Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * restrictinfo.c
4 : * RestrictInfo node manipulation routines.
5 : *
6 : * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/optimizer/util/restrictinfo.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : #include "postgres.h"
16 :
17 : #include "nodes/makefuncs.h"
18 : #include "nodes/nodeFuncs.h"
19 : #include "optimizer/clauses.h"
20 : #include "optimizer/optimizer.h"
21 : #include "optimizer/restrictinfo.h"
22 :
23 :
24 : static RestrictInfo *make_restrictinfo_internal(PlannerInfo *root,
25 : Expr *clause,
26 : Expr *orclause,
27 : bool is_pushed_down,
28 : bool has_clone,
29 : bool is_clone,
30 : bool pseudoconstant,
31 : Index security_level,
32 : Relids required_relids,
33 : Relids incompatible_relids,
34 : Relids outer_relids);
35 : static Expr *make_sub_restrictinfos(PlannerInfo *root,
36 : Expr *clause,
37 : bool is_pushed_down,
38 : bool has_clone,
39 : bool is_clone,
40 : bool pseudoconstant,
41 : Index security_level,
42 : Relids required_relids,
43 : Relids incompatible_relids,
44 : Relids outer_relids);
45 :
46 :
47 : /*
48 : * make_restrictinfo
49 : *
50 : * Build a RestrictInfo node containing the given subexpression.
51 : *
52 : * The is_pushed_down, has_clone, is_clone, and pseudoconstant flags for the
53 : * RestrictInfo must be supplied by the caller, as well as the correct values
54 : * for security_level, incompatible_relids, and outer_relids.
55 : * required_relids can be NULL, in which case it defaults to the actual clause
56 : * contents (i.e., clause_relids).
57 : *
58 : * We initialize fields that depend only on the given subexpression, leaving
59 : * others that depend on context (or may never be needed at all) to be filled
60 : * later.
61 : */
62 : RestrictInfo *
63 620220 : make_restrictinfo(PlannerInfo *root,
64 : Expr *clause,
65 : bool is_pushed_down,
66 : bool has_clone,
67 : bool is_clone,
68 : bool pseudoconstant,
69 : Index security_level,
70 : Relids required_relids,
71 : Relids incompatible_relids,
72 : Relids outer_relids)
73 : {
74 : /*
75 : * If it's an OR clause, build a modified copy with RestrictInfos inserted
76 : * above each subclause of the top-level AND/OR structure.
77 : */
78 620220 : if (is_orclause(clause))
79 8276 : return (RestrictInfo *) make_sub_restrictinfos(root,
80 : clause,
81 : is_pushed_down,
82 : has_clone,
83 : is_clone,
84 : pseudoconstant,
85 : security_level,
86 : required_relids,
87 : incompatible_relids,
88 : outer_relids);
89 :
90 : /* Shouldn't be an AND clause, else AND/OR flattening messed up */
91 : Assert(!is_andclause(clause));
92 :
93 611944 : return make_restrictinfo_internal(root,
94 : clause,
95 : NULL,
96 : is_pushed_down,
97 : has_clone,
98 : is_clone,
99 : pseudoconstant,
100 : security_level,
101 : required_relids,
102 : incompatible_relids,
103 : outer_relids);
104 : }
105 :
106 : /*
107 : * make_restrictinfo_internal
108 : *
109 : * Common code for the main entry points and the recursive cases.
110 : */
111 : static RestrictInfo *
112 643044 : make_restrictinfo_internal(PlannerInfo *root,
113 : Expr *clause,
114 : Expr *orclause,
115 : bool is_pushed_down,
116 : bool has_clone,
117 : bool is_clone,
118 : bool pseudoconstant,
119 : Index security_level,
120 : Relids required_relids,
121 : Relids incompatible_relids,
122 : Relids outer_relids)
123 : {
124 643044 : RestrictInfo *restrictinfo = makeNode(RestrictInfo);
125 : Relids baserels;
126 :
127 643044 : restrictinfo->clause = clause;
128 643044 : restrictinfo->orclause = orclause;
129 643044 : restrictinfo->is_pushed_down = is_pushed_down;
130 643044 : restrictinfo->pseudoconstant = pseudoconstant;
131 643044 : restrictinfo->has_clone = has_clone;
132 643044 : restrictinfo->is_clone = is_clone;
133 643044 : restrictinfo->can_join = false; /* may get set below */
134 643044 : restrictinfo->security_level = security_level;
135 643044 : restrictinfo->incompatible_relids = incompatible_relids;
136 643044 : restrictinfo->outer_relids = outer_relids;
137 :
138 : /*
139 : * If it's potentially delayable by lower-level security quals, figure out
140 : * whether it's leakproof. We can skip testing this for level-zero quals,
141 : * since they would never get delayed on security grounds anyway.
142 : */
143 643044 : if (security_level > 0)
144 4346 : restrictinfo->leakproof = !contain_leaked_vars((Node *) clause);
145 : else
146 638698 : restrictinfo->leakproof = false; /* really, "don't know" */
147 :
148 : /*
149 : * Mark volatility as unknown. The contain_volatile_functions function
150 : * will determine if there are any volatile functions when called for the
151 : * first time with this RestrictInfo.
152 : */
153 643044 : restrictinfo->has_volatile = VOLATILITY_UNKNOWN;
154 :
155 : /*
156 : * If it's a binary opclause, set up left/right relids info. In any case
157 : * set up the total clause relids info.
158 : */
159 643044 : if (is_opclause(clause) && list_length(((OpExpr *) clause)->args) == 2)
160 : {
161 538538 : restrictinfo->left_relids = pull_varnos(root, get_leftop(clause));
162 538538 : restrictinfo->right_relids = pull_varnos(root, get_rightop(clause));
163 :
164 1077076 : restrictinfo->clause_relids = bms_union(restrictinfo->left_relids,
165 538538 : restrictinfo->right_relids);
166 :
167 : /*
168 : * Does it look like a normal join clause, i.e., a binary operator
169 : * relating expressions that come from distinct relations? If so we
170 : * might be able to use it in a join algorithm. Note that this is a
171 : * purely syntactic test that is made regardless of context.
172 : */
173 538538 : if (!bms_is_empty(restrictinfo->left_relids) &&
174 528776 : !bms_is_empty(restrictinfo->right_relids) &&
175 188006 : !bms_overlap(restrictinfo->left_relids,
176 188006 : restrictinfo->right_relids))
177 : {
178 185698 : restrictinfo->can_join = true;
179 : /* pseudoconstant should certainly not be true */
180 : Assert(!restrictinfo->pseudoconstant);
181 : }
182 : }
183 : else
184 : {
185 : /* Not a binary opclause, so mark left/right relid sets as empty */
186 104506 : restrictinfo->left_relids = NULL;
187 104506 : restrictinfo->right_relids = NULL;
188 : /* and get the total relid set the hard way */
189 104506 : restrictinfo->clause_relids = pull_varnos(root, (Node *) clause);
190 : }
191 :
192 : /* required_relids defaults to clause_relids */
193 643044 : if (required_relids != NULL)
194 581956 : restrictinfo->required_relids = required_relids;
195 : else
196 61088 : restrictinfo->required_relids = restrictinfo->clause_relids;
197 :
198 : /*
199 : * Count the number of base rels appearing in clause_relids. To do this,
200 : * we just delete rels mentioned in root->outer_join_rels and count the
201 : * survivors. Because we are called during deconstruct_jointree which is
202 : * the same tree walk that populates outer_join_rels, this is a little bit
203 : * unsafe-looking; but it should be fine because the recursion in
204 : * deconstruct_jointree should already have visited any outer join that
205 : * could be mentioned in this clause.
206 : */
207 643044 : baserels = bms_difference(restrictinfo->clause_relids,
208 643044 : root->outer_join_rels);
209 643044 : restrictinfo->num_base_rels = bms_num_members(baserels);
210 643044 : bms_free(baserels);
211 :
212 : /*
213 : * Label this RestrictInfo with a fresh serial number.
214 : */
215 643044 : restrictinfo->rinfo_serial = ++(root->last_rinfo_serial);
216 :
217 : /*
218 : * Fill in all the cacheable fields with "not yet set" markers. None of
219 : * these will be computed until/unless needed. Note in particular that we
220 : * don't mark a binary opclause as mergejoinable or hashjoinable here;
221 : * that happens only if it appears in the right context (top level of a
222 : * joinclause list).
223 : */
224 643044 : restrictinfo->parent_ec = NULL;
225 :
226 643044 : restrictinfo->eval_cost.startup = -1;
227 643044 : restrictinfo->norm_selec = -1;
228 643044 : restrictinfo->outer_selec = -1;
229 :
230 643044 : restrictinfo->mergeopfamilies = NIL;
231 :
232 643044 : restrictinfo->left_ec = NULL;
233 643044 : restrictinfo->right_ec = NULL;
234 643044 : restrictinfo->left_em = NULL;
235 643044 : restrictinfo->right_em = NULL;
236 643044 : restrictinfo->scansel_cache = NIL;
237 :
238 643044 : restrictinfo->outer_is_left = false;
239 :
240 643044 : restrictinfo->hashjoinoperator = InvalidOid;
241 :
242 643044 : restrictinfo->left_bucketsize = -1;
243 643044 : restrictinfo->right_bucketsize = -1;
244 643044 : restrictinfo->left_mcvfreq = -1;
245 643044 : restrictinfo->right_mcvfreq = -1;
246 :
247 643044 : restrictinfo->left_hasheqoperator = InvalidOid;
248 643044 : restrictinfo->right_hasheqoperator = InvalidOid;
249 :
250 643044 : return restrictinfo;
251 : }
252 :
253 : /*
254 : * Recursively insert sub-RestrictInfo nodes into a boolean expression.
255 : *
256 : * We put RestrictInfos above simple (non-AND/OR) clauses and above
257 : * sub-OR clauses, but not above sub-AND clauses, because there's no need.
258 : * This may seem odd but it is closely related to the fact that we use
259 : * implicit-AND lists at top level of RestrictInfo lists. Only ORs and
260 : * simple clauses are valid RestrictInfos.
261 : *
262 : * The same is_pushed_down, has_clone, is_clone, and pseudoconstant flag
263 : * values can be applied to all RestrictInfo nodes in the result. Likewise
264 : * for security_level, incompatible_relids, and outer_relids.
265 : *
266 : * The given required_relids are attached to our top-level output,
267 : * but any OR-clause constituents are allowed to default to just the
268 : * contained rels.
269 : */
270 : static Expr *
271 33962 : make_sub_restrictinfos(PlannerInfo *root,
272 : Expr *clause,
273 : bool is_pushed_down,
274 : bool has_clone,
275 : bool is_clone,
276 : bool pseudoconstant,
277 : Index security_level,
278 : Relids required_relids,
279 : Relids incompatible_relids,
280 : Relids outer_relids)
281 : {
282 33962 : if (is_orclause(clause))
283 : {
284 8354 : List *orlist = NIL;
285 : ListCell *temp;
286 :
287 27792 : foreach(temp, ((BoolExpr *) clause)->args)
288 19438 : orlist = lappend(orlist,
289 19438 : make_sub_restrictinfos(root,
290 19438 : lfirst(temp),
291 : is_pushed_down,
292 : has_clone,
293 : is_clone,
294 : pseudoconstant,
295 : security_level,
296 : NULL,
297 : incompatible_relids,
298 : outer_relids));
299 8354 : return (Expr *) make_restrictinfo_internal(root,
300 : clause,
301 : make_orclause(orlist),
302 : is_pushed_down,
303 : has_clone,
304 : is_clone,
305 : pseudoconstant,
306 : security_level,
307 : required_relids,
308 : incompatible_relids,
309 : outer_relids);
310 : }
311 25608 : else if (is_andclause(clause))
312 : {
313 2862 : List *andlist = NIL;
314 : ListCell *temp;
315 :
316 9110 : foreach(temp, ((BoolExpr *) clause)->args)
317 6248 : andlist = lappend(andlist,
318 6248 : make_sub_restrictinfos(root,
319 6248 : lfirst(temp),
320 : is_pushed_down,
321 : has_clone,
322 : is_clone,
323 : pseudoconstant,
324 : security_level,
325 : required_relids,
326 : incompatible_relids,
327 : outer_relids));
328 2862 : return make_andclause(andlist);
329 : }
330 : else
331 22746 : return (Expr *) make_restrictinfo_internal(root,
332 : clause,
333 : NULL,
334 : is_pushed_down,
335 : has_clone,
336 : is_clone,
337 : pseudoconstant,
338 : security_level,
339 : required_relids,
340 : incompatible_relids,
341 : outer_relids);
342 : }
343 :
344 : /*
345 : * commute_restrictinfo
346 : *
347 : * Given a RestrictInfo containing a binary opclause, produce a RestrictInfo
348 : * representing the commutation of that clause. The caller must pass the
349 : * OID of the commutator operator (which it's presumably looked up, else
350 : * it would not know this is valid).
351 : *
352 : * Beware that the result shares sub-structure with the given RestrictInfo.
353 : * That's okay for the intended usage with derived index quals, but might
354 : * be hazardous if the source is subject to change. Also notice that we
355 : * assume without checking that the commutator op is a member of the same
356 : * btree and hash opclasses as the original op.
357 : */
358 : RestrictInfo *
359 52124 : commute_restrictinfo(RestrictInfo *rinfo, Oid comm_op)
360 : {
361 : RestrictInfo *result;
362 : OpExpr *newclause;
363 52124 : OpExpr *clause = castNode(OpExpr, rinfo->clause);
364 :
365 : Assert(list_length(clause->args) == 2);
366 :
367 : /* flat-copy all the fields of clause ... */
368 52124 : newclause = makeNode(OpExpr);
369 52124 : memcpy(newclause, clause, sizeof(OpExpr));
370 :
371 : /* ... and adjust those we need to change to commute it */
372 52124 : newclause->opno = comm_op;
373 52124 : newclause->opfuncid = InvalidOid;
374 52124 : newclause->args = list_make2(lsecond(clause->args),
375 : linitial(clause->args));
376 :
377 : /* likewise, flat-copy all the fields of rinfo ... */
378 52124 : result = makeNode(RestrictInfo);
379 52124 : memcpy(result, rinfo, sizeof(RestrictInfo));
380 :
381 : /*
382 : * ... and adjust those we need to change. Note in particular that we can
383 : * preserve any cached selectivity or cost estimates, since those ought to
384 : * be the same for the new clause. Likewise we can keep the source's
385 : * parent_ec. It's also important that we keep the same rinfo_serial.
386 : */
387 52124 : result->clause = (Expr *) newclause;
388 52124 : result->left_relids = rinfo->right_relids;
389 52124 : result->right_relids = rinfo->left_relids;
390 : Assert(result->orclause == NULL);
391 52124 : result->left_ec = rinfo->right_ec;
392 52124 : result->right_ec = rinfo->left_ec;
393 52124 : result->left_em = rinfo->right_em;
394 52124 : result->right_em = rinfo->left_em;
395 52124 : result->scansel_cache = NIL; /* not worth updating this */
396 52124 : if (rinfo->hashjoinoperator == clause->opno)
397 50446 : result->hashjoinoperator = comm_op;
398 : else
399 1678 : result->hashjoinoperator = InvalidOid;
400 52124 : result->left_bucketsize = rinfo->right_bucketsize;
401 52124 : result->right_bucketsize = rinfo->left_bucketsize;
402 52124 : result->left_mcvfreq = rinfo->right_mcvfreq;
403 52124 : result->right_mcvfreq = rinfo->left_mcvfreq;
404 52124 : result->left_hasheqoperator = InvalidOid;
405 52124 : result->right_hasheqoperator = InvalidOid;
406 :
407 52124 : return result;
408 : }
409 :
410 : /*
411 : * restriction_is_or_clause
412 : *
413 : * Returns t iff the restrictinfo node contains an 'or' clause.
414 : */
415 : bool
416 1816394 : restriction_is_or_clause(RestrictInfo *restrictinfo)
417 : {
418 1816394 : if (restrictinfo->orclause != NULL)
419 51192 : return true;
420 : else
421 1765202 : return false;
422 : }
423 :
424 : /*
425 : * restriction_is_securely_promotable
426 : *
427 : * Returns true if it's okay to evaluate this clause "early", that is before
428 : * other restriction clauses attached to the specified relation.
429 : */
430 : bool
431 1390956 : restriction_is_securely_promotable(RestrictInfo *restrictinfo,
432 : RelOptInfo *rel)
433 : {
434 : /*
435 : * It's okay if there are no baserestrictinfo clauses for the rel that
436 : * would need to go before this one, *or* if this one is leakproof.
437 : */
438 1390956 : if (restrictinfo->security_level <= rel->baserestrict_min_security ||
439 4562 : restrictinfo->leakproof)
440 1388896 : return true;
441 : else
442 2060 : return false;
443 : }
444 :
445 : /*
446 : * Detect whether a RestrictInfo's clause is constant TRUE (note that it's
447 : * surely of type boolean). No such WHERE clause could survive qual
448 : * canonicalization, but equivclass.c may generate such RestrictInfos for
449 : * reasons discussed therein. We should drop them again when creating
450 : * the finished plan, which is handled by the next few functions.
451 : */
452 : static inline bool
453 311728 : rinfo_is_constant_true(RestrictInfo *rinfo)
454 : {
455 313544 : return IsA(rinfo->clause, Const) &&
456 313484 : !((Const *) rinfo->clause)->constisnull &&
457 1756 : DatumGetBool(((Const *) rinfo->clause)->constvalue);
458 : }
459 :
460 : /*
461 : * get_actual_clauses
462 : *
463 : * Returns a list containing the bare clauses from 'restrictinfo_list'.
464 : *
465 : * This is only to be used in cases where none of the RestrictInfos can
466 : * be pseudoconstant clauses (for instance, it's OK on indexqual lists).
467 : */
468 : List *
469 59556 : get_actual_clauses(List *restrictinfo_list)
470 : {
471 59556 : List *result = NIL;
472 : ListCell *l;
473 :
474 122420 : foreach(l, restrictinfo_list)
475 : {
476 62864 : RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
477 :
478 : Assert(!rinfo->pseudoconstant);
479 : Assert(!rinfo_is_constant_true(rinfo));
480 :
481 62864 : result = lappend(result, rinfo->clause);
482 : }
483 59556 : return result;
484 : }
485 :
486 : /*
487 : * extract_actual_clauses
488 : *
489 : * Extract bare clauses from 'restrictinfo_list', returning either the
490 : * regular ones or the pseudoconstant ones per 'pseudoconstant'.
491 : * Constant-TRUE clauses are dropped in any case.
492 : */
493 : List *
494 589236 : extract_actual_clauses(List *restrictinfo_list,
495 : bool pseudoconstant)
496 : {
497 589236 : List *result = NIL;
498 : ListCell *l;
499 :
500 893808 : foreach(l, restrictinfo_list)
501 : {
502 304572 : RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
503 :
504 304572 : if (rinfo->pseudoconstant == pseudoconstant &&
505 279102 : !rinfo_is_constant_true(rinfo))
506 279102 : result = lappend(result, rinfo->clause);
507 : }
508 589236 : return result;
509 : }
510 :
511 : /*
512 : * extract_actual_join_clauses
513 : *
514 : * Extract bare clauses from 'restrictinfo_list', separating those that
515 : * semantically match the join level from those that were pushed down.
516 : * Pseudoconstant and constant-TRUE clauses are excluded from the results.
517 : *
518 : * This is only used at outer joins, since for plain joins we don't care
519 : * about pushed-down-ness.
520 : */
521 : void
522 34930 : extract_actual_join_clauses(List *restrictinfo_list,
523 : Relids joinrelids,
524 : List **joinquals,
525 : List **otherquals)
526 : {
527 : ListCell *l;
528 :
529 34930 : *joinquals = NIL;
530 34930 : *otherquals = NIL;
531 :
532 67568 : foreach(l, restrictinfo_list)
533 : {
534 32638 : RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
535 :
536 32638 : if (RINFO_IS_PUSHED_DOWN(rinfo, joinrelids))
537 : {
538 2912 : if (!rinfo->pseudoconstant &&
539 2900 : !rinfo_is_constant_true(rinfo))
540 2900 : *otherquals = lappend(*otherquals, rinfo->clause);
541 : }
542 : else
543 : {
544 : /* joinquals shouldn't have been marked pseudoconstant */
545 : Assert(!rinfo->pseudoconstant);
546 29726 : if (!rinfo_is_constant_true(rinfo))
547 28096 : *joinquals = lappend(*joinquals, rinfo->clause);
548 : }
549 : }
550 34930 : }
551 :
552 : /*
553 : * join_clause_is_movable_to
554 : * Test whether a join clause is a safe candidate for parameterization
555 : * of a scan on the specified base relation.
556 : *
557 : * A movable join clause is one that can safely be evaluated at a rel below
558 : * its normal semantic level (ie, its required_relids), if the values of
559 : * variables that it would need from other rels are provided.
560 : *
561 : * We insist that the clause actually reference the target relation; this
562 : * prevents undesirable movement of degenerate join clauses, and ensures
563 : * that there is a unique place that a clause can be moved down to.
564 : *
565 : * We cannot move an outer-join clause into the non-nullable side of its
566 : * outer join, as that would change the results (rows would be suppressed
567 : * rather than being null-extended).
568 : *
569 : * Also there must not be an outer join below the clause that would null the
570 : * Vars coming from the target relation. Otherwise the clause might give
571 : * results different from what it would give at its normal semantic level.
572 : *
573 : * Also, the join clause must not use any relations that have LATERAL
574 : * references to the target relation, since we could not put such rels on
575 : * the outer side of a nestloop with the target relation.
576 : *
577 : * Also, we reject is_clone versions of outer-join clauses. This has the
578 : * effect of preventing us from generating variant parameterized paths
579 : * that differ only in which outer joins null the parameterization rel(s).
580 : * Generating one path from the minimally-parameterized has_clone version
581 : * is sufficient.
582 : */
583 : bool
584 225604 : join_clause_is_movable_to(RestrictInfo *rinfo, RelOptInfo *baserel)
585 : {
586 : /* Clause must physically reference target rel */
587 225604 : if (!bms_is_member(baserel->relid, rinfo->clause_relids))
588 34908 : return false;
589 :
590 : /* Cannot move an outer-join clause into the join's outer side */
591 190696 : if (bms_is_member(baserel->relid, rinfo->outer_relids))
592 86302 : return false;
593 :
594 : /*
595 : * Target rel's Vars must not be nulled by any outer join. We can check
596 : * this without groveling through the individual Vars by seeing whether
597 : * clause_relids (which includes all such Vars' varnullingrels) includes
598 : * any outer join that can null the target rel. You might object that
599 : * this could reject the clause on the basis of an OJ relid that came from
600 : * some other rel's Var. However, that would still mean that the clause
601 : * came from above that outer join and shouldn't be pushed down; so there
602 : * should be no false positives.
603 : */
604 104394 : if (bms_overlap(rinfo->clause_relids, baserel->nulling_relids))
605 5338 : return false;
606 :
607 : /* Clause must not use any rels with LATERAL references to this rel */
608 99056 : if (bms_overlap(baserel->lateral_referencers, rinfo->clause_relids))
609 42 : return false;
610 :
611 : /* Ignore clones, too */
612 99014 : if (rinfo->is_clone)
613 8106 : return false;
614 :
615 90908 : return true;
616 : }
617 :
618 : /*
619 : * join_clause_is_movable_into
620 : * Test whether a join clause is movable and can be evaluated within
621 : * the current join context.
622 : *
623 : * currentrelids: the relids of the proposed evaluation location
624 : * current_and_outer: the union of currentrelids and the required_outer
625 : * relids (parameterization's outer relations)
626 : *
627 : * The API would be a bit clearer if we passed the current relids and the
628 : * outer relids separately and did bms_union internally; but since most
629 : * callers need to apply this function to multiple clauses, we make the
630 : * caller perform the union.
631 : *
632 : * Obviously, the clause must only refer to Vars available from the current
633 : * relation plus the outer rels. We also check that it does reference at
634 : * least one current Var, ensuring that the clause will be pushed down to
635 : * a unique place in a parameterized join tree. And we check that we're
636 : * not pushing the clause into its outer-join outer side.
637 : *
638 : * We used to need to check that we're not pushing the clause into a lower
639 : * outer join's inner side. However, now that clause_relids includes
640 : * references to potentially-nulling outer joins, the other tests handle that
641 : * concern. If the clause references any Var coming from the inside of a
642 : * lower outer join, its clause_relids will mention that outer join, causing
643 : * the evaluability check to fail; while if it references no such Vars, the
644 : * references-a-target-rel check will fail.
645 : *
646 : * There's no check here equivalent to join_clause_is_movable_to's test on
647 : * lateral_referencers. We assume the caller wouldn't be inquiring unless
648 : * it'd verified that the proposed outer rels don't have lateral references
649 : * to the current rel(s). (If we are considering join paths with the outer
650 : * rels on the outside and the current rels on the inside, then this should
651 : * have been checked at the outset of such consideration; see join_is_legal
652 : * and the path parameterization checks in joinpath.c.) On the other hand,
653 : * in join_clause_is_movable_to we are asking whether the clause could be
654 : * moved for some valid set of outer rels, so we don't have the benefit of
655 : * relying on prior checks for lateral-reference validity.
656 : *
657 : * Likewise, we don't check is_clone here: rejecting the inappropriate
658 : * variants of a cloned clause must be handled upstream.
659 : *
660 : * Note: if this returns true, it means that the clause could be moved to
661 : * this join relation, but that doesn't mean that this is the lowest join
662 : * it could be moved to. Caller may need to make additional calls to verify
663 : * that this doesn't succeed on either of the inputs of a proposed join.
664 : *
665 : * Note: get_joinrel_parampathinfo depends on the fact that if
666 : * current_and_outer is NULL, this function will always return false
667 : * (since one or the other of the first two tests must fail).
668 : */
669 : bool
670 288412 : join_clause_is_movable_into(RestrictInfo *rinfo,
671 : Relids currentrelids,
672 : Relids current_and_outer)
673 : {
674 : /* Clause must be evaluable given available context */
675 288412 : if (!bms_is_subset(rinfo->clause_relids, current_and_outer))
676 55146 : return false;
677 :
678 : /* Clause must physically reference at least one target rel */
679 233266 : if (!bms_overlap(currentrelids, rinfo->clause_relids))
680 17648 : return false;
681 :
682 : /* Cannot move an outer-join clause into the join's outer side */
683 215618 : if (bms_overlap(currentrelids, rinfo->outer_relids))
684 892 : return false;
685 :
686 214726 : return true;
687 : }
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