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 339930 : 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 339930 : restart:
97 383872 : foreach(lc, root->join_info_list)
98 : {
99 54904 : SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
100 : int innerrelid;
101 : int nremoved;
102 :
103 : /* Skip if not removable */
104 54904 : if (!join_is_removable(root, sjinfo))
105 43942 : 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 10962 : innerrelid = bms_singleton_member(sjinfo->min_righthand);
113 :
114 10962 : remove_leftjoinrel_from_query(root, innerrelid, sjinfo);
115 :
116 : /* We verify that exactly one reference gets removed from joinlist */
117 10962 : nremoved = 0;
118 10962 : joinlist = remove_rel_from_joinlist(joinlist, innerrelid, &nremoved);
119 10962 : 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 10962 : 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 10962 : goto restart;
136 : }
137 :
138 328968 : 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 54904 : join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo)
154 : {
155 : int innerrelid;
156 : RelOptInfo *innerrel;
157 : Relids inputrelids;
158 : Relids joinrelids;
159 54904 : 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 54904 : if (sjinfo->jointype != JOIN_LEFT)
168 9940 : return false;
169 :
170 44964 : if (!bms_get_singleton_member(sjinfo->min_righthand, &innerrelid))
171 1298 : 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 43666 : if (innerrelid == root->parse->resultRelation)
179 758 : return false;
180 :
181 42908 : 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 42908 : if (!rel_supports_distinctness(root, innerrel))
189 3116 : return false;
190 :
191 : /* Compute the relid set for the join we are considering */
192 39792 : inputrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
193 : Assert(sjinfo->ojrelid != 0);
194 39792 : joinrelids = bms_copy(inputrelids);
195 39792 : 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 356730 : for (attroff = innerrel->max_attr - innerrel->min_attr;
209 : attroff >= 0;
210 316938 : attroff--)
211 : {
212 345606 : if (!bms_is_subset(innerrel->attr_needed[attroff], inputrelids))
213 28668 : 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 11316 : 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 22486 : foreach(l, innerrel->joininfo)
258 : {
259 11398 : 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 11398 : if (restrictinfo->is_clone)
270 100 : 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 11298 : 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 11178 : if (!restrictinfo->can_join ||
283 11106 : restrictinfo->mergeopfamilies == NIL)
284 72 : 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 11106 : 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 11100 : 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 11088 : if (rel_is_distinct_for(root, innerrel, clause_list, NULL))
303 10962 : 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 11550 : remove_rel_from_query(PlannerInfo *root, RelOptInfo *rel,
324 : int subst, SpecialJoinInfo *sjinfo,
325 : Relids joinrelids)
326 : {
327 11550 : int relid = rel->relid;
328 : Index rti;
329 : ListCell *l;
330 :
331 : /*
332 : * Update all_baserels and related relid sets.
333 : */
334 11550 : root->all_baserels = adjust_relid_set(root->all_baserels, relid, subst);
335 11550 : root->all_query_rels = adjust_relid_set(root->all_query_rels, relid, subst);
336 :
337 11550 : if (sjinfo != NULL)
338 : {
339 21924 : root->outer_join_rels = bms_del_member(root->outer_join_rels,
340 10962 : sjinfo->ojrelid);
341 10962 : root->all_query_rels = bms_del_member(root->all_query_rels,
342 10962 : 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 26318 : foreach(l, root->join_info_list)
354 : {
355 14768 : 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 14768 : sjinf->min_lefthand = bms_copy(sjinf->min_lefthand);
364 14768 : sjinf->min_righthand = bms_copy(sjinf->min_righthand);
365 14768 : sjinf->syn_lefthand = bms_copy(sjinf->syn_lefthand);
366 14768 : sjinf->syn_righthand = bms_copy(sjinf->syn_righthand);
367 : /* Now remove relid from the sets: */
368 14768 : sjinf->min_lefthand = adjust_relid_set(sjinf->min_lefthand, relid, subst);
369 14768 : sjinf->min_righthand = adjust_relid_set(sjinf->min_righthand, relid, subst);
370 14768 : sjinf->syn_lefthand = adjust_relid_set(sjinf->syn_lefthand, relid, subst);
371 14768 : sjinf->syn_righthand = adjust_relid_set(sjinf->syn_righthand, relid, subst);
372 :
373 14768 : if (sjinfo != NULL)
374 : {
375 : Assert(subst <= 0);
376 :
377 : /* Remove sjinfo->ojrelid bits from the sets: */
378 29344 : sjinf->min_lefthand = bms_del_member(sjinf->min_lefthand,
379 14672 : sjinfo->ojrelid);
380 29344 : sjinf->min_righthand = bms_del_member(sjinf->min_righthand,
381 14672 : sjinfo->ojrelid);
382 29344 : sjinf->syn_lefthand = bms_del_member(sjinf->syn_lefthand,
383 14672 : sjinfo->ojrelid);
384 29344 : sjinf->syn_righthand = bms_del_member(sjinf->syn_righthand,
385 14672 : sjinfo->ojrelid);
386 : /* relid cannot appear in these fields, but ojrelid can: */
387 29344 : sjinf->commute_above_l = bms_del_member(sjinf->commute_above_l,
388 14672 : sjinfo->ojrelid);
389 29344 : sjinf->commute_above_r = bms_del_member(sjinf->commute_above_r,
390 14672 : sjinfo->ojrelid);
391 29344 : sjinf->commute_below_l = bms_del_member(sjinf->commute_below_l,
392 14672 : sjinfo->ojrelid);
393 14672 : sjinf->commute_below_r = bms_del_member(sjinf->commute_below_r,
394 14672 : 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 11760 : 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 60642 : foreach(l, root->eq_classes)
471 : {
472 49092 : EquivalenceClass *ec = (EquivalenceClass *) lfirst(l);
473 :
474 49092 : if (bms_is_member(relid, ec->ec_relids) ||
475 32340 : (sjinfo == NULL || bms_is_member(sjinfo->ojrelid, ec->ec_relids)))
476 16752 : 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 71978 : for (rti = 1; rti < root->simple_rel_array_size; rti++)
494 : {
495 60428 : RelOptInfo *otherrel = root->simple_rel_array[rti];
496 : int attroff;
497 :
498 : /* there may be empty slots corresponding to non-baserel RTEs */
499 60428 : if (otherrel == NULL)
500 29440 : continue;
501 :
502 : Assert(otherrel->relid == rti); /* sanity check on array */
503 :
504 687478 : for (attroff = otherrel->max_attr - otherrel->min_attr;
505 : attroff >= 0;
506 656490 : attroff--)
507 : {
508 656490 : if (bms_is_member(0, otherrel->attr_needed[attroff]))
509 46828 : otherrel->attr_needed[attroff] = bms_make_singleton(0);
510 : else
511 609662 : otherrel->attr_needed[attroff] = NULL;
512 : }
513 :
514 30988 : if (subst > 0)
515 1460 : ChangeVarNodes((Node *) otherrel->lateral_vars, relid, subst, 0);
516 : }
517 11550 : }
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 10962 : remove_leftjoinrel_from_query(PlannerInfo *root, int relid,
529 : SpecialJoinInfo *sjinfo)
530 : {
531 10962 : RelOptInfo *rel = find_base_rel(root, relid);
532 10962 : 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 10962 : joinrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
540 : Assert(ojrelid != 0);
541 10962 : joinrelids = bms_add_member(joinrelids, ojrelid);
542 :
543 10962 : 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 10962 : join_plus_commute = bms_union(joinrelids,
562 10962 : sjinfo->commute_above_r);
563 10962 : join_plus_commute = bms_add_members(join_plus_commute,
564 10962 : 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 10962 : joininfos = list_copy(rel->joininfo);
572 22258 : foreach(l, joininfos)
573 : {
574 11296 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
575 :
576 11296 : remove_join_clause_from_rels(root, rinfo, rinfo->required_relids);
577 :
578 11296 : 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 10962 : root->simple_rel_array[relid] = NULL;
618 :
619 : /* And nuke the RelOptInfo, just in case there's another access path */
620 10962 : pfree(rel);
621 :
622 : /*
623 : * Now repeat construction of attr_needed bits coming from all other
624 : * sources.
625 : */
626 10962 : rebuild_placeholder_attr_needed(root);
627 10962 : rebuild_joinclause_attr_needed(root);
628 10962 : rebuild_eclass_attr_needed(root);
629 10962 : rebuild_lateral_attr_needed(root);
630 10962 : }
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 4788 : 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 4788 : rinfo->clause_relids = bms_copy(rinfo->clause_relids);
651 4788 : rinfo->clause_relids = bms_del_member(rinfo->clause_relids, relid);
652 4788 : rinfo->clause_relids = bms_del_member(rinfo->clause_relids, ojrelid);
653 : /* Likewise for required_relids */
654 4788 : rinfo->required_relids = bms_copy(rinfo->required_relids);
655 4788 : rinfo->required_relids = bms_del_member(rinfo->required_relids, relid);
656 4788 : rinfo->required_relids = bms_del_member(rinfo->required_relids, ojrelid);
657 :
658 : /* If it's an OR, recurse to clean up sub-clauses */
659 4788 : 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 4788 : }
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 16752 : 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 16752 : ec->ec_relids = adjust_relid_set(ec->ec_relids, relid, subst);
709 16752 : if (sjinfo != NULL)
710 15714 : ec->ec_relids = adjust_relid_set(ec->ec_relids,
711 15714 : sjinfo->ojrelid, subst);
712 :
713 : /*
714 : * We don't expect any EC child members to exist at this point. Ensure
715 : * that's the case, otherwise, we might be getting asked to do something
716 : * this function hasn't been coded for.
717 : */
718 : Assert(ec->ec_childmembers == NULL);
719 :
720 : /*
721 : * Fix up the member expressions. Any non-const member that ends with
722 : * empty em_relids must be a Var or PHV of the removed relation. We don't
723 : * need it anymore, so we can drop it.
724 : */
725 38930 : foreach(lc, ec->ec_members)
726 : {
727 22178 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
728 :
729 22178 : if (bms_is_member(relid, cur_em->em_relids) ||
730 4656 : (sjinfo != NULL && bms_is_member(sjinfo->ojrelid,
731 4656 : cur_em->em_relids)))
732 : {
733 : Assert(!cur_em->em_is_const);
734 15714 : cur_em->em_relids = adjust_relid_set(cur_em->em_relids, relid, subst);
735 15714 : if (sjinfo != NULL)
736 15714 : cur_em->em_relids = adjust_relid_set(cur_em->em_relids,
737 15714 : sjinfo->ojrelid, subst);
738 15714 : if (bms_is_empty(cur_em->em_relids))
739 15702 : ec->ec_members = foreach_delete_current(ec->ec_members, lc);
740 : }
741 : }
742 :
743 : /* Fix up the source clauses, in case we can re-use them later */
744 22446 : foreach(lc, ec->ec_sources)
745 : {
746 5694 : RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
747 :
748 5694 : if (sjinfo == NULL)
749 1038 : ChangeVarNodes((Node *) rinfo, relid, subst, 0);
750 : else
751 4656 : remove_rel_from_restrictinfo(rinfo, relid, sjinfo->ojrelid);
752 : }
753 :
754 : /*
755 : * Rather than expend code on fixing up any already-derived clauses, just
756 : * drop them. (At this point, any such clauses would be base restriction
757 : * clauses, which we'd not need anymore anyway.)
758 : */
759 16752 : ec_clear_derived_clauses(ec);
760 16752 : }
761 :
762 : /*
763 : * Remove any occurrences of the target relid from a joinlist structure.
764 : *
765 : * It's easiest to build a whole new list structure, so we handle it that
766 : * way. Efficiency is not a big deal here.
767 : *
768 : * *nremoved is incremented by the number of occurrences removed (there
769 : * should be exactly one, but the caller checks that).
770 : */
771 : static List *
772 11814 : remove_rel_from_joinlist(List *joinlist, int relid, int *nremoved)
773 : {
774 11814 : List *result = NIL;
775 : ListCell *jl;
776 :
777 43066 : foreach(jl, joinlist)
778 : {
779 31252 : Node *jlnode = (Node *) lfirst(jl);
780 :
781 31252 : if (IsA(jlnode, RangeTblRef))
782 : {
783 30988 : int varno = ((RangeTblRef *) jlnode)->rtindex;
784 :
785 30988 : if (varno == relid)
786 11550 : (*nremoved)++;
787 : else
788 19438 : result = lappend(result, jlnode);
789 : }
790 264 : else if (IsA(jlnode, List))
791 : {
792 : /* Recurse to handle subproblem */
793 : List *sublist;
794 :
795 264 : sublist = remove_rel_from_joinlist((List *) jlnode,
796 : relid, nremoved);
797 : /* Avoid including empty sub-lists in the result */
798 264 : if (sublist)
799 264 : result = lappend(result, sublist);
800 : }
801 : else
802 : {
803 0 : elog(ERROR, "unrecognized joinlist node type: %d",
804 : (int) nodeTag(jlnode));
805 : }
806 : }
807 :
808 11814 : return result;
809 : }
810 :
811 :
812 : /*
813 : * reduce_unique_semijoins
814 : * Check for semijoins that can be simplified to plain inner joins
815 : * because the inner relation is provably unique for the join clauses.
816 : *
817 : * Ideally this would happen during reduce_outer_joins, but we don't have
818 : * enough information at that point.
819 : *
820 : * To perform the strength reduction when applicable, we need only delete
821 : * the semijoin's SpecialJoinInfo from root->join_info_list. (We don't
822 : * bother fixing the join type attributed to it in the query jointree,
823 : * since that won't be consulted again.)
824 : */
825 : void
826 328968 : reduce_unique_semijoins(PlannerInfo *root)
827 : {
828 : ListCell *lc;
829 :
830 : /*
831 : * Scan the join_info_list to find semijoins.
832 : */
833 372684 : foreach(lc, root->join_info_list)
834 : {
835 43716 : SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
836 : int innerrelid;
837 : RelOptInfo *innerrel;
838 : Relids joinrelids;
839 : List *restrictlist;
840 :
841 : /*
842 : * Must be a semijoin to a single baserel, else we aren't going to be
843 : * able to do anything with it.
844 : */
845 43716 : if (sjinfo->jointype != JOIN_SEMI)
846 43406 : continue;
847 :
848 4812 : if (!bms_get_singleton_member(sjinfo->min_righthand, &innerrelid))
849 164 : continue;
850 :
851 4648 : innerrel = find_base_rel(root, innerrelid);
852 :
853 : /*
854 : * Before we trouble to run generate_join_implied_equalities, make a
855 : * quick check to eliminate cases in which we will surely be unable to
856 : * prove uniqueness of the innerrel.
857 : */
858 4648 : if (!rel_supports_distinctness(root, innerrel))
859 944 : continue;
860 :
861 : /* Compute the relid set for the join we are considering */
862 3704 : joinrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
863 : Assert(sjinfo->ojrelid == 0); /* SEMI joins don't have RT indexes */
864 :
865 : /*
866 : * Since we're only considering a single-rel RHS, any join clauses it
867 : * has must be clauses linking it to the semijoin's min_lefthand. We
868 : * can also consider EC-derived join clauses.
869 : */
870 : restrictlist =
871 3704 : list_concat(generate_join_implied_equalities(root,
872 : joinrelids,
873 : sjinfo->min_lefthand,
874 : innerrel,
875 : NULL),
876 3704 : innerrel->joininfo);
877 :
878 : /* Test whether the innerrel is unique for those clauses. */
879 3704 : if (!innerrel_is_unique(root,
880 : joinrelids, sjinfo->min_lefthand, innerrel,
881 : JOIN_SEMI, restrictlist, true))
882 3394 : continue;
883 :
884 : /* OK, remove the SpecialJoinInfo from the list. */
885 310 : root->join_info_list = foreach_delete_current(root->join_info_list, lc);
886 : }
887 328968 : }
888 :
889 :
890 : /*
891 : * rel_supports_distinctness
892 : * Could the relation possibly be proven distinct on some set of columns?
893 : *
894 : * This is effectively a pre-checking function for rel_is_distinct_for().
895 : * It must return true if rel_is_distinct_for() could possibly return true
896 : * with this rel, but it should not expend a lot of cycles. The idea is
897 : * that callers can avoid doing possibly-expensive processing to compute
898 : * rel_is_distinct_for()'s argument lists if the call could not possibly
899 : * succeed.
900 : */
901 : static bool
902 614782 : rel_supports_distinctness(PlannerInfo *root, RelOptInfo *rel)
903 : {
904 : /* We only know about baserels ... */
905 614782 : if (rel->reloptkind != RELOPT_BASEREL)
906 201298 : return false;
907 413484 : if (rel->rtekind == RTE_RELATION)
908 : {
909 : /*
910 : * For a plain relation, we only know how to prove uniqueness by
911 : * reference to unique indexes. Make sure there's at least one
912 : * suitable unique index. It must be immediately enforced, and not a
913 : * partial index. (Keep these conditions in sync with
914 : * relation_has_unique_index_for!)
915 : */
916 : ListCell *lc;
917 :
918 523678 : foreach(lc, rel->indexlist)
919 : {
920 470414 : IndexOptInfo *ind = (IndexOptInfo *) lfirst(lc);
921 :
922 470414 : if (ind->unique && ind->immediate && ind->indpred == NIL)
923 322472 : return true;
924 : }
925 : }
926 37748 : else if (rel->rtekind == RTE_SUBQUERY)
927 : {
928 10130 : Query *subquery = root->simple_rte_array[rel->relid]->subquery;
929 :
930 : /* Check if the subquery has any qualities that support distinctness */
931 10130 : if (query_supports_distinctness(subquery))
932 8212 : return true;
933 : }
934 : /* We have no proof rules for any other rtekinds. */
935 82800 : return false;
936 : }
937 :
938 : /*
939 : * rel_is_distinct_for
940 : * Does the relation return only distinct rows according to clause_list?
941 : *
942 : * clause_list is a list of join restriction clauses involving this rel and
943 : * some other one. Return true if no two rows emitted by this rel could
944 : * possibly join to the same row of the other rel.
945 : *
946 : * The caller must have already determined that each condition is a
947 : * mergejoinable equality with an expression in this relation on one side, and
948 : * an expression not involving this relation on the other. The transient
949 : * outer_is_left flag is used to identify which side references this relation:
950 : * left side if outer_is_left is false, right side if it is true.
951 : *
952 : * Note that the passed-in clause_list may be destructively modified! This
953 : * is OK for current uses, because the clause_list is built by the caller for
954 : * the sole purpose of passing to this function.
955 : *
956 : * (*extra_clauses) to be set to the right sides of baserestrictinfo clauses,
957 : * looking like "x = const" if distinctness is derived from such clauses, not
958 : * joininfo clauses. Pass NULL to the extra_clauses if this value is not
959 : * needed.
960 : */
961 : static bool
962 209214 : rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel, List *clause_list,
963 : List **extra_clauses)
964 : {
965 : /*
966 : * We could skip a couple of tests here if we assume all callers checked
967 : * rel_supports_distinctness first, but it doesn't seem worth taking any
968 : * risk for.
969 : */
970 209214 : if (rel->reloptkind != RELOPT_BASEREL)
971 0 : return false;
972 209214 : if (rel->rtekind == RTE_RELATION)
973 : {
974 : /*
975 : * Examine the indexes to see if we have a matching unique index.
976 : * relation_has_unique_index_ext automatically adds any usable
977 : * restriction clauses for the rel, so we needn't do that here.
978 : */
979 204542 : if (relation_has_unique_index_ext(root, rel, clause_list, NIL, NIL,
980 : extra_clauses))
981 117166 : return true;
982 : }
983 4672 : else if (rel->rtekind == RTE_SUBQUERY)
984 : {
985 4672 : Index relid = rel->relid;
986 4672 : Query *subquery = root->simple_rte_array[relid]->subquery;
987 4672 : List *colnos = NIL;
988 4672 : List *opids = NIL;
989 : ListCell *l;
990 :
991 : /*
992 : * Build the argument lists for query_is_distinct_for: a list of
993 : * output column numbers that the query needs to be distinct over, and
994 : * a list of equality operators that the output columns need to be
995 : * distinct according to.
996 : *
997 : * (XXX we are not considering restriction clauses attached to the
998 : * subquery; is that worth doing?)
999 : */
1000 9308 : foreach(l, clause_list)
1001 : {
1002 4636 : RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
1003 : Oid op;
1004 : Var *var;
1005 :
1006 : /*
1007 : * Get the equality operator we need uniqueness according to.
1008 : * (This might be a cross-type operator and thus not exactly the
1009 : * same operator the subquery would consider; that's all right
1010 : * since query_is_distinct_for can resolve such cases.) The
1011 : * caller's mergejoinability test should have selected only
1012 : * OpExprs.
1013 : */
1014 4636 : op = castNode(OpExpr, rinfo->clause)->opno;
1015 :
1016 : /* caller identified the inner side for us */
1017 4636 : if (rinfo->outer_is_left)
1018 4298 : var = (Var *) get_rightop(rinfo->clause);
1019 : else
1020 338 : var = (Var *) get_leftop(rinfo->clause);
1021 :
1022 : /*
1023 : * We may ignore any RelabelType node above the operand. (There
1024 : * won't be more than one, since eval_const_expressions() has been
1025 : * applied already.)
1026 : */
1027 4636 : if (var && IsA(var, RelabelType))
1028 3176 : var = (Var *) ((RelabelType *) var)->arg;
1029 :
1030 : /*
1031 : * If inner side isn't a Var referencing a subquery output column,
1032 : * this clause doesn't help us.
1033 : */
1034 4636 : if (!var || !IsA(var, Var) ||
1035 4624 : var->varno != relid || var->varlevelsup != 0)
1036 12 : continue;
1037 :
1038 4624 : colnos = lappend_int(colnos, var->varattno);
1039 4624 : opids = lappend_oid(opids, op);
1040 : }
1041 :
1042 4672 : if (query_is_distinct_for(subquery, colnos, opids))
1043 212 : return true;
1044 : }
1045 91836 : return false;
1046 : }
1047 :
1048 :
1049 : /*
1050 : * query_supports_distinctness - could the query possibly be proven distinct
1051 : * on some set of output columns?
1052 : *
1053 : * This is effectively a pre-checking function for query_is_distinct_for().
1054 : * It must return true if query_is_distinct_for() could possibly return true
1055 : * with this query, but it should not expend a lot of cycles. The idea is
1056 : * that callers can avoid doing possibly-expensive processing to compute
1057 : * query_is_distinct_for()'s argument lists if the call could not possibly
1058 : * succeed.
1059 : */
1060 : bool
1061 13432 : query_supports_distinctness(Query *query)
1062 : {
1063 : /* SRFs break distinctness except with DISTINCT, see below */
1064 13432 : if (query->hasTargetSRFs && query->distinctClause == NIL)
1065 1008 : return false;
1066 :
1067 : /* check for features we can prove distinctness with */
1068 12424 : if (query->distinctClause != NIL ||
1069 12280 : query->groupClause != NIL ||
1070 12092 : query->groupingSets != NIL ||
1071 12092 : query->hasAggs ||
1072 11820 : query->havingQual ||
1073 11820 : query->setOperations)
1074 11460 : return true;
1075 :
1076 964 : return false;
1077 : }
1078 :
1079 : /*
1080 : * query_is_distinct_for - does query never return duplicates of the
1081 : * specified columns?
1082 : *
1083 : * query is a not-yet-planned subquery (in current usage, it's always from
1084 : * a subquery RTE, which the planner avoids scribbling on).
1085 : *
1086 : * colnos is an integer list of output column numbers (resno's). We are
1087 : * interested in whether rows consisting of just these columns are certain
1088 : * to be distinct. "Distinctness" is defined according to whether the
1089 : * corresponding upper-level equality operators listed in opids would think
1090 : * the values are distinct. (Note: the opids entries could be cross-type
1091 : * operators, and thus not exactly the equality operators that the subquery
1092 : * would use itself. We use equality_ops_are_compatible() to check
1093 : * compatibility. That looks at opfamily membership for index AMs that have
1094 : * declared that they support consistent equality semantics within an
1095 : * opfamily, and so should give trustworthy answers for all operators that we
1096 : * might need to deal with here.)
1097 : */
1098 : bool
1099 4868 : query_is_distinct_for(Query *query, List *colnos, List *opids)
1100 : {
1101 : ListCell *l;
1102 : Oid opid;
1103 :
1104 : Assert(list_length(colnos) == list_length(opids));
1105 :
1106 : /*
1107 : * DISTINCT (including DISTINCT ON) guarantees uniqueness if all the
1108 : * columns in the DISTINCT clause appear in colnos and operator semantics
1109 : * match. This is true even if there are SRFs in the DISTINCT columns or
1110 : * elsewhere in the tlist.
1111 : */
1112 4868 : if (query->distinctClause)
1113 : {
1114 150 : foreach(l, query->distinctClause)
1115 : {
1116 120 : SortGroupClause *sgc = (SortGroupClause *) lfirst(l);
1117 120 : TargetEntry *tle = get_sortgroupclause_tle(sgc,
1118 : query->targetList);
1119 :
1120 120 : opid = distinct_col_search(tle->resno, colnos, opids);
1121 120 : if (!OidIsValid(opid) ||
1122 48 : !equality_ops_are_compatible(opid, sgc->eqop))
1123 : break; /* exit early if no match */
1124 : }
1125 102 : if (l == NULL) /* had matches for all? */
1126 30 : return true;
1127 : }
1128 :
1129 : /*
1130 : * Otherwise, a set-returning function in the query's targetlist can
1131 : * result in returning duplicate rows, despite any grouping that might
1132 : * occur before tlist evaluation. (If all tlist SRFs are within GROUP BY
1133 : * columns, it would be safe because they'd be expanded before grouping.
1134 : * But it doesn't currently seem worth the effort to check for that.)
1135 : */
1136 4838 : if (query->hasTargetSRFs)
1137 0 : return false;
1138 :
1139 : /*
1140 : * Similarly, GROUP BY without GROUPING SETS guarantees uniqueness if all
1141 : * the grouped columns appear in colnos and operator semantics match.
1142 : */
1143 4838 : if (query->groupClause && !query->groupingSets)
1144 : {
1145 234 : foreach(l, query->groupClause)
1146 : {
1147 164 : SortGroupClause *sgc = (SortGroupClause *) lfirst(l);
1148 164 : TargetEntry *tle = get_sortgroupclause_tle(sgc,
1149 : query->targetList);
1150 :
1151 164 : opid = distinct_col_search(tle->resno, colnos, opids);
1152 164 : if (!OidIsValid(opid) ||
1153 112 : !equality_ops_are_compatible(opid, sgc->eqop))
1154 : break; /* exit early if no match */
1155 : }
1156 122 : if (l == NULL) /* had matches for all? */
1157 70 : return true;
1158 : }
1159 4716 : else if (query->groupingSets)
1160 : {
1161 : /*
1162 : * If we have grouping sets with expressions, we probably don't have
1163 : * uniqueness and analysis would be hard. Punt.
1164 : */
1165 0 : if (query->groupClause)
1166 0 : return false;
1167 :
1168 : /*
1169 : * If we have no groupClause (therefore no grouping expressions), we
1170 : * might have one or many empty grouping sets. If there's just one,
1171 : * then we're returning only one row and are certainly unique. But
1172 : * otherwise, we know we're certainly not unique.
1173 : */
1174 0 : if (list_length(query->groupingSets) == 1 &&
1175 0 : ((GroupingSet *) linitial(query->groupingSets))->kind == GROUPING_SET_EMPTY)
1176 0 : return true;
1177 : else
1178 0 : return false;
1179 : }
1180 : else
1181 : {
1182 : /*
1183 : * If we have no GROUP BY, but do have aggregates or HAVING, then the
1184 : * result is at most one row so it's surely unique, for any operators.
1185 : */
1186 4716 : if (query->hasAggs || query->havingQual)
1187 100 : return true;
1188 : }
1189 :
1190 : /*
1191 : * UNION, INTERSECT, EXCEPT guarantee uniqueness of the whole output row,
1192 : * except with ALL.
1193 : */
1194 4668 : if (query->setOperations)
1195 : {
1196 4544 : SetOperationStmt *topop = castNode(SetOperationStmt, query->setOperations);
1197 :
1198 : Assert(topop->op != SETOP_NONE);
1199 :
1200 4544 : if (!topop->all)
1201 : {
1202 : ListCell *lg;
1203 :
1204 : /* We're good if all the nonjunk output columns are in colnos */
1205 72 : lg = list_head(topop->groupClauses);
1206 90 : foreach(l, query->targetList)
1207 : {
1208 78 : TargetEntry *tle = (TargetEntry *) lfirst(l);
1209 : SortGroupClause *sgc;
1210 :
1211 78 : if (tle->resjunk)
1212 0 : continue; /* ignore resjunk columns */
1213 :
1214 : /* non-resjunk columns should have grouping clauses */
1215 : Assert(lg != NULL);
1216 78 : sgc = (SortGroupClause *) lfirst(lg);
1217 78 : lg = lnext(topop->groupClauses, lg);
1218 :
1219 78 : opid = distinct_col_search(tle->resno, colnos, opids);
1220 78 : if (!OidIsValid(opid) ||
1221 18 : !equality_ops_are_compatible(opid, sgc->eqop))
1222 : break; /* exit early if no match */
1223 : }
1224 72 : if (l == NULL) /* had matches for all? */
1225 12 : return true;
1226 : }
1227 : }
1228 :
1229 : /*
1230 : * XXX Are there any other cases in which we can easily see the result
1231 : * must be distinct?
1232 : *
1233 : * If you do add more smarts to this function, be sure to update
1234 : * query_supports_distinctness() to match.
1235 : */
1236 :
1237 4656 : return false;
1238 : }
1239 :
1240 : /*
1241 : * distinct_col_search - subroutine for query_is_distinct_for
1242 : *
1243 : * If colno is in colnos, return the corresponding element of opids,
1244 : * else return InvalidOid. (Ordinarily colnos would not contain duplicates,
1245 : * but if it does, we arbitrarily select the first match.)
1246 : */
1247 : static Oid
1248 362 : distinct_col_search(int colno, List *colnos, List *opids)
1249 : {
1250 : ListCell *lc1,
1251 : *lc2;
1252 :
1253 574 : forboth(lc1, colnos, lc2, opids)
1254 : {
1255 390 : if (colno == lfirst_int(lc1))
1256 178 : return lfirst_oid(lc2);
1257 : }
1258 184 : return InvalidOid;
1259 : }
1260 :
1261 :
1262 : /*
1263 : * innerrel_is_unique
1264 : * Check if the innerrel provably contains at most one tuple matching any
1265 : * tuple from the outerrel, based on join clauses in the 'restrictlist'.
1266 : *
1267 : * We need an actual RelOptInfo for the innerrel, but it's sufficient to
1268 : * identify the outerrel by its Relids. This asymmetry supports use of this
1269 : * function before joinrels have been built. (The caller is expected to
1270 : * also supply the joinrelids, just to save recalculating that.)
1271 : *
1272 : * The proof must be made based only on clauses that will be "joinquals"
1273 : * rather than "otherquals" at execution. For an inner join there's no
1274 : * difference; but if the join is outer, we must ignore pushed-down quals,
1275 : * as those will become "otherquals". Note that this means the answer might
1276 : * vary depending on whether IS_OUTER_JOIN(jointype); since we cache the
1277 : * answer without regard to that, callers must take care not to call this
1278 : * with jointypes that would be classified differently by IS_OUTER_JOIN().
1279 : *
1280 : * The actual proof is undertaken by is_innerrel_unique_for(); this function
1281 : * is a frontend that is mainly concerned with caching the answers.
1282 : * In particular, the force_cache argument allows overriding the internal
1283 : * heuristic about whether to cache negative answers; it should be "true"
1284 : * if making an inquiry that is not part of the normal bottom-up join search
1285 : * sequence.
1286 : */
1287 : bool
1288 667872 : innerrel_is_unique(PlannerInfo *root,
1289 : Relids joinrelids,
1290 : Relids outerrelids,
1291 : RelOptInfo *innerrel,
1292 : JoinType jointype,
1293 : List *restrictlist,
1294 : bool force_cache)
1295 : {
1296 667872 : return innerrel_is_unique_ext(root, joinrelids, outerrelids, innerrel,
1297 : jointype, restrictlist, force_cache, NULL);
1298 : }
1299 :
1300 : /*
1301 : * innerrel_is_unique_ext
1302 : * Do the same as innerrel_is_unique(), but also set to (*extra_clauses)
1303 : * additional clauses from a baserestrictinfo list used to prove the
1304 : * uniqueness.
1305 : *
1306 : * A non-NULL extra_clauses indicates that we're checking for self-join and
1307 : * correspondingly dealing with filtered clauses.
1308 : */
1309 : bool
1310 669848 : innerrel_is_unique_ext(PlannerInfo *root,
1311 : Relids joinrelids,
1312 : Relids outerrelids,
1313 : RelOptInfo *innerrel,
1314 : JoinType jointype,
1315 : List *restrictlist,
1316 : bool force_cache,
1317 : List **extra_clauses)
1318 : {
1319 : MemoryContext old_context;
1320 : ListCell *lc;
1321 : UniqueRelInfo *uniqueRelInfo;
1322 669848 : List *outer_exprs = NIL;
1323 669848 : bool self_join = (extra_clauses != NULL);
1324 :
1325 : /* Certainly can't prove uniqueness when there are no joinclauses */
1326 669848 : if (restrictlist == NIL)
1327 102622 : return false;
1328 :
1329 : /*
1330 : * Make a quick check to eliminate cases in which we will surely be unable
1331 : * to prove uniqueness of the innerrel.
1332 : */
1333 567226 : if (!rel_supports_distinctness(root, innerrel))
1334 280038 : return false;
1335 :
1336 : /*
1337 : * Query the cache to see if we've managed to prove that innerrel is
1338 : * unique for any subset of this outerrel. For non-self-join search, we
1339 : * don't need an exact match, as extra outerrels can't make the innerrel
1340 : * any less unique (or more formally, the restrictlist for a join to a
1341 : * superset outerrel must be a superset of the conditions we successfully
1342 : * used before). For self-join search, we require an exact match of
1343 : * outerrels because we need extra clauses to be valid for our case. Also,
1344 : * for self-join checking we've filtered the clauses list. Thus, we can
1345 : * match only the result cached for a self-join search for another
1346 : * self-join check.
1347 : */
1348 317602 : foreach(lc, innerrel->unique_for_rels)
1349 : {
1350 119152 : uniqueRelInfo = (UniqueRelInfo *) lfirst(lc);
1351 :
1352 119152 : if ((!self_join && bms_is_subset(uniqueRelInfo->outerrelids, outerrelids)) ||
1353 68 : (self_join && bms_equal(uniqueRelInfo->outerrelids, outerrelids) &&
1354 56 : uniqueRelInfo->self_join))
1355 : {
1356 88738 : if (extra_clauses)
1357 12 : *extra_clauses = uniqueRelInfo->extra_clauses;
1358 88738 : return true; /* Success! */
1359 : }
1360 : }
1361 :
1362 : /*
1363 : * Conversely, we may have already determined that this outerrel, or some
1364 : * superset thereof, cannot prove this innerrel to be unique.
1365 : */
1366 198934 : foreach(lc, innerrel->non_unique_for_rels)
1367 : {
1368 808 : Relids unique_for_rels = (Relids) lfirst(lc);
1369 :
1370 808 : if (bms_is_subset(outerrelids, unique_for_rels))
1371 324 : return false;
1372 : }
1373 :
1374 : /* No cached information, so try to make the proof. */
1375 198126 : if (is_innerrel_unique_for(root, joinrelids, outerrelids, innerrel,
1376 : jointype, restrictlist,
1377 : self_join ? &outer_exprs : NULL))
1378 : {
1379 : /*
1380 : * Cache the positive result for future probes, being sure to keep it
1381 : * in the planner_cxt even if we are working in GEQO.
1382 : *
1383 : * Note: one might consider trying to isolate the minimal subset of
1384 : * the outerrels that proved the innerrel unique. But it's not worth
1385 : * the trouble, because the planner builds up joinrels incrementally
1386 : * and so we'll see the minimally sufficient outerrels before any
1387 : * supersets of them anyway.
1388 : */
1389 106416 : old_context = MemoryContextSwitchTo(root->planner_cxt);
1390 106416 : uniqueRelInfo = makeNode(UniqueRelInfo);
1391 106416 : uniqueRelInfo->outerrelids = bms_copy(outerrelids);
1392 106416 : uniqueRelInfo->self_join = self_join;
1393 106416 : uniqueRelInfo->extra_clauses = outer_exprs;
1394 106416 : innerrel->unique_for_rels = lappend(innerrel->unique_for_rels,
1395 : uniqueRelInfo);
1396 106416 : MemoryContextSwitchTo(old_context);
1397 :
1398 106416 : if (extra_clauses)
1399 642 : *extra_clauses = outer_exprs;
1400 106416 : return true; /* Success! */
1401 : }
1402 : else
1403 : {
1404 : /*
1405 : * None of the join conditions for outerrel proved innerrel unique, so
1406 : * we can safely reject this outerrel or any subset of it in future
1407 : * checks.
1408 : *
1409 : * However, in normal planning mode, caching this knowledge is totally
1410 : * pointless; it won't be queried again, because we build up joinrels
1411 : * from smaller to larger. It is useful in GEQO mode, where the
1412 : * knowledge can be carried across successive planning attempts; and
1413 : * it's likely to be useful when using join-search plugins, too. Hence
1414 : * cache when join_search_private is non-NULL. (Yeah, that's a hack,
1415 : * but it seems reasonable.)
1416 : *
1417 : * Also, allow callers to override that heuristic and force caching;
1418 : * that's useful for reduce_unique_semijoins, which calls here before
1419 : * the normal join search starts.
1420 : */
1421 91710 : if (force_cache || root->join_search_private)
1422 : {
1423 3718 : old_context = MemoryContextSwitchTo(root->planner_cxt);
1424 3718 : innerrel->non_unique_for_rels =
1425 3718 : lappend(innerrel->non_unique_for_rels,
1426 3718 : bms_copy(outerrelids));
1427 3718 : MemoryContextSwitchTo(old_context);
1428 : }
1429 :
1430 91710 : return false;
1431 : }
1432 : }
1433 :
1434 : /*
1435 : * is_innerrel_unique_for
1436 : * Check if the innerrel provably contains at most one tuple matching any
1437 : * tuple from the outerrel, based on join clauses in the 'restrictlist'.
1438 : */
1439 : static bool
1440 198126 : is_innerrel_unique_for(PlannerInfo *root,
1441 : Relids joinrelids,
1442 : Relids outerrelids,
1443 : RelOptInfo *innerrel,
1444 : JoinType jointype,
1445 : List *restrictlist,
1446 : List **extra_clauses)
1447 : {
1448 198126 : List *clause_list = NIL;
1449 : ListCell *lc;
1450 :
1451 : /*
1452 : * Search for mergejoinable clauses that constrain the inner rel against
1453 : * the outer rel. If an operator is mergejoinable then it behaves like
1454 : * equality for some btree opclass, so it's what we want. The
1455 : * mergejoinability test also eliminates clauses containing volatile
1456 : * functions, which we couldn't depend on.
1457 : */
1458 436700 : foreach(lc, restrictlist)
1459 : {
1460 238574 : RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(lc);
1461 :
1462 : /*
1463 : * As noted above, if it's a pushed-down clause and we're at an outer
1464 : * join, we can't use it.
1465 : */
1466 238574 : if (IS_OUTER_JOIN(jointype) &&
1467 106470 : RINFO_IS_PUSHED_DOWN(restrictinfo, joinrelids))
1468 5030 : continue;
1469 :
1470 : /* Ignore if it's not a mergejoinable clause */
1471 233544 : if (!restrictinfo->can_join ||
1472 215750 : restrictinfo->mergeopfamilies == NIL)
1473 18720 : continue; /* not mergejoinable */
1474 :
1475 : /*
1476 : * Check if the clause has the form "outer op inner" or "inner op
1477 : * outer", and if so mark which side is inner.
1478 : */
1479 214824 : if (!clause_sides_match_join(restrictinfo, outerrelids,
1480 : innerrel->relids))
1481 40 : continue; /* no good for these input relations */
1482 :
1483 : /* OK, add to the list */
1484 214784 : clause_list = lappend(clause_list, restrictinfo);
1485 : }
1486 :
1487 : /* Let rel_is_distinct_for() do the hard work */
1488 198126 : return rel_is_distinct_for(root, innerrel, clause_list, extra_clauses);
1489 : }
1490 :
1491 : /*
1492 : * Update EC members to point to the remaining relation instead of the removed
1493 : * one, removing duplicates.
1494 : *
1495 : * Restriction clauses for base relations are already distributed to
1496 : * the respective baserestrictinfo lists (see
1497 : * generate_implied_equalities_for_column). The above code has already processed
1498 : * this list and updated these clauses to reference the remaining
1499 : * relation, so that we can skip them here based on their relids.
1500 : *
1501 : * Likewise, we have already processed the join clauses that join the
1502 : * removed relation to the remaining one.
1503 : *
1504 : * Finally, there might be join clauses tying the removed relation to
1505 : * some third relation. We can't just delete the source clauses and
1506 : * regenerate them from the EC because the corresponding equality
1507 : * operators might be missing (see the handling of ec_broken).
1508 : * Therefore, we will update the references in the source clauses.
1509 : *
1510 : * Derived clauses can be generated again, so it is simpler just to
1511 : * delete them.
1512 : */
1513 : static void
1514 900 : update_eclasses(EquivalenceClass *ec, int from, int to)
1515 : {
1516 900 : List *new_members = NIL;
1517 900 : List *new_sources = NIL;
1518 :
1519 : /*
1520 : * We don't expect any EC child members to exist at this point. Ensure
1521 : * that's the case, otherwise, we might be getting asked to do something
1522 : * this function hasn't been coded for.
1523 : */
1524 : Assert(ec->ec_childmembers == NULL);
1525 :
1526 3636 : foreach_node(EquivalenceMember, em, ec->ec_members)
1527 : {
1528 1836 : bool is_redundant = false;
1529 :
1530 1836 : if (!bms_is_member(from, em->em_relids))
1531 : {
1532 918 : new_members = lappend(new_members, em);
1533 918 : continue;
1534 : }
1535 :
1536 918 : em->em_relids = adjust_relid_set(em->em_relids, from, to);
1537 918 : em->em_jdomain->jd_relids = adjust_relid_set(em->em_jdomain->jd_relids, from, to);
1538 :
1539 : /* We only process inner joins */
1540 918 : ChangeVarNodes((Node *) em->em_expr, from, to, 0);
1541 :
1542 1860 : foreach_node(EquivalenceMember, other, new_members)
1543 : {
1544 298 : if (!equal(em->em_relids, other->em_relids))
1545 24 : continue;
1546 :
1547 274 : if (equal(em->em_expr, other->em_expr))
1548 : {
1549 274 : is_redundant = true;
1550 274 : break;
1551 : }
1552 : }
1553 :
1554 918 : if (!is_redundant)
1555 644 : new_members = lappend(new_members, em);
1556 : }
1557 :
1558 900 : list_free(ec->ec_members);
1559 900 : ec->ec_members = new_members;
1560 :
1561 900 : ec_clear_derived_clauses(ec);
1562 :
1563 : /* Update EC source expressions */
1564 2736 : foreach_node(RestrictInfo, rinfo, ec->ec_sources)
1565 : {
1566 936 : bool is_redundant = false;
1567 :
1568 936 : if (!bms_is_member(from, rinfo->required_relids))
1569 : {
1570 118 : new_sources = lappend(new_sources, rinfo);
1571 118 : continue;
1572 : }
1573 :
1574 818 : ChangeVarNodes((Node *) rinfo, from, to, 0);
1575 :
1576 : /*
1577 : * After switching the clause to the remaining relation, check it for
1578 : * redundancy with existing ones. We don't have to check for
1579 : * redundancy with derived clauses, because we've just deleted them.
1580 : */
1581 1660 : foreach_node(RestrictInfo, other, new_sources)
1582 : {
1583 36 : if (!equal(rinfo->clause_relids, other->clause_relids))
1584 24 : continue;
1585 :
1586 12 : if (equal(rinfo->clause, other->clause))
1587 : {
1588 12 : is_redundant = true;
1589 12 : break;
1590 : }
1591 : }
1592 :
1593 818 : if (!is_redundant)
1594 806 : new_sources = lappend(new_sources, rinfo);
1595 : }
1596 :
1597 900 : list_free(ec->ec_sources);
1598 900 : ec->ec_sources = new_sources;
1599 900 : ec->ec_relids = adjust_relid_set(ec->ec_relids, from, to);
1600 900 : }
1601 :
1602 : /*
1603 : * "Logically" compares two RestrictInfo's ignoring the 'rinfo_serial' field,
1604 : * which makes almost every RestrictInfo unique. This type of comparison is
1605 : * useful when removing duplicates while moving RestrictInfo's from removed
1606 : * relation to remaining relation during self-join elimination.
1607 : *
1608 : * XXX: In the future, we might remove the 'rinfo_serial' field completely and
1609 : * get rid of this function.
1610 : */
1611 : static bool
1612 506 : restrict_infos_logically_equal(RestrictInfo *a, RestrictInfo *b)
1613 : {
1614 506 : int saved_rinfo_serial = a->rinfo_serial;
1615 : bool result;
1616 :
1617 506 : a->rinfo_serial = b->rinfo_serial;
1618 506 : result = equal(a, b);
1619 506 : a->rinfo_serial = saved_rinfo_serial;
1620 :
1621 506 : return result;
1622 : }
1623 :
1624 : /*
1625 : * This function adds all non-redundant clauses to the keeping relation
1626 : * during self-join elimination. That is a contradictory operation. On the
1627 : * one hand, we reduce the length of the `restrict` lists, which can
1628 : * impact planning or executing time. Additionally, we improve the
1629 : * accuracy of cardinality estimation. On the other hand, it is one more
1630 : * place that can make planning time much longer in specific cases. It
1631 : * would have been better to avoid calling the equal() function here, but
1632 : * it's the only way to detect duplicated inequality expressions.
1633 : *
1634 : * (*keep_rinfo_list) is given by pointer because it might be altered by
1635 : * distribute_restrictinfo_to_rels().
1636 : */
1637 : static void
1638 1176 : add_non_redundant_clauses(PlannerInfo *root,
1639 : List *rinfo_candidates,
1640 : List **keep_rinfo_list,
1641 : Index removed_relid)
1642 : {
1643 3250 : foreach_node(RestrictInfo, rinfo, rinfo_candidates)
1644 : {
1645 898 : bool is_redundant = false;
1646 :
1647 : Assert(!bms_is_member(removed_relid, rinfo->required_relids));
1648 :
1649 2160 : foreach_node(RestrictInfo, src, (*keep_rinfo_list))
1650 : {
1651 518 : if (!bms_equal(src->clause_relids, rinfo->clause_relids))
1652 : /* Can't compare trivially different clauses */
1653 6 : continue;
1654 :
1655 512 : if (src == rinfo ||
1656 512 : (rinfo->parent_ec != NULL &&
1657 804 : src->parent_ec == rinfo->parent_ec) ||
1658 506 : restrict_infos_logically_equal(rinfo, src))
1659 : {
1660 154 : is_redundant = true;
1661 154 : break;
1662 : }
1663 : }
1664 898 : if (!is_redundant)
1665 744 : distribute_restrictinfo_to_rels(root, rinfo);
1666 : }
1667 1176 : }
1668 :
1669 : /*
1670 : * Remove a relation after we have proven that it participates only in an
1671 : * unneeded unique self-join.
1672 : *
1673 : * Replace any links in planner info structures.
1674 : *
1675 : * Transfer join and restriction clauses from the removed relation to the
1676 : * remaining one. We change the Vars of the clause to point to the
1677 : * remaining relation instead of the removed one. The clauses that require
1678 : * a subset of joinrelids become restriction clauses of the remaining
1679 : * relation, and others remain join clauses. We append them to
1680 : * baserestrictinfo and joininfo, respectively, trying not to introduce
1681 : * duplicates.
1682 : *
1683 : * We also have to process the 'joinclauses' list here, because it
1684 : * contains EC-derived join clauses which must become filter clauses. It
1685 : * is not enough to just correct the ECs because the EC-derived
1686 : * restrictions are generated before join removal (see
1687 : * generate_base_implied_equalities).
1688 : *
1689 : * NOTE: Remember to keep the code in sync with PlannerInfo to be sure all
1690 : * cached relids and relid bitmapsets can be correctly cleaned during the
1691 : * self-join elimination procedure.
1692 : */
1693 : static void
1694 588 : remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
1695 : RelOptInfo *toKeep, RelOptInfo *toRemove,
1696 : List *restrictlist)
1697 : {
1698 : List *joininfos;
1699 : ListCell *lc;
1700 : int i;
1701 588 : List *jinfo_candidates = NIL;
1702 588 : List *binfo_candidates = NIL;
1703 :
1704 : Assert(toKeep->relid > 0);
1705 : Assert(toRemove->relid > 0);
1706 :
1707 : /*
1708 : * Replace the index of the removing table with the keeping one. The
1709 : * technique of removing/distributing restrictinfo is used here to attach
1710 : * just appeared (for keeping relation) join clauses and avoid adding
1711 : * duplicates of those that already exist in the joininfo list.
1712 : */
1713 588 : joininfos = list_copy(toRemove->joininfo);
1714 1254 : foreach_node(RestrictInfo, rinfo, joininfos)
1715 : {
1716 78 : remove_join_clause_from_rels(root, rinfo, rinfo->required_relids);
1717 78 : ChangeVarNodes((Node *) rinfo, toRemove->relid, toKeep->relid, 0);
1718 :
1719 78 : if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
1720 60 : jinfo_candidates = lappend(jinfo_candidates, rinfo);
1721 : else
1722 18 : binfo_candidates = lappend(binfo_candidates, rinfo);
1723 : }
1724 :
1725 : /*
1726 : * Concatenate restrictlist to the list of base restrictions of the
1727 : * removing table just to simplify the replacement procedure: all of them
1728 : * weren't connected to any keeping relations and need to be added to some
1729 : * rels.
1730 : */
1731 588 : toRemove->baserestrictinfo = list_concat(toRemove->baserestrictinfo,
1732 : restrictlist);
1733 1996 : foreach_node(RestrictInfo, rinfo, toRemove->baserestrictinfo)
1734 : {
1735 820 : ChangeVarNodes((Node *) rinfo, toRemove->relid, toKeep->relid, 0);
1736 :
1737 820 : if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
1738 0 : jinfo_candidates = lappend(jinfo_candidates, rinfo);
1739 : else
1740 820 : binfo_candidates = lappend(binfo_candidates, rinfo);
1741 : }
1742 :
1743 : /*
1744 : * Now, add all non-redundant clauses to the keeping relation.
1745 : */
1746 588 : add_non_redundant_clauses(root, binfo_candidates,
1747 : &toKeep->baserestrictinfo, toRemove->relid);
1748 588 : add_non_redundant_clauses(root, jinfo_candidates,
1749 : &toKeep->joininfo, toRemove->relid);
1750 :
1751 588 : list_free(binfo_candidates);
1752 588 : list_free(jinfo_candidates);
1753 :
1754 : /*
1755 : * Arrange equivalence classes, mentioned removing a table, with the
1756 : * keeping one: varno of removing table should be replaced in members and
1757 : * sources lists. Also, remove duplicated elements if this replacement
1758 : * procedure created them.
1759 : */
1760 588 : i = -1;
1761 1488 : while ((i = bms_next_member(toRemove->eclass_indexes, i)) >= 0)
1762 : {
1763 900 : EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
1764 :
1765 900 : update_eclasses(ec, toRemove->relid, toKeep->relid);
1766 900 : toKeep->eclass_indexes = bms_add_member(toKeep->eclass_indexes, i);
1767 : }
1768 :
1769 : /*
1770 : * Transfer the targetlist and attr_needed flags.
1771 : */
1772 :
1773 2360 : foreach(lc, toRemove->reltarget->exprs)
1774 : {
1775 1772 : Node *node = lfirst(lc);
1776 :
1777 1772 : ChangeVarNodes(node, toRemove->relid, toKeep->relid, 0);
1778 1772 : if (!list_member(toKeep->reltarget->exprs, node))
1779 174 : toKeep->reltarget->exprs = lappend(toKeep->reltarget->exprs, node);
1780 : }
1781 :
1782 7470 : for (i = toKeep->min_attr; i <= toKeep->max_attr; i++)
1783 : {
1784 6882 : int attno = i - toKeep->min_attr;
1785 :
1786 13764 : toRemove->attr_needed[attno] = adjust_relid_set(toRemove->attr_needed[attno],
1787 6882 : toRemove->relid, toKeep->relid);
1788 6882 : toKeep->attr_needed[attno] = bms_add_members(toKeep->attr_needed[attno],
1789 6882 : toRemove->attr_needed[attno]);
1790 : }
1791 :
1792 : /*
1793 : * If the removed relation has a row mark, transfer it to the remaining
1794 : * one.
1795 : *
1796 : * If both rels have row marks, just keep the one corresponding to the
1797 : * remaining relation because we verified earlier that they have the same
1798 : * strength.
1799 : */
1800 588 : if (rmark)
1801 : {
1802 74 : if (kmark)
1803 : {
1804 : Assert(kmark->markType == rmark->markType);
1805 :
1806 74 : root->rowMarks = list_delete_ptr(root->rowMarks, rmark);
1807 : }
1808 : else
1809 : {
1810 : /* Shouldn't have inheritance children here. */
1811 : Assert(rmark->rti == rmark->prti);
1812 :
1813 0 : rmark->rti = rmark->prti = toKeep->relid;
1814 : }
1815 : }
1816 :
1817 : /*
1818 : * Replace varno in all the query structures, except nodes RangeTblRef
1819 : * otherwise later remove_rel_from_joinlist will yield errors.
1820 : */
1821 588 : ChangeVarNodesExtended((Node *) root->parse, toRemove->relid, toKeep->relid, 0, false);
1822 :
1823 : /* Replace links in the planner info */
1824 588 : remove_rel_from_query(root, toRemove, toKeep->relid, NULL, NULL);
1825 :
1826 : /* At last, replace varno in root targetlist and HAVING clause */
1827 588 : ChangeVarNodes((Node *) root->processed_tlist, toRemove->relid, toKeep->relid, 0);
1828 588 : ChangeVarNodes((Node *) root->processed_groupClause, toRemove->relid, toKeep->relid, 0);
1829 :
1830 588 : adjust_relid_set(root->all_result_relids, toRemove->relid, toKeep->relid);
1831 588 : adjust_relid_set(root->leaf_result_relids, toRemove->relid, toKeep->relid);
1832 :
1833 : /*
1834 : * There may be references to the rel in root->fkey_list, but if so,
1835 : * match_foreign_keys_to_quals() will get rid of them.
1836 : */
1837 :
1838 : /*
1839 : * Finally, remove the rel from the baserel array to prevent it from being
1840 : * referenced again. (We can't do this earlier because
1841 : * remove_join_clause_from_rels will touch it.)
1842 : */
1843 588 : root->simple_rel_array[toRemove->relid] = NULL;
1844 :
1845 : /* And nuke the RelOptInfo, just in case there's another access path. */
1846 588 : pfree(toRemove);
1847 :
1848 : /*
1849 : * Now repeat construction of attr_needed bits coming from all other
1850 : * sources.
1851 : */
1852 588 : rebuild_placeholder_attr_needed(root);
1853 588 : rebuild_joinclause_attr_needed(root);
1854 588 : rebuild_eclass_attr_needed(root);
1855 588 : rebuild_lateral_attr_needed(root);
1856 588 : }
1857 :
1858 : /*
1859 : * split_selfjoin_quals
1860 : * Processes 'joinquals' by building two lists: one containing the quals
1861 : * where the columns/exprs are on either side of the join match and
1862 : * another one containing the remaining quals.
1863 : *
1864 : * 'joinquals' must only contain quals for a RTE_RELATION being joined to
1865 : * itself.
1866 : */
1867 : static void
1868 1976 : split_selfjoin_quals(PlannerInfo *root, List *joinquals, List **selfjoinquals,
1869 : List **otherjoinquals, int from, int to)
1870 : {
1871 1976 : List *sjoinquals = NIL;
1872 1976 : List *ojoinquals = NIL;
1873 :
1874 6062 : foreach_node(RestrictInfo, rinfo, joinquals)
1875 : {
1876 : OpExpr *expr;
1877 : Node *leftexpr;
1878 : Node *rightexpr;
1879 :
1880 : /* In general, clause looks like F(arg1) = G(arg2) */
1881 4220 : if (!rinfo->mergeopfamilies ||
1882 4220 : bms_num_members(rinfo->clause_relids) != 2 ||
1883 4220 : bms_membership(rinfo->left_relids) != BMS_SINGLETON ||
1884 2110 : bms_membership(rinfo->right_relids) != BMS_SINGLETON)
1885 : {
1886 0 : ojoinquals = lappend(ojoinquals, rinfo);
1887 0 : continue;
1888 : }
1889 :
1890 2110 : expr = (OpExpr *) rinfo->clause;
1891 :
1892 2110 : if (!IsA(expr, OpExpr) || list_length(expr->args) != 2)
1893 : {
1894 0 : ojoinquals = lappend(ojoinquals, rinfo);
1895 0 : continue;
1896 : }
1897 :
1898 2110 : leftexpr = get_leftop(rinfo->clause);
1899 2110 : rightexpr = copyObject(get_rightop(rinfo->clause));
1900 :
1901 2110 : if (leftexpr && IsA(leftexpr, RelabelType))
1902 12 : leftexpr = (Node *) ((RelabelType *) leftexpr)->arg;
1903 2110 : if (rightexpr && IsA(rightexpr, RelabelType))
1904 6 : rightexpr = (Node *) ((RelabelType *) rightexpr)->arg;
1905 :
1906 : /*
1907 : * Quite an expensive operation, narrowing the use case. For example,
1908 : * when we have cast of the same var to different (but compatible)
1909 : * types.
1910 : */
1911 2110 : ChangeVarNodes(rightexpr, bms_singleton_member(rinfo->right_relids),
1912 2110 : bms_singleton_member(rinfo->left_relids), 0);
1913 :
1914 2110 : if (equal(leftexpr, rightexpr))
1915 1624 : sjoinquals = lappend(sjoinquals, rinfo);
1916 : else
1917 486 : ojoinquals = lappend(ojoinquals, rinfo);
1918 : }
1919 :
1920 1976 : *selfjoinquals = sjoinquals;
1921 1976 : *otherjoinquals = ojoinquals;
1922 1976 : }
1923 :
1924 : /*
1925 : * Check for a case when uniqueness is at least partly derived from a
1926 : * baserestrictinfo clause. In this case, we have a chance to return only
1927 : * one row (if such clauses on both sides of SJ are equal) or nothing (if they
1928 : * are different).
1929 : */
1930 : static bool
1931 654 : match_unique_clauses(PlannerInfo *root, RelOptInfo *outer, List *uclauses,
1932 : Index relid)
1933 : {
1934 1326 : foreach_node(RestrictInfo, rinfo, uclauses)
1935 : {
1936 : Expr *clause;
1937 : Node *iclause;
1938 : Node *c1;
1939 150 : bool matched = false;
1940 :
1941 : Assert(outer->relid > 0 && relid > 0);
1942 :
1943 : /* Only filters like f(R.x1,...,R.xN) == expr we should consider. */
1944 : Assert(bms_is_empty(rinfo->left_relids) ^
1945 : bms_is_empty(rinfo->right_relids));
1946 :
1947 150 : clause = (Expr *) copyObject(rinfo->clause);
1948 150 : ChangeVarNodes((Node *) clause, relid, outer->relid, 0);
1949 :
1950 150 : iclause = bms_is_empty(rinfo->left_relids) ? get_rightop(clause) :
1951 144 : get_leftop(clause);
1952 150 : c1 = bms_is_empty(rinfo->left_relids) ? get_leftop(clause) :
1953 144 : get_rightop(clause);
1954 :
1955 : /*
1956 : * Compare these left and right sides with the corresponding sides of
1957 : * the outer's filters. If no one is detected - return immediately.
1958 : */
1959 408 : foreach_node(RestrictInfo, orinfo, outer->baserestrictinfo)
1960 : {
1961 : Node *oclause;
1962 : Node *c2;
1963 :
1964 192 : if (orinfo->mergeopfamilies == NIL)
1965 : /* Don't consider clauses that aren't similar to 'F(X)=G(Y)' */
1966 60 : continue;
1967 :
1968 : Assert(is_opclause(orinfo->clause));
1969 :
1970 264 : oclause = bms_is_empty(orinfo->left_relids) ?
1971 132 : get_rightop(orinfo->clause) : get_leftop(orinfo->clause);
1972 264 : c2 = (bms_is_empty(orinfo->left_relids) ?
1973 132 : get_leftop(orinfo->clause) : get_rightop(orinfo->clause));
1974 :
1975 132 : if (equal(iclause, oclause) && equal(c1, c2))
1976 : {
1977 84 : matched = true;
1978 84 : break;
1979 : }
1980 : }
1981 :
1982 150 : if (!matched)
1983 66 : return false;
1984 : }
1985 :
1986 588 : return true;
1987 : }
1988 :
1989 : /*
1990 : * Find and remove unique self-joins in a group of base relations that have
1991 : * the same Oid.
1992 : *
1993 : * Returns a set of relids that were removed.
1994 : */
1995 : static Relids
1996 11430 : remove_self_joins_one_group(PlannerInfo *root, Relids relids)
1997 : {
1998 11430 : Relids result = NULL;
1999 : int k; /* Index of kept relation */
2000 11430 : int r = -1; /* Index of removed relation */
2001 :
2002 35466 : while ((r = bms_next_member(relids, r)) > 0)
2003 : {
2004 24036 : RelOptInfo *inner = root->simple_rel_array[r];
2005 :
2006 24036 : k = r;
2007 :
2008 37442 : while ((k = bms_next_member(relids, k)) > 0)
2009 : {
2010 13994 : Relids joinrelids = NULL;
2011 13994 : RelOptInfo *outer = root->simple_rel_array[k];
2012 : List *restrictlist;
2013 : List *selfjoinquals;
2014 : List *otherjoinquals;
2015 : ListCell *lc;
2016 13994 : bool jinfo_check = true;
2017 13994 : PlanRowMark *omark = NULL;
2018 13994 : PlanRowMark *imark = NULL;
2019 13994 : List *uclauses = NIL;
2020 :
2021 : /* A sanity check: the relations have the same Oid. */
2022 : Assert(root->simple_rte_array[k]->relid ==
2023 : root->simple_rte_array[r]->relid);
2024 :
2025 : /*
2026 : * It is impossible to eliminate the join of two relations if they
2027 : * belong to different rules of order. Otherwise, the planner
2028 : * can't find any variants of the correct query plan.
2029 : */
2030 17388 : foreach(lc, root->join_info_list)
2031 : {
2032 11096 : SpecialJoinInfo *info = (SpecialJoinInfo *) lfirst(lc);
2033 :
2034 22192 : if ((bms_is_member(k, info->syn_lefthand) ^
2035 15806 : bms_is_member(r, info->syn_lefthand)) ||
2036 4710 : (bms_is_member(k, info->syn_righthand) ^
2037 4710 : bms_is_member(r, info->syn_righthand)))
2038 : {
2039 7702 : jinfo_check = false;
2040 7702 : break;
2041 : }
2042 : }
2043 13994 : if (!jinfo_check)
2044 13406 : continue;
2045 :
2046 : /*
2047 : * Check Row Marks equivalence. We can't remove the join if the
2048 : * relations have row marks of different strength (e.g., one is
2049 : * locked FOR UPDATE, and another just has ROW_MARK_REFERENCE for
2050 : * EvalPlanQual rechecking).
2051 : */
2052 6500 : foreach(lc, root->rowMarks)
2053 : {
2054 380 : PlanRowMark *rowMark = (PlanRowMark *) lfirst(lc);
2055 :
2056 380 : if (rowMark->rti == k)
2057 : {
2058 : Assert(imark == NULL);
2059 172 : imark = rowMark;
2060 : }
2061 208 : else if (rowMark->rti == r)
2062 : {
2063 : Assert(omark == NULL);
2064 172 : omark = rowMark;
2065 : }
2066 :
2067 380 : if (omark && imark)
2068 172 : break;
2069 : }
2070 6292 : if (omark && imark && omark->markType != imark->markType)
2071 52 : continue;
2072 :
2073 : /*
2074 : * We only deal with base rels here, so their relids bitset
2075 : * contains only one member -- their relid.
2076 : */
2077 6240 : joinrelids = bms_add_member(joinrelids, r);
2078 6240 : joinrelids = bms_add_member(joinrelids, k);
2079 :
2080 : /*
2081 : * PHVs should not impose any constraints on removing self-joins.
2082 : */
2083 :
2084 : /*
2085 : * At this stage, joininfo lists of inner and outer can contain
2086 : * only clauses required for a superior outer join that can't
2087 : * influence this optimization. So, we can avoid to call the
2088 : * build_joinrel_restrictlist() routine.
2089 : */
2090 6240 : restrictlist = generate_join_implied_equalities(root, joinrelids,
2091 : inner->relids,
2092 : outer, NULL);
2093 6240 : if (restrictlist == NIL)
2094 4264 : continue;
2095 :
2096 : /*
2097 : * Process restrictlist to separate the self-join quals from the
2098 : * other quals. e.g., "x = x" goes to selfjoinquals and "a = b" to
2099 : * otherjoinquals.
2100 : */
2101 1976 : split_selfjoin_quals(root, restrictlist, &selfjoinquals,
2102 1976 : &otherjoinquals, inner->relid, outer->relid);
2103 :
2104 : Assert(list_length(restrictlist) ==
2105 : (list_length(selfjoinquals) + list_length(otherjoinquals)));
2106 :
2107 : /*
2108 : * To enable SJE for the only degenerate case without any self
2109 : * join clauses at all, add baserestrictinfo to this list. The
2110 : * degenerate case works only if both sides have the same clause.
2111 : * So doesn't matter which side to add.
2112 : */
2113 1976 : selfjoinquals = list_concat(selfjoinquals, outer->baserestrictinfo);
2114 :
2115 : /*
2116 : * Determine if the inner table can duplicate outer rows. We must
2117 : * bypass the unique rel cache here since we're possibly using a
2118 : * subset of join quals. We can use 'force_cache' == true when all
2119 : * join quals are self-join quals. Otherwise, we could end up
2120 : * putting false negatives in the cache.
2121 : */
2122 1976 : if (!innerrel_is_unique_ext(root, joinrelids, inner->relids,
2123 : outer, JOIN_INNER, selfjoinquals,
2124 1976 : list_length(otherjoinquals) == 0,
2125 : &uclauses))
2126 1322 : continue;
2127 :
2128 : /*
2129 : * 'uclauses' is the copy of outer->baserestrictinfo that are
2130 : * associated with an index. We proved by matching selfjoinquals
2131 : * to a unique index that the outer relation has at most one
2132 : * matching row for each inner row. Sometimes that is not enough.
2133 : * e.g. "WHERE s1.b = s2.b AND s1.a = 1 AND s2.a = 2" when the
2134 : * unique index is (a,b). Having non-empty uclauses, we must
2135 : * validate that the inner baserestrictinfo contains the same
2136 : * expressions, or we won't match the same row on each side of the
2137 : * join.
2138 : */
2139 654 : if (!match_unique_clauses(root, inner, uclauses, outer->relid))
2140 66 : continue;
2141 :
2142 : /*
2143 : * We can remove either relation, so remove the inner one in order
2144 : * to simplify this loop.
2145 : */
2146 588 : remove_self_join_rel(root, omark, imark, outer, inner, restrictlist);
2147 :
2148 588 : result = bms_add_member(result, r);
2149 :
2150 : /* We have removed the outer relation, try the next one. */
2151 588 : break;
2152 : }
2153 : }
2154 :
2155 11430 : return result;
2156 : }
2157 :
2158 : /*
2159 : * Gather indexes of base relations from the joinlist and try to eliminate self
2160 : * joins.
2161 : */
2162 : static Relids
2163 101154 : remove_self_joins_recurse(PlannerInfo *root, List *joinlist, Relids toRemove)
2164 : {
2165 : ListCell *jl;
2166 101154 : Relids relids = NULL;
2167 101154 : SelfJoinCandidate *candidates = NULL;
2168 : int i;
2169 : int j;
2170 : int numRels;
2171 :
2172 : /* Collect indexes of base relations of the join tree */
2173 337084 : foreach(jl, joinlist)
2174 : {
2175 235930 : Node *jlnode = (Node *) lfirst(jl);
2176 :
2177 235930 : if (IsA(jlnode, RangeTblRef))
2178 : {
2179 232564 : int varno = ((RangeTblRef *) jlnode)->rtindex;
2180 232564 : RangeTblEntry *rte = root->simple_rte_array[varno];
2181 :
2182 : /*
2183 : * We only consider ordinary relations as candidates to be
2184 : * removed, and these relations should not have TABLESAMPLE
2185 : * clauses specified. Removing a relation with TABLESAMPLE clause
2186 : * could potentially change the syntax of the query. Because of
2187 : * UPDATE/DELETE EPQ mechanism, currently Query->resultRelation or
2188 : * Query->mergeTargetRelation associated rel cannot be eliminated.
2189 : */
2190 232564 : if (rte->rtekind == RTE_RELATION &&
2191 201150 : rte->relkind == RELKIND_RELATION &&
2192 195968 : rte->tablesample == NULL &&
2193 195944 : varno != root->parse->resultRelation &&
2194 194160 : varno != root->parse->mergeTargetRelation)
2195 : {
2196 : Assert(!bms_is_member(varno, relids));
2197 194160 : relids = bms_add_member(relids, varno);
2198 : }
2199 : }
2200 3366 : else if (IsA(jlnode, List))
2201 : {
2202 : /* Recursively go inside the sub-joinlist */
2203 3366 : toRemove = remove_self_joins_recurse(root, (List *) jlnode,
2204 : toRemove);
2205 : }
2206 : else
2207 0 : elog(ERROR, "unrecognized joinlist node type: %d",
2208 : (int) nodeTag(jlnode));
2209 : }
2210 :
2211 101154 : numRels = bms_num_members(relids);
2212 :
2213 : /* Need at least two relations for the join */
2214 101154 : if (numRels < 2)
2215 30868 : return toRemove;
2216 :
2217 : /*
2218 : * In order to find relations with the same oid we first build an array of
2219 : * candidates and then sort it by oid.
2220 : */
2221 70286 : candidates = (SelfJoinCandidate *) palloc(sizeof(SelfJoinCandidate) *
2222 : numRels);
2223 70286 : i = -1;
2224 70286 : j = 0;
2225 242286 : while ((i = bms_next_member(relids, i)) >= 0)
2226 : {
2227 172000 : candidates[j].relid = i;
2228 172000 : candidates[j].reloid = root->simple_rte_array[i]->relid;
2229 172000 : j++;
2230 : }
2231 :
2232 70286 : qsort(candidates, numRels, sizeof(SelfJoinCandidate),
2233 : self_join_candidates_cmp);
2234 :
2235 : /*
2236 : * Iteratively form a group of relation indexes with the same oid and
2237 : * launch the routine that detects self-joins in this group and removes
2238 : * excessive range table entries.
2239 : *
2240 : * At the end of the iteration, exclude the group from the overall relids
2241 : * list. So each next iteration of the cycle will involve less and less
2242 : * value of relids.
2243 : */
2244 70286 : i = 0;
2245 242286 : for (j = 1; j < numRels + 1; j++)
2246 : {
2247 172000 : if (j == numRels || candidates[j].reloid != candidates[i].reloid)
2248 : {
2249 159466 : if (j - i >= 2)
2250 : {
2251 : /* Create a group of relation indexes with the same oid */
2252 11364 : Relids group = NULL;
2253 : Relids removed;
2254 :
2255 35262 : while (i < j)
2256 : {
2257 23898 : group = bms_add_member(group, candidates[i].relid);
2258 23898 : i++;
2259 : }
2260 11364 : relids = bms_del_members(relids, group);
2261 :
2262 : /*
2263 : * Try to remove self-joins from a group of identical entries.
2264 : * Make the next attempt iteratively - if something is deleted
2265 : * from a group, changes in clauses and equivalence classes
2266 : * can give us a chance to find more candidates.
2267 : */
2268 : do
2269 : {
2270 : Assert(!bms_overlap(group, toRemove));
2271 11430 : removed = remove_self_joins_one_group(root, group);
2272 11430 : toRemove = bms_add_members(toRemove, removed);
2273 11430 : group = bms_del_members(group, removed);
2274 564 : } while (!bms_is_empty(removed) &&
2275 11430 : bms_membership(group) == BMS_MULTIPLE);
2276 11364 : bms_free(removed);
2277 11364 : bms_free(group);
2278 : }
2279 : else
2280 : {
2281 : /* Single relation, just remove it from the set */
2282 148102 : relids = bms_del_member(relids, candidates[i].relid);
2283 148102 : i = j;
2284 : }
2285 : }
2286 : }
2287 :
2288 : Assert(bms_is_empty(relids));
2289 :
2290 70286 : return toRemove;
2291 : }
2292 :
2293 : /*
2294 : * Compare self-join candidates by their oids.
2295 : */
2296 : static int
2297 127170 : self_join_candidates_cmp(const void *a, const void *b)
2298 : {
2299 127170 : const SelfJoinCandidate *ca = (const SelfJoinCandidate *) a;
2300 127170 : const SelfJoinCandidate *cb = (const SelfJoinCandidate *) b;
2301 :
2302 127170 : if (ca->reloid != cb->reloid)
2303 114582 : return (ca->reloid < cb->reloid ? -1 : 1);
2304 : else
2305 12588 : return 0;
2306 : }
2307 :
2308 : /*
2309 : * Find and remove useless self joins.
2310 : *
2311 : * Search for joins where a relation is joined to itself. If the join clause
2312 : * for each tuple from one side of the join is proven to match the same
2313 : * physical row (or nothing) on the other side, that self-join can be
2314 : * eliminated from the query. Suitable join clauses are assumed to be in the
2315 : * form of X = X, and can be replaced with NOT NULL clauses.
2316 : *
2317 : * For the sake of simplicity, we don't apply this optimization to special
2318 : * joins. Here is a list of what we could do in some particular cases:
2319 : * 'a a1 semi join a a2': is reduced to inner by reduce_unique_semijoins,
2320 : * and then removed normally.
2321 : * 'a a1 anti join a a2': could simplify to a scan with 'outer quals AND
2322 : * (IS NULL on join columns OR NOT inner quals)'.
2323 : * 'a a1 left join a a2': could simplify to a scan like inner but without
2324 : * NOT NULL conditions on join columns.
2325 : * 'a a1 left join (a a2 join b)': can't simplify this, because join to b
2326 : * can both remove rows and introduce duplicates.
2327 : *
2328 : * To search for removable joins, we order all the relations on their Oid,
2329 : * go over each set with the same Oid, and consider each pair of relations
2330 : * in this set.
2331 : *
2332 : * To remove the join, we mark one of the participating relations as dead
2333 : * and rewrite all references to it to point to the remaining relation.
2334 : * This includes modifying RestrictInfos, EquivalenceClasses, and
2335 : * EquivalenceMembers. We also have to modify the row marks. The join clauses
2336 : * of the removed relation become either restriction or join clauses, based on
2337 : * whether they reference any relations not participating in the removed join.
2338 : *
2339 : * 'joinlist' is the top-level joinlist of the query. If it has any
2340 : * references to the removed relations, we update them to point to the
2341 : * remaining ones.
2342 : */
2343 : List *
2344 328968 : remove_useless_self_joins(PlannerInfo *root, List *joinlist)
2345 : {
2346 328968 : Relids toRemove = NULL;
2347 328968 : int relid = -1;
2348 :
2349 657936 : if (!enable_self_join_elimination || joinlist == NIL ||
2350 561016 : (list_length(joinlist) == 1 && !IsA(linitial(joinlist), List)))
2351 231180 : return joinlist;
2352 :
2353 : /*
2354 : * Merge pairs of relations participated in self-join. Remove unnecessary
2355 : * range table entries.
2356 : */
2357 97788 : toRemove = remove_self_joins_recurse(root, joinlist, toRemove);
2358 :
2359 97788 : if (unlikely(toRemove != NULL))
2360 : {
2361 : /* At the end, remove orphaned relation links */
2362 1146 : while ((relid = bms_next_member(toRemove, relid)) >= 0)
2363 : {
2364 588 : int nremoved = 0;
2365 :
2366 588 : joinlist = remove_rel_from_joinlist(joinlist, relid, &nremoved);
2367 588 : if (nremoved != 1)
2368 0 : elog(ERROR, "failed to find relation %d in joinlist", relid);
2369 : }
2370 : }
2371 :
2372 97788 : return joinlist;
2373 : }
|
