) >= 0)
2350 : {
2351 588 : int nremoved = 0;
2352 :
2353 588 : joinlist = remove_rel_from_joinlist(joinlist, relid, &nremoved);
2354 588 : if (nremoved != 1)
2355 0 : elog(ERROR, "failed to find relation %d in joinlist", relid);
2356 : }
2357 : }
2358 :
2359 92568 : return joinlist;
2360 : }
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