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
|
--
-- UNION (also INTERSECT, EXCEPT)
--
-- Simple UNION constructs
SELECT 1 AS two UNION SELECT 2;
two
-----
1
2
(2 rows)
SELECT 1 AS one UNION SELECT 1;
one
-----
1
(1 row)
SELECT 1 AS two UNION ALL SELECT 2;
two
-----
1
2
(2 rows)
SELECT 1 AS two UNION ALL SELECT 1;
two
-----
1
1
(2 rows)
SELECT 1 AS three UNION SELECT 2 UNION SELECT 3;
three
-------
1
2
3
(3 rows)
SELECT 1 AS two UNION SELECT 2 UNION SELECT 2;
two
-----
1
2
(2 rows)
SELECT 1 AS three UNION SELECT 2 UNION ALL SELECT 2;
three
-------
1
2
2
(3 rows)
SELECT 1.1 AS two UNION SELECT 2.2;
two
-----
1.1
2.2
(2 rows)
-- Mixed types
SELECT 1.1 AS two UNION SELECT 2;
two
-----
1.1
2
(2 rows)
SELECT 1 AS two UNION SELECT 2.2;
two
-----
1
2.2
(2 rows)
SELECT 1 AS one UNION SELECT 1.0::float8;
one
-----
1
(1 row)
SELECT 1.1 AS two UNION ALL SELECT 2;
two
-----
1.1
2
(2 rows)
SELECT 1.0::float8 AS two UNION ALL SELECT 1;
two
-----
1
1
(2 rows)
SELECT 1.1 AS three UNION SELECT 2 UNION SELECT 3;
three
-------
1.1
2
3
(3 rows)
SELECT 1.1::float8 AS two UNION SELECT 2 UNION SELECT 2.0::float8 ORDER BY 1;
two
-----
1.1
2
(2 rows)
SELECT 1.1 AS three UNION SELECT 2 UNION ALL SELECT 2;
three
-------
1.1
2
2
(3 rows)
SELECT 1.1 AS two UNION (SELECT 2 UNION ALL SELECT 2);
two
-----
1.1
2
(2 rows)
--
-- Try testing from tables...
--
SELECT f1 AS five FROM FLOAT8_TBL
UNION
SELECT f1 FROM FLOAT8_TBL
ORDER BY 1;
five
-----------------------
-1.2345678901234e+200
-1004.3
-34.84
-1.2345678901234e-200
0
(5 rows)
SELECT f1 AS ten FROM FLOAT8_TBL
UNION ALL
SELECT f1 FROM FLOAT8_TBL;
ten
-----------------------
0
-34.84
-1004.3
-1.2345678901234e+200
-1.2345678901234e-200
0
-34.84
-1004.3
-1.2345678901234e+200
-1.2345678901234e-200
(10 rows)
SELECT f1 AS nine FROM FLOAT8_TBL
UNION
SELECT f1 FROM INT4_TBL
ORDER BY 1;
nine
-----------------------
-1.2345678901234e+200
-2147483647
-123456
-1004.3
-34.84
-1.2345678901234e-200
0
123456
2147483647
(9 rows)
SELECT f1 AS ten FROM FLOAT8_TBL
UNION ALL
SELECT f1 FROM INT4_TBL;
ten
-----------------------
0
-34.84
-1004.3
-1.2345678901234e+200
-1.2345678901234e-200
0
123456
-123456
2147483647
-2147483647
(10 rows)
SELECT f1 AS five FROM FLOAT8_TBL
WHERE f1 BETWEEN -1e6 AND 1e6
UNION
SELECT f1 FROM INT4_TBL
WHERE f1 BETWEEN 0 AND 1000000;
five
-----------------------
-1004.3
-34.84
-1.2345678901234e-200
0
123456
(5 rows)
SELECT CAST(f1 AS char(4)) AS three FROM VARCHAR_TBL
UNION
SELECT f1 FROM CHAR_TBL
ORDER BY 1;
three
-------
a
ab
abcd
(3 rows)
SELECT f1 AS three FROM VARCHAR_TBL
UNION
SELECT CAST(f1 AS varchar) FROM CHAR_TBL
ORDER BY 1;
three
-------
a
ab
abcd
(3 rows)
SELECT f1 AS eight FROM VARCHAR_TBL
UNION ALL
SELECT f1 FROM CHAR_TBL;
eight
-------
a
ab
abcd
abcd
a
ab
abcd
abcd
(8 rows)
SELECT f1 AS five FROM TEXT_TBL
UNION
SELECT f1 FROM VARCHAR_TBL
UNION
SELECT TRIM(TRAILING FROM f1) FROM CHAR_TBL
ORDER BY 1;
five
-------------------
a
ab
abcd
doh!
hi de ho neighbor
(5 rows)
--
-- INTERSECT and EXCEPT
--
SELECT q2 FROM int8_tbl INTERSECT SELECT q1 FROM int8_tbl;
q2
------------------
4567890123456789
123
(2 rows)
SELECT q2 FROM int8_tbl INTERSECT ALL SELECT q1 FROM int8_tbl;
q2
------------------
4567890123456789
4567890123456789
123
(3 rows)
SELECT q2 FROM int8_tbl EXCEPT SELECT q1 FROM int8_tbl ORDER BY 1;
q2
-------------------
-4567890123456789
456
(2 rows)
SELECT q2 FROM int8_tbl EXCEPT ALL SELECT q1 FROM int8_tbl ORDER BY 1;
q2
-------------------
-4567890123456789
456
(2 rows)
SELECT q2 FROM int8_tbl EXCEPT ALL SELECT DISTINCT q1 FROM int8_tbl ORDER BY 1;
q2
-------------------
-4567890123456789
456
4567890123456789
(3 rows)
SELECT q1 FROM int8_tbl EXCEPT SELECT q2 FROM int8_tbl;
q1
----
(0 rows)
SELECT q1 FROM int8_tbl EXCEPT ALL SELECT q2 FROM int8_tbl;
q1
------------------
4567890123456789
123
(2 rows)
SELECT q1 FROM int8_tbl EXCEPT ALL SELECT DISTINCT q2 FROM int8_tbl;
q1
------------------
4567890123456789
4567890123456789
123
(3 rows)
SELECT q1 FROM int8_tbl EXCEPT ALL SELECT q1 FROM int8_tbl FOR NO KEY UPDATE;
ERROR: FOR NO KEY UPDATE is not allowed with UNION/INTERSECT/EXCEPT
--
-- Mixed types
--
SELECT f1 FROM float8_tbl INTERSECT SELECT f1 FROM int4_tbl;
f1
----
0
(1 row)
SELECT f1 FROM float8_tbl EXCEPT SELECT f1 FROM int4_tbl ORDER BY 1;
f1
-----------------------
-1.2345678901234e+200
-1004.3
-34.84
-1.2345678901234e-200
(4 rows)
--
-- Operator precedence and (((((extra))))) parentheses
--
SELECT q1 FROM int8_tbl INTERSECT SELECT q2 FROM int8_tbl UNION ALL SELECT q2 FROM int8_tbl;
q1
-------------------
4567890123456789
123
456
4567890123456789
123
4567890123456789
-4567890123456789
(7 rows)
SELECT q1 FROM int8_tbl INTERSECT (((SELECT q2 FROM int8_tbl UNION ALL SELECT q2 FROM int8_tbl)));
q1
------------------
4567890123456789
123
(2 rows)
(((SELECT q1 FROM int8_tbl INTERSECT SELECT q2 FROM int8_tbl))) UNION ALL SELECT q2 FROM int8_tbl;
q1
-------------------
4567890123456789
123
456
4567890123456789
123
4567890123456789
-4567890123456789
(7 rows)
SELECT q1 FROM int8_tbl UNION ALL SELECT q2 FROM int8_tbl EXCEPT SELECT q1 FROM int8_tbl ORDER BY 1;
q1
-------------------
-4567890123456789
456
(2 rows)
SELECT q1 FROM int8_tbl UNION ALL (((SELECT q2 FROM int8_tbl EXCEPT SELECT q1 FROM int8_tbl ORDER BY 1)));
q1
-------------------
123
123
4567890123456789
4567890123456789
4567890123456789
-4567890123456789
456
(7 rows)
(((SELECT q1 FROM int8_tbl UNION ALL SELECT q2 FROM int8_tbl))) EXCEPT SELECT q1 FROM int8_tbl ORDER BY 1;
q1
-------------------
-4567890123456789
456
(2 rows)
--
-- Subqueries with ORDER BY & LIMIT clauses
--
-- In this syntax, ORDER BY/LIMIT apply to the result of the EXCEPT
SELECT q1,q2 FROM int8_tbl EXCEPT SELECT q2,q1 FROM int8_tbl
ORDER BY q2,q1;
q1 | q2
------------------+-------------------
4567890123456789 | -4567890123456789
123 | 456
(2 rows)
-- This should fail, because q2 isn't a name of an EXCEPT output column
SELECT q1 FROM int8_tbl EXCEPT SELECT q2 FROM int8_tbl ORDER BY q2 LIMIT 1;
ERROR: column "q2" does not exist
LINE 1: ... int8_tbl EXCEPT SELECT q2 FROM int8_tbl ORDER BY q2 LIMIT 1...
^
HINT: There is a column named "q2" in table "*SELECT* 2", but it cannot be referenced from this part of the query.
-- But this should work:
SELECT q1 FROM int8_tbl EXCEPT (((SELECT q2 FROM int8_tbl ORDER BY q2 LIMIT 1)));
q1
------------------
4567890123456789
123
(2 rows)
--
-- New syntaxes (7.1) permit new tests
--
(((((select * from int8_tbl)))));
q1 | q2
------------------+-------------------
123 | 456
123 | 4567890123456789
4567890123456789 | 123
4567890123456789 | 4567890123456789
4567890123456789 | -4567890123456789
(5 rows)
--
-- Check handling of a case with unknown constants. We don't guarantee
-- an undecorated constant will work in all cases, but historically this
-- usage has worked, so test we don't break it.
--
SELECT a.f1 FROM (SELECT 'test' AS f1 FROM varchar_tbl) a
UNION
SELECT b.f1 FROM (SELECT f1 FROM varchar_tbl) b
ORDER BY 1;
f1
------
a
ab
abcd
test
(4 rows)
-- This should fail, but it should produce an error cursor
SELECT '3.4'::numeric UNION SELECT 'foo';
ERROR: invalid input syntax for type numeric: "foo"
LINE 1: SELECT '3.4'::numeric UNION SELECT 'foo';
^
--
-- Test that expression-index constraints can be pushed down through
-- UNION or UNION ALL
--
CREATE TEMP TABLE t1 (a text, b text);
CREATE INDEX t1_ab_idx on t1 ((a || b));
CREATE TEMP TABLE t2 (ab text primary key);
INSERT INTO t1 VALUES ('a', 'b'), ('x', 'y');
INSERT INTO t2 VALUES ('ab'), ('xy');
set enable_seqscan = off;
set enable_indexscan = on;
set enable_bitmapscan = off;
explain (costs off)
SELECT * FROM
(SELECT a || b AS ab FROM t1
UNION ALL
SELECT * FROM t2) t
WHERE ab = 'ab';
QUERY PLAN
---------------------------------------------
Append
-> Index Scan using t1_ab_idx on t1
Index Cond: ((a || b) = 'ab'::text)
-> Index Only Scan using t2_pkey on t2
Index Cond: (ab = 'ab'::text)
(5 rows)
explain (costs off)
SELECT * FROM
(SELECT a || b AS ab FROM t1
UNION
SELECT * FROM t2) t
WHERE ab = 'ab';
QUERY PLAN
---------------------------------------------------
HashAggregate
Group Key: ((t1.a || t1.b))
-> Append
-> Index Scan using t1_ab_idx on t1
Index Cond: ((a || b) = 'ab'::text)
-> Index Only Scan using t2_pkey on t2
Index Cond: (ab = 'ab'::text)
(7 rows)
--
-- Test that ORDER BY for UNION ALL can be pushed down to inheritance
-- children.
--
CREATE TEMP TABLE t1c (b text, a text);
ALTER TABLE t1c INHERIT t1;
CREATE TEMP TABLE t2c (primary key (ab)) INHERITS (t2);
INSERT INTO t1c VALUES ('v', 'w'), ('c', 'd'), ('m', 'n'), ('e', 'f');
INSERT INTO t2c VALUES ('vw'), ('cd'), ('mn'), ('ef');
CREATE INDEX t1c_ab_idx on t1c ((a || b));
set enable_seqscan = on;
set enable_indexonlyscan = off;
explain (costs off)
SELECT * FROM
(SELECT a || b AS ab FROM t1
UNION ALL
SELECT ab FROM t2) t
ORDER BY 1 LIMIT 8;
QUERY PLAN
------------------------------------------------
Limit
-> Merge Append
Sort Key: ((t1.a || t1.b))
-> Index Scan using t1_ab_idx on t1
-> Index Scan using t1c_ab_idx on t1c
-> Index Scan using t2_pkey on t2
-> Index Scan using t2c_pkey on t2c
(7 rows)
SELECT * FROM
(SELECT a || b AS ab FROM t1
UNION ALL
SELECT ab FROM t2) t
ORDER BY 1 LIMIT 8;
ab
----
ab
ab
cd
dc
ef
fe
mn
nm
(8 rows)
reset enable_seqscan;
reset enable_indexscan;
reset enable_bitmapscan;
-- This simpler variant of the above test has been observed to fail differently
create table events (event_id int primary key);
create table other_events (event_id int primary key);
create table events_child () inherits (events);
explain (costs off)
select event_id
from (select event_id from events
union all
select event_id from other_events) ss
order by event_id;
QUERY PLAN
----------------------------------------------------------
Merge Append
Sort Key: events.event_id
-> Index Scan using events_pkey on events
-> Sort
Sort Key: events_child.event_id
-> Seq Scan on events_child
-> Index Scan using other_events_pkey on other_events
(7 rows)
drop table events_child, events, other_events;
reset enable_indexonlyscan;
-- Test constraint exclusion of UNION ALL subqueries
explain (costs off)
SELECT * FROM
(SELECT 1 AS t, * FROM tenk1 a
UNION ALL
SELECT 2 AS t, * FROM tenk1 b) c
WHERE t = 2;
QUERY PLAN
---------------------------
Append
-> Seq Scan on tenk1 b
(2 rows)
-- Test that we push quals into UNION sub-selects only when it's safe
explain (costs off)
SELECT * FROM
(SELECT 1 AS t, 2 AS x
UNION
SELECT 2 AS t, 4 AS x) ss
WHERE x < 4;
QUERY PLAN
--------------------------------------------
Unique
-> Sort
Sort Key: (1), (2)
-> Append
-> Result
-> Result
One-Time Filter: false
(7 rows)
SELECT * FROM
(SELECT 1 AS t, 2 AS x
UNION
SELECT 2 AS t, 4 AS x) ss
WHERE x < 4;
t | x
---+---
1 | 2
(1 row)
explain (costs off)
SELECT * FROM
(SELECT 1 AS t, generate_series(1,10) AS x
UNION
SELECT 2 AS t, 4 AS x) ss
WHERE x < 4
ORDER BY x;
QUERY PLAN
--------------------------------------------------------
Sort
Sort Key: ss.x
-> Subquery Scan on ss
Filter: (ss.x < 4)
-> HashAggregate
Group Key: (1), (generate_series(1, 10))
-> Append
-> Result
-> Result
(9 rows)
SELECT * FROM
(SELECT 1 AS t, generate_series(1,10) AS x
UNION
SELECT 2 AS t, 4 AS x) ss
WHERE x < 4
ORDER BY x;
t | x
---+---
1 | 1
1 | 2
1 | 3
(3 rows)
explain (costs off)
SELECT * FROM
(SELECT 1 AS t, (random()*3)::int AS x
UNION
SELECT 2 AS t, 4 AS x) ss
WHERE x > 3;
QUERY PLAN
------------------------------------------------------------------------------
Subquery Scan on ss
Filter: (ss.x > 3)
-> Unique
-> Sort
Sort Key: (1), (((random() * '3'::double precision))::integer)
-> Append
-> Result
-> Result
(8 rows)
SELECT * FROM
(SELECT 1 AS t, (random()*3)::int AS x
UNION
SELECT 2 AS t, 4 AS x) ss
WHERE x > 3;
t | x
---+---
2 | 4
(1 row)
-- Test proper handling of parameterized appendrel paths when the
-- potential join qual is expensive
create function expensivefunc(int) returns int
language plpgsql immutable strict cost 10000
as $$begin return $1; end$$;
create temp table t3 as select generate_series(-1000,1000) as x;
create index t3i on t3 (expensivefunc(x));
analyze t3;
explain (costs off)
select * from
(select * from t3 a union all select * from t3 b) ss
join int4_tbl on f1 = expensivefunc(x);
QUERY PLAN
------------------------------------------------------------
Nested Loop
-> Seq Scan on int4_tbl
-> Append
-> Index Scan using t3i on t3 a
Index Cond: (expensivefunc(x) = int4_tbl.f1)
-> Index Scan using t3i on t3 b
Index Cond: (expensivefunc(x) = int4_tbl.f1)
(7 rows)
select * from
(select * from t3 a union all select * from t3 b) ss
join int4_tbl on f1 = expensivefunc(x);
x | f1
---+----
0 | 0
0 | 0
(2 rows)
drop table t3;
drop function expensivefunc(int);
|