Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * equivclass.c
4 : * Routines for managing EquivalenceClasses
5 : *
6 : * See src/backend/optimizer/README for discussion of EquivalenceClasses.
7 : *
8 : *
9 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
10 : * Portions Copyright (c) 1994, Regents of the University of California
11 : *
12 : * IDENTIFICATION
13 : * src/backend/optimizer/path/equivclass.c
14 : *
15 : *-------------------------------------------------------------------------
16 : */
17 : #include "postgres.h"
18 :
19 : #include <limits.h>
20 :
21 : #include "access/stratnum.h"
22 : #include "catalog/pg_type.h"
23 : #include "common/hashfn.h"
24 : #include "nodes/makefuncs.h"
25 : #include "nodes/nodeFuncs.h"
26 : #include "optimizer/appendinfo.h"
27 : #include "optimizer/clauses.h"
28 : #include "optimizer/optimizer.h"
29 : #include "optimizer/pathnode.h"
30 : #include "optimizer/paths.h"
31 : #include "optimizer/planmain.h"
32 : #include "optimizer/restrictinfo.h"
33 : #include "rewrite/rewriteManip.h"
34 : #include "utils/lsyscache.h"
35 :
36 :
37 : static EquivalenceMember *make_eq_member(EquivalenceClass *ec,
38 : Expr *expr, Relids relids,
39 : JoinDomain *jdomain,
40 : EquivalenceMember *parent,
41 : Oid datatype);
42 : static EquivalenceMember *add_eq_member(EquivalenceClass *ec,
43 : Expr *expr, Relids relids,
44 : JoinDomain *jdomain,
45 : Oid datatype);
46 : static EquivalenceMember *add_child_eq_member(PlannerInfo *root,
47 : EquivalenceClass *ec,
48 : int ec_index, Expr *expr,
49 : Relids relids,
50 : JoinDomain *jdomain,
51 : EquivalenceMember *parent_em,
52 : Oid datatype,
53 : Index child_relid);
54 : static void generate_base_implied_equalities_const(PlannerInfo *root,
55 : EquivalenceClass *ec);
56 : static void generate_base_implied_equalities_no_const(PlannerInfo *root,
57 : EquivalenceClass *ec);
58 : static void generate_base_implied_equalities_broken(PlannerInfo *root,
59 : EquivalenceClass *ec);
60 : static List *generate_join_implied_equalities_normal(PlannerInfo *root,
61 : EquivalenceClass *ec,
62 : Relids join_relids,
63 : Relids outer_relids,
64 : Relids inner_relids);
65 : static List *generate_join_implied_equalities_broken(PlannerInfo *root,
66 : EquivalenceClass *ec,
67 : Relids nominal_join_relids,
68 : Relids outer_relids,
69 : Relids nominal_inner_relids,
70 : RelOptInfo *inner_rel);
71 : static Oid select_equality_operator(EquivalenceClass *ec,
72 : Oid lefttype, Oid righttype);
73 : static RestrictInfo *create_join_clause(PlannerInfo *root,
74 : EquivalenceClass *ec, Oid opno,
75 : EquivalenceMember *leftem,
76 : EquivalenceMember *rightem,
77 : EquivalenceClass *parent_ec);
78 : static bool reconsider_outer_join_clause(PlannerInfo *root,
79 : OuterJoinClauseInfo *ojcinfo,
80 : bool outer_on_left);
81 : static bool reconsider_full_join_clause(PlannerInfo *root,
82 : OuterJoinClauseInfo *ojcinfo);
83 : static JoinDomain *find_join_domain(PlannerInfo *root, Relids relids);
84 : static Bitmapset *get_eclass_indexes_for_relids(PlannerInfo *root,
85 : Relids relids);
86 : static Bitmapset *get_common_eclass_indexes(PlannerInfo *root, Relids relids1,
87 : Relids relids2);
88 : static void ec_build_derives_hash(PlannerInfo *root, EquivalenceClass *ec);
89 : static void ec_add_derived_clauses(EquivalenceClass *ec, List *clauses);
90 : static void ec_add_derived_clause(EquivalenceClass *ec, RestrictInfo *clause);
91 : static void ec_add_clause_to_derives_hash(EquivalenceClass *ec, RestrictInfo *rinfo);
92 : static RestrictInfo *ec_search_clause_for_ems(PlannerInfo *root, EquivalenceClass *ec,
93 : EquivalenceMember *leftem,
94 : EquivalenceMember *rightem,
95 : EquivalenceClass *parent_ec);
96 : static RestrictInfo *ec_search_derived_clause_for_ems(PlannerInfo *root,
97 : EquivalenceClass *ec,
98 : EquivalenceMember *leftem,
99 : EquivalenceMember *rightem,
100 : EquivalenceClass *parent_ec);
101 :
102 : /*
103 : * Hash key identifying a derived clause.
104 : *
105 : * This structure should not be filled manually. Use fill_ec_derives_key() to
106 : * set it up in canonical form.
107 : */
108 : typedef struct
109 : {
110 : EquivalenceMember *em1;
111 : EquivalenceMember *em2;
112 : EquivalenceClass *parent_ec;
113 : } ECDerivesKey;
114 :
115 : /* Hash table entry in ec_derives_hash. */
116 : typedef struct
117 : {
118 : uint32 status;
119 : ECDerivesKey key;
120 : RestrictInfo *rinfo;
121 : } ECDerivesEntry;
122 :
123 : /* Threshold for switching from list to hash table */
124 : #define EC_DERIVES_HASH_THRESHOLD 32
125 :
126 : #define SH_PREFIX derives
127 : #define SH_ELEMENT_TYPE ECDerivesEntry
128 : #define SH_KEY_TYPE ECDerivesKey
129 : #define SH_KEY key
130 : #define SH_HASH_KEY(tb, key) \
131 : hash_bytes((const unsigned char *) &(key), sizeof(ECDerivesKey))
132 : #define SH_EQUAL(tb, a, b) \
133 : ((a).em1 == (b).em1 && (a).em2 == (b).em2 && (a).parent_ec == (b).parent_ec)
134 : #define SH_SCOPE static inline
135 : #define SH_DECLARE
136 : #define SH_DEFINE
137 : #include "lib/simplehash.h"
138 :
139 : /*
140 : * process_equivalence
141 : * The given clause has a mergejoinable operator and is not an outer-join
142 : * qualification, so its two sides can be considered equal
143 : * anywhere they are both computable; moreover that equality can be
144 : * extended transitively. Record this knowledge in the EquivalenceClass
145 : * data structure, if applicable. Returns true if successful, false if not
146 : * (in which case caller should treat the clause as ordinary, not an
147 : * equivalence).
148 : *
149 : * In some cases, although we cannot convert a clause into EquivalenceClass
150 : * knowledge, we can still modify it to a more useful form than the original.
151 : * Then, *p_restrictinfo will be replaced by a new RestrictInfo, which is what
152 : * the caller should use for further processing.
153 : *
154 : * jdomain is the join domain within which the given clause was found.
155 : * This limits the applicability of deductions from the EquivalenceClass,
156 : * as described in optimizer/README.
157 : *
158 : * We reject proposed equivalence clauses if they contain leaky functions
159 : * and have security_level above zero. The EC evaluation rules require us to
160 : * apply certain tests at certain joining levels, and we can't tolerate
161 : * delaying any test on security_level grounds. By rejecting candidate clauses
162 : * that might require security delays, we ensure it's safe to apply an EC
163 : * clause as soon as it's supposed to be applied.
164 : *
165 : * On success return, we have also initialized the clause's left_ec/right_ec
166 : * fields to point to the EquivalenceClass representing it. This saves lookup
167 : * effort later.
168 : *
169 : * Note: constructing merged EquivalenceClasses is a standard UNION-FIND
170 : * problem, for which there exist better data structures than simple lists.
171 : * If this code ever proves to be a bottleneck then it could be sped up ---
172 : * but for now, simple is beautiful.
173 : *
174 : * Note: this is only called during planner startup, not during GEQO
175 : * exploration, so we need not worry about whether we're in the right
176 : * memory context.
177 : */
178 : bool
179 180407 : process_equivalence(PlannerInfo *root,
180 : RestrictInfo **p_restrictinfo,
181 : JoinDomain *jdomain)
182 : {
183 180407 : RestrictInfo *restrictinfo = *p_restrictinfo;
184 180407 : Expr *clause = restrictinfo->clause;
185 : Oid opno,
186 : collation,
187 : item1_type,
188 : item2_type;
189 : Expr *item1;
190 : Expr *item2;
191 : Relids item1_relids,
192 : item2_relids;
193 : List *opfamilies;
194 : EquivalenceClass *ec1,
195 : *ec2;
196 : EquivalenceMember *em1,
197 : *em2;
198 : ListCell *lc1;
199 : int ec2_idx;
200 :
201 : /* Should not already be marked as having generated an eclass */
202 : Assert(restrictinfo->left_ec == NULL);
203 : Assert(restrictinfo->right_ec == NULL);
204 :
205 : /* Reject if it is potentially postponable by security considerations */
206 180407 : if (restrictinfo->security_level > 0 && !restrictinfo->leakproof)
207 104 : return false;
208 :
209 : /* Extract info from given clause */
210 : Assert(is_opclause(clause));
211 180303 : opno = ((OpExpr *) clause)->opno;
212 180303 : collation = ((OpExpr *) clause)->inputcollid;
213 180303 : item1 = (Expr *) get_leftop(clause);
214 180303 : item2 = (Expr *) get_rightop(clause);
215 180303 : item1_relids = restrictinfo->left_relids;
216 180303 : item2_relids = restrictinfo->right_relids;
217 :
218 : /*
219 : * Ensure both input expressions expose the desired collation (their types
220 : * should be OK already); see comments for canonicalize_ec_expression.
221 : */
222 180303 : item1 = canonicalize_ec_expression(item1,
223 : exprType((Node *) item1),
224 : collation);
225 180303 : item2 = canonicalize_ec_expression(item2,
226 : exprType((Node *) item2),
227 : collation);
228 :
229 : /*
230 : * Clauses of the form X=X cannot be translated into EquivalenceClasses.
231 : * We'd either end up with a single-entry EC, losing the knowledge that
232 : * the clause was present at all, or else make an EC with duplicate
233 : * entries, causing other issues.
234 : */
235 180303 : if (equal(item1, item2))
236 : {
237 : /*
238 : * If the operator is strict, then the clause can be treated as just
239 : * "X IS NOT NULL". (Since we know we are considering a top-level
240 : * qual, we can ignore the difference between FALSE and NULL results.)
241 : * It's worth making the conversion because we'll typically get a much
242 : * better selectivity estimate than we would for X=X.
243 : *
244 : * If the operator is not strict, we can't be sure what it will do
245 : * with NULLs, so don't attempt to optimize it.
246 : */
247 27 : set_opfuncid((OpExpr *) clause);
248 27 : if (func_strict(((OpExpr *) clause)->opfuncid))
249 : {
250 27 : NullTest *ntest = makeNode(NullTest);
251 :
252 27 : ntest->arg = item1;
253 27 : ntest->nulltesttype = IS_NOT_NULL;
254 27 : ntest->argisrow = false; /* correct even if composite arg */
255 27 : ntest->location = -1;
256 :
257 27 : *p_restrictinfo =
258 27 : make_restrictinfo(root,
259 : (Expr *) ntest,
260 27 : restrictinfo->is_pushed_down,
261 27 : restrictinfo->has_clone,
262 27 : restrictinfo->is_clone,
263 27 : restrictinfo->pseudoconstant,
264 : restrictinfo->security_level,
265 : NULL,
266 : restrictinfo->incompatible_relids,
267 : restrictinfo->outer_relids);
268 : }
269 27 : return false;
270 : }
271 :
272 : /*
273 : * We use the declared input types of the operator, not exprType() of the
274 : * inputs, as the nominal datatypes for opfamily lookup. This presumes
275 : * that btree operators are always registered with amoplefttype and
276 : * amoprighttype equal to their declared input types. We will need this
277 : * info anyway to build EquivalenceMember nodes, and by extracting it now
278 : * we can use type comparisons to short-circuit some equal() tests.
279 : */
280 180276 : op_input_types(opno, &item1_type, &item2_type);
281 :
282 180276 : opfamilies = restrictinfo->mergeopfamilies;
283 :
284 : /*
285 : * Sweep through the existing EquivalenceClasses looking for matches to
286 : * item1 and item2. These are the possible outcomes:
287 : *
288 : * 1. We find both in the same EC. The equivalence is already known, so
289 : * there's nothing to do.
290 : *
291 : * 2. We find both in different ECs. Merge the two ECs together.
292 : *
293 : * 3. We find just one. Add the other to its EC.
294 : *
295 : * 4. We find neither. Make a new, two-entry EC.
296 : *
297 : * Note: since all ECs are built through this process or the similar
298 : * search in get_eclass_for_sort_expr(), it's impossible that we'd match
299 : * an item in more than one existing nonvolatile EC. So it's okay to stop
300 : * at the first match.
301 : */
302 180276 : ec1 = ec2 = NULL;
303 180276 : em1 = em2 = NULL;
304 180276 : ec2_idx = -1;
305 308191 : foreach(lc1, root->eq_classes)
306 : {
307 127942 : EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
308 : ListCell *lc2;
309 :
310 : /* Never match to a volatile EC */
311 127942 : if (cur_ec->ec_has_volatile)
312 0 : continue;
313 :
314 : /*
315 : * The collation has to match; check this first since it's cheaper
316 : * than the opfamily comparison.
317 : */
318 127942 : if (collation != cur_ec->ec_collation)
319 10350 : continue;
320 :
321 : /*
322 : * A "match" requires matching sets of btree opfamilies. Use of
323 : * equal() for this test has implications discussed in the comments
324 : * for get_mergejoin_opfamilies().
325 : */
326 117592 : if (!equal(opfamilies, cur_ec->ec_opfamilies))
327 32968 : continue;
328 :
329 : /* We don't expect any children yet */
330 : Assert(cur_ec->ec_childmembers == NULL);
331 :
332 252892 : foreach(lc2, cur_ec->ec_members)
333 : {
334 168295 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
335 :
336 : /* Child members should not exist in ec_members */
337 : Assert(!cur_em->em_is_child);
338 :
339 : /*
340 : * Match constants only within the same JoinDomain (see
341 : * optimizer/README).
342 : */
343 168295 : if (cur_em->em_is_const && cur_em->em_jdomain != jdomain)
344 2462 : continue;
345 :
346 165833 : if (!ec1 &&
347 319123 : item1_type == cur_em->em_datatype &&
348 159479 : equal(item1, cur_em->em_expr))
349 : {
350 9541 : ec1 = cur_ec;
351 9541 : em1 = cur_em;
352 9541 : if (ec2)
353 15 : break;
354 : }
355 :
356 165818 : if (!ec2 &&
357 328254 : item2_type == cur_em->em_datatype &&
358 163977 : equal(item2, cur_em->em_expr))
359 : {
360 2499 : ec2 = cur_ec;
361 2499 : ec2_idx = foreach_current_index(lc1);
362 2499 : em2 = cur_em;
363 2499 : if (ec1)
364 12 : break;
365 : }
366 : }
367 :
368 84624 : if (ec1 && ec2)
369 27 : break;
370 : }
371 :
372 : /* Sweep finished, what did we find? */
373 :
374 180276 : if (ec1 && ec2)
375 : {
376 : /* If case 1, nothing to do, except add to sources */
377 27 : if (ec1 == ec2)
378 : {
379 6 : ec1->ec_sources = lappend(ec1->ec_sources, restrictinfo);
380 6 : ec1->ec_min_security = Min(ec1->ec_min_security,
381 : restrictinfo->security_level);
382 6 : ec1->ec_max_security = Max(ec1->ec_max_security,
383 : restrictinfo->security_level);
384 : /* mark the RI as associated with this eclass */
385 6 : restrictinfo->left_ec = ec1;
386 6 : restrictinfo->right_ec = ec1;
387 : /* mark the RI as usable with this pair of EMs */
388 6 : restrictinfo->left_em = em1;
389 6 : restrictinfo->right_em = em2;
390 6 : return true;
391 : }
392 :
393 : /*
394 : * Case 2: need to merge ec1 and ec2. This should never happen after
395 : * the ECs have reached canonical state; otherwise, pathkeys could be
396 : * rendered non-canonical by the merge, and relation eclass indexes
397 : * would get broken by removal of an eq_classes list entry.
398 : */
399 21 : if (root->ec_merging_done)
400 0 : elog(ERROR, "too late to merge equivalence classes");
401 :
402 : /*
403 : * We add ec2's items to ec1, then set ec2's ec_merged link to point
404 : * to ec1 and remove ec2 from the eq_classes list. We cannot simply
405 : * delete ec2 because that could leave dangling pointers in existing
406 : * PathKeys. We leave it behind with a link so that the merged EC can
407 : * be found.
408 : */
409 21 : ec1->ec_members = list_concat(ec1->ec_members, ec2->ec_members);
410 21 : ec1->ec_sources = list_concat(ec1->ec_sources, ec2->ec_sources);
411 :
412 : /*
413 : * Appends ec2's derived clauses to ec1->ec_derives_list and adds them
414 : * to ec1->ec_derives_hash if present.
415 : */
416 21 : ec_add_derived_clauses(ec1, ec2->ec_derives_list);
417 21 : ec1->ec_relids = bms_join(ec1->ec_relids, ec2->ec_relids);
418 21 : ec1->ec_has_const |= ec2->ec_has_const;
419 : /* can't need to set has_volatile */
420 21 : ec1->ec_min_security = Min(ec1->ec_min_security,
421 : ec2->ec_min_security);
422 21 : ec1->ec_max_security = Max(ec1->ec_max_security,
423 : ec2->ec_max_security);
424 21 : ec2->ec_merged = ec1;
425 21 : root->eq_classes = list_delete_nth_cell(root->eq_classes, ec2_idx);
426 : /* just to avoid debugging confusion w/ dangling pointers: */
427 21 : ec2->ec_members = NIL;
428 21 : ec2->ec_sources = NIL;
429 21 : ec_clear_derived_clauses(ec2);
430 21 : ec2->ec_relids = NULL;
431 21 : ec1->ec_sources = lappend(ec1->ec_sources, restrictinfo);
432 21 : ec1->ec_min_security = Min(ec1->ec_min_security,
433 : restrictinfo->security_level);
434 21 : ec1->ec_max_security = Max(ec1->ec_max_security,
435 : restrictinfo->security_level);
436 : /* mark the RI as associated with this eclass */
437 21 : restrictinfo->left_ec = ec1;
438 21 : restrictinfo->right_ec = ec1;
439 : /* mark the RI as usable with this pair of EMs */
440 21 : restrictinfo->left_em = em1;
441 21 : restrictinfo->right_em = em2;
442 : }
443 180249 : else if (ec1)
444 : {
445 : /* Case 3: add item2 to ec1 */
446 9514 : em2 = add_eq_member(ec1, item2, item2_relids,
447 : jdomain, item2_type);
448 9514 : ec1->ec_sources = lappend(ec1->ec_sources, restrictinfo);
449 9514 : ec1->ec_min_security = Min(ec1->ec_min_security,
450 : restrictinfo->security_level);
451 9514 : ec1->ec_max_security = Max(ec1->ec_max_security,
452 : restrictinfo->security_level);
453 : /* mark the RI as associated with this eclass */
454 9514 : restrictinfo->left_ec = ec1;
455 9514 : restrictinfo->right_ec = ec1;
456 : /* mark the RI as usable with this pair of EMs */
457 9514 : restrictinfo->left_em = em1;
458 9514 : restrictinfo->right_em = em2;
459 : }
460 170735 : else if (ec2)
461 : {
462 : /* Case 3: add item1 to ec2 */
463 2472 : em1 = add_eq_member(ec2, item1, item1_relids,
464 : jdomain, item1_type);
465 2472 : ec2->ec_sources = lappend(ec2->ec_sources, restrictinfo);
466 2472 : ec2->ec_min_security = Min(ec2->ec_min_security,
467 : restrictinfo->security_level);
468 2472 : ec2->ec_max_security = Max(ec2->ec_max_security,
469 : restrictinfo->security_level);
470 : /* mark the RI as associated with this eclass */
471 2472 : restrictinfo->left_ec = ec2;
472 2472 : restrictinfo->right_ec = ec2;
473 : /* mark the RI as usable with this pair of EMs */
474 2472 : restrictinfo->left_em = em1;
475 2472 : restrictinfo->right_em = em2;
476 : }
477 : else
478 : {
479 : /* Case 4: make a new, two-entry EC */
480 168263 : EquivalenceClass *ec = makeNode(EquivalenceClass);
481 :
482 168263 : ec->ec_opfamilies = opfamilies;
483 168263 : ec->ec_collation = collation;
484 168263 : ec->ec_childmembers_size = 0;
485 168263 : ec->ec_members = NIL;
486 168263 : ec->ec_childmembers = NULL;
487 168263 : ec->ec_sources = list_make1(restrictinfo);
488 168263 : ec->ec_derives_list = NIL;
489 168263 : ec->ec_derives_hash = NULL;
490 168263 : ec->ec_relids = NULL;
491 168263 : ec->ec_has_const = false;
492 168263 : ec->ec_has_volatile = false;
493 168263 : ec->ec_broken = false;
494 168263 : ec->ec_sortref = 0;
495 168263 : ec->ec_min_security = restrictinfo->security_level;
496 168263 : ec->ec_max_security = restrictinfo->security_level;
497 168263 : ec->ec_merged = NULL;
498 168263 : em1 = add_eq_member(ec, item1, item1_relids,
499 : jdomain, item1_type);
500 168263 : em2 = add_eq_member(ec, item2, item2_relids,
501 : jdomain, item2_type);
502 :
503 168263 : root->eq_classes = lappend(root->eq_classes, ec);
504 :
505 : /* mark the RI as associated with this eclass */
506 168263 : restrictinfo->left_ec = ec;
507 168263 : restrictinfo->right_ec = ec;
508 : /* mark the RI as usable with this pair of EMs */
509 168263 : restrictinfo->left_em = em1;
510 168263 : restrictinfo->right_em = em2;
511 : }
512 :
513 180270 : return true;
514 : }
515 :
516 : /*
517 : * canonicalize_ec_expression
518 : *
519 : * This function ensures that the expression exposes the expected type and
520 : * collation, so that it will be equal() to other equivalence-class expressions
521 : * that it ought to be equal() to.
522 : *
523 : * The rule for datatypes is that the exposed type should match what it would
524 : * be for an input to an operator of the EC's opfamilies; which is usually
525 : * the declared input type of the operator, but in the case of polymorphic
526 : * operators no relabeling is wanted (compare the behavior of parse_coerce.c).
527 : * Expressions coming in from quals will generally have the right type
528 : * already, but expressions coming from indexkeys may not (because they are
529 : * represented without any explicit relabel in pg_index), and the same problem
530 : * occurs for sort expressions (because the parser is likewise cavalier about
531 : * putting relabels on them). Such cases will be binary-compatible with the
532 : * real operators, so adding a RelabelType is sufficient.
533 : *
534 : * Also, the expression's exposed collation must match the EC's collation.
535 : * This is important because in comparisons like "foo < bar COLLATE baz",
536 : * only one of the expressions has the correct exposed collation as we receive
537 : * it from the parser. Forcing both of them to have it ensures that all
538 : * variant spellings of such a construct behave the same. Again, we can
539 : * stick on a RelabelType to force the right exposed collation. (It might
540 : * work to not label the collation at all in EC members, but this is risky
541 : * since some parts of the system expect exprCollation() to deliver the
542 : * right answer for a sort key.)
543 : */
544 : Expr *
545 1682583 : canonicalize_ec_expression(Expr *expr, Oid req_type, Oid req_collation)
546 : {
547 1682583 : Oid expr_type = exprType((Node *) expr);
548 :
549 : /*
550 : * For a polymorphic-input-type opclass, just keep the same exposed type.
551 : * RECORD opclasses work like polymorphic-type ones for this purpose.
552 : */
553 1682583 : if (IsPolymorphicType(req_type) || req_type == RECORDOID)
554 4893 : req_type = expr_type;
555 :
556 : /*
557 : * No work if the expression exposes the right type/collation already.
558 : */
559 3326830 : if (expr_type != req_type ||
560 1644247 : exprCollation((Node *) expr) != req_collation)
561 : {
562 : /*
563 : * If we have to change the type of the expression, set typmod to -1,
564 : * since the new type may not have the same typmod interpretation.
565 : * When we only have to change collation, preserve the exposed typmod.
566 : */
567 : int32 req_typmod;
568 :
569 39344 : if (expr_type != req_type)
570 38336 : req_typmod = -1;
571 : else
572 1008 : req_typmod = exprTypmod((Node *) expr);
573 :
574 : /*
575 : * Use applyRelabelType so that we preserve const-flatness. This is
576 : * important since eval_const_expressions has already been applied.
577 : */
578 39344 : expr = (Expr *) applyRelabelType((Node *) expr,
579 : req_type, req_typmod, req_collation,
580 : COERCE_IMPLICIT_CAST, -1, false);
581 : }
582 :
583 1682583 : return expr;
584 : }
585 :
586 : /*
587 : * make_eq_member
588 : * Build a new EquivalenceMember without adding it to an EC. If 'parent'
589 : * is NULL, the result will be a parent member, otherwise a child member.
590 : */
591 : static EquivalenceMember *
592 548054 : make_eq_member(EquivalenceClass *ec, Expr *expr, Relids relids,
593 : JoinDomain *jdomain, EquivalenceMember *parent, Oid datatype)
594 : {
595 548054 : EquivalenceMember *em = makeNode(EquivalenceMember);
596 :
597 548054 : em->em_expr = expr;
598 548054 : em->em_relids = relids;
599 548054 : em->em_is_const = false;
600 548054 : em->em_is_child = (parent != NULL);
601 548054 : em->em_datatype = datatype;
602 548054 : em->em_jdomain = jdomain;
603 548054 : em->em_parent = parent;
604 :
605 548054 : if (bms_is_empty(relids))
606 : {
607 : /*
608 : * No Vars, assume it's a pseudoconstant. This is correct for entries
609 : * generated from process_equivalence(), because a WHERE clause can't
610 : * contain aggregates or SRFs, and non-volatility was checked before
611 : * process_equivalence() ever got called. But
612 : * get_eclass_for_sort_expr() has to work harder. We put the tests
613 : * there not here to save cycles in the equivalence case.
614 : */
615 : Assert(!parent);
616 129223 : em->em_is_const = true;
617 129223 : ec->ec_has_const = true;
618 : /* it can't affect ec_relids */
619 : }
620 :
621 548054 : return em;
622 : }
623 :
624 : /*
625 : * add_eq_member - build a new non-child EquivalenceMember and add it to 'ec'.
626 : */
627 : static EquivalenceMember *
628 491486 : add_eq_member(EquivalenceClass *ec, Expr *expr, Relids relids,
629 : JoinDomain *jdomain, Oid datatype)
630 : {
631 491486 : EquivalenceMember *em = make_eq_member(ec, expr, relids, jdomain,
632 : NULL, datatype);
633 :
634 : /* add to the members list */
635 491486 : ec->ec_members = lappend(ec->ec_members, em);
636 :
637 : /* record the relids for parent members */
638 491486 : ec->ec_relids = bms_add_members(ec->ec_relids, relids);
639 :
640 491486 : return em;
641 : }
642 :
643 : /*
644 : * add_child_eq_member
645 : * Create an em_is_child=true EquivalenceMember and add it to 'ec'.
646 : *
647 : * 'root' is the PlannerInfo that 'ec' belongs to.
648 : * 'ec' is the EquivalenceClass to add the child member to.
649 : * 'ec_index' the index of 'ec' within root->eq_classes, or -1 if maintaining
650 : * the RelOptInfo.eclass_indexes isn't needed.
651 : * 'expr' is the em_expr for the new member.
652 : * 'relids' is the 'em_relids' for the new member.
653 : * 'jdomain' is the 'em_jdomain' for the new member.
654 : * 'parent_em' is the parent member of the child to create.
655 : * 'datatype' is the em_datatype of the new member.
656 : * 'child_relid' defines which element of ec_childmembers to add this member
657 : * to. This is generally a RELOPT_OTHER_MEMBER_REL, but for set operations
658 : * can be a RELOPT_BASEREL representing the set-op children.
659 : */
660 : static EquivalenceMember *
661 56568 : add_child_eq_member(PlannerInfo *root, EquivalenceClass *ec, int ec_index,
662 : Expr *expr, Relids relids, JoinDomain *jdomain,
663 : EquivalenceMember *parent_em, Oid datatype,
664 : Index child_relid)
665 : {
666 : EquivalenceMember *em;
667 :
668 : Assert(parent_em != NULL);
669 :
670 : /*
671 : * Allocate the array to store child members; an array of Lists indexed by
672 : * relid, or expand the existing one, if necessary.
673 : */
674 56568 : if (unlikely(ec->ec_childmembers_size < root->simple_rel_array_size))
675 : {
676 14790 : if (ec->ec_childmembers == NULL)
677 14790 : ec->ec_childmembers = palloc0_array(List *, root->simple_rel_array_size);
678 : else
679 0 : ec->ec_childmembers = repalloc0_array(ec->ec_childmembers, List *,
680 : ec->ec_childmembers_size,
681 : root->simple_rel_array_size);
682 :
683 14790 : ec->ec_childmembers_size = root->simple_rel_array_size;
684 : }
685 :
686 56568 : em = make_eq_member(ec, expr, relids, jdomain, parent_em, datatype);
687 :
688 : /* add member to the ec_childmembers List for the given child_relid */
689 56568 : ec->ec_childmembers[child_relid] = lappend(ec->ec_childmembers[child_relid], em);
690 :
691 : /* Record this EC index for the child rel */
692 56568 : if (ec_index >= 0)
693 : {
694 36105 : RelOptInfo *child_rel = root->simple_rel_array[child_relid];
695 :
696 36105 : child_rel->eclass_indexes =
697 36105 : bms_add_member(child_rel->eclass_indexes, ec_index);
698 : }
699 :
700 56568 : return em;
701 : }
702 :
703 :
704 : /*
705 : * get_eclass_for_sort_expr
706 : * Given an expression and opfamily/collation info, find an existing
707 : * equivalence class it is a member of; if none, optionally build a new
708 : * single-member EquivalenceClass for it.
709 : *
710 : * sortref is the SortGroupRef of the originating SortGroupClause, if any,
711 : * or zero if not. (It should never be zero if the expression is volatile!)
712 : *
713 : * If rel is not NULL, it identifies a specific relation we're considering
714 : * a path for, and indicates that child EC members for that relation can be
715 : * considered. Otherwise child members are ignored. (Note: since child EC
716 : * members aren't guaranteed unique, a non-NULL value means that there could
717 : * be more than one EC that matches the expression; if so it's order-dependent
718 : * which one you get. This is annoying but it only happens in corner cases,
719 : * so for now we live with just reporting the first match. See also
720 : * generate_implied_equalities_for_column and match_pathkeys_to_index.)
721 : *
722 : * If create_it is true, we'll build a new EquivalenceClass when there is no
723 : * match. If create_it is false, we just return NULL when no match.
724 : *
725 : * This can be used safely both before and after EquivalenceClass merging;
726 : * since it never causes merging it does not invalidate any existing ECs
727 : * or PathKeys. However, ECs added after path generation has begun are
728 : * of limited usefulness, so usually it's best to create them beforehand.
729 : *
730 : * Note: opfamilies must be chosen consistently with the way
731 : * process_equivalence() would do; that is, generated from a mergejoinable
732 : * equality operator. Else we might fail to detect valid equivalences,
733 : * generating poor (but not incorrect) plans.
734 : */
735 : EquivalenceClass *
736 1243499 : get_eclass_for_sort_expr(PlannerInfo *root,
737 : Expr *expr,
738 : List *opfamilies,
739 : Oid opcintype,
740 : Oid collation,
741 : Index sortref,
742 : Relids rel,
743 : bool create_it)
744 : {
745 : JoinDomain *jdomain;
746 : Relids expr_relids;
747 : EquivalenceClass *newec;
748 : EquivalenceMember *newem;
749 : ListCell *lc1;
750 : MemoryContext oldcontext;
751 :
752 : /*
753 : * Ensure the expression exposes the correct type and collation.
754 : */
755 1243499 : expr = canonicalize_ec_expression(expr, opcintype, collation);
756 :
757 : /*
758 : * Since SortGroupClause nodes are top-level expressions (GROUP BY, ORDER
759 : * BY, etc), they can be presumed to belong to the top JoinDomain.
760 : */
761 1243499 : jdomain = linitial_node(JoinDomain, root->join_domains);
762 :
763 : /*
764 : * Scan through the existing EquivalenceClasses for a match
765 : */
766 4159265 : foreach(lc1, root->eq_classes)
767 : {
768 3637571 : EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
769 : EquivalenceMemberIterator it;
770 : EquivalenceMember *cur_em;
771 :
772 : /*
773 : * Never match to a volatile EC, except when we are looking at another
774 : * reference to the same volatile SortGroupClause.
775 : */
776 3637571 : if (cur_ec->ec_has_volatile &&
777 18 : (sortref == 0 || sortref != cur_ec->ec_sortref))
778 1585150 : continue;
779 :
780 3637261 : if (collation != cur_ec->ec_collation)
781 981353 : continue;
782 2655908 : if (!equal(opfamilies, cur_ec->ec_opfamilies))
783 603487 : continue;
784 :
785 2052421 : setup_eclass_member_iterator(&it, cur_ec, rel);
786 4515519 : while ((cur_em = eclass_member_iterator_next(&it)) != NULL)
787 : {
788 : /*
789 : * Ignore child members unless they match the request.
790 : */
791 3184903 : if (cur_em->em_is_child &&
792 51324 : !bms_equal(cur_em->em_relids, rel))
793 0 : continue;
794 :
795 : /*
796 : * Match constants only within the same JoinDomain (see
797 : * optimizer/README).
798 : */
799 3184903 : if (cur_em->em_is_const && cur_em->em_jdomain != jdomain)
800 54229 : continue;
801 :
802 6233180 : if (opcintype == cur_em->em_datatype &&
803 3102506 : equal(expr, cur_em->em_expr))
804 721805 : return cur_ec; /* Match! */
805 : }
806 : }
807 :
808 : /* No match; does caller want a NULL result? */
809 521694 : if (!create_it)
810 378720 : return NULL;
811 :
812 : /*
813 : * OK, build a new single-member EC
814 : *
815 : * Here, we must be sure that we construct the EC in the right context.
816 : */
817 142974 : oldcontext = MemoryContextSwitchTo(root->planner_cxt);
818 :
819 142974 : newec = makeNode(EquivalenceClass);
820 142974 : newec->ec_opfamilies = list_copy(opfamilies);
821 142974 : newec->ec_collation = collation;
822 142974 : newec->ec_childmembers_size = 0;
823 142974 : newec->ec_members = NIL;
824 142974 : newec->ec_childmembers = NULL;
825 142974 : newec->ec_sources = NIL;
826 142974 : newec->ec_derives_list = NIL;
827 142974 : newec->ec_derives_hash = NULL;
828 142974 : newec->ec_relids = NULL;
829 142974 : newec->ec_has_const = false;
830 142974 : newec->ec_has_volatile = contain_volatile_functions((Node *) expr);
831 142974 : newec->ec_broken = false;
832 142974 : newec->ec_sortref = sortref;
833 142974 : newec->ec_min_security = UINT_MAX;
834 142974 : newec->ec_max_security = 0;
835 142974 : newec->ec_merged = NULL;
836 :
837 142974 : if (newec->ec_has_volatile && sortref == 0) /* should not happen */
838 0 : elog(ERROR, "volatile EquivalenceClass has no sortref");
839 :
840 : /*
841 : * Get the precise set of relids appearing in the expression.
842 : */
843 142974 : expr_relids = pull_varnos(root, (Node *) expr);
844 :
845 142974 : newem = add_eq_member(newec, copyObject(expr), expr_relids,
846 : jdomain, opcintype);
847 :
848 : /*
849 : * add_eq_member doesn't check for volatile functions, set-returning
850 : * functions, aggregates, or window functions, but such could appear in
851 : * sort expressions; so we have to check whether its const-marking was
852 : * correct.
853 : */
854 142974 : if (newec->ec_has_const)
855 : {
856 9896 : if (newec->ec_has_volatile ||
857 9755 : expression_returns_set((Node *) expr) ||
858 9592 : contain_agg_clause((Node *) expr) ||
859 4752 : contain_window_function((Node *) expr))
860 : {
861 232 : newec->ec_has_const = false;
862 232 : newem->em_is_const = false;
863 : }
864 : }
865 :
866 142974 : root->eq_classes = lappend(root->eq_classes, newec);
867 :
868 : /*
869 : * If EC merging is already complete, we have to mop up by adding the new
870 : * EC to the eclass_indexes of the relation(s) mentioned in it.
871 : */
872 142974 : if (root->ec_merging_done)
873 : {
874 82587 : int ec_index = list_length(root->eq_classes) - 1;
875 82587 : int i = -1;
876 :
877 159219 : while ((i = bms_next_member(newec->ec_relids, i)) > 0)
878 : {
879 76632 : RelOptInfo *rel = root->simple_rel_array[i];
880 :
881 : /* ignore the RTE_GROUP RTE */
882 76632 : if (i == root->group_rtindex)
883 356 : continue;
884 :
885 76276 : if (rel == NULL) /* must be an outer join */
886 : {
887 : Assert(bms_is_member(i, root->outer_join_rels));
888 3421 : continue;
889 : }
890 :
891 : Assert(rel->reloptkind == RELOPT_BASEREL);
892 :
893 72855 : rel->eclass_indexes = bms_add_member(rel->eclass_indexes,
894 : ec_index);
895 : }
896 : }
897 :
898 142974 : MemoryContextSwitchTo(oldcontext);
899 :
900 142974 : return newec;
901 : }
902 :
903 : /*
904 : * find_ec_member_matching_expr
905 : * Locate an EquivalenceClass member matching the given expr, if any;
906 : * return NULL if no match.
907 : *
908 : * "Matching" is defined as "equal after stripping RelabelTypes".
909 : * This is used for identifying sort expressions, and we need to allow
910 : * binary-compatible relabeling for some cases involving binary-compatible
911 : * sort operators.
912 : *
913 : * Child EC members are ignored unless they belong to given 'relids'.
914 : */
915 : EquivalenceMember *
916 183998 : find_ec_member_matching_expr(EquivalenceClass *ec,
917 : Expr *expr,
918 : Relids relids)
919 : {
920 : EquivalenceMemberIterator it;
921 : EquivalenceMember *em;
922 :
923 : /* We ignore binary-compatible relabeling on both ends */
924 197631 : while (expr && IsA(expr, RelabelType))
925 13633 : expr = ((RelabelType *) expr)->arg;
926 :
927 183998 : setup_eclass_member_iterator(&it, ec, relids);
928 308200 : while ((em = eclass_member_iterator_next(&it)) != NULL)
929 : {
930 : Expr *emexpr;
931 :
932 : /*
933 : * We shouldn't be trying to sort by an equivalence class that
934 : * contains a constant, so no need to consider such cases any further.
935 : */
936 203502 : if (em->em_is_const)
937 0 : continue;
938 :
939 : /*
940 : * Ignore child members unless they belong to the requested rel.
941 : */
942 203502 : if (em->em_is_child &&
943 6056 : !bms_is_subset(em->em_relids, relids))
944 2040 : continue;
945 :
946 : /*
947 : * Match if same expression (after stripping relabel).
948 : */
949 201462 : emexpr = em->em_expr;
950 205587 : while (emexpr && IsA(emexpr, RelabelType))
951 4125 : emexpr = ((RelabelType *) emexpr)->arg;
952 :
953 201462 : if (equal(emexpr, expr))
954 79300 : return em;
955 : }
956 :
957 104698 : return NULL;
958 : }
959 :
960 : /*
961 : * find_computable_ec_member
962 : * Locate an EquivalenceClass member that can be computed from the
963 : * expressions appearing in "exprs"; return NULL if no match.
964 : *
965 : * "exprs" can be either a list of bare expression trees, or a list of
966 : * TargetEntry nodes. Typically it will contain Vars and possibly Aggrefs
967 : * and WindowFuncs; however, when considering an appendrel member the list
968 : * could contain arbitrary expressions. We consider an EC member to be
969 : * computable if all the Vars, PlaceHolderVars, Aggrefs, and WindowFuncs
970 : * it needs are present in "exprs".
971 : *
972 : * There is some subtlety in that definition: for example, if an EC member is
973 : * Var_A + 1 while what is in "exprs" is Var_A + 2, it's still computable.
974 : * This works because in the final plan tree, the EC member's expression will
975 : * be computed as part of the same plan node targetlist that is currently
976 : * represented by "exprs". So if we have Var_A available for the existing
977 : * tlist member, it must be OK to use it in the EC expression too.
978 : *
979 : * Unlike find_ec_member_matching_expr, there's no special provision here
980 : * for binary-compatible relabeling. This is intentional: if we have to
981 : * compute an expression in this way, setrefs.c is going to insist on exact
982 : * matches of Vars to the source tlist.
983 : *
984 : * Child EC members are ignored unless they belong to given 'relids'.
985 : * Also, non-parallel-safe expressions are ignored if 'require_parallel_safe'.
986 : *
987 : * Note: some callers pass root == NULL for notational reasons. This is OK
988 : * when require_parallel_safe is false.
989 : */
990 : EquivalenceMember *
991 4155 : find_computable_ec_member(PlannerInfo *root,
992 : EquivalenceClass *ec,
993 : List *exprs,
994 : Relids relids,
995 : bool require_parallel_safe)
996 : {
997 : List *exprvars;
998 : EquivalenceMemberIterator it;
999 : EquivalenceMember *em;
1000 :
1001 : /*
1002 : * Pull out the Vars and quasi-Vars present in "exprs". In the typical
1003 : * non-appendrel case, this is just another representation of the same
1004 : * list. However, it does remove the distinction between the case of a
1005 : * list of plain expressions and a list of TargetEntrys.
1006 : */
1007 4155 : exprvars = pull_var_clause((Node *) exprs,
1008 : PVC_INCLUDE_AGGREGATES |
1009 : PVC_INCLUDE_WINDOWFUNCS |
1010 : PVC_INCLUDE_PLACEHOLDERS);
1011 :
1012 4155 : setup_eclass_member_iterator(&it, ec, relids);
1013 8350 : while ((em = eclass_member_iterator_next(&it)) != NULL)
1014 : {
1015 : List *emvars;
1016 : ListCell *lc2;
1017 :
1018 : /*
1019 : * We shouldn't be trying to sort by an equivalence class that
1020 : * contains a constant, so no need to consider such cases any further.
1021 : */
1022 4437 : if (em->em_is_const)
1023 0 : continue;
1024 :
1025 : /*
1026 : * Ignore child members unless they belong to the requested rel.
1027 : */
1028 4437 : if (em->em_is_child &&
1029 162 : !bms_is_subset(em->em_relids, relids))
1030 66 : continue;
1031 :
1032 : /*
1033 : * Match if all Vars and quasi-Vars are present in "exprs".
1034 : */
1035 4371 : emvars = pull_var_clause((Node *) em->em_expr,
1036 : PVC_INCLUDE_AGGREGATES |
1037 : PVC_INCLUDE_WINDOWFUNCS |
1038 : PVC_INCLUDE_PLACEHOLDERS);
1039 4728 : foreach(lc2, emvars)
1040 : {
1041 4471 : if (!list_member(exprvars, lfirst(lc2)))
1042 4114 : break;
1043 : }
1044 4371 : list_free(emvars);
1045 4371 : if (lc2)
1046 4114 : continue; /* we hit a non-available Var */
1047 :
1048 : /*
1049 : * If requested, reject expressions that are not parallel-safe. We
1050 : * check this last because it's a rather expensive test.
1051 : */
1052 257 : if (require_parallel_safe &&
1053 64 : !is_parallel_safe(root, (Node *) em->em_expr))
1054 15 : continue;
1055 :
1056 242 : return em; /* found usable expression */
1057 : }
1058 :
1059 3913 : return NULL;
1060 : }
1061 :
1062 : /*
1063 : * relation_can_be_sorted_early
1064 : * Can this relation be sorted on this EC before the final output step?
1065 : *
1066 : * To succeed, we must find an EC member that prepare_sort_from_pathkeys knows
1067 : * how to sort on, given the rel's reltarget as input. There are also a few
1068 : * additional constraints based on the fact that the desired sort will be done
1069 : * "early", within the scan/join part of the plan. Also, non-parallel-safe
1070 : * expressions are ignored if 'require_parallel_safe'.
1071 : *
1072 : * At some point we might want to return the identified EquivalenceMember,
1073 : * but for now, callers only want to know if there is one.
1074 : */
1075 : bool
1076 9973 : relation_can_be_sorted_early(PlannerInfo *root, RelOptInfo *rel,
1077 : EquivalenceClass *ec, bool require_parallel_safe)
1078 : {
1079 9973 : PathTarget *target = rel->reltarget;
1080 : EquivalenceMember *em;
1081 : ListCell *lc;
1082 :
1083 : /*
1084 : * Reject volatile ECs immediately; such sorts must always be postponed.
1085 : */
1086 9973 : if (ec->ec_has_volatile)
1087 36 : return false;
1088 :
1089 : /*
1090 : * Try to find an EM directly matching some reltarget member.
1091 : */
1092 22799 : foreach(lc, target->exprs)
1093 : {
1094 18837 : Expr *targetexpr = (Expr *) lfirst(lc);
1095 :
1096 18837 : em = find_ec_member_matching_expr(ec, targetexpr, rel->relids);
1097 18837 : if (!em)
1098 12862 : continue;
1099 :
1100 : /*
1101 : * Reject expressions involving set-returning functions, as those
1102 : * can't be computed early either. (Note: this test and the following
1103 : * one are effectively checking properties of targetexpr, so there's
1104 : * no point in asking whether some other EC member would be better.)
1105 : */
1106 5975 : if (expression_returns_set((Node *) em->em_expr))
1107 0 : continue;
1108 :
1109 : /*
1110 : * If requested, reject expressions that are not parallel-safe. We
1111 : * check this last because it's a rather expensive test.
1112 : */
1113 5975 : if (require_parallel_safe &&
1114 5975 : !is_parallel_safe(root, (Node *) em->em_expr))
1115 0 : continue;
1116 :
1117 5975 : return true;
1118 : }
1119 :
1120 : /*
1121 : * Try to find an expression computable from the reltarget.
1122 : */
1123 3962 : em = find_computable_ec_member(root, ec, target->exprs, rel->relids,
1124 : require_parallel_safe);
1125 3962 : if (!em)
1126 3913 : return false;
1127 :
1128 : /*
1129 : * Reject expressions involving set-returning functions, as those can't be
1130 : * computed early either. (There's no point in looking for another EC
1131 : * member in this case; since SRFs can't appear in WHERE, they cannot
1132 : * belong to multi-member ECs.)
1133 : */
1134 49 : if (expression_returns_set((Node *) em->em_expr))
1135 6 : return false;
1136 :
1137 43 : return true;
1138 : }
1139 :
1140 : /*
1141 : * generate_base_implied_equalities
1142 : * Generate any restriction clauses that we can deduce from equivalence
1143 : * classes.
1144 : *
1145 : * When an EC contains pseudoconstants, our strategy is to generate
1146 : * "member = const1" clauses where const1 is the first constant member, for
1147 : * every other member (including other constants). If we are able to do this
1148 : * then we don't need any "var = var" comparisons because we've successfully
1149 : * constrained all the vars at their points of creation. If we fail to
1150 : * generate any of these clauses due to lack of cross-type operators, we fall
1151 : * back to the "ec_broken" strategy described below. (XXX if there are
1152 : * multiple constants of different types, it's possible that we might succeed
1153 : * in forming all the required clauses if we started from a different const
1154 : * member; but this seems a sufficiently hokey corner case to not be worth
1155 : * spending lots of cycles on.)
1156 : *
1157 : * For ECs that contain no pseudoconstants, we generate derived clauses
1158 : * "member1 = member2" for each pair of members belonging to the same base
1159 : * relation (actually, if there are more than two for the same base relation,
1160 : * we only need enough clauses to link each to each other). This provides
1161 : * the base case for the recursion: each row emitted by a base relation scan
1162 : * will constrain all computable members of the EC to be equal. As each
1163 : * join path is formed, we'll add additional derived clauses on-the-fly
1164 : * to maintain this invariant (see generate_join_implied_equalities).
1165 : *
1166 : * If the opfamilies used by the EC do not provide complete sets of cross-type
1167 : * equality operators, it is possible that we will fail to generate a clause
1168 : * that must be generated to maintain the invariant. (An example: given
1169 : * "WHERE a.x = b.y AND b.y = a.z", the scheme breaks down if we cannot
1170 : * generate "a.x = a.z" as a restriction clause for A.) In this case we mark
1171 : * the EC "ec_broken" and fall back to regurgitating its original source
1172 : * RestrictInfos at appropriate times. We do not try to retract any derived
1173 : * clauses already generated from the broken EC, so the resulting plan could
1174 : * be poor due to bad selectivity estimates caused by redundant clauses. But
1175 : * the correct solution to that is to fix the opfamilies ...
1176 : *
1177 : * Equality clauses derived by this function are passed off to
1178 : * process_implied_equality (in plan/initsplan.c) to be inserted into the
1179 : * restrictinfo datastructures. Note that this must be called after initial
1180 : * scanning of the quals and before Path construction begins.
1181 : *
1182 : * We make no attempt to avoid generating duplicate RestrictInfos here: we
1183 : * don't search existing source or derived clauses in the EC for matches. It
1184 : * doesn't really seem worth the trouble to do so.
1185 : */
1186 : void
1187 182976 : generate_base_implied_equalities(PlannerInfo *root)
1188 : {
1189 : int ec_index;
1190 : ListCell *lc;
1191 :
1192 : /*
1193 : * At this point, we're done absorbing knowledge of equivalences in the
1194 : * query, so no further EC merging should happen, and ECs remaining in the
1195 : * eq_classes list can be considered canonical. (But note that it's still
1196 : * possible for new single-member ECs to be added through
1197 : * get_eclass_for_sort_expr().)
1198 : */
1199 182976 : root->ec_merging_done = true;
1200 :
1201 182976 : ec_index = 0;
1202 411605 : foreach(lc, root->eq_classes)
1203 : {
1204 228629 : EquivalenceClass *ec = (EquivalenceClass *) lfirst(lc);
1205 228629 : bool can_generate_joinclause = false;
1206 : int i;
1207 :
1208 : Assert(ec->ec_merged == NULL); /* else shouldn't be in list */
1209 : Assert(!ec->ec_broken); /* not yet anyway... */
1210 :
1211 : /*
1212 : * Generate implied equalities that are restriction clauses.
1213 : * Single-member ECs won't generate any deductions, either here or at
1214 : * the join level.
1215 : */
1216 228629 : if (list_length(ec->ec_members) > 1)
1217 : {
1218 169284 : if (ec->ec_has_const)
1219 124173 : generate_base_implied_equalities_const(root, ec);
1220 : else
1221 45111 : generate_base_implied_equalities_no_const(root, ec);
1222 :
1223 : /* Recover if we failed to generate required derived clauses */
1224 169284 : if (ec->ec_broken)
1225 15 : generate_base_implied_equalities_broken(root, ec);
1226 :
1227 : /* Detect whether this EC might generate join clauses */
1228 169284 : can_generate_joinclause =
1229 169284 : (bms_membership(ec->ec_relids) == BMS_MULTIPLE);
1230 : }
1231 :
1232 : /*
1233 : * Mark the base rels cited in each eclass (which should all exist by
1234 : * now) with the eq_classes indexes of all eclasses mentioning them.
1235 : * This will let us avoid searching in subsequent lookups. While
1236 : * we're at it, we can mark base rels that have pending eclass joins;
1237 : * this is a cheap version of has_relevant_eclass_joinclause().
1238 : */
1239 228629 : i = -1;
1240 514895 : while ((i = bms_next_member(ec->ec_relids, i)) > 0)
1241 : {
1242 286266 : RelOptInfo *rel = root->simple_rel_array[i];
1243 :
1244 : /* ignore the RTE_GROUP RTE */
1245 286266 : if (i == root->group_rtindex)
1246 0 : continue;
1247 :
1248 286266 : if (rel == NULL) /* must be an outer join */
1249 : {
1250 : Assert(bms_is_member(i, root->outer_join_rels));
1251 3038 : continue;
1252 : }
1253 :
1254 : Assert(rel->reloptkind == RELOPT_BASEREL);
1255 :
1256 283228 : rel->eclass_indexes = bms_add_member(rel->eclass_indexes,
1257 : ec_index);
1258 :
1259 283228 : if (can_generate_joinclause)
1260 108610 : rel->has_eclass_joins = true;
1261 : }
1262 :
1263 228629 : ec_index++;
1264 : }
1265 182976 : }
1266 :
1267 : /*
1268 : * generate_base_implied_equalities when EC contains pseudoconstant(s)
1269 : */
1270 : static void
1271 124173 : generate_base_implied_equalities_const(PlannerInfo *root,
1272 : EquivalenceClass *ec)
1273 : {
1274 124173 : EquivalenceMember *const_em = NULL;
1275 : ListCell *lc;
1276 :
1277 : /*
1278 : * In the trivial case where we just had one "var = const" clause, push
1279 : * the original clause back into the main planner machinery. There is
1280 : * nothing to be gained by doing it differently, and we save the effort to
1281 : * re-build and re-analyze an equality clause that will be exactly
1282 : * equivalent to the old one.
1283 : */
1284 238941 : if (list_length(ec->ec_members) == 2 &&
1285 114768 : list_length(ec->ec_sources) == 1)
1286 : {
1287 114768 : RestrictInfo *restrictinfo = (RestrictInfo *) linitial(ec->ec_sources);
1288 :
1289 114768 : distribute_restrictinfo_to_rels(root, restrictinfo);
1290 114768 : return;
1291 : }
1292 :
1293 : /* We don't expect any children yet */
1294 : Assert(ec->ec_childmembers == NULL);
1295 :
1296 : /*
1297 : * Find the constant member to use. We prefer an actual constant to
1298 : * pseudo-constants (such as Params), because the constraint exclusion
1299 : * machinery might be able to exclude relations on the basis of generated
1300 : * "var = const" equalities, but "var = param" won't work for that.
1301 : */
1302 21924 : foreach(lc, ec->ec_members)
1303 : {
1304 21882 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
1305 :
1306 21882 : if (cur_em->em_is_const)
1307 : {
1308 9408 : const_em = cur_em;
1309 9408 : if (IsA(cur_em->em_expr, Const))
1310 9363 : break;
1311 : }
1312 : }
1313 : Assert(const_em != NULL);
1314 :
1315 : /* Generate a derived equality against each other member */
1316 37686 : foreach(lc, ec->ec_members)
1317 : {
1318 28296 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
1319 : Oid eq_op;
1320 : RestrictInfo *rinfo;
1321 :
1322 : /* Child members should not exist in ec_members */
1323 : Assert(!cur_em->em_is_child);
1324 28296 : if (cur_em == const_em)
1325 9393 : continue;
1326 18903 : eq_op = select_equality_operator(ec,
1327 : cur_em->em_datatype,
1328 : const_em->em_datatype);
1329 18903 : if (!OidIsValid(eq_op))
1330 : {
1331 : /* failed... */
1332 15 : ec->ec_broken = true;
1333 15 : break;
1334 : }
1335 :
1336 : /*
1337 : * We use the constant's em_jdomain as qualscope, so that if the
1338 : * generated clause is variable-free (i.e, both EMs are consts) it
1339 : * will be enforced at the join domain level.
1340 : */
1341 18888 : rinfo = process_implied_equality(root, eq_op, ec->ec_collation,
1342 : cur_em->em_expr, const_em->em_expr,
1343 18888 : const_em->em_jdomain->jd_relids,
1344 : ec->ec_min_security,
1345 18888 : cur_em->em_is_const);
1346 :
1347 : /*
1348 : * If the clause didn't degenerate to a constant, fill in the correct
1349 : * markings for a mergejoinable clause, and save it as a derived
1350 : * clause. (We will not re-use such clauses directly, but selectivity
1351 : * estimation may consult those later. Note that this use of derived
1352 : * clauses does not overlap with its use for join clauses, since we
1353 : * never generate join clauses from an ec_has_const eclass.)
1354 : */
1355 18888 : if (rinfo && rinfo->mergeopfamilies)
1356 : {
1357 : /* it's not redundant, so don't set parent_ec */
1358 18822 : rinfo->left_ec = rinfo->right_ec = ec;
1359 18822 : rinfo->left_em = cur_em;
1360 18822 : rinfo->right_em = const_em;
1361 18822 : ec_add_derived_clause(ec, rinfo);
1362 : }
1363 : }
1364 : }
1365 :
1366 : /*
1367 : * generate_base_implied_equalities when EC contains no pseudoconstants
1368 : */
1369 : static void
1370 45111 : generate_base_implied_equalities_no_const(PlannerInfo *root,
1371 : EquivalenceClass *ec)
1372 : {
1373 : EquivalenceMember **prev_ems;
1374 : ListCell *lc;
1375 :
1376 : /*
1377 : * We scan the EC members once and track the last-seen member for each
1378 : * base relation. When we see another member of the same base relation,
1379 : * we generate "prev_em = cur_em". This results in the minimum number of
1380 : * derived clauses, but it's possible that it will fail when a different
1381 : * ordering would succeed. XXX FIXME: use a UNION-FIND algorithm similar
1382 : * to the way we build merged ECs. (Use a list-of-lists for each rel.)
1383 : */
1384 : prev_ems = (EquivalenceMember **)
1385 45111 : palloc0(root->simple_rel_array_size * sizeof(EquivalenceMember *));
1386 :
1387 : /* We don't expect any children yet */
1388 : Assert(ec->ec_childmembers == NULL);
1389 :
1390 136812 : foreach(lc, ec->ec_members)
1391 : {
1392 91701 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
1393 : int relid;
1394 :
1395 : /* Child members should not exist in ec_members */
1396 : Assert(!cur_em->em_is_child);
1397 :
1398 91701 : if (!bms_get_singleton_member(cur_em->em_relids, &relid))
1399 99 : continue;
1400 : Assert(relid < root->simple_rel_array_size);
1401 :
1402 91602 : if (prev_ems[relid] != NULL)
1403 : {
1404 227 : EquivalenceMember *prev_em = prev_ems[relid];
1405 : Oid eq_op;
1406 : RestrictInfo *rinfo;
1407 :
1408 227 : eq_op = select_equality_operator(ec,
1409 : prev_em->em_datatype,
1410 : cur_em->em_datatype);
1411 227 : if (!OidIsValid(eq_op))
1412 : {
1413 : /* failed... */
1414 0 : ec->ec_broken = true;
1415 0 : break;
1416 : }
1417 :
1418 : /*
1419 : * The expressions aren't constants, so the passed qualscope will
1420 : * never be used to place the generated clause. We just need to
1421 : * be sure it covers both expressions, which em_relids should do.
1422 : */
1423 227 : rinfo = process_implied_equality(root, eq_op, ec->ec_collation,
1424 : prev_em->em_expr, cur_em->em_expr,
1425 : cur_em->em_relids,
1426 : ec->ec_min_security,
1427 : false);
1428 :
1429 : /*
1430 : * If the clause didn't degenerate to a constant, fill in the
1431 : * correct markings for a mergejoinable clause. We don't record
1432 : * it as a derived clause, since we don't currently need to
1433 : * re-find such clauses, and don't want to clutter the
1434 : * derived-clause set with non-join clauses.
1435 : */
1436 227 : if (rinfo && rinfo->mergeopfamilies)
1437 : {
1438 : /* it's not redundant, so don't set parent_ec */
1439 227 : rinfo->left_ec = rinfo->right_ec = ec;
1440 227 : rinfo->left_em = prev_em;
1441 227 : rinfo->right_em = cur_em;
1442 : }
1443 : }
1444 91602 : prev_ems[relid] = cur_em;
1445 : }
1446 :
1447 45111 : pfree(prev_ems);
1448 :
1449 : /*
1450 : * We also have to make sure that all the Vars used in the member clauses
1451 : * will be available at any join node we might try to reference them at.
1452 : * For the moment we force all the Vars to be available at all join nodes
1453 : * for this eclass. Perhaps this could be improved by doing some
1454 : * pre-analysis of which members we prefer to join, but it's no worse than
1455 : * what happened in the pre-8.3 code. (Note: rebuild_eclass_attr_needed
1456 : * needs to match this code.)
1457 : */
1458 136812 : foreach(lc, ec->ec_members)
1459 : {
1460 91701 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
1461 91701 : List *vars = pull_var_clause((Node *) cur_em->em_expr,
1462 : PVC_RECURSE_AGGREGATES |
1463 : PVC_RECURSE_WINDOWFUNCS |
1464 : PVC_INCLUDE_PLACEHOLDERS);
1465 :
1466 91701 : add_vars_to_targetlist(root, vars, ec->ec_relids);
1467 91701 : list_free(vars);
1468 : }
1469 45111 : }
1470 :
1471 : /*
1472 : * generate_base_implied_equalities cleanup after failure
1473 : *
1474 : * What we must do here is push any zero- or one-relation source RestrictInfos
1475 : * of the EC back into the main restrictinfo datastructures. Multi-relation
1476 : * clauses will be regurgitated later by generate_join_implied_equalities().
1477 : * (We do it this way to maintain continuity with the case that ec_broken
1478 : * becomes set only after we've gone up a join level or two.) However, for
1479 : * an EC that contains constants, we can adopt a simpler strategy and just
1480 : * throw back all the source RestrictInfos immediately; that works because
1481 : * we know that such an EC can't become broken later. (This rule justifies
1482 : * ignoring ec_has_const ECs in generate_join_implied_equalities, even when
1483 : * they are broken.)
1484 : */
1485 : static void
1486 15 : generate_base_implied_equalities_broken(PlannerInfo *root,
1487 : EquivalenceClass *ec)
1488 : {
1489 : ListCell *lc;
1490 :
1491 48 : foreach(lc, ec->ec_sources)
1492 : {
1493 33 : RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(lc);
1494 :
1495 33 : if (ec->ec_has_const ||
1496 0 : bms_membership(restrictinfo->required_relids) != BMS_MULTIPLE)
1497 33 : distribute_restrictinfo_to_rels(root, restrictinfo);
1498 : }
1499 15 : }
1500 :
1501 :
1502 : /*
1503 : * generate_join_implied_equalities
1504 : * Generate any join clauses that we can deduce from equivalence classes.
1505 : *
1506 : * At a join node, we must enforce restriction clauses sufficient to ensure
1507 : * that all equivalence-class members computable at that node are equal.
1508 : * Since the set of clauses to enforce can vary depending on which subset
1509 : * relations are the inputs, we have to compute this afresh for each join
1510 : * relation pair. Hence a fresh List of RestrictInfo nodes is built and
1511 : * passed back on each call.
1512 : *
1513 : * In addition to its use at join nodes, this can be applied to generate
1514 : * eclass-based join clauses for use in a parameterized scan of a base rel.
1515 : * The reason for the asymmetry of specifying the inner rel as a RelOptInfo
1516 : * and the outer rel by Relids is that this usage occurs before we have
1517 : * built any join RelOptInfos.
1518 : *
1519 : * An annoying special case for parameterized scans is that the inner rel can
1520 : * be an appendrel child (an "other rel"). In this case we must generate
1521 : * appropriate clauses using child EC members. add_child_rel_equivalences
1522 : * must already have been done for the child rel.
1523 : *
1524 : * The results are sufficient for use in merge, hash, and plain nestloop join
1525 : * methods. We do not worry here about selecting clauses that are optimal
1526 : * for use in a parameterized indexscan. indxpath.c makes its own selections
1527 : * of clauses to use, and if the ones we pick here are redundant with those,
1528 : * the extras will be eliminated at createplan time, using the parent_ec
1529 : * markers that we provide (see is_redundant_derived_clause()).
1530 : *
1531 : * Because the same join clauses are likely to be needed multiple times as
1532 : * we consider different join paths, we avoid generating multiple copies:
1533 : * whenever we select a particular pair of EquivalenceMembers to join,
1534 : * we check to see if the pair matches any original clause (in ec_sources)
1535 : * or previously-built derived clause. This saves memory and allows
1536 : * re-use of information cached in RestrictInfos. We also avoid generating
1537 : * commutative duplicates, i.e. if the algorithm selects "a.x = b.y" but
1538 : * we already have "b.y = a.x", we return the existing clause.
1539 : *
1540 : * If we are considering an outer join, sjinfo is the associated OJ info,
1541 : * otherwise it can be NULL.
1542 : *
1543 : * join_relids should always equal bms_union(outer_relids, inner_rel->relids)
1544 : * plus whatever add_outer_joins_to_relids() would add. We could simplify
1545 : * this function's API by computing it internally, but most callers have the
1546 : * value at hand anyway.
1547 : */
1548 : List *
1549 330118 : generate_join_implied_equalities(PlannerInfo *root,
1550 : Relids join_relids,
1551 : Relids outer_relids,
1552 : RelOptInfo *inner_rel,
1553 : SpecialJoinInfo *sjinfo)
1554 : {
1555 330118 : List *result = NIL;
1556 330118 : Relids inner_relids = inner_rel->relids;
1557 : Relids nominal_inner_relids;
1558 : Relids nominal_join_relids;
1559 : Bitmapset *matching_ecs;
1560 : int i;
1561 :
1562 : /* If inner rel is a child, extra setup work is needed */
1563 330118 : if (IS_OTHER_REL(inner_rel))
1564 : {
1565 : Assert(!bms_is_empty(inner_rel->top_parent_relids));
1566 :
1567 : /* Fetch relid set for the topmost parent rel */
1568 3842 : nominal_inner_relids = inner_rel->top_parent_relids;
1569 : /* ECs will be marked with the parent's relid, not the child's */
1570 3842 : nominal_join_relids = bms_union(outer_relids, nominal_inner_relids);
1571 3842 : nominal_join_relids = add_outer_joins_to_relids(root,
1572 : nominal_join_relids,
1573 : sjinfo,
1574 : NULL);
1575 : }
1576 : else
1577 : {
1578 326276 : nominal_inner_relids = inner_relids;
1579 326276 : nominal_join_relids = join_relids;
1580 : }
1581 :
1582 : /*
1583 : * Examine all potentially-relevant eclasses.
1584 : *
1585 : * If we are considering an outer join, we must include "join" clauses
1586 : * that mention either input rel plus the outer join's relid; these
1587 : * represent post-join filter clauses that have to be applied at this
1588 : * join. We don't have infrastructure that would let us identify such
1589 : * eclasses cheaply, so just fall back to considering all eclasses
1590 : * mentioning anything in nominal_join_relids.
1591 : *
1592 : * At inner joins, we can be smarter: only consider eclasses mentioning
1593 : * both input rels.
1594 : */
1595 330118 : if (sjinfo && sjinfo->ojrelid != 0)
1596 56352 : matching_ecs = get_eclass_indexes_for_relids(root, nominal_join_relids);
1597 : else
1598 273766 : matching_ecs = get_common_eclass_indexes(root, nominal_inner_relids,
1599 : outer_relids);
1600 :
1601 330118 : i = -1;
1602 951632 : while ((i = bms_next_member(matching_ecs, i)) >= 0)
1603 : {
1604 621514 : EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
1605 621514 : List *sublist = NIL;
1606 :
1607 : /* ECs containing consts do not need any further enforcement */
1608 621514 : if (ec->ec_has_const)
1609 73493 : continue;
1610 :
1611 : /* Single-member ECs won't generate any deductions */
1612 548021 : if (list_length(ec->ec_members) <= 1)
1613 283652 : continue;
1614 :
1615 : /* Sanity check that this eclass overlaps the join */
1616 : Assert(bms_overlap(ec->ec_relids, nominal_join_relids));
1617 :
1618 264369 : if (!ec->ec_broken)
1619 264207 : sublist = generate_join_implied_equalities_normal(root,
1620 : ec,
1621 : join_relids,
1622 : outer_relids,
1623 : inner_relids);
1624 :
1625 : /* Recover if we failed to generate required derived clauses */
1626 264369 : if (ec->ec_broken)
1627 180 : sublist = generate_join_implied_equalities_broken(root,
1628 : ec,
1629 : nominal_join_relids,
1630 : outer_relids,
1631 : nominal_inner_relids,
1632 : inner_rel);
1633 :
1634 264369 : result = list_concat(result, sublist);
1635 : }
1636 :
1637 330118 : return result;
1638 : }
1639 :
1640 : /*
1641 : * generate_join_implied_equalities_for_ecs
1642 : * As above, but consider only the listed ECs.
1643 : *
1644 : * For the sole current caller, we can assume sjinfo == NULL, that is we are
1645 : * not interested in outer-join filter clauses. This might need to change
1646 : * in future.
1647 : */
1648 : List *
1649 3316 : generate_join_implied_equalities_for_ecs(PlannerInfo *root,
1650 : List *eclasses,
1651 : Relids join_relids,
1652 : Relids outer_relids,
1653 : RelOptInfo *inner_rel)
1654 : {
1655 3316 : List *result = NIL;
1656 3316 : Relids inner_relids = inner_rel->relids;
1657 : Relids nominal_inner_relids;
1658 : Relids nominal_join_relids;
1659 : ListCell *lc;
1660 :
1661 : /* If inner rel is a child, extra setup work is needed */
1662 3316 : if (IS_OTHER_REL(inner_rel))
1663 : {
1664 : Assert(!bms_is_empty(inner_rel->top_parent_relids));
1665 :
1666 : /* Fetch relid set for the topmost parent rel */
1667 9 : nominal_inner_relids = inner_rel->top_parent_relids;
1668 : /* ECs will be marked with the parent's relid, not the child's */
1669 9 : nominal_join_relids = bms_union(outer_relids, nominal_inner_relids);
1670 : }
1671 : else
1672 : {
1673 3307 : nominal_inner_relids = inner_relids;
1674 3307 : nominal_join_relids = join_relids;
1675 : }
1676 :
1677 6981 : foreach(lc, eclasses)
1678 : {
1679 3665 : EquivalenceClass *ec = (EquivalenceClass *) lfirst(lc);
1680 3665 : List *sublist = NIL;
1681 :
1682 : /* ECs containing consts do not need any further enforcement */
1683 3665 : if (ec->ec_has_const)
1684 0 : continue;
1685 :
1686 : /* Single-member ECs won't generate any deductions */
1687 3665 : if (list_length(ec->ec_members) <= 1)
1688 0 : continue;
1689 :
1690 : /* We can quickly ignore any that don't overlap the join, too */
1691 3665 : if (!bms_overlap(ec->ec_relids, nominal_join_relids))
1692 0 : continue;
1693 :
1694 3665 : if (!ec->ec_broken)
1695 3665 : sublist = generate_join_implied_equalities_normal(root,
1696 : ec,
1697 : join_relids,
1698 : outer_relids,
1699 : inner_relids);
1700 :
1701 : /* Recover if we failed to generate required derived clauses */
1702 3665 : if (ec->ec_broken)
1703 0 : sublist = generate_join_implied_equalities_broken(root,
1704 : ec,
1705 : nominal_join_relids,
1706 : outer_relids,
1707 : nominal_inner_relids,
1708 : inner_rel);
1709 :
1710 3665 : result = list_concat(result, sublist);
1711 : }
1712 :
1713 3316 : return result;
1714 : }
1715 :
1716 : /*
1717 : * generate_join_implied_equalities for a still-valid EC
1718 : */
1719 : static List *
1720 267872 : generate_join_implied_equalities_normal(PlannerInfo *root,
1721 : EquivalenceClass *ec,
1722 : Relids join_relids,
1723 : Relids outer_relids,
1724 : Relids inner_relids)
1725 : {
1726 267872 : List *result = NIL;
1727 267872 : List *new_members = NIL;
1728 267872 : List *outer_members = NIL;
1729 267872 : List *inner_members = NIL;
1730 : EquivalenceMemberIterator it;
1731 : EquivalenceMember *cur_em;
1732 :
1733 : /*
1734 : * First, scan the EC to identify member values that are computable at the
1735 : * outer rel, at the inner rel, or at this relation but not in either
1736 : * input rel. The outer-rel members should already be enforced equal,
1737 : * likewise for the inner-rel members. We'll need to create clauses to
1738 : * enforce that any newly computable members are all equal to each other
1739 : * as well as to at least one input member, plus enforce at least one
1740 : * outer-rel member equal to at least one inner-rel member.
1741 : */
1742 267872 : setup_eclass_member_iterator(&it, ec, join_relids);
1743 857126 : while ((cur_em = eclass_member_iterator_next(&it)) != NULL)
1744 : {
1745 : /*
1746 : * We don't need to check explicitly for child EC members. This test
1747 : * against join_relids will cause them to be ignored except when
1748 : * considering a child inner rel, which is what we want.
1749 : */
1750 589254 : if (!bms_is_subset(cur_em->em_relids, join_relids))
1751 53576 : continue; /* not computable yet, or wrong child */
1752 :
1753 535678 : if (bms_is_subset(cur_em->em_relids, outer_relids))
1754 308217 : outer_members = lappend(outer_members, cur_em);
1755 227461 : else if (bms_is_subset(cur_em->em_relids, inner_relids))
1756 226297 : inner_members = lappend(inner_members, cur_em);
1757 : else
1758 1164 : new_members = lappend(new_members, cur_em);
1759 : }
1760 :
1761 : /*
1762 : * First, select the joinclause if needed. We can equate any one outer
1763 : * member to any one inner member, but we have to find a datatype
1764 : * combination for which an opfamily member operator exists. If we have
1765 : * choices, we prefer simple Var members (possibly with RelabelType) since
1766 : * these are (a) cheapest to compute at runtime and (b) most likely to
1767 : * have useful statistics. Also, prefer operators that are also
1768 : * hashjoinable.
1769 : */
1770 267872 : if (outer_members && inner_members)
1771 : {
1772 219324 : EquivalenceMember *best_outer_em = NULL;
1773 219324 : EquivalenceMember *best_inner_em = NULL;
1774 219324 : Oid best_eq_op = InvalidOid;
1775 219324 : int best_score = -1;
1776 : RestrictInfo *rinfo;
1777 : ListCell *lc1;
1778 :
1779 227222 : foreach(lc1, outer_members)
1780 : {
1781 219363 : EquivalenceMember *outer_em = (EquivalenceMember *) lfirst(lc1);
1782 : ListCell *lc2;
1783 :
1784 227273 : foreach(lc2, inner_members)
1785 : {
1786 219375 : EquivalenceMember *inner_em = (EquivalenceMember *) lfirst(lc2);
1787 : Oid eq_op;
1788 : int score;
1789 :
1790 219375 : eq_op = select_equality_operator(ec,
1791 : outer_em->em_datatype,
1792 : inner_em->em_datatype);
1793 219375 : if (!OidIsValid(eq_op))
1794 18 : continue;
1795 219357 : score = 0;
1796 219357 : if (IsA(outer_em->em_expr, Var) ||
1797 8916 : (IsA(outer_em->em_expr, RelabelType) &&
1798 2168 : IsA(((RelabelType *) outer_em->em_expr)->arg, Var)))
1799 212561 : score++;
1800 219357 : if (IsA(inner_em->em_expr, Var) ||
1801 5818 : (IsA(inner_em->em_expr, RelabelType) &&
1802 4536 : IsA(((RelabelType *) inner_em->em_expr)->arg, Var)))
1803 218057 : score++;
1804 219357 : if (op_hashjoinable(eq_op,
1805 219357 : exprType((Node *) outer_em->em_expr)))
1806 219318 : score++;
1807 219357 : if (score > best_score)
1808 : {
1809 219306 : best_outer_em = outer_em;
1810 219306 : best_inner_em = inner_em;
1811 219306 : best_eq_op = eq_op;
1812 219306 : best_score = score;
1813 219306 : if (best_score == 3)
1814 211465 : break; /* no need to look further */
1815 : }
1816 : }
1817 219363 : if (best_score == 3)
1818 211465 : break; /* no need to look further */
1819 : }
1820 219324 : if (best_score < 0)
1821 : {
1822 : /* failed... */
1823 18 : ec->ec_broken = true;
1824 18 : return NIL;
1825 : }
1826 :
1827 : /*
1828 : * Create clause, setting parent_ec to mark it as redundant with other
1829 : * joinclauses
1830 : */
1831 219306 : rinfo = create_join_clause(root, ec, best_eq_op,
1832 : best_outer_em, best_inner_em,
1833 : ec);
1834 :
1835 219306 : result = lappend(result, rinfo);
1836 : }
1837 :
1838 : /*
1839 : * Now deal with building restrictions for any expressions that involve
1840 : * Vars from both sides of the join. We have to equate all of these to
1841 : * each other as well as to at least one old member (if any).
1842 : *
1843 : * XXX as in generate_base_implied_equalities_no_const, we could be a lot
1844 : * smarter here to avoid unnecessary failures in cross-type situations.
1845 : * For now, use the same left-to-right method used there.
1846 : */
1847 267854 : if (new_members)
1848 : {
1849 1146 : List *old_members = list_concat(outer_members, inner_members);
1850 1146 : EquivalenceMember *prev_em = NULL;
1851 : RestrictInfo *rinfo;
1852 : ListCell *lc1;
1853 :
1854 : /* For now, arbitrarily take the first old_member as the one to use */
1855 1146 : if (old_members)
1856 975 : new_members = lappend(new_members, linitial(old_members));
1857 :
1858 3285 : foreach(lc1, new_members)
1859 : {
1860 2139 : cur_em = (EquivalenceMember *) lfirst(lc1);
1861 :
1862 2139 : if (prev_em != NULL)
1863 : {
1864 : Oid eq_op;
1865 :
1866 993 : eq_op = select_equality_operator(ec,
1867 : prev_em->em_datatype,
1868 : cur_em->em_datatype);
1869 993 : if (!OidIsValid(eq_op))
1870 : {
1871 : /* failed... */
1872 0 : ec->ec_broken = true;
1873 0 : return NIL;
1874 : }
1875 : /* do NOT set parent_ec, this qual is not redundant! */
1876 993 : rinfo = create_join_clause(root, ec, eq_op,
1877 : prev_em, cur_em,
1878 : NULL);
1879 :
1880 993 : result = lappend(result, rinfo);
1881 : }
1882 2139 : prev_em = cur_em;
1883 : }
1884 : }
1885 :
1886 267854 : return result;
1887 : }
1888 :
1889 : /*
1890 : * generate_join_implied_equalities cleanup after failure
1891 : *
1892 : * Return any original RestrictInfos that are enforceable at this join.
1893 : *
1894 : * In the case of a child inner relation, we have to translate the
1895 : * original RestrictInfos from parent to child Vars.
1896 : */
1897 : static List *
1898 180 : generate_join_implied_equalities_broken(PlannerInfo *root,
1899 : EquivalenceClass *ec,
1900 : Relids nominal_join_relids,
1901 : Relids outer_relids,
1902 : Relids nominal_inner_relids,
1903 : RelOptInfo *inner_rel)
1904 : {
1905 180 : List *result = NIL;
1906 : ListCell *lc;
1907 :
1908 492 : foreach(lc, ec->ec_sources)
1909 : {
1910 312 : RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(lc);
1911 312 : Relids clause_relids = restrictinfo->required_relids;
1912 :
1913 312 : if (bms_is_subset(clause_relids, nominal_join_relids) &&
1914 168 : !bms_is_subset(clause_relids, outer_relids) &&
1915 156 : !bms_is_subset(clause_relids, nominal_inner_relids))
1916 156 : result = lappend(result, restrictinfo);
1917 : }
1918 :
1919 : /*
1920 : * If we have to translate, just brute-force apply adjust_appendrel_attrs
1921 : * to all the RestrictInfos at once. This will result in returning
1922 : * RestrictInfos that are not included in EC's derived clauses, but there
1923 : * shouldn't be any duplication, and it's a sufficiently narrow corner
1924 : * case that we shouldn't sweat too much over it anyway.
1925 : *
1926 : * Since inner_rel might be an indirect descendant of the baserel
1927 : * mentioned in the ec_sources clauses, we have to be prepared to apply
1928 : * multiple levels of Var translation.
1929 : */
1930 180 : if (IS_OTHER_REL(inner_rel) && result != NIL)
1931 81 : result = (List *) adjust_appendrel_attrs_multilevel(root,
1932 : (Node *) result,
1933 : inner_rel,
1934 81 : inner_rel->top_parent);
1935 :
1936 180 : return result;
1937 : }
1938 :
1939 :
1940 : /*
1941 : * select_equality_operator
1942 : * Select a suitable equality operator for comparing two EC members
1943 : *
1944 : * Returns InvalidOid if no operator can be found for this datatype combination
1945 : */
1946 : static Oid
1947 317866 : select_equality_operator(EquivalenceClass *ec, Oid lefttype, Oid righttype)
1948 : {
1949 : ListCell *lc;
1950 :
1951 317899 : foreach(lc, ec->ec_opfamilies)
1952 : {
1953 317866 : Oid opfamily = lfirst_oid(lc);
1954 : Oid opno;
1955 :
1956 317866 : opno = get_opfamily_member_for_cmptype(opfamily, lefttype, righttype, COMPARE_EQ);
1957 317866 : if (!OidIsValid(opno))
1958 33 : continue;
1959 : /* If no barrier quals in query, don't worry about leaky operators */
1960 317833 : if (ec->ec_max_security == 0)
1961 317833 : return opno;
1962 : /* Otherwise, insist that selected operators be leakproof */
1963 289 : if (get_func_leakproof(get_opcode(opno)))
1964 289 : return opno;
1965 : }
1966 33 : return InvalidOid;
1967 : }
1968 :
1969 :
1970 : /*
1971 : * create_join_clause
1972 : * Find or make a RestrictInfo comparing the two given EC members
1973 : * with the given operator (or, possibly, its commutator, because
1974 : * the ordering of the operands in the result is not guaranteed).
1975 : *
1976 : * parent_ec is either equal to ec (if the clause is a potentially-redundant
1977 : * join clause) or NULL (if not). We have to treat this as part of the
1978 : * match requirements --- it's possible that a clause comparing the same two
1979 : * EMs is a join clause in one join path and a restriction clause in another.
1980 : */
1981 : static RestrictInfo *
1982 299841 : create_join_clause(PlannerInfo *root,
1983 : EquivalenceClass *ec, Oid opno,
1984 : EquivalenceMember *leftem,
1985 : EquivalenceMember *rightem,
1986 : EquivalenceClass *parent_ec)
1987 : {
1988 : RestrictInfo *rinfo;
1989 299841 : RestrictInfo *parent_rinfo = NULL;
1990 : MemoryContext oldcontext;
1991 :
1992 299841 : rinfo = ec_search_clause_for_ems(root, ec, leftem, rightem, parent_ec);
1993 299841 : if (rinfo)
1994 249784 : return rinfo;
1995 :
1996 : /*
1997 : * Not there, so build it, in planner context so we can re-use it. (Not
1998 : * important in normal planning, but definitely so in GEQO.)
1999 : */
2000 50057 : oldcontext = MemoryContextSwitchTo(root->planner_cxt);
2001 :
2002 : /*
2003 : * If either EM is a child, recursively create the corresponding
2004 : * parent-to-parent clause, so that we can duplicate its rinfo_serial.
2005 : */
2006 50057 : if (leftem->em_is_child || rightem->em_is_child)
2007 : {
2008 2234 : EquivalenceMember *leftp = leftem->em_parent ? leftem->em_parent : leftem;
2009 2234 : EquivalenceMember *rightp = rightem->em_parent ? rightem->em_parent : rightem;
2010 :
2011 2234 : parent_rinfo = create_join_clause(root, ec, opno,
2012 : leftp, rightp,
2013 : parent_ec);
2014 : }
2015 :
2016 50057 : rinfo = build_implied_join_equality(root,
2017 : opno,
2018 : ec->ec_collation,
2019 : leftem->em_expr,
2020 : rightem->em_expr,
2021 50057 : bms_union(leftem->em_relids,
2022 50057 : rightem->em_relids),
2023 : ec->ec_min_security);
2024 :
2025 : /*
2026 : * If either EM is a child, force the clause's clause_relids to include
2027 : * the relid(s) of the child rel. In normal cases it would already, but
2028 : * not if we are considering appendrel child relations with pseudoconstant
2029 : * translated variables (i.e., UNION ALL sub-selects with constant output
2030 : * items). We must do this so that join_clause_is_movable_into() will
2031 : * think that the clause should be evaluated at the correct place.
2032 : */
2033 50057 : if (leftem->em_is_child)
2034 1958 : rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
2035 1958 : leftem->em_relids);
2036 50057 : if (rightem->em_is_child)
2037 276 : rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
2038 276 : rightem->em_relids);
2039 :
2040 : /* If it's a child clause, copy the parent's rinfo_serial */
2041 50057 : if (parent_rinfo)
2042 2234 : rinfo->rinfo_serial = parent_rinfo->rinfo_serial;
2043 :
2044 : /* Mark the clause as redundant, or not */
2045 50057 : rinfo->parent_ec = parent_ec;
2046 :
2047 : /*
2048 : * We know the correct values for left_ec/right_ec, ie this particular EC,
2049 : * so we can just set them directly instead of forcing another lookup.
2050 : */
2051 50057 : rinfo->left_ec = ec;
2052 50057 : rinfo->right_ec = ec;
2053 :
2054 : /* Mark it as usable with these EMs */
2055 50057 : rinfo->left_em = leftem;
2056 50057 : rinfo->right_em = rightem;
2057 : /* and save it for possible re-use */
2058 50057 : ec_add_derived_clause(ec, rinfo);
2059 :
2060 50057 : MemoryContextSwitchTo(oldcontext);
2061 :
2062 50057 : return rinfo;
2063 : }
2064 :
2065 :
2066 : /*
2067 : * reconsider_outer_join_clauses
2068 : * Re-examine any outer-join clauses that were set aside by
2069 : * distribute_qual_to_rels(), and see if we can derive any
2070 : * EquivalenceClasses from them. Then, if they were not made
2071 : * redundant, push them out into the regular join-clause lists.
2072 : *
2073 : * When we have mergejoinable clauses A = B that are outer-join clauses,
2074 : * we can't blindly combine them with other clauses A = C to deduce B = C,
2075 : * since in fact the "equality" A = B won't necessarily hold above the
2076 : * outer join (one of the variables might be NULL instead). Nonetheless
2077 : * there are cases where we can add qual clauses using transitivity.
2078 : *
2079 : * One case that we look for here is an outer-join clause OUTERVAR = INNERVAR
2080 : * for which there is also an equivalence clause OUTERVAR = CONSTANT.
2081 : * It is safe and useful to push a clause INNERVAR = CONSTANT into the
2082 : * evaluation of the inner (nullable) relation, because any inner rows not
2083 : * meeting this condition will not contribute to the outer-join result anyway.
2084 : * (Any outer rows they could join to will be eliminated by the pushed-down
2085 : * equivalence clause.)
2086 : *
2087 : * Note that the above rule does not work for full outer joins; nor is it
2088 : * very interesting to consider cases where the generated equivalence clause
2089 : * would involve relations outside the outer join, since such clauses couldn't
2090 : * be pushed into the inner side's scan anyway. So the restriction to
2091 : * outervar = pseudoconstant is not really giving up anything.
2092 : *
2093 : * For full-join cases, we can only do something useful if it's a FULL JOIN
2094 : * USING and a merged column has an equivalence MERGEDVAR = CONSTANT.
2095 : * By the time it gets here, the merged column will look like
2096 : * COALESCE(LEFTVAR, RIGHTVAR)
2097 : * and we will have a full-join clause LEFTVAR = RIGHTVAR that we can match
2098 : * the COALESCE expression to. In this situation we can push LEFTVAR = CONSTANT
2099 : * and RIGHTVAR = CONSTANT into the input relations, since any rows not
2100 : * meeting these conditions cannot contribute to the join result.
2101 : *
2102 : * Again, there isn't any traction to be gained by trying to deal with
2103 : * clauses comparing a mergedvar to a non-pseudoconstant. So we can make
2104 : * use of the EquivalenceClasses to search for matching variables that were
2105 : * equivalenced to constants. The interesting outer-join clauses were
2106 : * accumulated for us by distribute_qual_to_rels.
2107 : *
2108 : * When we find one of these cases, we implement the changes we want by
2109 : * generating a new equivalence clause INNERVAR = CONSTANT (or LEFTVAR, etc)
2110 : * and pushing it into the EquivalenceClass structures. This is because we
2111 : * may already know that INNERVAR is equivalenced to some other var(s), and
2112 : * we'd like the constant to propagate to them too. Note that it would be
2113 : * unsafe to merge any existing EC for INNERVAR with the OUTERVAR's EC ---
2114 : * that could result in propagating constant restrictions from
2115 : * INNERVAR to OUTERVAR, which would be very wrong.
2116 : *
2117 : * It's possible that the INNERVAR is also an OUTERVAR for some other
2118 : * outer-join clause, in which case the process can be repeated. So we repeat
2119 : * looping over the lists of clauses until no further deductions can be made.
2120 : * Whenever we do make a deduction, we remove the generating clause from the
2121 : * lists, since we don't want to make the same deduction twice.
2122 : *
2123 : * If we don't find any match for a set-aside outer join clause, we must
2124 : * throw it back into the regular joinclause processing by passing it to
2125 : * distribute_restrictinfo_to_rels(). If we do generate a derived clause,
2126 : * however, the outer-join clause is redundant. We must still put some
2127 : * clause into the regular processing, because otherwise the join will be
2128 : * seen as a clauseless join and avoided during join order searching.
2129 : * We handle this by generating a constant-TRUE clause that is marked with
2130 : * the same required_relids etc as the removed outer-join clause, thus
2131 : * making it a join clause between the correct relations.
2132 : */
2133 : void
2134 182976 : reconsider_outer_join_clauses(PlannerInfo *root)
2135 : {
2136 : bool found;
2137 : ListCell *cell;
2138 :
2139 : /* Outer loop repeats until we find no more deductions */
2140 : do
2141 : {
2142 184006 : found = false;
2143 :
2144 : /* Process the LEFT JOIN clauses */
2145 199254 : foreach(cell, root->left_join_clauses)
2146 : {
2147 15248 : OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
2148 :
2149 15248 : if (reconsider_outer_join_clause(root, ojcinfo, true))
2150 : {
2151 493 : RestrictInfo *rinfo = ojcinfo->rinfo;
2152 :
2153 493 : found = true;
2154 : /* remove it from the list */
2155 493 : root->left_join_clauses =
2156 493 : foreach_delete_current(root->left_join_clauses, cell);
2157 : /* throw back a dummy replacement clause (see notes above) */
2158 493 : rinfo = make_restrictinfo(root,
2159 493 : (Expr *) makeBoolConst(true, false),
2160 493 : rinfo->is_pushed_down,
2161 493 : rinfo->has_clone,
2162 493 : rinfo->is_clone,
2163 : false, /* pseudoconstant */
2164 : 0, /* security_level */
2165 : rinfo->required_relids,
2166 : rinfo->incompatible_relids,
2167 : rinfo->outer_relids);
2168 493 : distribute_restrictinfo_to_rels(root, rinfo);
2169 : }
2170 : }
2171 :
2172 : /* Process the RIGHT JOIN clauses */
2173 201906 : foreach(cell, root->right_join_clauses)
2174 : {
2175 17900 : OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
2176 :
2177 17900 : if (reconsider_outer_join_clause(root, ojcinfo, false))
2178 : {
2179 540 : RestrictInfo *rinfo = ojcinfo->rinfo;
2180 :
2181 540 : found = true;
2182 : /* remove it from the list */
2183 540 : root->right_join_clauses =
2184 540 : foreach_delete_current(root->right_join_clauses, cell);
2185 : /* throw back a dummy replacement clause (see notes above) */
2186 540 : rinfo = make_restrictinfo(root,
2187 540 : (Expr *) makeBoolConst(true, false),
2188 540 : rinfo->is_pushed_down,
2189 540 : rinfo->has_clone,
2190 540 : rinfo->is_clone,
2191 : false, /* pseudoconstant */
2192 : 0, /* security_level */
2193 : rinfo->required_relids,
2194 : rinfo->incompatible_relids,
2195 : rinfo->outer_relids);
2196 540 : distribute_restrictinfo_to_rels(root, rinfo);
2197 : }
2198 : }
2199 :
2200 : /* Process the FULL JOIN clauses */
2201 184660 : foreach(cell, root->full_join_clauses)
2202 : {
2203 654 : OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
2204 :
2205 654 : if (reconsider_full_join_clause(root, ojcinfo))
2206 : {
2207 3 : RestrictInfo *rinfo = ojcinfo->rinfo;
2208 :
2209 3 : found = true;
2210 : /* remove it from the list */
2211 3 : root->full_join_clauses =
2212 3 : foreach_delete_current(root->full_join_clauses, cell);
2213 : /* throw back a dummy replacement clause (see notes above) */
2214 3 : rinfo = make_restrictinfo(root,
2215 3 : (Expr *) makeBoolConst(true, false),
2216 3 : rinfo->is_pushed_down,
2217 3 : rinfo->has_clone,
2218 3 : rinfo->is_clone,
2219 : false, /* pseudoconstant */
2220 : 0, /* security_level */
2221 : rinfo->required_relids,
2222 : rinfo->incompatible_relids,
2223 : rinfo->outer_relids);
2224 3 : distribute_restrictinfo_to_rels(root, rinfo);
2225 : }
2226 : }
2227 184006 : } while (found);
2228 :
2229 : /* Now, any remaining clauses have to be thrown back */
2230 197364 : foreach(cell, root->left_join_clauses)
2231 : {
2232 14388 : OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
2233 :
2234 14388 : distribute_restrictinfo_to_rels(root, ojcinfo->rinfo);
2235 : }
2236 199772 : foreach(cell, root->right_join_clauses)
2237 : {
2238 16796 : OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
2239 :
2240 16796 : distribute_restrictinfo_to_rels(root, ojcinfo->rinfo);
2241 : }
2242 183627 : foreach(cell, root->full_join_clauses)
2243 : {
2244 651 : OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
2245 :
2246 651 : distribute_restrictinfo_to_rels(root, ojcinfo->rinfo);
2247 : }
2248 182976 : }
2249 :
2250 : /*
2251 : * reconsider_outer_join_clauses for a single LEFT/RIGHT JOIN clause
2252 : *
2253 : * Returns true if we were able to propagate a constant through the clause.
2254 : */
2255 : static bool
2256 33148 : reconsider_outer_join_clause(PlannerInfo *root, OuterJoinClauseInfo *ojcinfo,
2257 : bool outer_on_left)
2258 : {
2259 33148 : RestrictInfo *rinfo = ojcinfo->rinfo;
2260 33148 : SpecialJoinInfo *sjinfo = ojcinfo->sjinfo;
2261 : Expr *outervar,
2262 : *innervar;
2263 : Oid opno,
2264 : collation,
2265 : left_type,
2266 : right_type,
2267 : inner_datatype;
2268 : Relids inner_relids;
2269 : ListCell *lc1;
2270 :
2271 : Assert(is_opclause(rinfo->clause));
2272 33148 : opno = ((OpExpr *) rinfo->clause)->opno;
2273 33148 : collation = ((OpExpr *) rinfo->clause)->inputcollid;
2274 :
2275 : /* Extract needed info from the clause */
2276 33148 : op_input_types(opno, &left_type, &right_type);
2277 33148 : if (outer_on_left)
2278 : {
2279 15248 : outervar = (Expr *) get_leftop(rinfo->clause);
2280 15248 : innervar = (Expr *) get_rightop(rinfo->clause);
2281 15248 : inner_datatype = right_type;
2282 15248 : inner_relids = rinfo->right_relids;
2283 : }
2284 : else
2285 : {
2286 17900 : outervar = (Expr *) get_rightop(rinfo->clause);
2287 17900 : innervar = (Expr *) get_leftop(rinfo->clause);
2288 17900 : inner_datatype = left_type;
2289 17900 : inner_relids = rinfo->left_relids;
2290 : }
2291 :
2292 : /* Scan EquivalenceClasses for a match to outervar */
2293 219070 : foreach(lc1, root->eq_classes)
2294 : {
2295 186955 : EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
2296 : bool match;
2297 : ListCell *lc2;
2298 :
2299 : /* We don't expect any children yet */
2300 : Assert(cur_ec->ec_childmembers == NULL);
2301 :
2302 : /* Ignore EC unless it contains pseudoconstants */
2303 186955 : if (!cur_ec->ec_has_const)
2304 143831 : continue;
2305 : /* Never match to a volatile EC */
2306 43124 : if (cur_ec->ec_has_volatile)
2307 0 : continue;
2308 : /* It has to match the outer-join clause as to semantics, too */
2309 43124 : if (collation != cur_ec->ec_collation)
2310 2682 : continue;
2311 40442 : if (!equal(rinfo->mergeopfamilies, cur_ec->ec_opfamilies))
2312 10365 : continue;
2313 : /* Does it contain a match to outervar? */
2314 30077 : match = false;
2315 93145 : foreach(lc2, cur_ec->ec_members)
2316 : {
2317 64101 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
2318 :
2319 : /* Child members should not exist in ec_members */
2320 : Assert(!cur_em->em_is_child);
2321 64101 : if (equal(outervar, cur_em->em_expr))
2322 : {
2323 1033 : match = true;
2324 1033 : break;
2325 : }
2326 : }
2327 30077 : if (!match)
2328 29044 : continue; /* no match, so ignore this EC */
2329 :
2330 : /*
2331 : * Yes it does! Try to generate a clause INNERVAR = CONSTANT for each
2332 : * CONSTANT in the EC. Note that we must succeed with at least one
2333 : * constant before we can decide to throw away the outer-join clause.
2334 : */
2335 1033 : match = false;
2336 3644 : foreach(lc2, cur_ec->ec_members)
2337 : {
2338 2611 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
2339 : Oid eq_op;
2340 : RestrictInfo *newrinfo;
2341 : JoinDomain *jdomain;
2342 :
2343 2611 : if (!cur_em->em_is_const)
2344 1557 : continue; /* ignore non-const members */
2345 1054 : eq_op = select_equality_operator(cur_ec,
2346 : inner_datatype,
2347 : cur_em->em_datatype);
2348 1054 : if (!OidIsValid(eq_op))
2349 0 : continue; /* can't generate equality */
2350 1054 : newrinfo = build_implied_join_equality(root,
2351 : eq_op,
2352 : cur_ec->ec_collation,
2353 : innervar,
2354 : cur_em->em_expr,
2355 : bms_copy(inner_relids),
2356 : cur_ec->ec_min_security);
2357 : /* This equality holds within the OJ's child JoinDomain */
2358 1054 : jdomain = find_join_domain(root, sjinfo->syn_righthand);
2359 1054 : if (process_equivalence(root, &newrinfo, jdomain))
2360 1054 : match = true;
2361 : }
2362 :
2363 : /*
2364 : * If we were able to equate INNERVAR to any constant, report success.
2365 : * Otherwise, fall out of the search loop, since we know the OUTERVAR
2366 : * appears in at most one EC.
2367 : */
2368 1033 : if (match)
2369 1033 : return true;
2370 : else
2371 0 : break;
2372 : }
2373 :
2374 32115 : return false; /* failed to make any deduction */
2375 : }
2376 :
2377 : /*
2378 : * reconsider_outer_join_clauses for a single FULL JOIN clause
2379 : *
2380 : * Returns true if we were able to propagate a constant through the clause.
2381 : */
2382 : static bool
2383 654 : reconsider_full_join_clause(PlannerInfo *root, OuterJoinClauseInfo *ojcinfo)
2384 : {
2385 654 : RestrictInfo *rinfo = ojcinfo->rinfo;
2386 654 : SpecialJoinInfo *sjinfo = ojcinfo->sjinfo;
2387 654 : Relids fjrelids = bms_make_singleton(sjinfo->ojrelid);
2388 : Expr *leftvar;
2389 : Expr *rightvar;
2390 : Oid opno,
2391 : collation,
2392 : left_type,
2393 : right_type;
2394 : Relids left_relids,
2395 : right_relids;
2396 : ListCell *lc1;
2397 :
2398 : /* Extract needed info from the clause */
2399 : Assert(is_opclause(rinfo->clause));
2400 654 : opno = ((OpExpr *) rinfo->clause)->opno;
2401 654 : collation = ((OpExpr *) rinfo->clause)->inputcollid;
2402 654 : op_input_types(opno, &left_type, &right_type);
2403 654 : leftvar = (Expr *) get_leftop(rinfo->clause);
2404 654 : rightvar = (Expr *) get_rightop(rinfo->clause);
2405 654 : left_relids = rinfo->left_relids;
2406 654 : right_relids = rinfo->right_relids;
2407 :
2408 3318 : foreach(lc1, root->eq_classes)
2409 : {
2410 2667 : EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
2411 2667 : EquivalenceMember *coal_em = NULL;
2412 : bool match;
2413 : bool matchleft;
2414 : bool matchright;
2415 : ListCell *lc2;
2416 2667 : int coal_idx = -1;
2417 :
2418 : /* We don't expect any children yet */
2419 : Assert(cur_ec->ec_childmembers == NULL);
2420 :
2421 : /* Ignore EC unless it contains pseudoconstants */
2422 2667 : if (!cur_ec->ec_has_const)
2423 2519 : continue;
2424 : /* Never match to a volatile EC */
2425 148 : if (cur_ec->ec_has_volatile)
2426 0 : continue;
2427 : /* It has to match the outer-join clause as to semantics, too */
2428 148 : if (collation != cur_ec->ec_collation)
2429 18 : continue;
2430 130 : if (!equal(rinfo->mergeopfamilies, cur_ec->ec_opfamilies))
2431 0 : continue;
2432 :
2433 : /*
2434 : * Does it contain a COALESCE(leftvar, rightvar) construct?
2435 : *
2436 : * We can assume the COALESCE() inputs are in the same order as the
2437 : * join clause, since both were automatically generated in the cases
2438 : * we care about.
2439 : *
2440 : * XXX currently this may fail to match in cross-type cases because
2441 : * the COALESCE will contain typecast operations while the join clause
2442 : * may not (if there is a cross-type mergejoin operator available for
2443 : * the two column types). Is it OK to strip implicit coercions from
2444 : * the COALESCE arguments?
2445 : */
2446 130 : match = false;
2447 381 : foreach(lc2, cur_ec->ec_members)
2448 : {
2449 254 : coal_em = (EquivalenceMember *) lfirst(lc2);
2450 :
2451 : /* Child members should not exist in ec_members */
2452 : Assert(!coal_em->em_is_child);
2453 254 : if (IsA(coal_em->em_expr, CoalesceExpr))
2454 : {
2455 9 : CoalesceExpr *cexpr = (CoalesceExpr *) coal_em->em_expr;
2456 : Node *cfirst;
2457 : Node *csecond;
2458 :
2459 9 : if (list_length(cexpr->args) != 2)
2460 0 : continue;
2461 9 : cfirst = (Node *) linitial(cexpr->args);
2462 9 : csecond = (Node *) lsecond(cexpr->args);
2463 :
2464 : /*
2465 : * The COALESCE arguments will be marked as possibly nulled by
2466 : * the full join, while we wish to generate clauses that apply
2467 : * to the join's inputs. So we must strip the join from the
2468 : * nullingrels fields of cfirst/csecond before comparing them
2469 : * to leftvar/rightvar. (Perhaps with a less hokey
2470 : * representation for FULL JOIN USING output columns, this
2471 : * wouldn't be needed?)
2472 : */
2473 9 : cfirst = remove_nulling_relids(cfirst, fjrelids, NULL);
2474 9 : csecond = remove_nulling_relids(csecond, fjrelids, NULL);
2475 :
2476 9 : if (equal(leftvar, cfirst) && equal(rightvar, csecond))
2477 : {
2478 3 : coal_idx = foreach_current_index(lc2);
2479 3 : match = true;
2480 3 : break;
2481 : }
2482 : }
2483 : }
2484 130 : if (!match)
2485 127 : continue; /* no match, so ignore this EC */
2486 :
2487 : /*
2488 : * Yes it does! Try to generate clauses LEFTVAR = CONSTANT and
2489 : * RIGHTVAR = CONSTANT for each CONSTANT in the EC. Note that we must
2490 : * succeed with at least one constant for each var before we can
2491 : * decide to throw away the outer-join clause.
2492 : */
2493 3 : matchleft = matchright = false;
2494 9 : foreach(lc2, cur_ec->ec_members)
2495 : {
2496 6 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
2497 : Oid eq_op;
2498 : RestrictInfo *newrinfo;
2499 : JoinDomain *jdomain;
2500 :
2501 6 : if (!cur_em->em_is_const)
2502 3 : continue; /* ignore non-const members */
2503 3 : eq_op = select_equality_operator(cur_ec,
2504 : left_type,
2505 : cur_em->em_datatype);
2506 3 : if (OidIsValid(eq_op))
2507 : {
2508 3 : newrinfo = build_implied_join_equality(root,
2509 : eq_op,
2510 : cur_ec->ec_collation,
2511 : leftvar,
2512 : cur_em->em_expr,
2513 : bms_copy(left_relids),
2514 : cur_ec->ec_min_security);
2515 : /* This equality holds within the lefthand child JoinDomain */
2516 3 : jdomain = find_join_domain(root, sjinfo->syn_lefthand);
2517 3 : if (process_equivalence(root, &newrinfo, jdomain))
2518 3 : matchleft = true;
2519 : }
2520 3 : eq_op = select_equality_operator(cur_ec,
2521 : right_type,
2522 : cur_em->em_datatype);
2523 3 : if (OidIsValid(eq_op))
2524 : {
2525 3 : newrinfo = build_implied_join_equality(root,
2526 : eq_op,
2527 : cur_ec->ec_collation,
2528 : rightvar,
2529 : cur_em->em_expr,
2530 : bms_copy(right_relids),
2531 : cur_ec->ec_min_security);
2532 : /* This equality holds within the righthand child JoinDomain */
2533 3 : jdomain = find_join_domain(root, sjinfo->syn_righthand);
2534 3 : if (process_equivalence(root, &newrinfo, jdomain))
2535 3 : matchright = true;
2536 : }
2537 : }
2538 :
2539 : /*
2540 : * If we were able to equate both vars to constants, we're done, and
2541 : * we can throw away the full-join clause as redundant. Moreover, we
2542 : * can remove the COALESCE entry from the EC, since the added
2543 : * restrictions ensure it will always have the expected value. (We
2544 : * don't bother trying to update ec_relids or ec_sources.)
2545 : */
2546 3 : if (matchleft && matchright)
2547 : {
2548 3 : cur_ec->ec_members = list_delete_nth_cell(cur_ec->ec_members, coal_idx);
2549 3 : return true;
2550 : }
2551 :
2552 : /*
2553 : * Otherwise, fall out of the search loop, since we know the COALESCE
2554 : * appears in at most one EC (XXX might stop being true if we allow
2555 : * stripping of coercions above?)
2556 : */
2557 0 : break;
2558 : }
2559 :
2560 651 : return false; /* failed to make any deduction */
2561 : }
2562 :
2563 : /*
2564 : * rebuild_eclass_attr_needed
2565 : * Put back attr_needed bits for Vars/PHVs needed for join eclasses.
2566 : *
2567 : * This is used to rebuild attr_needed/ph_needed sets after removal of a
2568 : * useless outer join. It should match what
2569 : * generate_base_implied_equalities_no_const did, except that we call
2570 : * add_vars_to_attr_needed not add_vars_to_targetlist.
2571 : */
2572 : void
2573 6595 : rebuild_eclass_attr_needed(PlannerInfo *root)
2574 : {
2575 : ListCell *lc;
2576 :
2577 36158 : foreach(lc, root->eq_classes)
2578 : {
2579 29563 : EquivalenceClass *ec = (EquivalenceClass *) lfirst(lc);
2580 :
2581 : /*
2582 : * We don't expect any EC child members to exist at this point. Ensure
2583 : * that's the case, otherwise, we might be getting asked to do
2584 : * something this function hasn't been coded for.
2585 : */
2586 : Assert(ec->ec_childmembers == NULL);
2587 :
2588 : /* Need do anything only for a multi-member, no-const EC. */
2589 29563 : if (list_length(ec->ec_members) > 1 && !ec->ec_has_const)
2590 : {
2591 : ListCell *lc2;
2592 :
2593 9702 : foreach(lc2, ec->ec_members)
2594 : {
2595 6477 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
2596 6477 : List *vars = pull_var_clause((Node *) cur_em->em_expr,
2597 : PVC_RECURSE_AGGREGATES |
2598 : PVC_RECURSE_WINDOWFUNCS |
2599 : PVC_INCLUDE_PLACEHOLDERS);
2600 :
2601 6477 : add_vars_to_attr_needed(root, vars, ec->ec_relids);
2602 6477 : list_free(vars);
2603 : }
2604 : }
2605 : }
2606 6595 : }
2607 :
2608 : /*
2609 : * find_join_domain
2610 : * Find the highest JoinDomain enclosed within the given relid set.
2611 : *
2612 : * (We could avoid this search at the cost of complicating APIs elsewhere,
2613 : * which doesn't seem worth it.)
2614 : */
2615 : static JoinDomain *
2616 1060 : find_join_domain(PlannerInfo *root, Relids relids)
2617 : {
2618 : ListCell *lc;
2619 :
2620 2168 : foreach(lc, root->join_domains)
2621 : {
2622 2168 : JoinDomain *jdomain = (JoinDomain *) lfirst(lc);
2623 :
2624 2168 : if (bms_is_subset(jdomain->jd_relids, relids))
2625 1060 : return jdomain;
2626 : }
2627 0 : elog(ERROR, "failed to find appropriate JoinDomain");
2628 : return NULL; /* keep compiler quiet */
2629 : }
2630 :
2631 :
2632 : /*
2633 : * exprs_known_equal
2634 : * Detect whether two expressions are known equal due to equivalence
2635 : * relationships.
2636 : *
2637 : * If opfamily is given, the expressions must be known equal per the semantics
2638 : * of that opfamily (note it has to be a btree opfamily, since those are the
2639 : * only opfamilies equivclass.c deals with). If opfamily is InvalidOid, we'll
2640 : * return true if they're equal according to any opfamily, which is fuzzy but
2641 : * OK for estimation purposes.
2642 : *
2643 : * Note: does not bother to check for "equal(item1, item2)"; caller must
2644 : * check that case if it's possible to pass identical items.
2645 : */
2646 : bool
2647 3010 : exprs_known_equal(PlannerInfo *root, Node *item1, Node *item2, Oid opfamily)
2648 : {
2649 : ListCell *lc1;
2650 :
2651 16574 : foreach(lc1, root->eq_classes)
2652 : {
2653 13747 : EquivalenceClass *ec = (EquivalenceClass *) lfirst(lc1);
2654 13747 : bool item1member = false;
2655 13747 : bool item2member = false;
2656 : ListCell *lc2;
2657 :
2658 : /* Never match to a volatile EC */
2659 13747 : if (ec->ec_has_volatile)
2660 0 : continue;
2661 :
2662 : /*
2663 : * It's okay to consider ec_broken ECs here. Brokenness just means we
2664 : * couldn't derive all the implied clauses we'd have liked to; it does
2665 : * not invalidate our knowledge that the members are equal.
2666 : */
2667 :
2668 : /* Ignore if this EC doesn't use specified opfamily */
2669 13747 : if (OidIsValid(opfamily) &&
2670 330 : !list_member_oid(ec->ec_opfamilies, opfamily))
2671 114 : continue;
2672 :
2673 : /* Ignore children here */
2674 33461 : foreach(lc2, ec->ec_members)
2675 : {
2676 20011 : EquivalenceMember *em = (EquivalenceMember *) lfirst(lc2);
2677 :
2678 : /* Child members should not exist in ec_members */
2679 : Assert(!em->em_is_child);
2680 20011 : if (equal(item1, em->em_expr))
2681 1715 : item1member = true;
2682 18296 : else if (equal(item2, em->em_expr))
2683 1890 : item2member = true;
2684 : /* Exit as soon as equality is proven */
2685 20011 : if (item1member && item2member)
2686 183 : return true;
2687 : }
2688 : }
2689 2827 : return false;
2690 : }
2691 :
2692 :
2693 : /*
2694 : * match_eclasses_to_foreign_key_col
2695 : * See whether a foreign key column match is proven by any eclass.
2696 : *
2697 : * If the referenced and referencing Vars of the fkey's colno'th column are
2698 : * known equal due to any eclass, return that eclass; otherwise return NULL.
2699 : * (In principle there might be more than one matching eclass if multiple
2700 : * collations are involved, but since collation doesn't matter for equality,
2701 : * we ignore that fine point here.) This is much like exprs_known_equal,
2702 : * except for the format of the input.
2703 : *
2704 : * On success, we also set fkinfo->eclass[colno] to the matching eclass,
2705 : * and set fkinfo->fk_eclass_member[colno] to the eclass member for the
2706 : * referencing Var.
2707 : */
2708 : EquivalenceClass *
2709 1212 : match_eclasses_to_foreign_key_col(PlannerInfo *root,
2710 : ForeignKeyOptInfo *fkinfo,
2711 : int colno)
2712 : {
2713 1212 : Index var1varno = fkinfo->con_relid;
2714 1212 : AttrNumber var1attno = fkinfo->conkey[colno];
2715 1212 : Index var2varno = fkinfo->ref_relid;
2716 1212 : AttrNumber var2attno = fkinfo->confkey[colno];
2717 1212 : Oid eqop = fkinfo->conpfeqop[colno];
2718 1212 : RelOptInfo *rel1 = root->simple_rel_array[var1varno];
2719 1212 : RelOptInfo *rel2 = root->simple_rel_array[var2varno];
2720 1212 : List *opfamilies = NIL; /* compute only if needed */
2721 : Bitmapset *matching_ecs;
2722 : int i;
2723 :
2724 : /* Consider only eclasses mentioning both relations */
2725 : Assert(root->ec_merging_done);
2726 : Assert(IS_SIMPLE_REL(rel1));
2727 : Assert(IS_SIMPLE_REL(rel2));
2728 1212 : matching_ecs = bms_intersect(rel1->eclass_indexes,
2729 1212 : rel2->eclass_indexes);
2730 :
2731 1212 : i = -1;
2732 1260 : while ((i = bms_next_member(matching_ecs, i)) >= 0)
2733 : {
2734 269 : EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes,
2735 : i);
2736 269 : EquivalenceMember *item1_em = NULL;
2737 269 : EquivalenceMember *item2_em = NULL;
2738 : ListCell *lc2;
2739 :
2740 : /* Never match to a volatile EC */
2741 269 : if (ec->ec_has_volatile)
2742 0 : continue;
2743 :
2744 : /*
2745 : * It's okay to consider "broken" ECs here, see exprs_known_equal.
2746 : * Ignore children here.
2747 : */
2748 637 : foreach(lc2, ec->ec_members)
2749 : {
2750 589 : EquivalenceMember *em = (EquivalenceMember *) lfirst(lc2);
2751 : Var *var;
2752 :
2753 : /* Child members should not exist in ec_members */
2754 : Assert(!em->em_is_child);
2755 :
2756 : /* EM must be a Var, possibly with RelabelType */
2757 589 : var = (Var *) em->em_expr;
2758 589 : while (var && IsA(var, RelabelType))
2759 0 : var = (Var *) ((RelabelType *) var)->arg;
2760 589 : if (!(var && IsA(var, Var)))
2761 3 : continue;
2762 :
2763 : /* Match? */
2764 586 : if (var->varno == var1varno && var->varattno == var1attno)
2765 221 : item1_em = em;
2766 365 : else if (var->varno == var2varno && var->varattno == var2attno)
2767 221 : item2_em = em;
2768 :
2769 : /* Have we found both PK and FK column in this EC? */
2770 586 : if (item1_em && item2_em)
2771 : {
2772 : /*
2773 : * Succeed if eqop matches EC's opfamilies. We could test
2774 : * this before scanning the members, but it's probably cheaper
2775 : * to test for member matches first.
2776 : */
2777 221 : if (opfamilies == NIL) /* compute if we didn't already */
2778 221 : opfamilies = get_mergejoin_opfamilies(eqop);
2779 221 : if (equal(opfamilies, ec->ec_opfamilies))
2780 : {
2781 221 : fkinfo->eclass[colno] = ec;
2782 221 : fkinfo->fk_eclass_member[colno] = item2_em;
2783 221 : return ec;
2784 : }
2785 : /* Otherwise, done with this EC, move on to the next */
2786 0 : break;
2787 : }
2788 : }
2789 : }
2790 991 : return NULL;
2791 : }
2792 :
2793 : /*
2794 : * find_derived_clause_for_ec_member
2795 : * Search for a previously-derived clause mentioning the given EM.
2796 : *
2797 : * The eclass should be an ec_has_const EC, of which the EM is a non-const
2798 : * member. This should ensure there is just one derived clause mentioning
2799 : * the EM (and equating it to a constant).
2800 : * Returns NULL if no such clause can be found.
2801 : */
2802 : RestrictInfo *
2803 3 : find_derived_clause_for_ec_member(PlannerInfo *root,
2804 : EquivalenceClass *ec,
2805 : EquivalenceMember *em)
2806 : {
2807 : Assert(ec->ec_has_const);
2808 : Assert(!em->em_is_const);
2809 :
2810 3 : return ec_search_derived_clause_for_ems(root, ec, em, NULL, NULL);
2811 : }
2812 :
2813 :
2814 : /*
2815 : * add_child_rel_equivalences
2816 : * Search for EC members that reference the root parent of child_rel, and
2817 : * add transformed members referencing the child_rel.
2818 : *
2819 : * Note that this function won't be called at all unless we have at least some
2820 : * reason to believe that the EC members it generates will be useful.
2821 : *
2822 : * parent_rel and child_rel could be derived from appinfo, but since the
2823 : * caller has already computed them, we might as well just pass them in.
2824 : *
2825 : * The passed-in AppendRelInfo is not used when the parent_rel is not a
2826 : * top-level baserel, since it shows the mapping from the parent_rel but
2827 : * we need to translate EC expressions that refer to the top-level parent.
2828 : * Using it is faster than using adjust_appendrel_attrs_multilevel(), though,
2829 : * so we prefer it when we can.
2830 : */
2831 : void
2832 19190 : add_child_rel_equivalences(PlannerInfo *root,
2833 : AppendRelInfo *appinfo,
2834 : RelOptInfo *parent_rel,
2835 : RelOptInfo *child_rel)
2836 : {
2837 19190 : Relids top_parent_relids = child_rel->top_parent_relids;
2838 19190 : Relids child_relids = child_rel->relids;
2839 : int i;
2840 :
2841 : /*
2842 : * EC merging should be complete already, so we can use the parent rel's
2843 : * eclass_indexes to avoid searching all of root->eq_classes.
2844 : */
2845 : Assert(root->ec_merging_done);
2846 : Assert(IS_SIMPLE_REL(parent_rel));
2847 :
2848 19190 : i = -1;
2849 56432 : while ((i = bms_next_member(parent_rel->eclass_indexes, i)) >= 0)
2850 : {
2851 37242 : EquivalenceClass *cur_ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
2852 :
2853 : /*
2854 : * If this EC contains a volatile expression, then generating child
2855 : * EMs would be downright dangerous, so skip it. We rely on a
2856 : * volatile EC having only one EM.
2857 : */
2858 37242 : if (cur_ec->ec_has_volatile)
2859 0 : continue;
2860 :
2861 : /* Sanity check eclass_indexes only contain ECs for parent_rel */
2862 : Assert(bms_is_subset(top_parent_relids, cur_ec->ec_relids));
2863 :
2864 125406 : foreach_node(EquivalenceMember, cur_em, cur_ec->ec_members)
2865 : {
2866 50922 : if (cur_em->em_is_const)
2867 1716 : continue; /* ignore consts here */
2868 :
2869 : /* Child members should not exist in ec_members */
2870 : Assert(!cur_em->em_is_child);
2871 :
2872 : /*
2873 : * Consider only members that reference and can be computed at
2874 : * child's topmost parent rel. In particular we want to exclude
2875 : * parent-rel Vars that have nonempty varnullingrels. Translating
2876 : * those might fail, if the transformed expression wouldn't be a
2877 : * simple Var; and in any case it wouldn't produce a member that
2878 : * has any use in creating plans for the child rel.
2879 : */
2880 49206 : if (bms_is_subset(cur_em->em_relids, top_parent_relids) &&
2881 36105 : !bms_is_empty(cur_em->em_relids))
2882 : {
2883 : /* OK, generate transformed child version */
2884 : Expr *child_expr;
2885 : Relids new_relids;
2886 :
2887 36105 : if (parent_rel->reloptkind == RELOPT_BASEREL)
2888 : {
2889 : /* Simple single-level transformation */
2890 : child_expr = (Expr *)
2891 31743 : adjust_appendrel_attrs(root,
2892 31743 : (Node *) cur_em->em_expr,
2893 : 1, &appinfo);
2894 : }
2895 : else
2896 : {
2897 : /* Must do multi-level transformation */
2898 : child_expr = (Expr *)
2899 4362 : adjust_appendrel_attrs_multilevel(root,
2900 4362 : (Node *) cur_em->em_expr,
2901 : child_rel,
2902 4362 : child_rel->top_parent);
2903 : }
2904 :
2905 : /*
2906 : * Transform em_relids to match. Note we do *not* do
2907 : * pull_varnos(child_expr) here, as for example the
2908 : * transformation might have substituted a constant, but we
2909 : * don't want the child member to be marked as constant.
2910 : */
2911 36105 : new_relids = bms_difference(cur_em->em_relids,
2912 : top_parent_relids);
2913 36105 : new_relids = bms_add_members(new_relids, child_relids);
2914 :
2915 36105 : add_child_eq_member(root,
2916 : cur_ec,
2917 : i,
2918 : child_expr,
2919 : new_relids,
2920 : cur_em->em_jdomain,
2921 : cur_em,
2922 : cur_em->em_datatype,
2923 : child_rel->relid);
2924 : }
2925 : }
2926 : }
2927 19190 : }
2928 :
2929 : /*
2930 : * add_child_join_rel_equivalences
2931 : * Like add_child_rel_equivalences(), but for joinrels
2932 : *
2933 : * Here we find the ECs relevant to the top parent joinrel and add transformed
2934 : * member expressions that refer to this child joinrel.
2935 : *
2936 : * Note that this function won't be called at all unless we have at least some
2937 : * reason to believe that the EC members it generates will be useful.
2938 : */
2939 : void
2940 8963 : add_child_join_rel_equivalences(PlannerInfo *root,
2941 : int nappinfos, AppendRelInfo **appinfos,
2942 : RelOptInfo *parent_joinrel,
2943 : RelOptInfo *child_joinrel)
2944 : {
2945 8963 : Relids top_parent_relids = child_joinrel->top_parent_relids;
2946 8963 : Relids child_relids = child_joinrel->relids;
2947 : Bitmapset *matching_ecs;
2948 : MemoryContext oldcontext;
2949 : int i;
2950 :
2951 : Assert(IS_JOIN_REL(child_joinrel) && IS_JOIN_REL(parent_joinrel));
2952 :
2953 : /* We need consider only ECs that mention the parent joinrel */
2954 8963 : matching_ecs = get_eclass_indexes_for_relids(root, top_parent_relids);
2955 :
2956 : /*
2957 : * If we're being called during GEQO join planning, we still have to
2958 : * create any new EC members in the main planner context, to avoid having
2959 : * a corrupt EC data structure after the GEQO context is reset. This is
2960 : * problematic since we'll leak memory across repeated GEQO cycles. For
2961 : * now, though, bloat is better than crash. If it becomes a real issue
2962 : * we'll have to do something to avoid generating duplicate EC members.
2963 : */
2964 8963 : oldcontext = MemoryContextSwitchTo(root->planner_cxt);
2965 :
2966 8963 : i = -1;
2967 23991 : while ((i = bms_next_member(matching_ecs, i)) >= 0)
2968 : {
2969 15028 : EquivalenceClass *cur_ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
2970 :
2971 : /*
2972 : * If this EC contains a volatile expression, then generating child
2973 : * EMs would be downright dangerous, so skip it. We rely on a
2974 : * volatile EC having only one EM.
2975 : */
2976 15028 : if (cur_ec->ec_has_volatile)
2977 0 : continue;
2978 :
2979 : /* Sanity check on get_eclass_indexes_for_relids result */
2980 : Assert(bms_overlap(top_parent_relids, cur_ec->ec_relids));
2981 :
2982 55942 : foreach_node(EquivalenceMember, cur_em, cur_ec->ec_members)
2983 : {
2984 25886 : if (cur_em->em_is_const)
2985 1170 : continue; /* ignore consts here */
2986 :
2987 : /* Child members should not exist in ec_members */
2988 : Assert(!cur_em->em_is_child);
2989 :
2990 : /*
2991 : * We may ignore expressions that reference a single baserel,
2992 : * because add_child_rel_equivalences should have handled them.
2993 : */
2994 24716 : if (bms_membership(cur_em->em_relids) != BMS_MULTIPLE)
2995 23405 : continue;
2996 :
2997 : /* Does this member reference child's topmost parent rel? */
2998 1311 : if (bms_overlap(cur_em->em_relids, top_parent_relids))
2999 : {
3000 : /* Yes, generate transformed child version */
3001 : Expr *child_expr;
3002 : Relids new_relids;
3003 :
3004 1311 : if (parent_joinrel->reloptkind == RELOPT_JOINREL)
3005 : {
3006 : /* Simple single-level transformation */
3007 : child_expr = (Expr *)
3008 1263 : adjust_appendrel_attrs(root,
3009 1263 : (Node *) cur_em->em_expr,
3010 : nappinfos, appinfos);
3011 : }
3012 : else
3013 : {
3014 : /* Must do multi-level transformation */
3015 : Assert(parent_joinrel->reloptkind == RELOPT_OTHER_JOINREL);
3016 : child_expr = (Expr *)
3017 48 : adjust_appendrel_attrs_multilevel(root,
3018 48 : (Node *) cur_em->em_expr,
3019 : child_joinrel,
3020 48 : child_joinrel->top_parent);
3021 : }
3022 :
3023 : /*
3024 : * Transform em_relids to match. Note we do *not* do
3025 : * pull_varnos(child_expr) here, as for example the
3026 : * transformation might have substituted a constant, but we
3027 : * don't want the child member to be marked as constant.
3028 : */
3029 1311 : new_relids = bms_difference(cur_em->em_relids,
3030 : top_parent_relids);
3031 1311 : new_relids = bms_add_members(new_relids, child_relids);
3032 :
3033 : /*
3034 : * Add new child member to the EquivalenceClass. Because this
3035 : * is a RELOPT_OTHER_JOINREL which has multiple component
3036 : * relids, there is no ideal place to store these members in
3037 : * the class. Ordinarily, child members are stored in the
3038 : * ec_childmembers[] array element corresponding to their
3039 : * relid, however, here we have multiple component relids, so
3040 : * there's no single ec_childmembers[] array element to store
3041 : * this member. So that we still correctly find this member
3042 : * in loops iterating over an EquivalenceMemberIterator, we
3043 : * opt to store the member in the ec_childmembers array in
3044 : * only the first component relid slot of the array. This
3045 : * allows the member to be found, providing callers of
3046 : * setup_eclass_member_iterator() specify all the component
3047 : * relids for the RELOPT_OTHER_JOINREL, which they do. If we
3048 : * opted to store the member in each ec_childmembers[] element
3049 : * for all the component relids, then that would just result
3050 : * in eclass_member_iterator_next() finding the member
3051 : * multiple times, which is a waste of effort.
3052 : */
3053 1311 : add_child_eq_member(root,
3054 : cur_ec,
3055 : -1,
3056 : child_expr,
3057 : new_relids,
3058 : cur_em->em_jdomain,
3059 : cur_em,
3060 : cur_em->em_datatype,
3061 1311 : bms_next_member(child_joinrel->relids, -1));
3062 : }
3063 : }
3064 : }
3065 :
3066 8963 : MemoryContextSwitchTo(oldcontext);
3067 8963 : }
3068 :
3069 : /*
3070 : * add_setop_child_rel_equivalences
3071 : * Add equivalence members for each non-resjunk target in 'child_tlist'
3072 : * to the EquivalenceClass in the corresponding setop_pathkey's pk_eclass.
3073 : *
3074 : * 'root' is the PlannerInfo belonging to the top-level set operation.
3075 : * 'child_rel' is the RelOptInfo of the child relation we're adding
3076 : * EquivalenceMembers for.
3077 : * 'child_tlist' is the target list for the setop child relation. The target
3078 : * list expressions are what we add as EquivalenceMembers.
3079 : * 'setop_pathkeys' is a list of PathKeys which must contain an entry for each
3080 : * non-resjunk target in 'child_tlist'.
3081 : */
3082 : void
3083 6268 : add_setop_child_rel_equivalences(PlannerInfo *root, RelOptInfo *child_rel,
3084 : List *child_tlist, List *setop_pathkeys)
3085 : {
3086 : ListCell *lc;
3087 6268 : ListCell *lc2 = list_head(setop_pathkeys);
3088 :
3089 25420 : foreach(lc, child_tlist)
3090 : {
3091 19152 : TargetEntry *tle = lfirst_node(TargetEntry, lc);
3092 : EquivalenceMember *parent_em;
3093 : PathKey *pk;
3094 :
3095 19152 : if (tle->resjunk)
3096 0 : continue;
3097 :
3098 19152 : if (lc2 == NULL)
3099 0 : elog(ERROR, "too few pathkeys for set operation");
3100 :
3101 19152 : pk = lfirst_node(PathKey, lc2);
3102 19152 : parent_em = linitial(pk->pk_eclass->ec_members);
3103 :
3104 : /*
3105 : * We can safely pass the parent member as the first member in the
3106 : * ec_members list as this is added first in generate_union_paths,
3107 : * likewise, the JoinDomain can be that of the initial member of the
3108 : * Pathkey's EquivalenceClass. We pass -1 for ec_index since we
3109 : * maintain the eclass_indexes for the child_rel after the loop.
3110 : */
3111 19152 : add_child_eq_member(root,
3112 : pk->pk_eclass,
3113 : -1,
3114 : tle->expr,
3115 : child_rel->relids,
3116 : parent_em->em_jdomain,
3117 : parent_em,
3118 19152 : exprType((Node *) tle->expr),
3119 : child_rel->relid);
3120 :
3121 19152 : lc2 = lnext(setop_pathkeys, lc2);
3122 : }
3123 :
3124 : /*
3125 : * transformSetOperationStmt() ensures that the targetlist never contains
3126 : * any resjunk columns, so all eclasses that exist in 'root' must have
3127 : * received a new member in the loop above. Add them to the child_rel's
3128 : * eclass_indexes.
3129 : */
3130 6268 : child_rel->eclass_indexes = bms_add_range(child_rel->eclass_indexes, 0,
3131 6268 : list_length(root->eq_classes) - 1);
3132 6268 : }
3133 :
3134 : /*
3135 : * setup_eclass_member_iterator
3136 : * Setup an EquivalenceMemberIterator 'it' to iterate over all parent
3137 : * EquivalenceMembers and child members belonging to the given 'ec'.
3138 : *
3139 : * This iterator returns:
3140 : * - All parent members stored directly in ec_members for 'ec', and;
3141 : * - Any child member added to the given ec by add_child_eq_member() where
3142 : * the child_relid specified in the add_child_eq_member() call is a member
3143 : * of the 'child_relids' parameter.
3144 : *
3145 : * Note:
3146 : * The given 'child_relids' must remain allocated and not be changed for the
3147 : * lifetime of the iterator.
3148 : *
3149 : * Parameters:
3150 : * 'it' is a pointer to the iterator to set up. Normally stack allocated.
3151 : * 'ec' is the EquivalenceClass from which to iterate members for.
3152 : * 'child_relids' is the relids to return child members for.
3153 : */
3154 : void
3155 2877429 : setup_eclass_member_iterator(EquivalenceMemberIterator *it,
3156 : EquivalenceClass *ec, Relids child_relids)
3157 : {
3158 2877429 : it->ec = ec;
3159 : /* no need to set this if the class has no child members array set */
3160 2877429 : it->child_relids = ec->ec_childmembers != NULL ? child_relids : NULL;
3161 2877429 : it->current_relid = -1;
3162 2877429 : it->current_list = ec->ec_members;
3163 2877429 : it->current_cell = list_head(it->current_list);
3164 2877429 : }
3165 :
3166 : /*
3167 : * eclass_member_iterator_next
3168 : * Get the next EquivalenceMember from the EquivalenceMemberIterator 'it',
3169 : * as setup by setup_eclass_member_iterator(). NULL is returned if there
3170 : * are no members left, after which callers must not call
3171 : * eclass_member_iterator_next() again for the given iterator.
3172 : */
3173 : EquivalenceMember *
3174 6708439 : eclass_member_iterator_next(EquivalenceMemberIterator *it)
3175 : {
3176 6708439 : while (it->current_list != NULL)
3177 : {
3178 6696845 : while (it->current_cell != NULL)
3179 : {
3180 : EquivalenceMember *em;
3181 :
3182 4640741 : nextcell:
3183 4707354 : em = lfirst_node(EquivalenceMember, it->current_cell);
3184 4707354 : it->current_cell = lnext(it->current_list, it->current_cell);
3185 4707354 : return em;
3186 : }
3187 :
3188 : /* Search for the next list to return members from */
3189 2122983 : while ((it->current_relid = bms_next_member(it->child_relids, it->current_relid)) > 0)
3190 : {
3191 : /*
3192 : * Be paranoid in case we're given relids above what we've sized
3193 : * the ec_childmembers array to.
3194 : */
3195 133492 : if (it->current_relid >= it->ec->ec_childmembers_size)
3196 0 : return NULL;
3197 :
3198 133492 : it->current_list = it->ec->ec_childmembers[it->current_relid];
3199 :
3200 : /* If there are members in this list, use it. */
3201 133492 : if (it->current_list != NIL)
3202 : {
3203 : /* point current_cell to the head of this list */
3204 66613 : it->current_cell = list_head(it->current_list);
3205 66613 : goto nextcell;
3206 : }
3207 : }
3208 1989491 : return NULL;
3209 : }
3210 :
3211 11594 : return NULL;
3212 : }
3213 :
3214 : /*
3215 : * generate_implied_equalities_for_column
3216 : * Create EC-derived joinclauses usable with a specific column.
3217 : *
3218 : * This is used by indxpath.c to extract potentially indexable joinclauses
3219 : * from ECs, and can be used by foreign data wrappers for similar purposes.
3220 : * We assume that only expressions in Vars of a single table are of interest,
3221 : * but the caller provides a callback function to identify exactly which
3222 : * such expressions it would like to know about.
3223 : *
3224 : * We assume that any given table/index column could appear in only one EC.
3225 : * (This should be true in all but the most pathological cases, and if it
3226 : * isn't, we stop on the first match anyway.) Therefore, what we return
3227 : * is a redundant list of clauses equating the table/index column to each of
3228 : * the other-relation values it is known to be equal to. Any one of
3229 : * these clauses can be used to create a parameterized path, and there
3230 : * is no value in using more than one. (But it *is* worthwhile to create
3231 : * a separate parameterized path for each one, since that leads to different
3232 : * join orders.)
3233 : *
3234 : * The caller can pass a Relids set of rels we aren't interested in joining
3235 : * to, so as to save the work of creating useless clauses.
3236 : */
3237 : List *
3238 365929 : generate_implied_equalities_for_column(PlannerInfo *root,
3239 : RelOptInfo *rel,
3240 : ec_matches_callback_type callback,
3241 : void *callback_arg,
3242 : Relids prohibited_rels)
3243 : {
3244 365929 : List *result = NIL;
3245 365929 : bool is_child_rel = (rel->reloptkind == RELOPT_OTHER_MEMBER_REL);
3246 : Relids parent_relids;
3247 : int i;
3248 :
3249 : /* Should be OK to rely on eclass_indexes */
3250 : Assert(root->ec_merging_done);
3251 :
3252 : /* Indexes are available only on base or "other" member relations. */
3253 : Assert(IS_SIMPLE_REL(rel));
3254 :
3255 : /* If it's a child rel, we'll need to know what its parent(s) are */
3256 365929 : if (is_child_rel)
3257 6819 : parent_relids = find_childrel_parents(root, rel);
3258 : else
3259 359110 : parent_relids = NULL; /* not used, but keep compiler quiet */
3260 :
3261 365929 : i = -1;
3262 1048243 : while ((i = bms_next_member(rel->eclass_indexes, i)) >= 0)
3263 : {
3264 755304 : EquivalenceClass *cur_ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
3265 : EquivalenceMemberIterator it;
3266 : EquivalenceMember *cur_em;
3267 : ListCell *lc2;
3268 :
3269 : /* Sanity check eclass_indexes only contain ECs for rel */
3270 : Assert(is_child_rel || bms_is_subset(rel->relids, cur_ec->ec_relids));
3271 :
3272 : /*
3273 : * Won't generate joinclauses if const or single-member (the latter
3274 : * test covers the volatile case too)
3275 : */
3276 755304 : if (cur_ec->ec_has_const || list_length(cur_ec->ec_members) <= 1)
3277 682085 : continue;
3278 :
3279 : /*
3280 : * Scan members, looking for a match to the target column. Note that
3281 : * child EC members are considered, but only when they belong to the
3282 : * target relation. (Unlike regular members, the same expression
3283 : * could be a child member of more than one EC. Therefore, it's
3284 : * potentially order-dependent which EC a child relation's target
3285 : * column gets matched to. This is annoying but it only happens in
3286 : * corner cases, so for now we live with just reporting the first
3287 : * match. See also get_eclass_for_sort_expr.)
3288 : */
3289 366639 : setup_eclass_member_iterator(&it, cur_ec, rel->relids);
3290 1382010 : while ((cur_em = eclass_member_iterator_next(&it)) != NULL)
3291 : {
3292 1089176 : if (bms_equal(cur_em->em_relids, rel->relids) &&
3293 367225 : callback(root, rel, cur_ec, cur_em, callback_arg))
3294 73219 : break;
3295 : }
3296 :
3297 366639 : if (!cur_em)
3298 293420 : continue;
3299 :
3300 : /*
3301 : * Found our match. Scan the other EC members and attempt to generate
3302 : * joinclauses. Ignore children here.
3303 : */
3304 224050 : foreach(lc2, cur_ec->ec_members)
3305 : {
3306 150831 : EquivalenceMember *other_em = (EquivalenceMember *) lfirst(lc2);
3307 : Oid eq_op;
3308 : RestrictInfo *rinfo;
3309 :
3310 : /* Child members should not exist in ec_members */
3311 : Assert(!other_em->em_is_child);
3312 :
3313 : /* Make sure it'll be a join to a different rel */
3314 230090 : if (other_em == cur_em ||
3315 79259 : bms_overlap(other_em->em_relids, rel->relids))
3316 71756 : continue;
3317 :
3318 : /* Forget it if caller doesn't want joins to this rel */
3319 79075 : if (bms_overlap(other_em->em_relids, prohibited_rels))
3320 78 : continue;
3321 :
3322 : /*
3323 : * Also, if this is a child rel, avoid generating a useless join
3324 : * to its parent rel(s).
3325 : */
3326 82686 : if (is_child_rel &&
3327 3689 : bms_overlap(parent_relids, other_em->em_relids))
3328 1689 : continue;
3329 :
3330 77308 : eq_op = select_equality_operator(cur_ec,
3331 : cur_em->em_datatype,
3332 : other_em->em_datatype);
3333 77308 : if (!OidIsValid(eq_op))
3334 0 : continue;
3335 :
3336 : /* set parent_ec to mark as redundant with other joinclauses */
3337 77308 : rinfo = create_join_clause(root, cur_ec, eq_op,
3338 : cur_em, other_em,
3339 : cur_ec);
3340 :
3341 77308 : result = lappend(result, rinfo);
3342 : }
3343 :
3344 : /*
3345 : * If somehow we failed to create any join clauses, we might as well
3346 : * keep scanning the ECs for another match. But if we did make any,
3347 : * we're done, because we don't want to return non-redundant clauses.
3348 : */
3349 73219 : if (result)
3350 72990 : break;
3351 : }
3352 :
3353 365929 : return result;
3354 : }
3355 :
3356 : /*
3357 : * have_relevant_eclass_joinclause
3358 : * Detect whether there is an EquivalenceClass that could produce
3359 : * a joinclause involving the two given relations.
3360 : *
3361 : * This is essentially a very cut-down version of
3362 : * generate_join_implied_equalities(). Note it's OK to occasionally say "yes"
3363 : * incorrectly. Hence we don't bother with details like whether the lack of a
3364 : * cross-type operator might prevent the clause from actually being generated.
3365 : * False negatives are not always fatal either: they will discourage, but not
3366 : * completely prevent, investigation of particular join pathways.
3367 : */
3368 : bool
3369 122302 : have_relevant_eclass_joinclause(PlannerInfo *root,
3370 : RelOptInfo *rel1, RelOptInfo *rel2)
3371 : {
3372 : Bitmapset *matching_ecs;
3373 : int i;
3374 :
3375 : /*
3376 : * Examine only eclasses mentioning both rel1 and rel2.
3377 : *
3378 : * Note that we do not consider the possibility of an eclass generating
3379 : * "join" clauses that mention just one of the rels plus an outer join
3380 : * that could be formed from them. Although such clauses must be
3381 : * correctly enforced when we form the outer join, they don't seem like
3382 : * sufficient reason to prioritize this join over other ones. The join
3383 : * ordering rules will force the join to be made when necessary.
3384 : */
3385 122302 : matching_ecs = get_common_eclass_indexes(root, rel1->relids,
3386 : rel2->relids);
3387 :
3388 122302 : i = -1;
3389 122311 : while ((i = bms_next_member(matching_ecs, i)) >= 0)
3390 : {
3391 103748 : EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes,
3392 : i);
3393 :
3394 : /*
3395 : * Sanity check that get_common_eclass_indexes gave only ECs
3396 : * containing both rels.
3397 : */
3398 : Assert(bms_overlap(rel1->relids, ec->ec_relids));
3399 : Assert(bms_overlap(rel2->relids, ec->ec_relids));
3400 :
3401 : /*
3402 : * Won't generate joinclauses if single-member (this test covers the
3403 : * volatile case too)
3404 : */
3405 103748 : if (list_length(ec->ec_members) <= 1)
3406 9 : continue;
3407 :
3408 : /*
3409 : * We do not need to examine the individual members of the EC, because
3410 : * all that we care about is whether each rel overlaps the relids of
3411 : * at least one member, and get_common_eclass_indexes() and the single
3412 : * member check above are sufficient to prove that. (As with
3413 : * have_relevant_joinclause(), it is not necessary that the EC be able
3414 : * to form a joinclause relating exactly the two given rels, only that
3415 : * it be able to form a joinclause mentioning both, and this will
3416 : * surely be true if both of them overlap ec_relids.)
3417 : *
3418 : * Note we don't test ec_broken; if we did, we'd need a separate code
3419 : * path to look through ec_sources. Checking the membership anyway is
3420 : * OK as a possibly-overoptimistic heuristic.
3421 : *
3422 : * We don't test ec_has_const either, even though a const eclass won't
3423 : * generate real join clauses. This is because if we had "WHERE a.x =
3424 : * b.y and a.x = 42", it is worth considering a join between a and b,
3425 : * since the join result is likely to be small even though it'll end
3426 : * up being an unqualified nestloop.
3427 : */
3428 :
3429 103739 : return true;
3430 : }
3431 :
3432 18563 : return false;
3433 : }
3434 :
3435 :
3436 : /*
3437 : * has_relevant_eclass_joinclause
3438 : * Detect whether there is an EquivalenceClass that could produce
3439 : * a joinclause involving the given relation and anything else.
3440 : *
3441 : * This is the same as have_relevant_eclass_joinclause with the other rel
3442 : * implicitly defined as "everything else in the query".
3443 : */
3444 : bool
3445 129446 : has_relevant_eclass_joinclause(PlannerInfo *root, RelOptInfo *rel1)
3446 : {
3447 : Bitmapset *matched_ecs;
3448 : int i;
3449 :
3450 : /* Examine only eclasses mentioning rel1 */
3451 129446 : matched_ecs = get_eclass_indexes_for_relids(root, rel1->relids);
3452 :
3453 129446 : i = -1;
3454 456234 : while ((i = bms_next_member(matched_ecs, i)) >= 0)
3455 : {
3456 376110 : EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes,
3457 : i);
3458 :
3459 : /*
3460 : * Won't generate joinclauses if single-member (this test covers the
3461 : * volatile case too)
3462 : */
3463 376110 : if (list_length(ec->ec_members) <= 1)
3464 167341 : continue;
3465 :
3466 : /*
3467 : * Per the comment in have_relevant_eclass_joinclause, it's sufficient
3468 : * to find an EC that mentions both this rel and some other rel.
3469 : */
3470 208769 : if (!bms_is_subset(ec->ec_relids, rel1->relids))
3471 49322 : return true;
3472 : }
3473 :
3474 80124 : return false;
3475 : }
3476 :
3477 :
3478 : /*
3479 : * eclass_useful_for_merging
3480 : * Detect whether the EC could produce any mergejoinable join clauses
3481 : * against the specified relation.
3482 : *
3483 : * This is just a heuristic test and doesn't have to be exact; it's better
3484 : * to say "yes" incorrectly than "no". Hence we don't bother with details
3485 : * like whether the lack of a cross-type operator might prevent the clause
3486 : * from actually being generated.
3487 : */
3488 : bool
3489 476916 : eclass_useful_for_merging(PlannerInfo *root,
3490 : EquivalenceClass *eclass,
3491 : RelOptInfo *rel)
3492 : {
3493 : Relids relids;
3494 : ListCell *lc;
3495 :
3496 : Assert(!eclass->ec_merged);
3497 :
3498 : /*
3499 : * Won't generate joinclauses if const or single-member (the latter test
3500 : * covers the volatile case too)
3501 : */
3502 476916 : if (eclass->ec_has_const || list_length(eclass->ec_members) <= 1)
3503 21853 : return false;
3504 :
3505 : /*
3506 : * Note we don't test ec_broken; if we did, we'd need a separate code path
3507 : * to look through ec_sources. Checking the members anyway is OK as a
3508 : * possibly-overoptimistic heuristic.
3509 : */
3510 :
3511 : /* If specified rel is a child, we must consider the topmost parent rel */
3512 455063 : if (IS_OTHER_REL(rel))
3513 : {
3514 : Assert(!bms_is_empty(rel->top_parent_relids));
3515 3101 : relids = rel->top_parent_relids;
3516 : }
3517 : else
3518 451962 : relids = rel->relids;
3519 :
3520 : /* If rel already includes all members of eclass, no point in searching */
3521 455063 : if (bms_is_subset(eclass->ec_relids, relids))
3522 176949 : return false;
3523 :
3524 : /*
3525 : * To join, we need a member not in the given rel. Ignore children here.
3526 : */
3527 427135 : foreach(lc, eclass->ec_members)
3528 : {
3529 426784 : EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
3530 :
3531 : /* Child members should not exist in ec_members */
3532 : Assert(!cur_em->em_is_child);
3533 :
3534 426784 : if (!bms_overlap(cur_em->em_relids, relids))
3535 277763 : return true;
3536 : }
3537 :
3538 351 : return false;
3539 : }
3540 :
3541 :
3542 : /*
3543 : * is_redundant_derived_clause
3544 : * Test whether rinfo is derived from same EC as any clause in clauselist;
3545 : * if so, it can be presumed to represent a condition that's redundant
3546 : * with that member of the list.
3547 : */
3548 : bool
3549 42 : is_redundant_derived_clause(RestrictInfo *rinfo, List *clauselist)
3550 : {
3551 42 : EquivalenceClass *parent_ec = rinfo->parent_ec;
3552 : ListCell *lc;
3553 :
3554 : /* Fail if it's not a potentially-redundant clause from some EC */
3555 42 : if (parent_ec == NULL)
3556 42 : return false;
3557 :
3558 0 : foreach(lc, clauselist)
3559 : {
3560 0 : RestrictInfo *otherrinfo = (RestrictInfo *) lfirst(lc);
3561 :
3562 0 : if (otherrinfo->parent_ec == parent_ec)
3563 0 : return true;
3564 : }
3565 :
3566 0 : return false;
3567 : }
3568 :
3569 : /*
3570 : * is_redundant_with_indexclauses
3571 : * Test whether rinfo is redundant with any clause in the IndexClause
3572 : * list. Here, for convenience, we test both simple identity and
3573 : * whether it is derived from the same EC as any member of the list.
3574 : */
3575 : bool
3576 849198 : is_redundant_with_indexclauses(RestrictInfo *rinfo, List *indexclauses)
3577 : {
3578 849198 : EquivalenceClass *parent_ec = rinfo->parent_ec;
3579 : ListCell *lc;
3580 :
3581 1175581 : foreach(lc, indexclauses)
3582 : {
3583 867836 : IndexClause *iclause = lfirst_node(IndexClause, lc);
3584 867836 : RestrictInfo *otherrinfo = iclause->rinfo;
3585 :
3586 : /* If indexclause is lossy, it won't enforce the condition exactly */
3587 867836 : if (iclause->lossy)
3588 3627 : continue;
3589 :
3590 : /* Match if it's same clause (pointer equality should be enough) */
3591 864209 : if (rinfo == otherrinfo)
3592 541453 : return true;
3593 : /* Match if derived from same EC */
3594 322957 : if (parent_ec && otherrinfo->parent_ec == parent_ec)
3595 201 : return true;
3596 :
3597 : /*
3598 : * No need to look at the derived clauses in iclause->indexquals; they
3599 : * couldn't match if the parent clause didn't.
3600 : */
3601 : }
3602 :
3603 307745 : return false;
3604 : }
3605 :
3606 : /*
3607 : * get_eclass_indexes_for_relids
3608 : * Build and return a Bitmapset containing the indexes into root's
3609 : * eq_classes list for all eclasses that mention any of these relids
3610 : */
3611 : static Bitmapset *
3612 678870 : get_eclass_indexes_for_relids(PlannerInfo *root, Relids relids)
3613 : {
3614 678870 : Bitmapset *ec_indexes = NULL;
3615 678870 : int i = -1;
3616 :
3617 : /* Should be OK to rely on eclass_indexes */
3618 : Assert(root->ec_merging_done);
3619 :
3620 2160551 : while ((i = bms_next_member(relids, i)) > 0)
3621 : {
3622 1481681 : RelOptInfo *rel = root->simple_rel_array[i];
3623 :
3624 : /* ignore the RTE_GROUP RTE */
3625 1481681 : if (i == root->group_rtindex)
3626 0 : continue;
3627 :
3628 1481681 : if (rel == NULL) /* must be an outer join */
3629 : {
3630 : Assert(bms_is_member(i, root->outer_join_rels));
3631 199301 : continue;
3632 : }
3633 :
3634 1282380 : ec_indexes = bms_add_members(ec_indexes, rel->eclass_indexes);
3635 : }
3636 678870 : return ec_indexes;
3637 : }
3638 :
3639 : /*
3640 : * get_common_eclass_indexes
3641 : * Build and return a Bitmapset containing the indexes into root's
3642 : * eq_classes list for all eclasses that mention rels in both
3643 : * relids1 and relids2.
3644 : */
3645 : static Bitmapset *
3646 396068 : get_common_eclass_indexes(PlannerInfo *root, Relids relids1, Relids relids2)
3647 : {
3648 : Bitmapset *rel1ecs;
3649 : Bitmapset *rel2ecs;
3650 : int relid;
3651 :
3652 396068 : rel1ecs = get_eclass_indexes_for_relids(root, relids1);
3653 :
3654 : /*
3655 : * We can get away with just using the relation's eclass_indexes directly
3656 : * when relids2 is a singleton set.
3657 : */
3658 396068 : if (bms_get_singleton_member(relids2, &relid))
3659 308027 : rel2ecs = root->simple_rel_array[relid]->eclass_indexes;
3660 : else
3661 88041 : rel2ecs = get_eclass_indexes_for_relids(root, relids2);
3662 :
3663 : /* Calculate and return the common EC indexes, recycling the left input. */
3664 396068 : return bms_int_members(rel1ecs, rel2ecs);
3665 : }
3666 :
3667 : /*
3668 : * ec_build_derives_hash
3669 : * Construct the auxiliary hash table for derived clause lookups.
3670 : */
3671 : static void
3672 0 : ec_build_derives_hash(PlannerInfo *root, EquivalenceClass *ec)
3673 : {
3674 : Assert(!ec->ec_derives_hash);
3675 :
3676 : /*
3677 : * Create the hash table.
3678 : *
3679 : * We pass list_length(ec->ec_derives_list) as the initial size.
3680 : * Simplehash will divide this by the fillfactor (typically 0.9) and round
3681 : * up to the next power of two, so this will usually give us at least 64
3682 : * buckets around the threshold. That avoids immediate resizing without
3683 : * hardcoding a specific size.
3684 : */
3685 0 : ec->ec_derives_hash = derives_create(root->planner_cxt,
3686 0 : list_length(ec->ec_derives_list),
3687 : NULL);
3688 :
3689 0 : foreach_node(RestrictInfo, rinfo, ec->ec_derives_list)
3690 0 : ec_add_clause_to_derives_hash(ec, rinfo);
3691 0 : }
3692 :
3693 : /*
3694 : * ec_add_derived_clause
3695 : * Add a clause to the set of derived clauses for the given
3696 : * EquivalenceClass. Always appends to ec_derives_list; also adds
3697 : * to ec_derives_hash if it exists.
3698 : *
3699 : * Also asserts expected invariants of derived clauses.
3700 : */
3701 : static void
3702 68879 : ec_add_derived_clause(EquivalenceClass *ec, RestrictInfo *clause)
3703 : {
3704 : /*
3705 : * Constant, if present, is always placed on the RHS; see
3706 : * generate_base_implied_equalities_const(). LHS is never a constant.
3707 : */
3708 : Assert(!clause->left_em->em_is_const);
3709 :
3710 : /*
3711 : * Clauses containing a constant are never considered redundant, so
3712 : * parent_ec is not set.
3713 : */
3714 : Assert(!clause->parent_ec || !clause->right_em->em_is_const);
3715 :
3716 68879 : ec->ec_derives_list = lappend(ec->ec_derives_list, clause);
3717 68879 : if (ec->ec_derives_hash)
3718 0 : ec_add_clause_to_derives_hash(ec, clause);
3719 68879 : }
3720 :
3721 : /*
3722 : * ec_add_derived_clauses
3723 : * Add a list of clauses to the set of clauses derived from the given
3724 : * EquivalenceClass; adding to the list and hash table if needed.
3725 : *
3726 : * This function is similar to ec_add_derived_clause() but optimized for adding
3727 : * multiple clauses at a time to the ec_derives_list. The assertions from
3728 : * ec_add_derived_clause() are not repeated here, as the input clauses are
3729 : * assumed to have already been validated.
3730 : */
3731 : static void
3732 21 : ec_add_derived_clauses(EquivalenceClass *ec, List *clauses)
3733 : {
3734 21 : ec->ec_derives_list = list_concat(ec->ec_derives_list, clauses);
3735 21 : if (ec->ec_derives_hash)
3736 0 : foreach_node(RestrictInfo, rinfo, clauses)
3737 0 : ec_add_clause_to_derives_hash(ec, rinfo);
3738 21 : }
3739 :
3740 : /*
3741 : * fill_ec_derives_key
3742 : * Compute a canonical key for ec_derives_hash lookup or insertion.
3743 : *
3744 : * Derived clauses are looked up using a pair of EquivalenceMembers and a
3745 : * parent EquivalenceClass. To avoid storing or searching for both EM orderings,
3746 : * we canonicalize the key:
3747 : *
3748 : * - For clauses involving two non-constant EMs, em1 is set to the EM with lower
3749 : * memory address and em2 is set to the other one.
3750 : * - For clauses involving a constant EM, the caller must pass the non-constant
3751 : * EM as leftem and NULL as rightem; we then set em1 = NULL and em2 = leftem.
3752 : */
3753 : static inline void
3754 0 : fill_ec_derives_key(ECDerivesKey *key,
3755 : EquivalenceMember *leftem,
3756 : EquivalenceMember *rightem,
3757 : EquivalenceClass *parent_ec)
3758 : {
3759 : Assert(leftem); /* Always required for lookup or insertion */
3760 :
3761 0 : if (rightem == NULL)
3762 : {
3763 0 : key->em1 = NULL;
3764 0 : key->em2 = leftem;
3765 : }
3766 0 : else if (leftem < rightem)
3767 : {
3768 0 : key->em1 = leftem;
3769 0 : key->em2 = rightem;
3770 : }
3771 : else
3772 : {
3773 0 : key->em1 = rightem;
3774 0 : key->em2 = leftem;
3775 : }
3776 0 : key->parent_ec = parent_ec;
3777 0 : }
3778 :
3779 : /*
3780 : * ec_add_clause_to_derives_hash
3781 : * Add a derived clause to ec_derives_hash in the given EquivalenceClass.
3782 : *
3783 : * Each clause is associated with a canonicalized key. For constant-containing
3784 : * clauses, only the non-constant EM is used for lookup; see comments in
3785 : * fill_ec_derives_key().
3786 : */
3787 : static void
3788 0 : ec_add_clause_to_derives_hash(EquivalenceClass *ec, RestrictInfo *rinfo)
3789 : {
3790 : ECDerivesKey key;
3791 : ECDerivesEntry *entry;
3792 : bool found;
3793 :
3794 : /*
3795 : * Constants are always placed on the RHS; see
3796 : * generate_base_implied_equalities_const().
3797 : */
3798 : Assert(!rinfo->left_em->em_is_const);
3799 :
3800 : /*
3801 : * Clauses containing a constant are never considered redundant, so
3802 : * parent_ec is not set.
3803 : */
3804 : Assert(!rinfo->parent_ec || !rinfo->right_em->em_is_const);
3805 :
3806 : /*
3807 : * See fill_ec_derives_key() for details: we use a canonicalized key to
3808 : * avoid storing both EM orderings. For constant EMs, only the
3809 : * non-constant EM is included in the key.
3810 : */
3811 0 : fill_ec_derives_key(&key,
3812 : rinfo->left_em,
3813 0 : rinfo->right_em->em_is_const ? NULL : rinfo->right_em,
3814 : rinfo->parent_ec);
3815 0 : entry = derives_insert(ec->ec_derives_hash, key, &found);
3816 : Assert(!found);
3817 0 : entry->rinfo = rinfo;
3818 0 : }
3819 :
3820 : /*
3821 : * ec_clear_derived_clauses
3822 : * Reset ec_derives_list and ec_derives_hash.
3823 : *
3824 : * We destroy the hash table explicitly, since it may consume significant
3825 : * space. The list holds the same set of entries and can become equally large
3826 : * when thousands of partitions are involved, so we free it as well -- even
3827 : * though we do not typically free lists.
3828 : */
3829 : void
3830 9712 : ec_clear_derived_clauses(EquivalenceClass *ec)
3831 : {
3832 9712 : list_free(ec->ec_derives_list);
3833 9712 : ec->ec_derives_list = NIL;
3834 :
3835 9712 : if (ec->ec_derives_hash)
3836 : {
3837 0 : derives_destroy(ec->ec_derives_hash);
3838 0 : ec->ec_derives_hash = NULL;
3839 : }
3840 9712 : }
3841 :
3842 : /*
3843 : * ec_search_clause_for_ems
3844 : * Search for an existing RestrictInfo that equates the given pair
3845 : * of EquivalenceMembers, either from ec_sources or ec_derives.
3846 : *
3847 : * Returns a clause with matching operands in either given order or commuted
3848 : * order. We used to require matching operator OIDs, but dropped that since any
3849 : * semantically different operator here would indicate a broken operator family.
3850 : *
3851 : * Returns NULL if no matching clause is found.
3852 : */
3853 : static RestrictInfo *
3854 299841 : ec_search_clause_for_ems(PlannerInfo *root, EquivalenceClass *ec,
3855 : EquivalenceMember *leftem, EquivalenceMember *rightem,
3856 : EquivalenceClass *parent_ec)
3857 : {
3858 : /* Check original source clauses */
3859 949483 : foreach_node(RestrictInfo, rinfo, ec->ec_sources)
3860 : {
3861 351463 : if (rinfo->left_em == leftem &&
3862 161305 : rinfo->right_em == rightem &&
3863 143466 : rinfo->parent_ec == parent_ec)
3864 831 : return rinfo;
3865 351409 : if (rinfo->left_em == rightem &&
3866 154451 : rinfo->right_em == leftem &&
3867 139757 : rinfo->parent_ec == parent_ec)
3868 777 : return rinfo;
3869 : }
3870 :
3871 : /* Not found in ec_sources; search derived clauses */
3872 299010 : return ec_search_derived_clause_for_ems(root, ec, leftem, rightem,
3873 : parent_ec);
3874 : }
3875 :
3876 : /*
3877 : * ec_search_derived_clause_for_ems
3878 : * Search for an existing derived clause between two EquivalenceMembers.
3879 : *
3880 : * If the number of derived clauses exceeds a threshold, switch to hash table
3881 : * lookup; otherwise, scan ec_derives_list linearly.
3882 : *
3883 : * Clauses involving constants are looked up by passing the non-constant EM
3884 : * as leftem and setting rightem to NULL. In that case, we expect to find a
3885 : * clause with a constant on the RHS.
3886 : *
3887 : * While searching the list, we compare each given EM with both sides of each
3888 : * clause. But for hash table lookups, we construct a canonicalized key and
3889 : * perform a single lookup.
3890 : */
3891 : static RestrictInfo *
3892 299013 : ec_search_derived_clause_for_ems(PlannerInfo *root, EquivalenceClass *ec,
3893 : EquivalenceMember *leftem,
3894 : EquivalenceMember *rightem,
3895 : EquivalenceClass *parent_ec)
3896 : {
3897 : /* Switch to using hash lookup when list grows "too long". */
3898 598026 : if (!ec->ec_derives_hash &&
3899 299013 : list_length(ec->ec_derives_list) >= EC_DERIVES_HASH_THRESHOLD)
3900 0 : ec_build_derives_hash(root, ec);
3901 :
3902 : /* Perform hash table lookup if available */
3903 299013 : if (ec->ec_derives_hash)
3904 : {
3905 : ECDerivesKey key;
3906 : RestrictInfo *rinfo;
3907 : ECDerivesEntry *entry;
3908 :
3909 0 : fill_ec_derives_key(&key, leftem, rightem, parent_ec);
3910 0 : entry = derives_lookup(ec->ec_derives_hash, key);
3911 0 : if (entry)
3912 : {
3913 0 : rinfo = entry->rinfo;
3914 : Assert(rinfo);
3915 : Assert(rightem || rinfo->right_em->em_is_const);
3916 0 : return rinfo;
3917 : }
3918 : }
3919 : else
3920 : {
3921 : /* Fallback to linear search over ec_derives_list */
3922 421907 : foreach_node(RestrictInfo, rinfo, ec->ec_derives_list)
3923 : {
3924 : /* Handle special case: lookup by non-const EM alone */
3925 321793 : if (!rightem &&
3926 3 : rinfo->left_em == leftem)
3927 : {
3928 : Assert(rinfo->right_em->em_is_const);
3929 248956 : return rinfo;
3930 : }
3931 321790 : if (rinfo->left_em == leftem &&
3932 134897 : rinfo->right_em == rightem &&
3933 122765 : rinfo->parent_ec == parent_ec)
3934 122759 : return rinfo;
3935 199031 : if (rinfo->left_em == rightem &&
3936 133108 : rinfo->right_em == leftem &&
3937 126194 : rinfo->parent_ec == parent_ec)
3938 126194 : return rinfo;
3939 : }
3940 : }
3941 :
3942 50057 : return NULL;
3943 : }
|
