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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * dependencies.c
4 : : * POSTGRES functional dependencies
5 : : *
6 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : : * Portions Copyright (c) 1994, Regents of the University of California
8 : : *
9 : : * IDENTIFICATION
10 : : * src/backend/statistics/dependencies.c
11 : : *
12 : : *-------------------------------------------------------------------------
13 : : */
14 : : #include "postgres.h"
15 : :
16 : : #include "access/htup_details.h"
17 : : #include "catalog/pg_statistic_ext.h"
18 : : #include "catalog/pg_statistic_ext_data.h"
19 : : #include "nodes/nodeFuncs.h"
20 : : #include "optimizer/clauses.h"
21 : : #include "optimizer/optimizer.h"
22 : : #include "parser/parsetree.h"
23 : : #include "statistics/extended_stats_internal.h"
24 : : #include "utils/fmgroids.h"
25 : : #include "utils/lsyscache.h"
26 : : #include "utils/memutils.h"
27 : : #include "utils/selfuncs.h"
28 : : #include "utils/syscache.h"
29 : : #include "utils/typcache.h"
30 : :
31 : : /* size of the struct header fields (magic, type, ndeps) */
32 : : #define SizeOfHeader (3 * sizeof(uint32))
33 : :
34 : : /* size of a serialized dependency (degree, natts, atts) */
35 : : #define SizeOfItem(natts) \
36 : : (sizeof(double) + sizeof(AttrNumber) * (1 + (natts)))
37 : :
38 : : /* minimal size of a dependency (with two attributes) */
39 : : #define MinSizeOfItem SizeOfItem(2)
40 : :
41 : : /* minimal size of dependencies, when all deps are minimal */
42 : : #define MinSizeOfItems(ndeps) \
43 : : (SizeOfHeader + (ndeps) * MinSizeOfItem)
44 : :
45 : : /*
46 : : * Internal state for DependencyGenerator of dependencies. Dependencies are similar to
47 : : * k-permutations of n elements, except that the order does not matter for the
48 : : * first (k-1) elements. That is, (a,b=>c) and (b,a=>c) are equivalent.
49 : : */
50 : : typedef struct DependencyGeneratorData
51 : : {
52 : : int k; /* size of the dependency */
53 : : int n; /* number of possible attributes */
54 : : int current; /* next dependency to return (index) */
55 : : AttrNumber ndependencies; /* number of dependencies generated */
56 : : AttrNumber *dependencies; /* array of pre-generated dependencies */
57 : : } DependencyGeneratorData;
58 : :
59 : : typedef DependencyGeneratorData *DependencyGenerator;
60 : :
61 : : static void generate_dependencies_recurse(DependencyGenerator state,
62 : : int index, AttrNumber start, AttrNumber *current);
63 : : static void generate_dependencies(DependencyGenerator state);
64 : : static DependencyGenerator DependencyGenerator_init(int n, int k);
65 : : static void DependencyGenerator_free(DependencyGenerator state);
66 : : static AttrNumber *DependencyGenerator_next(DependencyGenerator state);
67 : : static double dependency_degree(StatsBuildData *data, int k, AttrNumber *dependency);
68 : : static bool dependency_is_fully_matched(MVDependency *dependency,
69 : : Bitmapset *attnums);
70 : : static bool dependency_is_compatible_clause(Node *clause, Index relid,
71 : : AttrNumber *attnum);
72 : : static bool dependency_is_compatible_expression(Node *clause, Index relid,
73 : : List *statlist, Node **expr);
74 : : static MVDependency *find_strongest_dependency(MVDependencies **dependencies,
75 : : int ndependencies, Bitmapset *attnums);
76 : : static Selectivity clauselist_apply_dependencies(PlannerInfo *root, List *clauses,
77 : : int varRelid, JoinType jointype,
78 : : SpecialJoinInfo *sjinfo,
79 : : MVDependency **dependencies,
80 : : int ndependencies,
81 : : AttrNumber *list_attnums,
82 : : Bitmapset **estimatedclauses);
83 : :
84 : : static void
85 : 974 : generate_dependencies_recurse(DependencyGenerator state, int index,
86 : : AttrNumber start, AttrNumber *current)
87 : : {
88 : : /*
89 : : * The generator handles the first (k-1) elements differently from the
90 : : * last element.
91 : : */
92 [ + + ]: 974 : if (index < (state->k - 1))
93 : : {
94 : : AttrNumber i;
95 : :
96 : : /*
97 : : * The first (k-1) values have to be in ascending order, which we
98 : : * generate recursively.
99 : : */
100 : :
101 [ + + ]: 1194 : for (i = start; i < state->n; i++)
102 : : {
103 : 768 : current[index] = i;
104 : 768 : generate_dependencies_recurse(state, (index + 1), (i + 1), current);
105 : : }
106 : : }
107 : : else
108 : : {
109 : : int i;
110 : :
111 : : /*
112 : : * the last element is the implied value, which does not respect the
113 : : * ascending order. We just need to check that the value is not in the
114 : : * first (k-1) elements.
115 : : */
116 : :
117 [ + + ]: 2084 : for (i = 0; i < state->n; i++)
118 : : {
119 : : int j;
120 : 1536 : bool match = false;
121 : :
122 : 1536 : current[index] = i;
123 : :
124 [ + + ]: 2824 : for (j = 0; j < index; j++)
125 : : {
126 [ + + ]: 2056 : if (current[j] == i)
127 : : {
128 : 768 : match = true;
129 : 768 : break;
130 : : }
131 : : }
132 : :
133 : : /*
134 : : * If the value is not found in the first part of the dependency,
135 : : * we're done.
136 : : */
137 [ + + ]: 1536 : if (!match)
138 : : {
139 : 1536 : state->dependencies = (AttrNumber *) repalloc(state->dependencies,
140 : 768 : state->k * (state->ndependencies + 1) * sizeof(AttrNumber));
141 : 768 : memcpy(&state->dependencies[(state->k * state->ndependencies)],
142 : 768 : current, state->k * sizeof(AttrNumber));
143 : 768 : state->ndependencies++;
144 : : }
145 : : }
146 : : }
147 : 974 : }
148 : :
149 : : /* generate all dependencies (k-permutations of n elements) */
150 : : static void
151 : 206 : generate_dependencies(DependencyGenerator state)
152 : : {
153 : 206 : AttrNumber *current = palloc0_array(AttrNumber, state->k);
154 : :
155 : 206 : generate_dependencies_recurse(state, 0, 0, current);
156 : :
157 : 206 : pfree(current);
158 : 206 : }
159 : :
160 : : /*
161 : : * initialize the DependencyGenerator of variations, and prebuild the variations
162 : : *
163 : : * This pre-builds all the variations. We could also generate them in
164 : : * DependencyGenerator_next(), but this seems simpler.
165 : : */
166 : : static DependencyGenerator
167 : 206 : DependencyGenerator_init(int n, int k)
168 : : {
169 : : DependencyGenerator state;
170 : :
171 : : Assert((n >= k) && (k > 0));
172 : :
173 : : /* allocate the DependencyGenerator state */
174 : 206 : state = palloc0_object(DependencyGeneratorData);
175 : 206 : state->dependencies = palloc_array(AttrNumber, k);
176 : :
177 : 206 : state->ndependencies = 0;
178 : 206 : state->current = 0;
179 : 206 : state->k = k;
180 : 206 : state->n = n;
181 : :
182 : : /* now actually pre-generate all the variations */
183 : 206 : generate_dependencies(state);
184 : :
185 : 206 : return state;
186 : : }
187 : :
188 : : /* free the DependencyGenerator state */
189 : : static void
190 : 206 : DependencyGenerator_free(DependencyGenerator state)
191 : : {
192 : 206 : pfree(state->dependencies);
193 : 206 : pfree(state);
194 : 206 : }
195 : :
196 : : /* generate next combination */
197 : : static AttrNumber *
198 : 974 : DependencyGenerator_next(DependencyGenerator state)
199 : : {
200 [ + + ]: 974 : if (state->current == state->ndependencies)
201 : 206 : return NULL;
202 : :
203 : 768 : return &state->dependencies[state->k * state->current++];
204 : : }
205 : :
206 : :
207 : : /*
208 : : * validates functional dependency on the data
209 : : *
210 : : * An actual work horse of detecting functional dependencies. Given a variation
211 : : * of k attributes, it checks that the first (k-1) are sufficient to determine
212 : : * the last one.
213 : : */
214 : : static double
215 : 768 : dependency_degree(StatsBuildData *data, int k, AttrNumber *dependency)
216 : : {
217 : : int i,
218 : : nitems;
219 : : MultiSortSupport mss;
220 : : SortItem *items;
221 : : AttrNumber *attnums_dep;
222 : :
223 : : /* counters valid within a group */
224 : 768 : int group_size = 0;
225 : 768 : int n_violations = 0;
226 : :
227 : : /* total number of rows supporting (consistent with) the dependency */
228 : 768 : int n_supporting_rows = 0;
229 : :
230 : : /* Make sure we have at least two input attributes. */
231 : : Assert(k >= 2);
232 : :
233 : : /* sort info for all attributes columns */
234 : 768 : mss = multi_sort_init(k);
235 : :
236 : : /*
237 : : * Translate the array of indexes to regular attnums for the dependency
238 : : * (we will need this to identify the columns in StatsBuildData).
239 : : */
240 : 768 : attnums_dep = palloc_array(AttrNumber, k);
241 [ + + ]: 2572 : for (i = 0; i < k; i++)
242 : 1804 : attnums_dep[i] = data->attnums[dependency[i]];
243 : :
244 : : /*
245 : : * Verify the dependency (a,b,...)->z, using a rather simple algorithm:
246 : : *
247 : : * (a) sort the data lexicographically
248 : : *
249 : : * (b) split the data into groups by first (k-1) columns
250 : : *
251 : : * (c) for each group count different values in the last column
252 : : *
253 : : * We use the column data types' default sort operators and collations;
254 : : * perhaps at some point it'd be worth using column-specific collations?
255 : : */
256 : :
257 : : /* prepare the sort function for the dimensions */
258 [ + + ]: 2572 : for (i = 0; i < k; i++)
259 : : {
260 : 1804 : VacAttrStats *colstat = data->stats[dependency[i]];
261 : : TypeCacheEntry *type;
262 : :
263 : 1804 : type = lookup_type_cache(colstat->attrtypid, TYPECACHE_LT_OPR);
264 [ - + ]: 1804 : if (type->lt_opr == InvalidOid) /* shouldn't happen */
265 [ # # ]: 0 : elog(ERROR, "cache lookup failed for ordering operator for type %u",
266 : : colstat->attrtypid);
267 : :
268 : : /* prepare the sort function for this dimension */
269 : 1804 : multi_sort_add_dimension(mss, i, type->lt_opr, colstat->attrcollid);
270 : : }
271 : :
272 : : /*
273 : : * build an array of SortItem(s) sorted using the multi-sort support
274 : : *
275 : : * XXX This relies on all stats entries pointing to the same tuple
276 : : * descriptor. For now that assumption holds, but it might change in the
277 : : * future for example if we support statistics on multiple tables.
278 : : */
279 : 768 : items = build_sorted_items(data, &nitems, mss, k, attnums_dep);
280 : :
281 : : /*
282 : : * Walk through the sorted array, split it into rows according to the
283 : : * first (k-1) columns. If there's a single value in the last column, we
284 : : * count the group as 'supporting' the functional dependency. Otherwise we
285 : : * count it as contradicting.
286 : : */
287 : :
288 : : /* start with the first row forming a group */
289 : 768 : group_size = 1;
290 : :
291 : : /* loop 1 beyond the end of the array so that we count the final group */
292 [ + + ]: 1006864 : for (i = 1; i <= nitems; i++)
293 : : {
294 : : /*
295 : : * Check if the group ended, which may be either because we processed
296 : : * all the items (i==nitems), or because the i-th item is not equal to
297 : : * the preceding one.
298 : : */
299 [ + + + + ]: 2011424 : if (i == nitems ||
300 : 1005328 : multi_sort_compare_dims(0, k - 2, &items[i - 1], &items[i], mss) != 0)
301 : : {
302 : : /*
303 : : * If no violations were found in the group then track the rows of
304 : : * the group as supporting the functional dependency.
305 : : */
306 [ + + ]: 23512 : if (n_violations == 0)
307 : 14936 : n_supporting_rows += group_size;
308 : :
309 : : /* Reset counters for the new group */
310 : 23512 : n_violations = 0;
311 : 23512 : group_size = 1;
312 : 23512 : continue;
313 : : }
314 : : /* first columns match, but the last one does not (so contradicting) */
315 [ + + ]: 982584 : else if (multi_sort_compare_dim(k - 1, &items[i - 1], &items[i], mss) != 0)
316 : 40644 : n_violations++;
317 : :
318 : 982584 : group_size++;
319 : : }
320 : :
321 : : /* Compute the 'degree of validity' as (supporting/total). */
322 : 768 : return (n_supporting_rows * 1.0 / data->numrows);
323 : : }
324 : :
325 : : /*
326 : : * detects functional dependencies between groups of columns
327 : : *
328 : : * Generates all possible subsets of columns (variations) and computes
329 : : * the degree of validity for each one. For example when creating statistics
330 : : * on three columns (a,b,c) there are 9 possible dependencies
331 : : *
332 : : * two columns three columns
333 : : * ----------- -------------
334 : : * (a) -> b (a,b) -> c
335 : : * (a) -> c (a,c) -> b
336 : : * (b) -> a (b,c) -> a
337 : : * (b) -> c
338 : : * (c) -> a
339 : : * (c) -> b
340 : : */
341 : : MVDependencies *
342 : 154 : statext_dependencies_build(StatsBuildData *data)
343 : : {
344 : : int i,
345 : : k;
346 : :
347 : : /* result */
348 : 154 : MVDependencies *dependencies = NULL;
349 : : MemoryContext cxt;
350 : :
351 : : Assert(data->nattnums >= 2);
352 : :
353 : : /* tracks memory allocated by dependency_degree calls */
354 : 154 : cxt = AllocSetContextCreate(CurrentMemoryContext,
355 : : "dependency_degree cxt",
356 : : ALLOCSET_DEFAULT_SIZES);
357 : :
358 : : /*
359 : : * We'll try build functional dependencies starting from the smallest ones
360 : : * covering just 2 columns, to the largest ones, covering all columns
361 : : * included in the statistics object. We start from the smallest ones
362 : : * because we want to be able to skip already implied ones.
363 : : */
364 [ + + ]: 360 : for (k = 2; k <= data->nattnums; k++)
365 : : {
366 : : AttrNumber *dependency; /* array with k elements */
367 : :
368 : : /* prepare a DependencyGenerator of variation */
369 : 206 : DependencyGenerator DependencyGenerator = DependencyGenerator_init(data->nattnums, k);
370 : :
371 : : /* generate all possible variations of k values (out of n) */
372 [ + + ]: 974 : while ((dependency = DependencyGenerator_next(DependencyGenerator)))
373 : : {
374 : : double degree;
375 : : MVDependency *d;
376 : : MemoryContext oldcxt;
377 : :
378 : : /* release memory used by dependency degree calculation */
379 : 768 : oldcxt = MemoryContextSwitchTo(cxt);
380 : :
381 : : /* compute how valid the dependency seems */
382 : 768 : degree = dependency_degree(data, k, dependency);
383 : :
384 : 768 : MemoryContextSwitchTo(oldcxt);
385 : 768 : MemoryContextReset(cxt);
386 : :
387 : : /*
388 : : * if the dependency seems entirely invalid, don't store it
389 : : */
390 [ + + ]: 768 : if (degree == 0.0)
391 : 186 : continue;
392 : :
393 : 582 : d = (MVDependency *) palloc0(offsetof(MVDependency, attributes)
394 : 582 : + k * sizeof(AttrNumber));
395 : :
396 : : /* copy the dependency (and keep the indexes into stxkeys) */
397 : 582 : d->degree = degree;
398 : 582 : d->nattributes = k;
399 [ + + ]: 1966 : for (i = 0; i < k; i++)
400 : 1384 : d->attributes[i] = data->attnums[dependency[i]];
401 : :
402 : : /* initialize the list of dependencies */
403 [ + + ]: 582 : if (dependencies == NULL)
404 : : {
405 : 142 : dependencies = palloc0_object(MVDependencies);
406 : :
407 : 142 : dependencies->magic = STATS_DEPS_MAGIC;
408 : 142 : dependencies->type = STATS_DEPS_TYPE_BASIC;
409 : 142 : dependencies->ndeps = 0;
410 : : }
411 : :
412 : 582 : dependencies->ndeps++;
413 : 582 : dependencies = (MVDependencies *) repalloc(dependencies,
414 : : offsetof(MVDependencies, deps)
415 : 582 : + dependencies->ndeps * sizeof(MVDependency *));
416 : :
417 : 582 : dependencies->deps[dependencies->ndeps - 1] = d;
418 : : }
419 : :
420 : : /*
421 : : * we're done with variations of k elements, so free the
422 : : * DependencyGenerator
423 : : */
424 : 206 : DependencyGenerator_free(DependencyGenerator);
425 : : }
426 : :
427 : 154 : MemoryContextDelete(cxt);
428 : :
429 : 154 : return dependencies;
430 : : }
431 : :
432 : :
433 : : /*
434 : : * Serialize list of dependencies into a bytea value.
435 : : */
436 : : bytea *
437 : 195 : statext_dependencies_serialize(MVDependencies *dependencies)
438 : : {
439 : : bytea *output;
440 : : char *tmp;
441 : : Size len;
442 : :
443 : : /* we need to store ndeps, with a number of attributes for each one */
444 : 195 : len = VARHDRSZ + SizeOfHeader;
445 : :
446 : : /* and also include space for the actual attribute numbers and degrees */
447 [ + + ]: 914 : for (uint32 i = 0; i < dependencies->ndeps; i++)
448 : 719 : len += SizeOfItem(dependencies->deps[i]->nattributes);
449 : :
450 : 195 : output = (bytea *) palloc0(len);
451 : 195 : SET_VARSIZE(output, len);
452 : :
453 : 195 : tmp = VARDATA(output);
454 : :
455 : : /* Store the base struct values (magic, type, ndeps) */
456 : 195 : memcpy(tmp, &dependencies->magic, sizeof(uint32));
457 : 195 : tmp += sizeof(uint32);
458 : 195 : memcpy(tmp, &dependencies->type, sizeof(uint32));
459 : 195 : tmp += sizeof(uint32);
460 : 195 : memcpy(tmp, &dependencies->ndeps, sizeof(uint32));
461 : 195 : tmp += sizeof(uint32);
462 : :
463 : : /* store number of attributes and attribute numbers for each dependency */
464 [ + + ]: 914 : for (uint32 i = 0; i < dependencies->ndeps; i++)
465 : : {
466 : 719 : MVDependency *d = dependencies->deps[i];
467 : :
468 : 719 : memcpy(tmp, &d->degree, sizeof(double));
469 : 719 : tmp += sizeof(double);
470 : :
471 : 719 : memcpy(tmp, &d->nattributes, sizeof(AttrNumber));
472 : 719 : tmp += sizeof(AttrNumber);
473 : :
474 : 719 : memcpy(tmp, d->attributes, sizeof(AttrNumber) * d->nattributes);
475 : 719 : tmp += sizeof(AttrNumber) * d->nattributes;
476 : :
477 : : /* protect against overflow */
478 : : Assert(tmp <= ((char *) output + len));
479 : : }
480 : :
481 : : /* make sure we've produced exactly the right amount of data */
482 : : Assert(tmp == ((char *) output + len));
483 : :
484 : 195 : return output;
485 : : }
486 : :
487 : : /*
488 : : * Reads serialized dependencies into MVDependencies structure.
489 : : */
490 : : MVDependencies *
491 : 1452 : statext_dependencies_deserialize(bytea *data)
492 : : {
493 : : Size min_expected_size;
494 : : MVDependencies *dependencies;
495 : : char *tmp;
496 : :
497 [ - + ]: 1452 : if (data == NULL)
498 : 0 : return NULL;
499 : :
500 [ - + ]: 1452 : if (VARSIZE_ANY_EXHDR(data) < SizeOfHeader)
501 [ # # ]: 0 : elog(ERROR, "invalid MVDependencies size %zu (expected at least %zu)",
502 : : VARSIZE_ANY_EXHDR(data), SizeOfHeader);
503 : :
504 : : /* read the MVDependencies header */
505 : 1452 : dependencies = palloc0_object(MVDependencies);
506 : :
507 : : /* initialize pointer to the data part (skip the varlena header) */
508 : 1452 : tmp = VARDATA_ANY(data);
509 : :
510 : : /* read the header fields and perform basic sanity checks */
511 : 1452 : memcpy(&dependencies->magic, tmp, sizeof(uint32));
512 : 1452 : tmp += sizeof(uint32);
513 : 1452 : memcpy(&dependencies->type, tmp, sizeof(uint32));
514 : 1452 : tmp += sizeof(uint32);
515 : 1452 : memcpy(&dependencies->ndeps, tmp, sizeof(uint32));
516 : 1452 : tmp += sizeof(uint32);
517 : :
518 [ - + ]: 1452 : if (dependencies->magic != STATS_DEPS_MAGIC)
519 [ # # ]: 0 : elog(ERROR, "invalid dependency magic %d (expected %d)",
520 : : dependencies->magic, STATS_DEPS_MAGIC);
521 : :
522 [ - + ]: 1452 : if (dependencies->type != STATS_DEPS_TYPE_BASIC)
523 [ # # ]: 0 : elog(ERROR, "invalid dependency type %d (expected %d)",
524 : : dependencies->type, STATS_DEPS_TYPE_BASIC);
525 : :
526 [ - + ]: 1452 : if (dependencies->ndeps == 0)
527 [ # # ]: 0 : elog(ERROR, "invalid zero-length item array in MVDependencies");
528 : :
529 : : /* what minimum bytea size do we expect for those parameters */
530 : 1452 : min_expected_size = MinSizeOfItems(dependencies->ndeps);
531 : :
532 [ - + ]: 1452 : if (VARSIZE_ANY_EXHDR(data) < min_expected_size)
533 [ # # ]: 0 : elog(ERROR, "invalid dependencies size %zu (expected at least %zu)",
534 : : VARSIZE_ANY_EXHDR(data), min_expected_size);
535 : :
536 : : /* allocate space for the MCV items */
537 : 1452 : dependencies = repalloc(dependencies, offsetof(MVDependencies, deps)
538 : 1452 : + (dependencies->ndeps * sizeof(MVDependency *)));
539 : :
540 [ + + ]: 8435 : for (uint32 i = 0; i < dependencies->ndeps; i++)
541 : : {
542 : : double degree;
543 : : AttrNumber k;
544 : : MVDependency *d;
545 : :
546 : : /* degree of validity */
547 : 6983 : memcpy(°ree, tmp, sizeof(double));
548 : 6983 : tmp += sizeof(double);
549 : :
550 : : /* number of attributes */
551 : 6983 : memcpy(&k, tmp, sizeof(AttrNumber));
552 : 6983 : tmp += sizeof(AttrNumber);
553 : :
554 : : /* is the number of attributes valid? */
555 : : Assert((k >= 2) && (k <= STATS_MAX_DIMENSIONS));
556 : :
557 : : /* now that we know the number of attributes, allocate the dependency */
558 : 6983 : d = (MVDependency *) palloc0(offsetof(MVDependency, attributes)
559 : 6983 : + (k * sizeof(AttrNumber)));
560 : :
561 : 6983 : d->degree = degree;
562 : 6983 : d->nattributes = k;
563 : :
564 : : /* copy attribute numbers */
565 : 6983 : memcpy(d->attributes, tmp, sizeof(AttrNumber) * d->nattributes);
566 : 6983 : tmp += sizeof(AttrNumber) * d->nattributes;
567 : :
568 : 6983 : dependencies->deps[i] = d;
569 : :
570 : : /* still within the bytea */
571 : : Assert(tmp <= ((char *) data + VARSIZE_ANY(data)));
572 : : }
573 : :
574 : : /* we should have consumed the whole bytea exactly */
575 : : Assert(tmp == ((char *) data + VARSIZE_ANY(data)));
576 : :
577 : 1452 : return dependencies;
578 : : }
579 : :
580 : : /*
581 : : * Free allocations of a MVDependencies.
582 : : */
583 : : void
584 : 29 : statext_dependencies_free(MVDependencies *dependencies)
585 : : {
586 [ + + ]: 234 : for (uint32 i = 0; i < dependencies->ndeps; i++)
587 : 205 : pfree(dependencies->deps[i]);
588 : 29 : pfree(dependencies);
589 : 29 : }
590 : :
591 : : /*
592 : : * Validate a set of MVDependencies against the extended statistics object
593 : : * definition.
594 : : *
595 : : * Every MVDependencies must be checked to ensure that the attnums in the
596 : : * attributes list correspond to attnums/expressions defined by the
597 : : * extended statistics object.
598 : : *
599 : : * Positive attnums are attributes which must be found in the stxkeys, while
600 : : * negative attnums correspond to an expression number, no attribute number
601 : : * can be below (0 - numexprs).
602 : : */
603 : : bool
604 : 29 : statext_dependencies_validate(const MVDependencies *dependencies,
605 : : const int2vector *stxkeys,
606 : : int numexprs, int elevel)
607 : : {
608 : 29 : int attnum_expr_lowbound = 0 - numexprs;
609 : :
610 : : /* Scan through each dependency entry */
611 [ + + ]: 218 : for (uint32 i = 0; i < dependencies->ndeps; i++)
612 : : {
613 : 197 : const MVDependency *dep = dependencies->deps[i];
614 : :
615 : : /*
616 : : * Cross-check each attribute in a dependency entry with the extended
617 : : * stats object definition.
618 : : */
619 [ + + ]: 685 : for (int j = 0; j < dep->nattributes; j++)
620 : : {
621 : 496 : AttrNumber attnum = dep->attributes[j];
622 : 496 : bool ok = false;
623 : :
624 [ + + ]: 496 : if (attnum > 0)
625 : : {
626 : : /* attribute number in stxkeys */
627 [ + + ]: 404 : for (int k = 0; k < stxkeys->dim1; k++)
628 : : {
629 [ + + ]: 396 : if (attnum == stxkeys->values[k])
630 : : {
631 : 256 : ok = true;
632 : 256 : break;
633 : : }
634 : : }
635 : : }
636 [ + - + - ]: 232 : else if ((attnum < 0) && (attnum >= attnum_expr_lowbound))
637 : : {
638 : : /* attribute number for an expression */
639 : 232 : ok = true;
640 : : }
641 : :
642 [ + + ]: 496 : if (!ok)
643 : : {
644 [ + - ]: 8 : ereport(elevel,
645 : : (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
646 : : errmsg("could not validate \"%s\" object: invalid attribute number %d found",
647 : : "pg_dependencies", attnum)));
648 : 8 : return false;
649 : : }
650 : : }
651 : : }
652 : :
653 : 21 : return true;
654 : : }
655 : :
656 : : /*
657 : : * dependency_is_fully_matched
658 : : * checks that a functional dependency is fully matched given clauses on
659 : : * attributes (assuming the clauses are suitable equality clauses)
660 : : */
661 : : static bool
662 : 5130 : dependency_is_fully_matched(MVDependency *dependency, Bitmapset *attnums)
663 : : {
664 : : int j;
665 : :
666 : : /*
667 : : * Check that the dependency actually is fully covered by clauses. We have
668 : : * to translate all attribute numbers, as those are referenced
669 : : */
670 [ + + ]: 13035 : for (j = 0; j < dependency->nattributes; j++)
671 : : {
672 : 10465 : int attnum = dependency->attributes[j];
673 : :
674 [ + + ]: 10465 : if (!bms_is_member(attnum, attnums))
675 : 2560 : return false;
676 : : }
677 : :
678 : 2570 : return true;
679 : : }
680 : :
681 : : /*
682 : : * statext_dependencies_load
683 : : * Load the functional dependencies for the indicated pg_statistic_ext tuple
684 : : */
685 : : MVDependencies *
686 : 1340 : statext_dependencies_load(Oid mvoid, bool inh)
687 : : {
688 : : MVDependencies *result;
689 : : bool isnull;
690 : : Datum deps;
691 : : HeapTuple htup;
692 : :
693 : 1340 : htup = SearchSysCache2(STATEXTDATASTXOID,
694 : : ObjectIdGetDatum(mvoid),
695 : : BoolGetDatum(inh));
696 [ - + ]: 1340 : if (!HeapTupleIsValid(htup))
697 [ # # ]: 0 : elog(ERROR, "cache lookup failed for statistics object %u", mvoid);
698 : :
699 : 1340 : deps = SysCacheGetAttr(STATEXTDATASTXOID, htup,
700 : : Anum_pg_statistic_ext_data_stxddependencies, &isnull);
701 [ - + ]: 1340 : if (isnull)
702 [ # # ]: 0 : elog(ERROR,
703 : : "requested statistics kind \"%c\" is not yet built for statistics object %u",
704 : : STATS_EXT_DEPENDENCIES, mvoid);
705 : :
706 : 1340 : result = statext_dependencies_deserialize(DatumGetByteaPP(deps));
707 : :
708 : 1340 : ReleaseSysCache(htup);
709 : :
710 : 1340 : return result;
711 : : }
712 : :
713 : : /*
714 : : * dependency_is_compatible_clause
715 : : * Determines if the clause is compatible with functional dependencies
716 : : *
717 : : * Only clauses that have the form of equality to a pseudoconstant, or can be
718 : : * interpreted that way, are currently accepted. Furthermore the variable
719 : : * part of the clause must be a simple Var belonging to the specified
720 : : * relation, whose attribute number we return in *attnum on success.
721 : : */
722 : : static bool
723 : 3300 : dependency_is_compatible_clause(Node *clause, Index relid, AttrNumber *attnum)
724 : : {
725 : : Var *var;
726 : : Node *clause_expr;
727 : :
728 [ + + ]: 3300 : if (IsA(clause, RestrictInfo))
729 : : {
730 : 3200 : RestrictInfo *rinfo = (RestrictInfo *) clause;
731 : :
732 : : /* Pseudoconstants are not interesting (they couldn't contain a Var) */
733 [ + + ]: 3200 : if (rinfo->pseudoconstant)
734 : 5 : return false;
735 : :
736 : : /* Clauses referencing multiple, or no, varnos are incompatible */
737 [ - + ]: 3195 : if (bms_membership(rinfo->clause_relids) != BMS_SINGLETON)
738 : 0 : return false;
739 : :
740 : 3195 : clause = (Node *) rinfo->clause;
741 : : }
742 : :
743 [ + + ]: 3295 : if (is_opclause(clause))
744 : : {
745 : : /* If it's an opclause, check for Var = Const or Const = Var. */
746 : 1205 : OpExpr *expr = (OpExpr *) clause;
747 : :
748 : : /* Only expressions with two arguments are candidates. */
749 [ - + ]: 1205 : if (list_length(expr->args) != 2)
750 : 0 : return false;
751 : :
752 : : /* Make sure non-selected argument is a pseudoconstant. */
753 [ + - ]: 1205 : if (is_pseudo_constant_clause(lsecond(expr->args)))
754 : 1205 : clause_expr = linitial(expr->args);
755 [ # # ]: 0 : else if (is_pseudo_constant_clause(linitial(expr->args)))
756 : 0 : clause_expr = lsecond(expr->args);
757 : : else
758 : 0 : return false;
759 : :
760 : : /*
761 : : * If it's not an "=" operator, just ignore the clause, as it's not
762 : : * compatible with functional dependencies.
763 : : *
764 : : * This uses the function for estimating selectivity, not the operator
765 : : * directly (a bit awkward, but well ...).
766 : : *
767 : : * XXX this is pretty dubious; probably it'd be better to check btree
768 : : * or hash opclass membership, so as not to be fooled by custom
769 : : * selectivity functions, and to be more consistent with decisions
770 : : * elsewhere in the planner.
771 : : */
772 [ + + ]: 1205 : if (get_oprrest(expr->opno) != F_EQSEL)
773 : 30 : return false;
774 : :
775 : : /* OK to proceed with checking "var" */
776 : : }
777 [ + + ]: 2090 : else if (IsA(clause, ScalarArrayOpExpr))
778 : : {
779 : : /* If it's a scalar array operator, check for Var IN Const. */
780 : 2030 : ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) clause;
781 : :
782 : : /*
783 : : * Reject ALL() variant, we only care about ANY/IN.
784 : : *
785 : : * XXX Maybe we should check if all the values are the same, and allow
786 : : * ALL in that case? Doesn't seem very practical, though.
787 : : */
788 [ + + ]: 2030 : if (!expr->useOr)
789 : 30 : return false;
790 : :
791 : : /* Only expressions with two arguments are candidates. */
792 [ - + ]: 2000 : if (list_length(expr->args) != 2)
793 : 0 : return false;
794 : :
795 : : /*
796 : : * We know it's always (Var IN Const), so we assume the var is the
797 : : * first argument, and pseudoconstant is the second one.
798 : : */
799 [ - + ]: 2000 : if (!is_pseudo_constant_clause(lsecond(expr->args)))
800 : 0 : return false;
801 : :
802 : 2000 : clause_expr = linitial(expr->args);
803 : :
804 : : /*
805 : : * If it's not an "=" operator, just ignore the clause, as it's not
806 : : * compatible with functional dependencies. The operator is identified
807 : : * simply by looking at which function it uses to estimate
808 : : * selectivity. That's a bit strange, but it's what other similar
809 : : * places do.
810 : : */
811 [ + + ]: 2000 : if (get_oprrest(expr->opno) != F_EQSEL)
812 : 150 : return false;
813 : :
814 : : /* OK to proceed with checking "var" */
815 : : }
816 [ + - ]: 60 : else if (is_orclause(clause))
817 : : {
818 : 60 : BoolExpr *bool_expr = (BoolExpr *) clause;
819 : : ListCell *lc;
820 : :
821 : : /* start with no attribute number */
822 : 60 : *attnum = InvalidAttrNumber;
823 : :
824 [ + - + + : 125 : foreach(lc, bool_expr->args)
+ + ]
825 : : {
826 : : AttrNumber clause_attnum;
827 : :
828 : : /*
829 : : * Had we found incompatible clause in the arguments, treat the
830 : : * whole clause as incompatible.
831 : : */
832 [ + + ]: 100 : if (!dependency_is_compatible_clause((Node *) lfirst(lc),
833 : : relid, &clause_attnum))
834 : 35 : return false;
835 : :
836 [ + + ]: 70 : if (*attnum == InvalidAttrNumber)
837 : 30 : *attnum = clause_attnum;
838 : :
839 : : /* ensure all the variables are the same (same attnum) */
840 [ + + ]: 70 : if (*attnum != clause_attnum)
841 : 5 : return false;
842 : : }
843 : :
844 : : /* the Var is already checked by the recursive call */
845 : 25 : return true;
846 : : }
847 [ # # ]: 0 : else if (is_notclause(clause))
848 : : {
849 : : /*
850 : : * "NOT x" can be interpreted as "x = false", so get the argument and
851 : : * proceed with seeing if it's a suitable Var.
852 : : */
853 : 0 : clause_expr = (Node *) get_notclausearg(clause);
854 : : }
855 : : else
856 : : {
857 : : /*
858 : : * A boolean expression "x" can be interpreted as "x = true", so
859 : : * proceed with seeing if it's a suitable Var.
860 : : */
861 : 0 : clause_expr = clause;
862 : : }
863 : :
864 : : /*
865 : : * We may ignore any RelabelType node above the operand. (There won't be
866 : : * more than one, since eval_const_expressions has been applied already.)
867 : : */
868 [ - + ]: 3025 : if (IsA(clause_expr, RelabelType))
869 : 0 : clause_expr = (Node *) ((RelabelType *) clause_expr)->arg;
870 : :
871 : : /* We only support plain Vars for now */
872 [ + + ]: 3025 : if (!IsA(clause_expr, Var))
873 : 240 : return false;
874 : :
875 : : /* OK, we know we have a Var */
876 : 2785 : var = (Var *) clause_expr;
877 : :
878 : : /* Ensure Var is from the correct relation */
879 [ - + ]: 2785 : if (var->varno != relid)
880 : 0 : return false;
881 : :
882 : : /* We also better ensure the Var is from the current level */
883 [ - + ]: 2785 : if (var->varlevelsup != 0)
884 : 0 : return false;
885 : :
886 : : /* Also ignore system attributes (we don't allow stats on those) */
887 [ - + ]: 2785 : if (!AttrNumberIsForUserDefinedAttr(var->varattno))
888 : 0 : return false;
889 : :
890 : 2785 : *attnum = var->varattno;
891 : 2785 : return true;
892 : : }
893 : :
894 : : /*
895 : : * find_strongest_dependency
896 : : * find the strongest dependency on the attributes
897 : : *
898 : : * When applying functional dependencies, we start with the strongest
899 : : * dependencies. That is, we select the dependency that:
900 : : *
901 : : * (a) has all attributes covered by equality clauses
902 : : *
903 : : * (b) has the most attributes
904 : : *
905 : : * (c) has the highest degree of validity
906 : : *
907 : : * This guarantees that we eliminate the most redundant conditions first
908 : : * (see the comment in dependencies_clauselist_selectivity).
909 : : */
910 : : static MVDependency *
911 : 2905 : find_strongest_dependency(MVDependencies **dependencies, int ndependencies,
912 : : Bitmapset *attnums)
913 : : {
914 : 2905 : MVDependency *strongest = NULL;
915 : :
916 : : /* number of attnums in clauses */
917 : 2905 : int nattnums = bms_num_members(attnums);
918 : :
919 : : /*
920 : : * Iterate over the MVDependency items and find the strongest one from the
921 : : * fully-matched dependencies. We do the cheap checks first, before
922 : : * matching it against the attnums.
923 : : */
924 [ + + ]: 5840 : for (int i = 0; i < ndependencies; i++)
925 : : {
926 [ + + ]: 16900 : for (uint32 j = 0; j < dependencies[i]->ndeps; j++)
927 : : {
928 : 13965 : MVDependency *dependency = dependencies[i]->deps[j];
929 : :
930 : : /*
931 : : * Skip dependencies referencing more attributes than available
932 : : * clauses, as those can't be fully matched.
933 : : */
934 [ + + ]: 13965 : if (dependency->nattributes > nattnums)
935 : 8835 : continue;
936 : :
937 [ + + ]: 5130 : if (strongest)
938 : : {
939 : : /* skip dependencies on fewer attributes than the strongest. */
940 [ - + ]: 3280 : if (dependency->nattributes < strongest->nattributes)
941 : 0 : continue;
942 : :
943 : : /* also skip weaker dependencies when attribute count matches */
944 [ + + ]: 3280 : if (strongest->nattributes == dependency->nattributes &&
945 [ - + ]: 3045 : strongest->degree > dependency->degree)
946 : 0 : continue;
947 : : }
948 : :
949 : : /*
950 : : * this dependency is stronger, but we must still check that it's
951 : : * fully matched to these attnums. We perform this check last as
952 : : * it's slightly more expensive than the previous checks.
953 : : */
954 [ + + ]: 5130 : if (dependency_is_fully_matched(dependency, attnums))
955 : 2570 : strongest = dependency; /* save new best match */
956 : : }
957 : : }
958 : :
959 : 2905 : return strongest;
960 : : }
961 : :
962 : : /*
963 : : * clauselist_apply_dependencies
964 : : * Apply the specified functional dependencies to a list of clauses and
965 : : * return the estimated selectivity of the clauses that are compatible
966 : : * with any of the given dependencies.
967 : : *
968 : : * This will estimate all not-already-estimated clauses that are compatible
969 : : * with functional dependencies, and which have an attribute mentioned by any
970 : : * of the given dependencies (either as an implying or implied attribute).
971 : : *
972 : : * Given (lists of) clauses on attributes (a,b) and a functional dependency
973 : : * (a=>b), the per-column selectivities P(a) and P(b) are notionally combined
974 : : * using the formula
975 : : *
976 : : * P(a,b) = f * P(a) + (1-f) * P(a) * P(b)
977 : : *
978 : : * where 'f' is the degree of dependency. This reflects the fact that we
979 : : * expect a fraction f of all rows to be consistent with the dependency
980 : : * (a=>b), and so have a selectivity of P(a), while the remaining rows are
981 : : * treated as independent.
982 : : *
983 : : * In practice, we use a slightly modified version of this formula, which uses
984 : : * a selectivity of Min(P(a), P(b)) for the dependent rows, since the result
985 : : * should obviously not exceed either column's individual selectivity. I.e.,
986 : : * we actually combine selectivities using the formula
987 : : *
988 : : * P(a,b) = f * Min(P(a), P(b)) + (1-f) * P(a) * P(b)
989 : : *
990 : : * This can make quite a difference if the specific values matching the
991 : : * clauses are not consistent with the functional dependency.
992 : : */
993 : : static Selectivity
994 : 1330 : clauselist_apply_dependencies(PlannerInfo *root, List *clauses,
995 : : int varRelid, JoinType jointype,
996 : : SpecialJoinInfo *sjinfo,
997 : : MVDependency **dependencies, int ndependencies,
998 : : AttrNumber *list_attnums,
999 : : Bitmapset **estimatedclauses)
1000 : : {
1001 : : Bitmapset *attnums;
1002 : : int i;
1003 : : int j;
1004 : : int nattrs;
1005 : : Selectivity *attr_sel;
1006 : : int attidx;
1007 : : int listidx;
1008 : : ListCell *l;
1009 : : Selectivity s1;
1010 : :
1011 : : /*
1012 : : * Extract the attnums of all implying and implied attributes from all the
1013 : : * given dependencies. Each of these attributes is expected to have at
1014 : : * least 1 not-already-estimated compatible clause that we will estimate
1015 : : * here.
1016 : : */
1017 : 1330 : attnums = NULL;
1018 [ + + ]: 2905 : for (i = 0; i < ndependencies; i++)
1019 : : {
1020 [ + + ]: 4960 : for (j = 0; j < dependencies[i]->nattributes; j++)
1021 : : {
1022 : 3385 : AttrNumber attnum = dependencies[i]->attributes[j];
1023 : :
1024 : 3385 : attnums = bms_add_member(attnums, attnum);
1025 : : }
1026 : : }
1027 : :
1028 : : /*
1029 : : * Compute per-column selectivity estimates for each of these attributes,
1030 : : * and mark all the corresponding clauses as estimated.
1031 : : */
1032 : 1330 : nattrs = bms_num_members(attnums);
1033 : 1330 : attr_sel = palloc_array(Selectivity, nattrs);
1034 : :
1035 : 1330 : attidx = 0;
1036 : 1330 : i = -1;
1037 [ + + ]: 4245 : while ((i = bms_next_member(attnums, i)) >= 0)
1038 : : {
1039 : 2915 : List *attr_clauses = NIL;
1040 : : Selectivity simple_sel;
1041 : :
1042 : 2915 : listidx = -1;
1043 [ + - + + : 9530 : foreach(l, clauses)
+ + ]
1044 : : {
1045 : 6615 : Node *clause = (Node *) lfirst(l);
1046 : :
1047 : 6615 : listidx++;
1048 [ + + ]: 6615 : if (list_attnums[listidx] == i)
1049 : : {
1050 : 2915 : attr_clauses = lappend(attr_clauses, clause);
1051 : 2915 : *estimatedclauses = bms_add_member(*estimatedclauses, listidx);
1052 : : }
1053 : : }
1054 : :
1055 : 2915 : simple_sel = clauselist_selectivity_ext(root, attr_clauses, varRelid,
1056 : : jointype, sjinfo, false);
1057 : 2915 : attr_sel[attidx++] = simple_sel;
1058 : : }
1059 : :
1060 : : /*
1061 : : * Now combine these selectivities using the dependency information. For
1062 : : * chains of dependencies such as a -> b -> c, the b -> c dependency will
1063 : : * come before the a -> b dependency in the array, so we traverse the
1064 : : * array backwards to ensure such chains are computed in the right order.
1065 : : *
1066 : : * As explained above, pairs of selectivities are combined using the
1067 : : * formula
1068 : : *
1069 : : * P(a,b) = f * Min(P(a), P(b)) + (1-f) * P(a) * P(b)
1070 : : *
1071 : : * to ensure that the combined selectivity is never greater than either
1072 : : * individual selectivity.
1073 : : *
1074 : : * Where multiple dependencies apply (e.g., a -> b -> c), we use
1075 : : * conditional probabilities to compute the overall result as follows:
1076 : : *
1077 : : * P(a,b,c) = P(c|a,b) * P(a,b) = P(c|a,b) * P(b|a) * P(a)
1078 : : *
1079 : : * so we replace the selectivities of all implied attributes with
1080 : : * conditional probabilities, that are conditional on all their implying
1081 : : * attributes. The selectivities of all other non-implied attributes are
1082 : : * left as they are.
1083 : : */
1084 [ + + ]: 2905 : for (i = ndependencies - 1; i >= 0; i--)
1085 : : {
1086 : 1575 : MVDependency *dependency = dependencies[i];
1087 : : AttrNumber attnum;
1088 : : Selectivity s2;
1089 : : double f;
1090 : :
1091 : : /* Selectivity of all the implying attributes */
1092 : 1575 : s1 = 1.0;
1093 [ + + ]: 3385 : for (j = 0; j < dependency->nattributes - 1; j++)
1094 : : {
1095 : 1810 : attnum = dependency->attributes[j];
1096 : 1810 : attidx = bms_member_index(attnums, attnum);
1097 : 1810 : s1 *= attr_sel[attidx];
1098 : : }
1099 : :
1100 : : /* Original selectivity of the implied attribute */
1101 : 1575 : attnum = dependency->attributes[j];
1102 : 1575 : attidx = bms_member_index(attnums, attnum);
1103 : 1575 : s2 = attr_sel[attidx];
1104 : :
1105 : : /*
1106 : : * Replace s2 with the conditional probability s2 given s1, computed
1107 : : * using the formula P(b|a) = P(a,b) / P(a), which simplifies to
1108 : : *
1109 : : * P(b|a) = f * Min(P(a), P(b)) / P(a) + (1-f) * P(b)
1110 : : *
1111 : : * where P(a) = s1, the selectivity of the implying attributes, and
1112 : : * P(b) = s2, the selectivity of the implied attribute.
1113 : : */
1114 : 1575 : f = dependency->degree;
1115 : :
1116 [ + + ]: 1575 : if (s1 <= s2)
1117 : 1485 : attr_sel[attidx] = f + (1 - f) * s2;
1118 : : else
1119 : 90 : attr_sel[attidx] = f * s2 / s1 + (1 - f) * s2;
1120 : : }
1121 : :
1122 : : /*
1123 : : * The overall selectivity of all the clauses on all these attributes is
1124 : : * then the product of all the original (non-implied) probabilities and
1125 : : * the new conditional (implied) probabilities.
1126 : : */
1127 : 1330 : s1 = 1.0;
1128 [ + + ]: 4245 : for (i = 0; i < nattrs; i++)
1129 : 2915 : s1 *= attr_sel[i];
1130 : :
1131 [ - + - + ]: 1330 : CLAMP_PROBABILITY(s1);
1132 : :
1133 : 1330 : pfree(attr_sel);
1134 : 1330 : bms_free(attnums);
1135 : :
1136 : 1330 : return s1;
1137 : : }
1138 : :
1139 : : /*
1140 : : * dependency_is_compatible_expression
1141 : : * Determines if the expression is compatible with functional dependencies
1142 : : *
1143 : : * Similar to dependency_is_compatible_clause, but doesn't enforce that the
1144 : : * expression is a simple Var. On success, return the matching statistics
1145 : : * expression into *expr.
1146 : : */
1147 : : static bool
1148 : 535 : dependency_is_compatible_expression(Node *clause, Index relid, List *statlist, Node **expr)
1149 : : {
1150 : : ListCell *lc,
1151 : : *lc2;
1152 : : Node *clause_expr;
1153 : :
1154 [ + + ]: 535 : if (IsA(clause, RestrictInfo))
1155 : : {
1156 : 460 : RestrictInfo *rinfo = (RestrictInfo *) clause;
1157 : :
1158 : : /* Pseudoconstants are not interesting (they couldn't contain a Var) */
1159 [ + + ]: 460 : if (rinfo->pseudoconstant)
1160 : 5 : return false;
1161 : :
1162 : : /* Clauses referencing multiple, or no, varnos are incompatible */
1163 [ - + ]: 455 : if (bms_membership(rinfo->clause_relids) != BMS_SINGLETON)
1164 : 0 : return false;
1165 : :
1166 : 455 : clause = (Node *) rinfo->clause;
1167 : : }
1168 : :
1169 [ + + ]: 530 : if (is_opclause(clause))
1170 : : {
1171 : : /* If it's an opclause, check for Var = Const or Const = Var. */
1172 : 170 : OpExpr *expr = (OpExpr *) clause;
1173 : :
1174 : : /* Only expressions with two arguments are candidates. */
1175 [ - + ]: 170 : if (list_length(expr->args) != 2)
1176 : 0 : return false;
1177 : :
1178 : : /* Make sure non-selected argument is a pseudoconstant. */
1179 [ + - ]: 170 : if (is_pseudo_constant_clause(lsecond(expr->args)))
1180 : 170 : clause_expr = linitial(expr->args);
1181 [ # # ]: 0 : else if (is_pseudo_constant_clause(linitial(expr->args)))
1182 : 0 : clause_expr = lsecond(expr->args);
1183 : : else
1184 : 0 : return false;
1185 : :
1186 : : /*
1187 : : * If it's not an "=" operator, just ignore the clause, as it's not
1188 : : * compatible with functional dependencies.
1189 : : *
1190 : : * This uses the function for estimating selectivity, not the operator
1191 : : * directly (a bit awkward, but well ...).
1192 : : *
1193 : : * XXX this is pretty dubious; probably it'd be better to check btree
1194 : : * or hash opclass membership, so as not to be fooled by custom
1195 : : * selectivity functions, and to be more consistent with decisions
1196 : : * elsewhere in the planner.
1197 : : */
1198 [ + + ]: 170 : if (get_oprrest(expr->opno) != F_EQSEL)
1199 : 30 : return false;
1200 : :
1201 : : /* OK to proceed with checking "var" */
1202 : : }
1203 [ + + ]: 360 : else if (IsA(clause, ScalarArrayOpExpr))
1204 : : {
1205 : : /* If it's a scalar array operator, check for Var IN Const. */
1206 : 325 : ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) clause;
1207 : :
1208 : : /*
1209 : : * Reject ALL() variant, we only care about ANY/IN.
1210 : : *
1211 : : * FIXME Maybe we should check if all the values are the same, and
1212 : : * allow ALL in that case? Doesn't seem very practical, though.
1213 : : */
1214 [ + + ]: 325 : if (!expr->useOr)
1215 : 30 : return false;
1216 : :
1217 : : /* Only expressions with two arguments are candidates. */
1218 [ - + ]: 295 : if (list_length(expr->args) != 2)
1219 : 0 : return false;
1220 : :
1221 : : /*
1222 : : * We know it's always (Var IN Const), so we assume the var is the
1223 : : * first argument, and pseudoconstant is the second one.
1224 : : */
1225 [ - + ]: 295 : if (!is_pseudo_constant_clause(lsecond(expr->args)))
1226 : 0 : return false;
1227 : :
1228 : 295 : clause_expr = linitial(expr->args);
1229 : :
1230 : : /*
1231 : : * If it's not an "=" operator, just ignore the clause, as it's not
1232 : : * compatible with functional dependencies. The operator is identified
1233 : : * simply by looking at which function it uses to estimate
1234 : : * selectivity. That's a bit strange, but it's what other similar
1235 : : * places do.
1236 : : */
1237 [ + + ]: 295 : if (get_oprrest(expr->opno) != F_EQSEL)
1238 : 150 : return false;
1239 : :
1240 : : /* OK to proceed with checking "var" */
1241 : : }
1242 [ + - ]: 35 : else if (is_orclause(clause))
1243 : : {
1244 : 35 : BoolExpr *bool_expr = (BoolExpr *) clause;
1245 : :
1246 : : /* start with no expression (we'll use the first match) */
1247 : 35 : *expr = NULL;
1248 : :
1249 [ + - + + : 100 : foreach(lc, bool_expr->args)
+ + ]
1250 : : {
1251 : 75 : Node *or_expr = NULL;
1252 : :
1253 : : /*
1254 : : * Had we found incompatible expression in the arguments, treat
1255 : : * the whole expression as incompatible.
1256 : : */
1257 [ + + ]: 75 : if (!dependency_is_compatible_expression((Node *) lfirst(lc), relid,
1258 : : statlist, &or_expr))
1259 : 10 : return false;
1260 : :
1261 [ + + ]: 70 : if (*expr == NULL)
1262 : 30 : *expr = or_expr;
1263 : :
1264 : : /* ensure all the expressions are the same */
1265 [ + + ]: 70 : if (!equal(or_expr, *expr))
1266 : 5 : return false;
1267 : : }
1268 : :
1269 : : /* the expression is already checked by the recursive call */
1270 : 25 : return true;
1271 : : }
1272 [ # # ]: 0 : else if (is_notclause(clause))
1273 : : {
1274 : : /*
1275 : : * "NOT x" can be interpreted as "x = false", so get the argument and
1276 : : * proceed with seeing if it's a suitable Var.
1277 : : */
1278 : 0 : clause_expr = (Node *) get_notclausearg(clause);
1279 : : }
1280 : : else
1281 : : {
1282 : : /*
1283 : : * A boolean expression "x" can be interpreted as "x = true", so
1284 : : * proceed with seeing if it's a suitable Var.
1285 : : */
1286 : 0 : clause_expr = clause;
1287 : : }
1288 : :
1289 : : /*
1290 : : * We may ignore any RelabelType node above the operand. (There won't be
1291 : : * more than one, since eval_const_expressions has been applied already.)
1292 : : */
1293 [ - + ]: 285 : if (IsA(clause_expr, RelabelType))
1294 : 0 : clause_expr = (Node *) ((RelabelType *) clause_expr)->arg;
1295 : :
1296 : : /*
1297 : : * Search for a matching statistics expression.
1298 : : */
1299 [ + - + + : 290 : foreach(lc, statlist)
+ + ]
1300 : : {
1301 : 285 : StatisticExtInfo *info = (StatisticExtInfo *) lfirst(lc);
1302 : :
1303 : : /* ignore stats without dependencies */
1304 [ - + ]: 285 : if (info->kind != STATS_EXT_DEPENDENCIES)
1305 : 0 : continue;
1306 : :
1307 [ + + + - : 465 : foreach(lc2, info->exprs)
+ + ]
1308 : : {
1309 : 460 : Node *stat_expr = (Node *) lfirst(lc2);
1310 : :
1311 [ + + ]: 460 : if (equal(clause_expr, stat_expr))
1312 : : {
1313 : 280 : *expr = stat_expr;
1314 : 280 : return true;
1315 : : }
1316 : : }
1317 : : }
1318 : :
1319 : 5 : return false;
1320 : : }
1321 : :
1322 : : /*
1323 : : * dependencies_clauselist_selectivity
1324 : : * Return the estimated selectivity of (a subset of) the given clauses
1325 : : * using functional dependency statistics, or 1.0 if no useful functional
1326 : : * dependency statistic exists.
1327 : : *
1328 : : * 'estimatedclauses' is an input/output argument that gets a bit set
1329 : : * corresponding to the (zero-based) list index of each clause that is included
1330 : : * in the estimated selectivity.
1331 : : *
1332 : : * Given equality clauses on attributes (a,b) we find the strongest dependency
1333 : : * between them, i.e. either (a=>b) or (b=>a). Assuming (a=>b) is the selected
1334 : : * dependency, we then combine the per-clause selectivities using the formula
1335 : : *
1336 : : * P(a,b) = f * P(a) + (1-f) * P(a) * P(b)
1337 : : *
1338 : : * where 'f' is the degree of the dependency. (Actually we use a slightly
1339 : : * modified version of this formula -- see clauselist_apply_dependencies()).
1340 : : *
1341 : : * With clauses on more than two attributes, the dependencies are applied
1342 : : * recursively, starting with the widest/strongest dependencies. For example
1343 : : * P(a,b,c) is first split like this:
1344 : : *
1345 : : * P(a,b,c) = f * P(a,b) + (1-f) * P(a,b) * P(c)
1346 : : *
1347 : : * assuming (a,b=>c) is the strongest dependency.
1348 : : */
1349 : : Selectivity
1350 : 2040 : dependencies_clauselist_selectivity(PlannerInfo *root,
1351 : : List *clauses,
1352 : : int varRelid,
1353 : : JoinType jointype,
1354 : : SpecialJoinInfo *sjinfo,
1355 : : RelOptInfo *rel,
1356 : : Bitmapset **estimatedclauses)
1357 : : {
1358 : 2040 : Selectivity s1 = 1.0;
1359 : : ListCell *l;
1360 : 2040 : Bitmapset *clauses_attnums = NULL;
1361 : : AttrNumber *list_attnums;
1362 : : int listidx;
1363 : : MVDependencies **func_dependencies;
1364 : : int nfunc_dependencies;
1365 : : int total_ndeps;
1366 : : MVDependency **dependencies;
1367 : : int ndependencies;
1368 : : AttrNumber attnum_offset;
1369 [ + - ]: 2040 : RangeTblEntry *rte = planner_rt_fetch(rel->relid, root);
1370 : :
1371 : : /* unique expressions */
1372 : : Node **unique_exprs;
1373 : : int unique_exprs_cnt;
1374 : :
1375 : : /* check if there's any stats that might be useful for us. */
1376 [ + + ]: 2040 : if (!has_stats_of_kind(rel->statlist, STATS_EXT_DEPENDENCIES))
1377 : 550 : return 1.0;
1378 : :
1379 : 1490 : list_attnums = palloc_array(AttrNumber, list_length(clauses));
1380 : :
1381 : : /*
1382 : : * We allocate space as if every clause was a unique expression, although
1383 : : * that's probably overkill. Some will be simple column references that
1384 : : * we'll translate to attnums, and there might be duplicates. But it's
1385 : : * easier and cheaper to just do one allocation than repalloc later.
1386 : : */
1387 : 1490 : unique_exprs = palloc_array(Node *, list_length(clauses));
1388 : 1490 : unique_exprs_cnt = 0;
1389 : :
1390 : : /*
1391 : : * Pre-process the clauses list to extract the attnums seen in each item.
1392 : : * We need to determine if there's any clauses which will be useful for
1393 : : * dependency selectivity estimations. Along the way we'll record all of
1394 : : * the attnums for each clause in a list which we'll reference later so we
1395 : : * don't need to repeat the same work again. We'll also keep track of all
1396 : : * attnums seen.
1397 : : *
1398 : : * We also skip clauses that we already estimated using different types of
1399 : : * statistics (we treat them as incompatible).
1400 : : *
1401 : : * To handle expressions, we assign them negative attnums, as if it was a
1402 : : * system attribute (this is fine, as we only allow extended stats on user
1403 : : * attributes). And then we offset everything by the number of
1404 : : * expressions, so that we can store the values in a bitmapset.
1405 : : */
1406 : 1490 : listidx = 0;
1407 [ + - + + : 4725 : foreach(l, clauses)
+ + ]
1408 : : {
1409 : 3235 : Node *clause = (Node *) lfirst(l);
1410 : : AttrNumber attnum;
1411 : 3235 : Node *expr = NULL;
1412 : :
1413 : : /* ignore clause by default */
1414 : 3235 : list_attnums[listidx] = InvalidAttrNumber;
1415 : :
1416 [ + + ]: 3235 : if (!bms_is_member(listidx, *estimatedclauses))
1417 : : {
1418 : : /*
1419 : : * If it's a simple column reference, just extract the attnum. If
1420 : : * it's an expression, assign a negative attnum as if it was a
1421 : : * system attribute.
1422 : : */
1423 [ + + ]: 3200 : if (dependency_is_compatible_clause(clause, rel->relid, &attnum))
1424 : : {
1425 : 2740 : list_attnums[listidx] = attnum;
1426 : : }
1427 [ + + ]: 460 : else if (dependency_is_compatible_expression(clause, rel->relid,
1428 : : rel->statlist,
1429 : : &expr))
1430 : : {
1431 : : /* special attnum assigned to this expression */
1432 : 235 : attnum = InvalidAttrNumber;
1433 : :
1434 : : Assert(expr != NULL);
1435 : :
1436 : : /* If the expression is duplicate, use the same attnum. */
1437 [ + + ]: 395 : for (int i = 0; i < unique_exprs_cnt; i++)
1438 : : {
1439 [ - + ]: 160 : if (equal(unique_exprs[i], expr))
1440 : : {
1441 : : /* negative attribute number to expression */
1442 : 0 : attnum = -(i + 1);
1443 : 0 : break;
1444 : : }
1445 : : }
1446 : :
1447 : : /* not found in the list, so add it */
1448 [ + - ]: 235 : if (attnum == InvalidAttrNumber)
1449 : : {
1450 : 235 : unique_exprs[unique_exprs_cnt++] = expr;
1451 : :
1452 : : /* after incrementing the value, to get -1, -2, ... */
1453 : 235 : attnum = (-unique_exprs_cnt);
1454 : : }
1455 : :
1456 : : /* remember which attnum was assigned to this clause */
1457 : 235 : list_attnums[listidx] = attnum;
1458 : : }
1459 : : }
1460 : :
1461 : 3235 : listidx++;
1462 : : }
1463 : :
1464 : : Assert(listidx == list_length(clauses));
1465 : :
1466 : : /*
1467 : : * How much we need to offset the attnums? If there are no expressions,
1468 : : * then no offset is needed. Otherwise we need to offset enough for the
1469 : : * lowest value (-unique_exprs_cnt) to become 1.
1470 : : */
1471 [ + + ]: 1490 : if (unique_exprs_cnt > 0)
1472 : 110 : attnum_offset = (unique_exprs_cnt + 1);
1473 : : else
1474 : 1380 : attnum_offset = 0;
1475 : :
1476 : : /*
1477 : : * Now that we know how many expressions there are, we can offset the
1478 : : * values just enough to build the bitmapset.
1479 : : */
1480 [ + + ]: 4725 : for (int i = 0; i < list_length(clauses); i++)
1481 : : {
1482 : : AttrNumber attnum;
1483 : :
1484 : : /* ignore incompatible or already estimated clauses */
1485 [ + + ]: 3235 : if (list_attnums[i] == InvalidAttrNumber)
1486 : 260 : continue;
1487 : :
1488 : : /* make sure the attnum is in the expected range */
1489 : : Assert(list_attnums[i] >= (-unique_exprs_cnt));
1490 : : Assert(list_attnums[i] <= MaxHeapAttributeNumber);
1491 : :
1492 : : /* make sure the attnum is positive (valid AttrNumber) */
1493 : 2975 : attnum = list_attnums[i] + attnum_offset;
1494 : :
1495 : : /*
1496 : : * Either it's a regular attribute, or it's an expression, in which
1497 : : * case we must not have seen it before (expressions are unique).
1498 : : *
1499 : : * XXX Check whether it's a regular attribute has to be done using the
1500 : : * original attnum, while the second check has to use the value with
1501 : : * an offset.
1502 : : */
1503 : : Assert(AttrNumberIsForUserDefinedAttr(list_attnums[i]) ||
1504 : : !bms_is_member(attnum, clauses_attnums));
1505 : :
1506 : : /*
1507 : : * Remember the offset attnum, both for attributes and expressions.
1508 : : * We'll pass list_attnums to clauselist_apply_dependencies, which
1509 : : * uses it to identify clauses in a bitmap. We could also pass the
1510 : : * offset, but this is more convenient.
1511 : : */
1512 : 2975 : list_attnums[i] = attnum;
1513 : :
1514 : 2975 : clauses_attnums = bms_add_member(clauses_attnums, attnum);
1515 : : }
1516 : :
1517 : : /*
1518 : : * If there's not at least two distinct attnums and expressions, then
1519 : : * reject the whole list of clauses. We must return 1.0 so the calling
1520 : : * function's selectivity is unaffected.
1521 : : */
1522 [ + + ]: 1490 : if (bms_membership(clauses_attnums) != BMS_MULTIPLE)
1523 : : {
1524 : 160 : bms_free(clauses_attnums);
1525 : 160 : pfree(list_attnums);
1526 : 160 : return 1.0;
1527 : : }
1528 : :
1529 : : /*
1530 : : * Load all functional dependencies matching at least two parameters. We
1531 : : * can simply consider all dependencies at once, without having to search
1532 : : * for the best statistics object.
1533 : : *
1534 : : * To not waste cycles and memory, we deserialize dependencies only for
1535 : : * statistics that match at least two attributes. The array is allocated
1536 : : * with the assumption that all objects match - we could grow the array to
1537 : : * make it just the right size, but it's likely wasteful anyway thanks to
1538 : : * moving the freed chunks to freelists etc.
1539 : : */
1540 : 1330 : func_dependencies = palloc_array(MVDependencies *, list_length(rel->statlist));
1541 : 1330 : nfunc_dependencies = 0;
1542 : 1330 : total_ndeps = 0;
1543 : :
1544 [ + - + + : 2775 : foreach(l, rel->statlist)
+ + ]
1545 : : {
1546 : 1445 : StatisticExtInfo *stat = (StatisticExtInfo *) lfirst(l);
1547 : : int nmatched;
1548 : : int nexprs;
1549 : : int k;
1550 : : MVDependencies *deps;
1551 : :
1552 : : /* skip statistics that are not of the correct type */
1553 [ + + ]: 1445 : if (stat->kind != STATS_EXT_DEPENDENCIES)
1554 : 90 : continue;
1555 : :
1556 : : /* skip statistics with mismatching stxdinherit value */
1557 [ - + ]: 1355 : if (stat->inherit != rte->inh)
1558 : 0 : continue;
1559 : :
1560 : : /*
1561 : : * Count matching attributes - we have to undo the attnum offsets. The
1562 : : * input attribute numbers are not offset (expressions are not
1563 : : * included in stat->keys, so it's not necessary). But we need to
1564 : : * offset it before checking against clauses_attnums.
1565 : : */
1566 : 1355 : nmatched = 0;
1567 : 1355 : k = -1;
1568 [ + + ]: 5100 : while ((k = bms_next_member(stat->keys, k)) >= 0)
1569 : : {
1570 : 3745 : AttrNumber attnum = (AttrNumber) k;
1571 : :
1572 : : /* skip expressions */
1573 [ - + ]: 3745 : if (!AttrNumberIsForUserDefinedAttr(attnum))
1574 : 0 : continue;
1575 : :
1576 : : /* apply the same offset as above */
1577 : 3745 : attnum += attnum_offset;
1578 : :
1579 [ + + ]: 3745 : if (bms_is_member(attnum, clauses_attnums))
1580 : 2700 : nmatched++;
1581 : : }
1582 : :
1583 : : /* count matching expressions */
1584 : 1355 : nexprs = 0;
1585 [ + + ]: 1570 : for (int i = 0; i < unique_exprs_cnt; i++)
1586 : : {
1587 : : ListCell *lc;
1588 : :
1589 [ + - + + : 860 : foreach(lc, stat->exprs)
+ + ]
1590 : : {
1591 : 645 : Node *stat_expr = (Node *) lfirst(lc);
1592 : :
1593 : : /* try to match it */
1594 [ + + ]: 645 : if (equal(stat_expr, unique_exprs[i]))
1595 : 215 : nexprs++;
1596 : : }
1597 : : }
1598 : :
1599 : : /*
1600 : : * Skip objects matching fewer than two attributes/expressions from
1601 : : * clauses.
1602 : : */
1603 [ + + ]: 1355 : if (nmatched + nexprs < 2)
1604 : 15 : continue;
1605 : :
1606 : 1340 : deps = statext_dependencies_load(stat->statOid, rte->inh);
1607 : :
1608 : : /*
1609 : : * The expressions may be represented by different attnums in the
1610 : : * stats, we need to remap them to be consistent with the clauses.
1611 : : * That will make the later steps (e.g. picking the strongest item and
1612 : : * so on) much simpler and cheaper, because it won't need to care
1613 : : * about the offset at all.
1614 : : *
1615 : : * When we're at it, we can ignore dependencies that are not fully
1616 : : * matched by clauses (i.e. referencing attributes or expressions that
1617 : : * are not in the clauses).
1618 : : *
1619 : : * We have to do this for all statistics, as long as there are any
1620 : : * expressions - we need to shift the attnums in all dependencies.
1621 : : *
1622 : : * XXX Maybe we should do this always, because it also eliminates some
1623 : : * of the dependencies early. It might be cheaper than having to walk
1624 : : * the longer list in find_strongest_dependency later, especially as
1625 : : * we need to do that repeatedly?
1626 : : *
1627 : : * XXX We have to do this even when there are no expressions in
1628 : : * clauses, otherwise find_strongest_dependency may fail for stats
1629 : : * with expressions (due to lookup of negative value in bitmap). So we
1630 : : * need to at least filter out those dependencies. Maybe we could do
1631 : : * it in a cheaper way (if there are no expr clauses, we can just
1632 : : * discard all negative attnums without any lookups).
1633 : : */
1634 [ + + - + ]: 1340 : if (unique_exprs_cnt > 0 || stat->exprs != NIL)
1635 : : {
1636 : 90 : uint32 ndeps = 0;
1637 : :
1638 [ + + ]: 540 : for (uint32 i = 0; i < deps->ndeps; i++)
1639 : : {
1640 : 450 : bool skip = false;
1641 : 450 : MVDependency *dep = deps->deps[i];
1642 : :
1643 [ + + ]: 1255 : for (int j = 0; j < dep->nattributes; j++)
1644 : : {
1645 : : int idx;
1646 : : Node *expr;
1647 : 1025 : AttrNumber unique_attnum = InvalidAttrNumber;
1648 : : AttrNumber attnum;
1649 : :
1650 : : /* undo the per-statistics offset */
1651 : 1025 : attnum = dep->attributes[j];
1652 : :
1653 : : /*
1654 : : * For regular attributes we can simply check if it
1655 : : * matches any clause. If there's no matching clause, we
1656 : : * can just ignore it. We need to offset the attnum
1657 : : * though.
1658 : : */
1659 [ - + ]: 1025 : if (AttrNumberIsForUserDefinedAttr(attnum))
1660 : : {
1661 : 0 : dep->attributes[j] = attnum + attnum_offset;
1662 : :
1663 [ # # ]: 0 : if (!bms_is_member(dep->attributes[j], clauses_attnums))
1664 : : {
1665 : 0 : skip = true;
1666 : 0 : break;
1667 : : }
1668 : :
1669 : 0 : continue;
1670 : : }
1671 : :
1672 : : /*
1673 : : * the attnum should be a valid system attnum (-1, -2,
1674 : : * ...)
1675 : : */
1676 : : Assert(AttributeNumberIsValid(attnum));
1677 : :
1678 : : /*
1679 : : * For expressions, we need to do two translations. First
1680 : : * we have to translate the negative attnum to index in
1681 : : * the list of expressions (in the statistics object).
1682 : : * Then we need to see if there's a matching clause. The
1683 : : * index of the unique expression determines the attnum
1684 : : * (and we offset it).
1685 : : */
1686 : 1025 : idx = -(1 + attnum);
1687 : :
1688 : : /* Is the expression index is valid? */
1689 : : Assert((idx >= 0) && (idx < list_length(stat->exprs)));
1690 : :
1691 : 1025 : expr = (Node *) list_nth(stat->exprs, idx);
1692 : :
1693 : : /* try to find the expression in the unique list */
1694 [ + + ]: 2050 : for (int m = 0; m < unique_exprs_cnt; m++)
1695 : : {
1696 : : /*
1697 : : * found a matching unique expression, use the attnum
1698 : : * (derived from index of the unique expression)
1699 : : */
1700 [ + + ]: 1830 : if (equal(unique_exprs[m], expr))
1701 : : {
1702 : 805 : unique_attnum = -(m + 1) + attnum_offset;
1703 : 805 : break;
1704 : : }
1705 : : }
1706 : :
1707 : : /*
1708 : : * Found no matching expression, so we can simply skip
1709 : : * this dependency, because there's no chance it will be
1710 : : * fully covered.
1711 : : */
1712 [ + + ]: 1025 : if (unique_attnum == InvalidAttrNumber)
1713 : : {
1714 : 220 : skip = true;
1715 : 220 : break;
1716 : : }
1717 : :
1718 : : /* otherwise remap it to the new attnum */
1719 : 805 : dep->attributes[j] = unique_attnum;
1720 : : }
1721 : :
1722 : : /* if found a matching dependency, keep it */
1723 [ + + ]: 450 : if (!skip)
1724 : : {
1725 : : /* maybe we've skipped something earlier, so move it */
1726 [ - + ]: 230 : if (ndeps != i)
1727 : 0 : deps->deps[ndeps] = deps->deps[i];
1728 : :
1729 : 230 : ndeps++;
1730 : : }
1731 : : }
1732 : :
1733 : 90 : deps->ndeps = ndeps;
1734 : : }
1735 : :
1736 : : /*
1737 : : * It's possible we've removed all dependencies, in which case we
1738 : : * don't bother adding it to the list.
1739 : : */
1740 [ + - ]: 1340 : if (deps->ndeps > 0)
1741 : : {
1742 : 1340 : func_dependencies[nfunc_dependencies] = deps;
1743 : 1340 : total_ndeps += deps->ndeps;
1744 : 1340 : nfunc_dependencies++;
1745 : : }
1746 : : }
1747 : :
1748 : : /* if no matching stats could be found then we've nothing to do */
1749 [ - + ]: 1330 : if (nfunc_dependencies == 0)
1750 : : {
1751 : 0 : pfree(func_dependencies);
1752 : 0 : bms_free(clauses_attnums);
1753 : 0 : pfree(list_attnums);
1754 : 0 : pfree(unique_exprs);
1755 : 0 : return 1.0;
1756 : : }
1757 : :
1758 : : /*
1759 : : * Work out which dependencies we can apply, starting with the
1760 : : * widest/strongest ones, and proceeding to smaller/weaker ones.
1761 : : */
1762 : 1330 : dependencies = palloc_array(MVDependency *, total_ndeps);
1763 : 1330 : ndependencies = 0;
1764 : :
1765 : : while (true)
1766 : 1575 : {
1767 : : MVDependency *dependency;
1768 : : AttrNumber attnum;
1769 : :
1770 : : /* the widest/strongest dependency, fully matched by clauses */
1771 : 2905 : dependency = find_strongest_dependency(func_dependencies,
1772 : : nfunc_dependencies,
1773 : : clauses_attnums);
1774 [ + + ]: 2905 : if (!dependency)
1775 : 1330 : break;
1776 : :
1777 : 1575 : dependencies[ndependencies++] = dependency;
1778 : :
1779 : : /* Ignore dependencies using this implied attribute in later loops */
1780 : 1575 : attnum = dependency->attributes[dependency->nattributes - 1];
1781 : 1575 : clauses_attnums = bms_del_member(clauses_attnums, attnum);
1782 : : }
1783 : :
1784 : : /*
1785 : : * If we found applicable dependencies, use them to estimate all
1786 : : * compatible clauses on attributes that they refer to.
1787 : : */
1788 [ + - ]: 1330 : if (ndependencies != 0)
1789 : 1330 : s1 = clauselist_apply_dependencies(root, clauses, varRelid, jointype,
1790 : : sjinfo, dependencies, ndependencies,
1791 : : list_attnums, estimatedclauses);
1792 : :
1793 : : /* free deserialized functional dependencies (and then the array) */
1794 [ + + ]: 2670 : for (int i = 0; i < nfunc_dependencies; i++)
1795 : 1340 : pfree(func_dependencies[i]);
1796 : :
1797 : 1330 : pfree(dependencies);
1798 : 1330 : pfree(func_dependencies);
1799 : 1330 : bms_free(clauses_attnums);
1800 : 1330 : pfree(list_attnums);
1801 : 1330 : pfree(unique_exprs);
1802 : :
1803 : 1330 : return s1;
1804 : : }
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