1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
|
/*-------------------------------------------------------------------------
*
* prepunion.c
* Routines to plan set-operation queries. The filename is a leftover
* from a time when only UNIONs were implemented.
*
* There are two code paths in the planner for set-operation queries.
* If a subquery consists entirely of simple UNION ALL operations, it
* is converted into an "append relation". Otherwise, it is handled
* by the general code in this module (plan_set_operations and its
* subroutines). There is some support code here for the append-relation
* case, but most of the heavy lifting for that is done elsewhere,
* notably in prepjointree.c and allpaths.c.
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/optimizer/prep/prepunion.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "catalog/partition.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/cost.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/planmain.h"
#include "optimizer/planner.h"
#include "optimizer/prep.h"
#include "optimizer/tlist.h"
#include "parser/parse_coerce.h"
#include "parser/parsetree.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/selfuncs.h"
#include "utils/syscache.h"
static RelOptInfo *recurse_set_operations(Node *setOp, PlannerInfo *root,
List *colTypes, List *colCollations,
bool junkOK,
int flag, List *refnames_tlist,
List **pTargetList,
double *pNumGroups);
static RelOptInfo *generate_recursion_path(SetOperationStmt *setOp,
PlannerInfo *root,
List *refnames_tlist,
List **pTargetList);
static RelOptInfo *generate_union_paths(SetOperationStmt *op, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList);
static RelOptInfo *generate_nonunion_paths(SetOperationStmt *op, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList);
static List *plan_union_children(PlannerInfo *root,
SetOperationStmt *top_union,
List *refnames_tlist,
List **tlist_list);
static Path *make_union_unique(SetOperationStmt *op, Path *path, List *tlist,
PlannerInfo *root);
static void postprocess_setop_rel(PlannerInfo *root, RelOptInfo *rel);
static bool choose_hashed_setop(PlannerInfo *root, List *groupClauses,
Path *input_path,
double dNumGroups, double dNumOutputRows,
const char *construct);
static List *generate_setop_tlist(List *colTypes, List *colCollations,
int flag,
Index varno,
bool hack_constants,
List *input_tlist,
List *refnames_tlist,
bool *trivial_tlist);
static List *generate_append_tlist(List *colTypes, List *colCollations,
bool flag,
List *input_tlists,
List *refnames_tlist);
static List *generate_setop_grouplist(SetOperationStmt *op, List *targetlist);
/*
* plan_set_operations
*
* Plans the queries for a tree of set operations (UNION/INTERSECT/EXCEPT)
*
* This routine only deals with the setOperations tree of the given query.
* Any top-level ORDER BY requested in root->parse->sortClause will be handled
* when we return to grouping_planner; likewise for LIMIT.
*
* What we return is an "upperrel" RelOptInfo containing at least one Path
* that implements the set-operation tree. In addition, root->processed_tlist
* receives a targetlist representing the output of the topmost setop node.
*/
RelOptInfo *
plan_set_operations(PlannerInfo *root)
{
Query *parse = root->parse;
SetOperationStmt *topop = castNode(SetOperationStmt, parse->setOperations);
Node *node;
RangeTblEntry *leftmostRTE;
Query *leftmostQuery;
RelOptInfo *setop_rel;
List *top_tlist;
Assert(topop);
/* check for unsupported stuff */
Assert(parse->jointree->fromlist == NIL);
Assert(parse->jointree->quals == NULL);
Assert(parse->groupClause == NIL);
Assert(parse->havingQual == NULL);
Assert(parse->windowClause == NIL);
Assert(parse->distinctClause == NIL);
/*
* In the outer query level, we won't have any true equivalences to deal
* with; but we do want to be able to make pathkeys, which will require
* single-member EquivalenceClasses. Indicate that EC merging is complete
* so that pathkeys.c won't complain.
*/
Assert(root->eq_classes == NIL);
root->ec_merging_done = true;
/*
* We'll need to build RelOptInfos for each of the leaf subqueries, which
* are RTE_SUBQUERY rangetable entries in this Query. Prepare the index
* arrays for those, and for AppendRelInfos in case they're needed.
*/
setup_simple_rel_arrays(root);
/*
* Find the leftmost component Query. We need to use its column names for
* all generated tlists (else SELECT INTO won't work right).
*/
node = topop->larg;
while (node && IsA(node, SetOperationStmt))
node = ((SetOperationStmt *) node)->larg;
Assert(node && IsA(node, RangeTblRef));
leftmostRTE = root->simple_rte_array[((RangeTblRef *) node)->rtindex];
leftmostQuery = leftmostRTE->subquery;
Assert(leftmostQuery != NULL);
/*
* If the topmost node is a recursive union, it needs special processing.
*/
if (root->hasRecursion)
{
setop_rel = generate_recursion_path(topop, root,
leftmostQuery->targetList,
&top_tlist);
}
else
{
/*
* Recurse on setOperations tree to generate paths for set ops. The
* final output paths should have just the column types shown as the
* output from the top-level node, plus possibly resjunk working
* columns (we can rely on upper-level nodes to deal with that).
*/
setop_rel = recurse_set_operations((Node *) topop, root,
topop->colTypes, topop->colCollations,
true, -1,
leftmostQuery->targetList,
&top_tlist,
NULL);
}
/* Must return the built tlist into root->processed_tlist. */
root->processed_tlist = top_tlist;
return setop_rel;
}
/*
* recurse_set_operations
* Recursively handle one step in a tree of set operations
*
* colTypes: OID list of set-op's result column datatypes
* colCollations: OID list of set-op's result column collations
* junkOK: if true, child resjunk columns may be left in the result
* flag: if >= 0, add a resjunk output column indicating value of flag
* refnames_tlist: targetlist to take column names from
*
* Returns a RelOptInfo for the subtree, as well as these output parameters:
* *pTargetList: receives the fully-fledged tlist for the subtree's top plan
* *pNumGroups: if not NULL, we estimate the number of distinct groups
* in the result, and store it there
*
* The pTargetList output parameter is mostly redundant with the pathtarget
* of the returned RelOptInfo, but for the moment we need it because much of
* the logic in this file depends on flag columns being marked resjunk.
* Pending a redesign of how that works, this is the easy way out.
*
* We don't have to care about typmods here: the only allowed difference
* between set-op input and output typmods is input is a specific typmod
* and output is -1, and that does not require a coercion.
*/
static RelOptInfo *
recurse_set_operations(Node *setOp, PlannerInfo *root,
List *colTypes, List *colCollations,
bool junkOK,
int flag, List *refnames_tlist,
List **pTargetList,
double *pNumGroups)
{
RelOptInfo *rel = NULL; /* keep compiler quiet */
/* Guard against stack overflow due to overly complex setop nests */
check_stack_depth();
if (IsA(setOp, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) setOp;
RangeTblEntry *rte = root->simple_rte_array[rtr->rtindex];
Query *subquery = rte->subquery;
PlannerInfo *subroot;
RelOptInfo *final_rel;
Path *subpath;
Path *path;
List *tlist;
bool trivial_tlist;
Assert(subquery != NULL);
/* Build a RelOptInfo for this leaf subquery. */
rel = build_simple_rel(root, rtr->rtindex, NULL);
/* plan_params should not be in use in current query level */
Assert(root->plan_params == NIL);
/* Generate a subroot and Paths for the subquery */
subroot = rel->subroot = subquery_planner(root->glob, subquery,
root,
false,
root->tuple_fraction);
/*
* It should not be possible for the primitive query to contain any
* cross-references to other primitive queries in the setop tree.
*/
if (root->plan_params)
elog(ERROR, "unexpected outer reference in set operation subquery");
/* Figure out the appropriate target list for this subquery. */
tlist = generate_setop_tlist(colTypes, colCollations,
flag,
rtr->rtindex,
true,
subroot->processed_tlist,
refnames_tlist,
&trivial_tlist);
rel->reltarget = create_pathtarget(root, tlist);
/* Return the fully-fledged tlist to caller, too */
*pTargetList = tlist;
/*
* Mark rel with estimated output rows, width, etc. Note that we have
* to do this before generating outer-query paths, else
* cost_subqueryscan is not happy.
*/
set_subquery_size_estimates(root, rel);
/*
* Since we may want to add a partial path to this relation, we must
* set its consider_parallel flag correctly.
*/
final_rel = fetch_upper_rel(subroot, UPPERREL_FINAL, NULL);
rel->consider_parallel = final_rel->consider_parallel;
/*
* For the moment, we consider only a single Path for the subquery.
* This should change soon (make it look more like
* set_subquery_pathlist).
*/
subpath = get_cheapest_fractional_path(final_rel,
root->tuple_fraction);
/*
* Stick a SubqueryScanPath atop that.
*
* We don't bother to determine the subquery's output ordering since
* it won't be reflected in the set-op result anyhow; so just label
* the SubqueryScanPath with nil pathkeys. (XXX that should change
* soon too, likely.)
*/
path = (Path *) create_subqueryscan_path(root, rel, subpath,
trivial_tlist,
NIL, NULL);
add_path(rel, path);
/*
* If we have a partial path for the child relation, we can use that
* to build a partial path for this relation. But there's no point in
* considering any path but the cheapest.
*/
if (rel->consider_parallel && bms_is_empty(rel->lateral_relids) &&
final_rel->partial_pathlist != NIL)
{
Path *partial_subpath;
Path *partial_path;
partial_subpath = linitial(final_rel->partial_pathlist);
partial_path = (Path *)
create_subqueryscan_path(root, rel, partial_subpath,
trivial_tlist,
NIL, NULL);
add_partial_path(rel, partial_path);
}
/*
* Estimate number of groups if caller wants it. If the subquery used
* grouping or aggregation, its output is probably mostly unique
* anyway; otherwise do statistical estimation.
*
* XXX you don't really want to know about this: we do the estimation
* using the subquery's original targetlist expressions, not the
* subroot->processed_tlist which might seem more appropriate. The
* reason is that if the subquery is itself a setop, it may return a
* processed_tlist containing "varno 0" Vars generated by
* generate_append_tlist, and those would confuse estimate_num_groups
* mightily. We ought to get rid of the "varno 0" hack, but that
* requires a redesign of the parsetree representation of setops, so
* that there can be an RTE corresponding to each setop's output.
*/
if (pNumGroups)
{
if (subquery->groupClause || subquery->groupingSets ||
subquery->distinctClause ||
subroot->hasHavingQual || subquery->hasAggs)
*pNumGroups = subpath->rows;
else
*pNumGroups = estimate_num_groups(subroot,
get_tlist_exprs(subquery->targetList, false),
subpath->rows,
NULL,
NULL);
}
}
else if (IsA(setOp, SetOperationStmt))
{
SetOperationStmt *op = (SetOperationStmt *) setOp;
/* UNIONs are much different from INTERSECT/EXCEPT */
if (op->op == SETOP_UNION)
rel = generate_union_paths(op, root,
refnames_tlist,
pTargetList);
else
rel = generate_nonunion_paths(op, root,
refnames_tlist,
pTargetList);
if (pNumGroups)
*pNumGroups = rel->rows;
/*
* If necessary, add a Result node to project the caller-requested
* output columns.
*
* XXX you don't really want to know about this: setrefs.c will apply
* fix_upper_expr() to the Result node's tlist. This would fail if the
* Vars generated by generate_setop_tlist() were not exactly equal()
* to the corresponding tlist entries of the subplan. However, since
* the subplan was generated by generate_union_paths() or
* generate_nonunion_paths(), and hence its tlist was generated by
* generate_append_tlist(), this will work. We just tell
* generate_setop_tlist() to use varno 0.
*/
if (flag >= 0 ||
!tlist_same_datatypes(*pTargetList, colTypes, junkOK) ||
!tlist_same_collations(*pTargetList, colCollations, junkOK))
{
PathTarget *target;
bool trivial_tlist;
ListCell *lc;
*pTargetList = generate_setop_tlist(colTypes, colCollations,
flag,
0,
false,
*pTargetList,
refnames_tlist,
&trivial_tlist);
target = create_pathtarget(root, *pTargetList);
/* Apply projection to each path */
foreach(lc, rel->pathlist)
{
Path *subpath = (Path *) lfirst(lc);
Path *path;
Assert(subpath->param_info == NULL);
path = apply_projection_to_path(root, subpath->parent,
subpath, target);
/* If we had to add a Result, path is different from subpath */
if (path != subpath)
lfirst(lc) = path;
}
/* Apply projection to each partial path */
foreach(lc, rel->partial_pathlist)
{
Path *subpath = (Path *) lfirst(lc);
Path *path;
Assert(subpath->param_info == NULL);
/* avoid apply_projection_to_path, in case of multiple refs */
path = (Path *) create_projection_path(root, subpath->parent,
subpath, target);
lfirst(lc) = path;
}
}
}
else
{
elog(ERROR, "unrecognized node type: %d",
(int) nodeTag(setOp));
*pTargetList = NIL;
}
postprocess_setop_rel(root, rel);
return rel;
}
/*
* Generate paths for a recursive UNION node
*/
static RelOptInfo *
generate_recursion_path(SetOperationStmt *setOp, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList)
{
RelOptInfo *result_rel;
Path *path;
RelOptInfo *lrel,
*rrel;
Path *lpath;
Path *rpath;
List *lpath_tlist;
List *rpath_tlist;
List *tlist;
List *groupList;
double dNumGroups;
/* Parser should have rejected other cases */
if (setOp->op != SETOP_UNION)
elog(ERROR, "only UNION queries can be recursive");
/* Worktable ID should be assigned */
Assert(root->wt_param_id >= 0);
/*
* Unlike a regular UNION node, process the left and right inputs
* separately without any intention of combining them into one Append.
*/
lrel = recurse_set_operations(setOp->larg, root,
setOp->colTypes, setOp->colCollations,
false, -1,
refnames_tlist,
&lpath_tlist,
NULL);
lpath = lrel->cheapest_total_path;
/* The right path will want to look at the left one ... */
root->non_recursive_path = lpath;
rrel = recurse_set_operations(setOp->rarg, root,
setOp->colTypes, setOp->colCollations,
false, -1,
refnames_tlist,
&rpath_tlist,
NULL);
rpath = rrel->cheapest_total_path;
root->non_recursive_path = NULL;
/*
* Generate tlist for RecursiveUnion path node --- same as in Append cases
*/
tlist = generate_append_tlist(setOp->colTypes, setOp->colCollations, false,
list_make2(lpath_tlist, rpath_tlist),
refnames_tlist);
*pTargetList = tlist;
/* Build result relation. */
result_rel = fetch_upper_rel(root, UPPERREL_SETOP,
bms_union(lrel->relids, rrel->relids));
result_rel->reltarget = create_pathtarget(root, tlist);
/*
* If UNION, identify the grouping operators
*/
if (setOp->all)
{
groupList = NIL;
dNumGroups = 0;
}
else
{
/* Identify the grouping semantics */
groupList = generate_setop_grouplist(setOp, tlist);
/* We only support hashing here */
if (!grouping_is_hashable(groupList))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("could not implement recursive UNION"),
errdetail("All column datatypes must be hashable.")));
/*
* For the moment, take the number of distinct groups as equal to the
* total input size, ie, the worst case.
*/
dNumGroups = lpath->rows + rpath->rows * 10;
}
/*
* And make the path node.
*/
path = (Path *) create_recursiveunion_path(root,
result_rel,
lpath,
rpath,
result_rel->reltarget,
groupList,
root->wt_param_id,
dNumGroups);
add_path(result_rel, path);
postprocess_setop_rel(root, result_rel);
return result_rel;
}
/*
* Generate paths for a UNION or UNION ALL node
*/
static RelOptInfo *
generate_union_paths(SetOperationStmt *op, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList)
{
Relids relids = NULL;
RelOptInfo *result_rel;
double save_fraction = root->tuple_fraction;
ListCell *lc;
List *pathlist = NIL;
List *partial_pathlist = NIL;
bool partial_paths_valid = true;
bool consider_parallel = true;
List *rellist;
List *tlist_list;
List *tlist;
Path *path;
/*
* If plain UNION, tell children to fetch all tuples.
*
* Note: in UNION ALL, we pass the top-level tuple_fraction unmodified to
* each arm of the UNION ALL. One could make a case for reducing the
* tuple fraction for later arms (discounting by the expected size of the
* earlier arms' results) but it seems not worth the trouble. The normal
* case where tuple_fraction isn't already zero is a LIMIT at top level,
* and passing it down as-is is usually enough to get the desired result
* of preferring fast-start plans.
*/
if (!op->all)
root->tuple_fraction = 0.0;
/*
* If any of my children are identical UNION nodes (same op, all-flag, and
* colTypes) then they can be merged into this node so that we generate
* only one Append and unique-ification for the lot. Recurse to find such
* nodes and compute their children's paths.
*/
rellist = plan_union_children(root, op, refnames_tlist, &tlist_list);
/*
* Generate tlist for Append plan node.
*
* The tlist for an Append plan isn't important as far as the Append is
* concerned, but we must make it look real anyway for the benefit of the
* next plan level up.
*/
tlist = generate_append_tlist(op->colTypes, op->colCollations, false,
tlist_list, refnames_tlist);
*pTargetList = tlist;
/* Build path lists and relid set. */
foreach(lc, rellist)
{
RelOptInfo *rel = lfirst(lc);
pathlist = lappend(pathlist, rel->cheapest_total_path);
if (consider_parallel)
{
if (!rel->consider_parallel)
{
consider_parallel = false;
partial_paths_valid = false;
}
else if (rel->partial_pathlist == NIL)
partial_paths_valid = false;
else
partial_pathlist = lappend(partial_pathlist,
linitial(rel->partial_pathlist));
}
relids = bms_union(relids, rel->relids);
}
/* Build result relation. */
result_rel = fetch_upper_rel(root, UPPERREL_SETOP, relids);
result_rel->reltarget = create_pathtarget(root, tlist);
result_rel->consider_parallel = consider_parallel;
/*
* Append the child results together.
*/
path = (Path *) create_append_path(root, result_rel, pathlist, NIL,
NIL, NULL, 0, false, -1);
/*
* For UNION ALL, we just need the Append path. For UNION, need to add
* node(s) to remove duplicates.
*/
if (!op->all)
path = make_union_unique(op, path, tlist, root);
add_path(result_rel, path);
/*
* Estimate number of groups. For now we just assume the output is unique
* --- this is certainly true for the UNION case, and we want worst-case
* estimates anyway.
*/
result_rel->rows = path->rows;
/*
* Now consider doing the same thing using the partial paths plus Append
* plus Gather.
*/
if (partial_paths_valid)
{
Path *ppath;
int parallel_workers = 0;
/* Find the highest number of workers requested for any subpath. */
foreach(lc, partial_pathlist)
{
Path *subpath = lfirst(lc);
parallel_workers = Max(parallel_workers,
subpath->parallel_workers);
}
Assert(parallel_workers > 0);
/*
* If the use of parallel append is permitted, always request at least
* log2(# of children) paths. We assume it can be useful to have
* extra workers in this case because they will be spread out across
* the children. The precise formula is just a guess; see
* add_paths_to_append_rel.
*/
if (enable_parallel_append)
{
parallel_workers = Max(parallel_workers,
pg_leftmost_one_pos32(list_length(partial_pathlist)) + 1);
parallel_workers = Min(parallel_workers,
max_parallel_workers_per_gather);
}
Assert(parallel_workers > 0);
ppath = (Path *)
create_append_path(root, result_rel, NIL, partial_pathlist,
NIL, NULL,
parallel_workers, enable_parallel_append,
-1);
ppath = (Path *)
create_gather_path(root, result_rel, ppath,
result_rel->reltarget, NULL, NULL);
if (!op->all)
ppath = make_union_unique(op, ppath, tlist, root);
add_path(result_rel, ppath);
}
/* Undo effects of possibly forcing tuple_fraction to 0 */
root->tuple_fraction = save_fraction;
return result_rel;
}
/*
* Generate paths for an INTERSECT, INTERSECT ALL, EXCEPT, or EXCEPT ALL node
*/
static RelOptInfo *
generate_nonunion_paths(SetOperationStmt *op, PlannerInfo *root,
List *refnames_tlist,
List **pTargetList)
{
RelOptInfo *result_rel;
RelOptInfo *lrel,
*rrel;
double save_fraction = root->tuple_fraction;
Path *lpath,
*rpath,
*path;
List *lpath_tlist,
*rpath_tlist,
*tlist_list,
*tlist,
*groupList,
*pathlist;
double dLeftGroups,
dRightGroups,
dNumGroups,
dNumOutputRows;
bool use_hash;
SetOpCmd cmd;
int firstFlag;
/*
* Tell children to fetch all tuples.
*/
root->tuple_fraction = 0.0;
/* Recurse on children, ensuring their outputs are marked */
lrel = recurse_set_operations(op->larg, root,
op->colTypes, op->colCollations,
false, 0,
refnames_tlist,
&lpath_tlist,
&dLeftGroups);
lpath = lrel->cheapest_total_path;
rrel = recurse_set_operations(op->rarg, root,
op->colTypes, op->colCollations,
false, 1,
refnames_tlist,
&rpath_tlist,
&dRightGroups);
rpath = rrel->cheapest_total_path;
/* Undo effects of forcing tuple_fraction to 0 */
root->tuple_fraction = save_fraction;
/*
* For EXCEPT, we must put the left input first. For INTERSECT, either
* order should give the same results, and we prefer to put the smaller
* input first in order to minimize the size of the hash table in the
* hashing case. "Smaller" means the one with the fewer groups.
*/
if (op->op == SETOP_EXCEPT || dLeftGroups <= dRightGroups)
{
pathlist = list_make2(lpath, rpath);
tlist_list = list_make2(lpath_tlist, rpath_tlist);
firstFlag = 0;
}
else
{
pathlist = list_make2(rpath, lpath);
tlist_list = list_make2(rpath_tlist, lpath_tlist);
firstFlag = 1;
}
/*
* Generate tlist for Append plan node.
*
* The tlist for an Append plan isn't important as far as the Append is
* concerned, but we must make it look real anyway for the benefit of the
* next plan level up. In fact, it has to be real enough that the flag
* column is shown as a variable not a constant, else setrefs.c will get
* confused.
*/
tlist = generate_append_tlist(op->colTypes, op->colCollations, true,
tlist_list, refnames_tlist);
*pTargetList = tlist;
/* Build result relation. */
result_rel = fetch_upper_rel(root, UPPERREL_SETOP,
bms_union(lrel->relids, rrel->relids));
result_rel->reltarget = create_pathtarget(root, tlist);
/*
* Append the child results together.
*/
path = (Path *) create_append_path(root, result_rel, pathlist, NIL,
NIL, NULL, 0, false, -1);
/* Identify the grouping semantics */
groupList = generate_setop_grouplist(op, tlist);
/*
* Estimate number of distinct groups that we'll need hashtable entries
* for; this is the size of the left-hand input for EXCEPT, or the smaller
* input for INTERSECT. Also estimate the number of eventual output rows.
* In non-ALL cases, we estimate each group produces one output row; in
* ALL cases use the relevant relation size. These are worst-case
* estimates, of course, but we need to be conservative.
*/
if (op->op == SETOP_EXCEPT)
{
dNumGroups = dLeftGroups;
dNumOutputRows = op->all ? lpath->rows : dNumGroups;
}
else
{
dNumGroups = Min(dLeftGroups, dRightGroups);
dNumOutputRows = op->all ? Min(lpath->rows, rpath->rows) : dNumGroups;
}
/*
* Decide whether to hash or sort, and add a sort node if needed.
*/
use_hash = choose_hashed_setop(root, groupList, path,
dNumGroups, dNumOutputRows,
(op->op == SETOP_INTERSECT) ? "INTERSECT" : "EXCEPT");
if (groupList && !use_hash)
path = (Path *) create_sort_path(root,
result_rel,
path,
make_pathkeys_for_sortclauses(root,
groupList,
tlist),
-1.0);
/*
* Finally, add a SetOp path node to generate the correct output.
*/
switch (op->op)
{
case SETOP_INTERSECT:
cmd = op->all ? SETOPCMD_INTERSECT_ALL : SETOPCMD_INTERSECT;
break;
case SETOP_EXCEPT:
cmd = op->all ? SETOPCMD_EXCEPT_ALL : SETOPCMD_EXCEPT;
break;
default:
elog(ERROR, "unrecognized set op: %d", (int) op->op);
cmd = SETOPCMD_INTERSECT; /* keep compiler quiet */
break;
}
path = (Path *) create_setop_path(root,
result_rel,
path,
cmd,
use_hash ? SETOP_HASHED : SETOP_SORTED,
groupList,
list_length(op->colTypes) + 1,
use_hash ? firstFlag : -1,
dNumGroups,
dNumOutputRows);
result_rel->rows = path->rows;
add_path(result_rel, path);
return result_rel;
}
/*
* Pull up children of a UNION node that are identically-propertied UNIONs.
*
* NOTE: we can also pull a UNION ALL up into a UNION, since the distinct
* output rows will be lost anyway.
*
* NOTE: currently, we ignore collations while determining if a child has
* the same properties. This is semantically sound only so long as all
* collations have the same notion of equality. It is valid from an
* implementation standpoint because we don't care about the ordering of
* a UNION child's result: UNION ALL results are always unordered, and
* generate_union_paths will force a fresh sort if the top level is a UNION.
*/
static List *
plan_union_children(PlannerInfo *root,
SetOperationStmt *top_union,
List *refnames_tlist,
List **tlist_list)
{
List *pending_rels = list_make1(top_union);
List *result = NIL;
List *child_tlist;
*tlist_list = NIL;
while (pending_rels != NIL)
{
Node *setOp = linitial(pending_rels);
pending_rels = list_delete_first(pending_rels);
if (IsA(setOp, SetOperationStmt))
{
SetOperationStmt *op = (SetOperationStmt *) setOp;
if (op->op == top_union->op &&
(op->all == top_union->all || op->all) &&
equal(op->colTypes, top_union->colTypes))
{
/* Same UNION, so fold children into parent */
pending_rels = lcons(op->rarg, pending_rels);
pending_rels = lcons(op->larg, pending_rels);
continue;
}
}
/*
* Not same, so plan this child separately.
*
* Note we disallow any resjunk columns in child results. This is
* necessary since the Append node that implements the union won't do
* any projection, and upper levels will get confused if some of our
* output tuples have junk and some don't. This case only arises when
* we have an EXCEPT or INTERSECT as child, else there won't be
* resjunk anyway.
*/
result = lappend(result, recurse_set_operations(setOp, root,
top_union->colTypes,
top_union->colCollations,
false, -1,
refnames_tlist,
&child_tlist,
NULL));
*tlist_list = lappend(*tlist_list, child_tlist);
}
return result;
}
/*
* Add nodes to the given path tree to unique-ify the result of a UNION.
*/
static Path *
make_union_unique(SetOperationStmt *op, Path *path, List *tlist,
PlannerInfo *root)
{
RelOptInfo *result_rel = fetch_upper_rel(root, UPPERREL_SETOP, NULL);
List *groupList;
double dNumGroups;
/* Identify the grouping semantics */
groupList = generate_setop_grouplist(op, tlist);
/*
* XXX for the moment, take the number of distinct groups as equal to the
* total input size, ie, the worst case. This is too conservative, but
* it's not clear how to get a decent estimate of the true size. One
* should note as well the propensity of novices to write UNION rather
* than UNION ALL even when they don't expect any duplicates...
*/
dNumGroups = path->rows;
/* Decide whether to hash or sort */
if (choose_hashed_setop(root, groupList, path,
dNumGroups, dNumGroups,
"UNION"))
{
/* Hashed aggregate plan --- no sort needed */
path = (Path *) create_agg_path(root,
result_rel,
path,
create_pathtarget(root, tlist),
AGG_HASHED,
AGGSPLIT_SIMPLE,
groupList,
NIL,
NULL,
dNumGroups);
}
else
{
/* Sort and Unique */
if (groupList)
path = (Path *)
create_sort_path(root,
result_rel,
path,
make_pathkeys_for_sortclauses(root,
groupList,
tlist),
-1.0);
path = (Path *) create_upper_unique_path(root,
result_rel,
path,
list_length(path->pathkeys),
dNumGroups);
}
return path;
}
/*
* postprocess_setop_rel - perform steps required after adding paths
*/
static void
postprocess_setop_rel(PlannerInfo *root, RelOptInfo *rel)
{
/*
* We don't currently worry about allowing FDWs to contribute paths to
* this relation, but give extensions a chance.
*/
if (create_upper_paths_hook)
(*create_upper_paths_hook) (root, UPPERREL_SETOP,
NULL, rel, NULL);
/* Select cheapest path */
set_cheapest(rel);
}
/*
* choose_hashed_setop - should we use hashing for a set operation?
*/
static bool
choose_hashed_setop(PlannerInfo *root, List *groupClauses,
Path *input_path,
double dNumGroups, double dNumOutputRows,
const char *construct)
{
int numGroupCols = list_length(groupClauses);
Size hash_mem_limit = get_hash_memory_limit();
bool can_sort;
bool can_hash;
Size hashentrysize;
Path hashed_p;
Path sorted_p;
double tuple_fraction;
/* Check whether the operators support sorting or hashing */
can_sort = grouping_is_sortable(groupClauses);
can_hash = grouping_is_hashable(groupClauses);
if (can_hash && can_sort)
{
/* we have a meaningful choice to make, continue ... */
}
else if (can_hash)
return true;
else if (can_sort)
return false;
else
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
/* translator: %s is UNION, INTERSECT, or EXCEPT */
errmsg("could not implement %s", construct),
errdetail("Some of the datatypes only support hashing, while others only support sorting.")));
/* Prefer sorting when enable_hashagg is off */
if (!enable_hashagg)
return false;
/*
* Don't do it if it doesn't look like the hashtable will fit into
* hash_mem.
*/
hashentrysize = MAXALIGN(input_path->pathtarget->width) + MAXALIGN(SizeofMinimalTupleHeader);
if (hashentrysize * dNumGroups > hash_mem_limit)
return false;
/*
* See if the estimated cost is no more than doing it the other way.
*
* We need to consider input_plan + hashagg versus input_plan + sort +
* group. Note that the actual result plan might involve a SetOp or
* Unique node, not Agg or Group, but the cost estimates for Agg and Group
* should be close enough for our purposes here.
*
* These path variables are dummies that just hold cost fields; we don't
* make actual Paths for these steps.
*/
cost_agg(&hashed_p, root, AGG_HASHED, NULL,
numGroupCols, dNumGroups,
NIL,
input_path->startup_cost, input_path->total_cost,
input_path->rows, input_path->pathtarget->width);
/*
* Now for the sorted case. Note that the input is *always* unsorted,
* since it was made by appending unrelated sub-relations together.
*/
sorted_p.startup_cost = input_path->startup_cost;
sorted_p.total_cost = input_path->total_cost;
/* XXX cost_sort doesn't actually look at pathkeys, so just pass NIL */
cost_sort(&sorted_p, root, NIL, sorted_p.total_cost,
input_path->rows, input_path->pathtarget->width,
0.0, work_mem, -1.0);
cost_group(&sorted_p, root, numGroupCols, dNumGroups,
NIL,
sorted_p.startup_cost, sorted_p.total_cost,
input_path->rows);
/*
* Now make the decision using the top-level tuple fraction. First we
* have to convert an absolute count (LIMIT) into fractional form.
*/
tuple_fraction = root->tuple_fraction;
if (tuple_fraction >= 1.0)
tuple_fraction /= dNumOutputRows;
if (compare_fractional_path_costs(&hashed_p, &sorted_p,
tuple_fraction) < 0)
{
/* Hashed is cheaper, so use it */
return true;
}
return false;
}
/*
* Generate targetlist for a set-operation plan node
*
* colTypes: OID list of set-op's result column datatypes
* colCollations: OID list of set-op's result column collations
* flag: -1 if no flag column needed, 0 or 1 to create a const flag column
* varno: varno to use in generated Vars
* hack_constants: true to copy up constants (see comments in code)
* input_tlist: targetlist of this node's input node
* refnames_tlist: targetlist to take column names from
* trivial_tlist: output parameter, set to true if targetlist is trivial
*/
static List *
generate_setop_tlist(List *colTypes, List *colCollations,
int flag,
Index varno,
bool hack_constants,
List *input_tlist,
List *refnames_tlist,
bool *trivial_tlist)
{
List *tlist = NIL;
int resno = 1;
ListCell *ctlc,
*cclc,
*itlc,
*rtlc;
TargetEntry *tle;
Node *expr;
*trivial_tlist = true; /* until proven differently */
forfour(ctlc, colTypes, cclc, colCollations,
itlc, input_tlist, rtlc, refnames_tlist)
{
Oid colType = lfirst_oid(ctlc);
Oid colColl = lfirst_oid(cclc);
TargetEntry *inputtle = (TargetEntry *) lfirst(itlc);
TargetEntry *reftle = (TargetEntry *) lfirst(rtlc);
Assert(inputtle->resno == resno);
Assert(reftle->resno == resno);
Assert(!inputtle->resjunk);
Assert(!reftle->resjunk);
/*
* Generate columns referencing input columns and having appropriate
* data types and column names. Insert datatype coercions where
* necessary.
*
* HACK: constants in the input's targetlist are copied up as-is
* rather than being referenced as subquery outputs. This is mainly
* to ensure that when we try to coerce them to the output column's
* datatype, the right things happen for UNKNOWN constants. But do
* this only at the first level of subquery-scan plans; we don't want
* phony constants appearing in the output tlists of upper-level
* nodes!
*
* Note that copying a constant doesn't in itself require us to mark
* the tlist nontrivial; see trivial_subqueryscan() in setrefs.c.
*/
if (hack_constants && inputtle->expr && IsA(inputtle->expr, Const))
expr = (Node *) inputtle->expr;
else
expr = (Node *) makeVar(varno,
inputtle->resno,
exprType((Node *) inputtle->expr),
exprTypmod((Node *) inputtle->expr),
exprCollation((Node *) inputtle->expr),
0);
if (exprType(expr) != colType)
{
/*
* Note: it's not really cool to be applying coerce_to_common_type
* here; one notable point is that assign_expr_collations never
* gets run on any generated nodes. For the moment that's not a
* problem because we force the correct exposed collation below.
* It would likely be best to make the parser generate the correct
* output tlist for every set-op to begin with, though.
*/
expr = coerce_to_common_type(NULL, /* no UNKNOWNs here */
expr,
colType,
"UNION/INTERSECT/EXCEPT");
*trivial_tlist = false; /* the coercion makes it not trivial */
}
/*
* Ensure the tlist entry's exposed collation matches the set-op. This
* is necessary because plan_set_operations() reports the result
* ordering as a list of SortGroupClauses, which don't carry collation
* themselves but just refer to tlist entries. If we don't show the
* right collation then planner.c might do the wrong thing in
* higher-level queries.
*
* Note we use RelabelType, not CollateExpr, since this expression
* will reach the executor without any further processing.
*/
if (exprCollation(expr) != colColl)
{
expr = applyRelabelType(expr,
exprType(expr), exprTypmod(expr), colColl,
COERCE_IMPLICIT_CAST, -1, false);
*trivial_tlist = false; /* the relabel makes it not trivial */
}
tle = makeTargetEntry((Expr *) expr,
(AttrNumber) resno++,
pstrdup(reftle->resname),
false);
/*
* By convention, all non-resjunk columns in a setop tree have
* ressortgroupref equal to their resno. In some cases the ref isn't
* needed, but this is a cleaner way than modifying the tlist later.
*/
tle->ressortgroupref = tle->resno;
tlist = lappend(tlist, tle);
}
if (flag >= 0)
{
/* Add a resjunk flag column */
/* flag value is the given constant */
expr = (Node *) makeConst(INT4OID,
-1,
InvalidOid,
sizeof(int32),
Int32GetDatum(flag),
false,
true);
tle = makeTargetEntry((Expr *) expr,
(AttrNumber) resno++,
pstrdup("flag"),
true);
tlist = lappend(tlist, tle);
*trivial_tlist = false; /* the extra entry makes it not trivial */
}
return tlist;
}
/*
* Generate targetlist for a set-operation Append node
*
* colTypes: OID list of set-op's result column datatypes
* colCollations: OID list of set-op's result column collations
* flag: true to create a flag column copied up from subplans
* input_tlists: list of tlists for sub-plans of the Append
* refnames_tlist: targetlist to take column names from
*
* The entries in the Append's targetlist should always be simple Vars;
* we just have to make sure they have the right datatypes/typmods/collations.
* The Vars are always generated with varno 0.
*
* XXX a problem with the varno-zero approach is that set_pathtarget_cost_width
* cannot figure out a realistic width for the tlist we make here. But we
* ought to refactor this code to produce a PathTarget directly, anyway.
*/
static List *
generate_append_tlist(List *colTypes, List *colCollations,
bool flag,
List *input_tlists,
List *refnames_tlist)
{
List *tlist = NIL;
int resno = 1;
ListCell *curColType;
ListCell *curColCollation;
ListCell *ref_tl_item;
int colindex;
TargetEntry *tle;
Node *expr;
ListCell *tlistl;
int32 *colTypmods;
/*
* First extract typmods to use.
*
* If the inputs all agree on type and typmod of a particular column, use
* that typmod; else use -1.
*/
colTypmods = (int32 *) palloc(list_length(colTypes) * sizeof(int32));
foreach(tlistl, input_tlists)
{
List *subtlist = (List *) lfirst(tlistl);
ListCell *subtlistl;
curColType = list_head(colTypes);
colindex = 0;
foreach(subtlistl, subtlist)
{
TargetEntry *subtle = (TargetEntry *) lfirst(subtlistl);
if (subtle->resjunk)
continue;
Assert(curColType != NULL);
if (exprType((Node *) subtle->expr) == lfirst_oid(curColType))
{
/* If first subplan, copy the typmod; else compare */
int32 subtypmod = exprTypmod((Node *) subtle->expr);
if (tlistl == list_head(input_tlists))
colTypmods[colindex] = subtypmod;
else if (subtypmod != colTypmods[colindex])
colTypmods[colindex] = -1;
}
else
{
/* types disagree, so force typmod to -1 */
colTypmods[colindex] = -1;
}
curColType = lnext(colTypes, curColType);
colindex++;
}
Assert(curColType == NULL);
}
/*
* Now we can build the tlist for the Append.
*/
colindex = 0;
forthree(curColType, colTypes, curColCollation, colCollations,
ref_tl_item, refnames_tlist)
{
Oid colType = lfirst_oid(curColType);
int32 colTypmod = colTypmods[colindex++];
Oid colColl = lfirst_oid(curColCollation);
TargetEntry *reftle = (TargetEntry *) lfirst(ref_tl_item);
Assert(reftle->resno == resno);
Assert(!reftle->resjunk);
expr = (Node *) makeVar(0,
resno,
colType,
colTypmod,
colColl,
0);
tle = makeTargetEntry((Expr *) expr,
(AttrNumber) resno++,
pstrdup(reftle->resname),
false);
/*
* By convention, all non-resjunk columns in a setop tree have
* ressortgroupref equal to their resno. In some cases the ref isn't
* needed, but this is a cleaner way than modifying the tlist later.
*/
tle->ressortgroupref = tle->resno;
tlist = lappend(tlist, tle);
}
if (flag)
{
/* Add a resjunk flag column */
/* flag value is shown as copied up from subplan */
expr = (Node *) makeVar(0,
resno,
INT4OID,
-1,
InvalidOid,
0);
tle = makeTargetEntry((Expr *) expr,
(AttrNumber) resno++,
pstrdup("flag"),
true);
tlist = lappend(tlist, tle);
}
pfree(colTypmods);
return tlist;
}
/*
* generate_setop_grouplist
* Build a SortGroupClause list defining the sort/grouping properties
* of the setop's output columns.
*
* Parse analysis already determined the properties and built a suitable
* list, except that the entries do not have sortgrouprefs set because
* the parser output representation doesn't include a tlist for each
* setop. So what we need to do here is copy that list and install
* proper sortgrouprefs into it (copying those from the targetlist).
*/
static List *
generate_setop_grouplist(SetOperationStmt *op, List *targetlist)
{
List *grouplist = copyObject(op->groupClauses);
ListCell *lg;
ListCell *lt;
lg = list_head(grouplist);
foreach(lt, targetlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(lt);
SortGroupClause *sgc;
if (tle->resjunk)
{
/* resjunk columns should not have sortgrouprefs */
Assert(tle->ressortgroupref == 0);
continue; /* ignore resjunk columns */
}
/* non-resjunk columns should have sortgroupref = resno */
Assert(tle->ressortgroupref == tle->resno);
/* non-resjunk columns should have grouping clauses */
Assert(lg != NULL);
sgc = (SortGroupClause *) lfirst(lg);
lg = lnext(grouplist, lg);
Assert(sgc->tleSortGroupRef == 0);
sgc->tleSortGroupRef = tle->ressortgroupref;
}
Assert(lg == NULL);
return grouplist;
}
|