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|
-- only use parallelism when explicitly intending to do so
SET max_parallel_maintenance_workers = 0;
SET max_parallel_workers = 0;
-- A table with contents that, when sorted, triggers abbreviated
-- key aborts. One easy way to achieve that is to use uuids that all
-- have the same prefix, as abbreviated keys for uuids just use the
-- first sizeof(Datum) bytes.
CREATE TEMP TABLE abbrev_abort_uuids (
id serial not null,
abort_increasing uuid,
abort_decreasing uuid,
noabort_increasing uuid,
noabort_decreasing uuid);
INSERT INTO abbrev_abort_uuids (abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing)
SELECT
('00000000-0000-0000-0000-'||to_char(g.i, '000000000000FM'))::uuid abort_increasing,
('00000000-0000-0000-0000-'||to_char(20000 - g.i, '000000000000FM'))::uuid abort_decreasing,
(to_char(g.i % 10009, '00000000FM')||'-0000-0000-0000-'||to_char(g.i, '000000000000FM'))::uuid noabort_increasing,
(to_char(((20000 - g.i) % 10009), '00000000FM')||'-0000-0000-0000-'||to_char(20000 - g.i, '000000000000FM'))::uuid noabort_decreasing
FROM generate_series(0, 20000, 1) g(i);
-- and a few NULLs
INSERT INTO abbrev_abort_uuids(id) VALUES(0);
INSERT INTO abbrev_abort_uuids DEFAULT VALUES;
INSERT INTO abbrev_abort_uuids DEFAULT VALUES;
-- add just a few duplicates
INSERT INTO abbrev_abort_uuids (abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing)
SELECT abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
FROM abbrev_abort_uuids
WHERE (id < 10 OR id > 19990) AND id % 3 = 0 AND abort_increasing is not null;
----
-- Check sort node uses of tuplesort wrt. abbreviated keys
----
-- plain sort triggering abbreviated abort
SELECT abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_increasing OFFSET 20000 - 4;
abort_increasing | abort_decreasing
--------------------------------------+--------------------------------------
00000000-0000-0000-0000-000000019992 | 00000000-0000-0000-0000-000000000008
00000000-0000-0000-0000-000000019993 | 00000000-0000-0000-0000-000000000007
00000000-0000-0000-0000-000000019994 | 00000000-0000-0000-0000-000000000006
00000000-0000-0000-0000-000000019994 | 00000000-0000-0000-0000-000000000006
00000000-0000-0000-0000-000000019995 | 00000000-0000-0000-0000-000000000005
00000000-0000-0000-0000-000000019996 | 00000000-0000-0000-0000-000000000004
00000000-0000-0000-0000-000000019997 | 00000000-0000-0000-0000-000000000003
00000000-0000-0000-0000-000000019997 | 00000000-0000-0000-0000-000000000003
00000000-0000-0000-0000-000000019998 | 00000000-0000-0000-0000-000000000002
00000000-0000-0000-0000-000000019999 | 00000000-0000-0000-0000-000000000001
00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
|
|
|
(15 rows)
SELECT abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_decreasing NULLS FIRST OFFSET 20000 - 4;
abort_increasing | abort_decreasing
--------------------------------------+--------------------------------------
00000000-0000-0000-0000-000000000011 | 00000000-0000-0000-0000-000000019989
00000000-0000-0000-0000-000000000010 | 00000000-0000-0000-0000-000000019990
00000000-0000-0000-0000-000000000009 | 00000000-0000-0000-0000-000000019991
00000000-0000-0000-0000-000000000008 | 00000000-0000-0000-0000-000000019992
00000000-0000-0000-0000-000000000008 | 00000000-0000-0000-0000-000000019992
00000000-0000-0000-0000-000000000007 | 00000000-0000-0000-0000-000000019993
00000000-0000-0000-0000-000000000006 | 00000000-0000-0000-0000-000000019994
00000000-0000-0000-0000-000000000005 | 00000000-0000-0000-0000-000000019995
00000000-0000-0000-0000-000000000005 | 00000000-0000-0000-0000-000000019995
00000000-0000-0000-0000-000000000004 | 00000000-0000-0000-0000-000000019996
00000000-0000-0000-0000-000000000003 | 00000000-0000-0000-0000-000000019997
00000000-0000-0000-0000-000000000002 | 00000000-0000-0000-0000-000000019998
00000000-0000-0000-0000-000000000002 | 00000000-0000-0000-0000-000000019998
00000000-0000-0000-0000-000000000001 | 00000000-0000-0000-0000-000000019999
00000000-0000-0000-0000-000000000000 | 00000000-0000-0000-0000-000000020000
(15 rows)
-- plain sort not triggering abbreviated abort
SELECT noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_increasing OFFSET 20000 - 4;
noabort_increasing | noabort_decreasing
--------------------------------------+--------------------------------------
00009997-0000-0000-0000-000000009997 | 00010003-0000-0000-0000-000000010003
00009998-0000-0000-0000-000000009998 | 00010002-0000-0000-0000-000000010002
00009999-0000-0000-0000-000000009999 | 00010001-0000-0000-0000-000000010001
00010000-0000-0000-0000-000000010000 | 00010000-0000-0000-0000-000000010000
00010001-0000-0000-0000-000000010001 | 00009999-0000-0000-0000-000000009999
00010002-0000-0000-0000-000000010002 | 00009998-0000-0000-0000-000000009998
00010003-0000-0000-0000-000000010003 | 00009997-0000-0000-0000-000000009997
00010004-0000-0000-0000-000000010004 | 00009996-0000-0000-0000-000000009996
00010005-0000-0000-0000-000000010005 | 00009995-0000-0000-0000-000000009995
00010006-0000-0000-0000-000000010006 | 00009994-0000-0000-0000-000000009994
00010007-0000-0000-0000-000000010007 | 00009993-0000-0000-0000-000000009993
00010008-0000-0000-0000-000000010008 | 00009992-0000-0000-0000-000000009992
|
|
|
(15 rows)
SELECT noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing NULLS FIRST OFFSET 20000 - 4;
noabort_increasing | noabort_decreasing
--------------------------------------+--------------------------------------
00010006-0000-0000-0000-000000010006 | 00009994-0000-0000-0000-000000009994
00010005-0000-0000-0000-000000010005 | 00009995-0000-0000-0000-000000009995
00010004-0000-0000-0000-000000010004 | 00009996-0000-0000-0000-000000009996
00010003-0000-0000-0000-000000010003 | 00009997-0000-0000-0000-000000009997
00010002-0000-0000-0000-000000010002 | 00009998-0000-0000-0000-000000009998
00010001-0000-0000-0000-000000010001 | 00009999-0000-0000-0000-000000009999
00010000-0000-0000-0000-000000010000 | 00010000-0000-0000-0000-000000010000
00009999-0000-0000-0000-000000009999 | 00010001-0000-0000-0000-000000010001
00009998-0000-0000-0000-000000009998 | 00010002-0000-0000-0000-000000010002
00009997-0000-0000-0000-000000009997 | 00010003-0000-0000-0000-000000010003
00009996-0000-0000-0000-000000009996 | 00010004-0000-0000-0000-000000010004
00009995-0000-0000-0000-000000009995 | 00010005-0000-0000-0000-000000010005
00009994-0000-0000-0000-000000009994 | 00010006-0000-0000-0000-000000010006
00009993-0000-0000-0000-000000009993 | 00010007-0000-0000-0000-000000010007
00009992-0000-0000-0000-000000009992 | 00010008-0000-0000-0000-000000010008
(15 rows)
-- bounded sort (disables abbreviated keys)
SELECT abort_increasing, noabort_increasing FROM abbrev_abort_uuids ORDER BY abort_increasing LIMIT 5;
abort_increasing | noabort_increasing
--------------------------------------+--------------------------------------
00000000-0000-0000-0000-000000000000 | 00000000-0000-0000-0000-000000000000
00000000-0000-0000-0000-000000000001 | 00000001-0000-0000-0000-000000000001
00000000-0000-0000-0000-000000000002 | 00000002-0000-0000-0000-000000000002
00000000-0000-0000-0000-000000000002 | 00000002-0000-0000-0000-000000000002
00000000-0000-0000-0000-000000000003 | 00000003-0000-0000-0000-000000000003
(5 rows)
SELECT abort_increasing, noabort_increasing FROM abbrev_abort_uuids ORDER BY noabort_increasing NULLS FIRST LIMIT 5;
abort_increasing | noabort_increasing
--------------------------------------+--------------------------------------
|
|
|
00000000-0000-0000-0000-000000000000 | 00000000-0000-0000-0000-000000000000
00000000-0000-0000-0000-000000010009 | 00000000-0000-0000-0000-000000010009
(5 rows)
----
-- Check index creation uses of tuplesort wrt. abbreviated keys
----
-- index creation using abbreviated keys successfully
CREATE INDEX abbrev_abort_uuids__noabort_increasing_idx ON abbrev_abort_uuids (noabort_increasing);
CREATE INDEX abbrev_abort_uuids__noabort_decreasing_idx ON abbrev_abort_uuids (noabort_decreasing);
-- verify
EXPLAIN (COSTS OFF)
SELECT id, noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_increasing LIMIT 5;
QUERY PLAN
-----------------------------------------------------------------------------------------
Limit
-> Index Scan using abbrev_abort_uuids__noabort_increasing_idx on abbrev_abort_uuids
(2 rows)
SELECT id, noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_increasing LIMIT 5;
id | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------
1 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000
10010 | 00000000-0000-0000-0000-000000010009 | 00009991-0000-0000-0000-000000009991
2 | 00000001-0000-0000-0000-000000000001 | 00009990-0000-0000-0000-000000019999
10011 | 00000001-0000-0000-0000-000000010010 | 00009990-0000-0000-0000-000000009990
3 | 00000002-0000-0000-0000-000000000002 | 00009989-0000-0000-0000-000000019998
(5 rows)
EXPLAIN (COSTS OFF)
SELECT id, noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing LIMIT 5;
QUERY PLAN
-----------------------------------------------------------------------------------------
Limit
-> Index Scan using abbrev_abort_uuids__noabort_decreasing_idx on abbrev_abort_uuids
(2 rows)
SELECT id, noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing LIMIT 5;
id | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------
20001 | 00009991-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
20010 | 00009991-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
9992 | 00009991-0000-0000-0000-000000009991 | 00000000-0000-0000-0000-000000010009
20000 | 00009990-0000-0000-0000-000000019999 | 00000001-0000-0000-0000-000000000001
9991 | 00009990-0000-0000-0000-000000009990 | 00000001-0000-0000-0000-000000010010
(5 rows)
-- index creation using abbreviated keys, hitting abort
CREATE INDEX abbrev_abort_uuids__abort_increasing_idx ON abbrev_abort_uuids (abort_increasing);
CREATE INDEX abbrev_abort_uuids__abort_decreasing_idx ON abbrev_abort_uuids (abort_decreasing);
-- verify
EXPLAIN (COSTS OFF)
SELECT id, abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_increasing LIMIT 5;
QUERY PLAN
---------------------------------------------------------------------------------------
Limit
-> Index Scan using abbrev_abort_uuids__abort_increasing_idx on abbrev_abort_uuids
(2 rows)
SELECT id, abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_increasing LIMIT 5;
id | abort_increasing | abort_decreasing
-------+--------------------------------------+--------------------------------------
1 | 00000000-0000-0000-0000-000000000000 | 00000000-0000-0000-0000-000000020000
2 | 00000000-0000-0000-0000-000000000001 | 00000000-0000-0000-0000-000000019999
3 | 00000000-0000-0000-0000-000000000002 | 00000000-0000-0000-0000-000000019998
20004 | 00000000-0000-0000-0000-000000000002 | 00000000-0000-0000-0000-000000019998
4 | 00000000-0000-0000-0000-000000000003 | 00000000-0000-0000-0000-000000019997
(5 rows)
EXPLAIN (COSTS OFF)
SELECT id, abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_decreasing LIMIT 5;
QUERY PLAN
---------------------------------------------------------------------------------------
Limit
-> Index Scan using abbrev_abort_uuids__abort_decreasing_idx on abbrev_abort_uuids
(2 rows)
SELECT id, abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_decreasing LIMIT 5;
id | abort_increasing | abort_decreasing
-------+--------------------------------------+--------------------------------------
20001 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
20010 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
20000 | 00000000-0000-0000-0000-000000019999 | 00000000-0000-0000-0000-000000000001
19999 | 00000000-0000-0000-0000-000000019998 | 00000000-0000-0000-0000-000000000002
19998 | 00000000-0000-0000-0000-000000019997 | 00000000-0000-0000-0000-000000000003
(5 rows)
----
-- Check CLUSTER uses of tuplesort wrt. abbreviated keys
----
-- when aborting, increasing order
BEGIN;
SET LOCAL enable_indexscan = false;
CLUSTER abbrev_abort_uuids USING abbrev_abort_uuids__abort_increasing_idx;
-- head
SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
FROM abbrev_abort_uuids
ORDER BY ctid LIMIT 5;
id | abort_increasing | abort_decreasing | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------+--------------------------------------+--------------------------------------
1 | 00000000-0000-0000-0000-000000000000 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000
2 | 00000000-0000-0000-0000-000000000001 | 00000000-0000-0000-0000-000000019999 | 00000001-0000-0000-0000-000000000001 | 00009990-0000-0000-0000-000000019999
3 | 00000000-0000-0000-0000-000000000002 | 00000000-0000-0000-0000-000000019998 | 00000002-0000-0000-0000-000000000002 | 00009989-0000-0000-0000-000000019998
20004 | 00000000-0000-0000-0000-000000000002 | 00000000-0000-0000-0000-000000019998 | 00000002-0000-0000-0000-000000000002 | 00009989-0000-0000-0000-000000019998
4 | 00000000-0000-0000-0000-000000000003 | 00000000-0000-0000-0000-000000019997 | 00000003-0000-0000-0000-000000000003 | 00009988-0000-0000-0000-000000019997
(5 rows)
-- tail
SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
FROM abbrev_abort_uuids
ORDER BY ctid DESC LIMIT 5;
id | abort_increasing | abort_decreasing | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------+--------------------------------------+--------------------------------------
0 | | | |
20002 | | | |
20003 | | | |
20001 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
20010 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
(5 rows)
ROLLBACK;
-- when aborting, decreasing order
BEGIN;
SET LOCAL enable_indexscan = false;
CLUSTER abbrev_abort_uuids USING abbrev_abort_uuids__abort_decreasing_idx;
-- head
SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
FROM abbrev_abort_uuids
ORDER BY ctid LIMIT 5;
id | abort_increasing | abort_decreasing | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------+--------------------------------------+--------------------------------------
20010 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
20001 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
20000 | 00000000-0000-0000-0000-000000019999 | 00000000-0000-0000-0000-000000000001 | 00009990-0000-0000-0000-000000019999 | 00000001-0000-0000-0000-000000000001
19999 | 00000000-0000-0000-0000-000000019998 | 00000000-0000-0000-0000-000000000002 | 00009989-0000-0000-0000-000000019998 | 00000002-0000-0000-0000-000000000002
20009 | 00000000-0000-0000-0000-000000019997 | 00000000-0000-0000-0000-000000000003 | 00009988-0000-0000-0000-000000019997 | 00000003-0000-0000-0000-000000000003
(5 rows)
-- tail
SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
FROM abbrev_abort_uuids
ORDER BY ctid DESC LIMIT 5;
id | abort_increasing | abort_decreasing | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------+--------------------------------------+--------------------------------------
0 | | | |
20002 | | | |
20003 | | | |
1 | 00000000-0000-0000-0000-000000000000 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000
2 | 00000000-0000-0000-0000-000000000001 | 00000000-0000-0000-0000-000000019999 | 00000001-0000-0000-0000-000000000001 | 00009990-0000-0000-0000-000000019999
(5 rows)
ROLLBACK;
-- when not aborting, increasing order
BEGIN;
SET LOCAL enable_indexscan = false;
CLUSTER abbrev_abort_uuids USING abbrev_abort_uuids__noabort_increasing_idx;
-- head
SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
FROM abbrev_abort_uuids
ORDER BY ctid LIMIT 5;
id | abort_increasing | abort_decreasing | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------+--------------------------------------+--------------------------------------
1 | 00000000-0000-0000-0000-000000000000 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000
10010 | 00000000-0000-0000-0000-000000010009 | 00000000-0000-0000-0000-000000009991 | 00000000-0000-0000-0000-000000010009 | 00009991-0000-0000-0000-000000009991
2 | 00000000-0000-0000-0000-000000000001 | 00000000-0000-0000-0000-000000019999 | 00000001-0000-0000-0000-000000000001 | 00009990-0000-0000-0000-000000019999
10011 | 00000000-0000-0000-0000-000000010010 | 00000000-0000-0000-0000-000000009990 | 00000001-0000-0000-0000-000000010010 | 00009990-0000-0000-0000-000000009990
20004 | 00000000-0000-0000-0000-000000000002 | 00000000-0000-0000-0000-000000019998 | 00000002-0000-0000-0000-000000000002 | 00009989-0000-0000-0000-000000019998
(5 rows)
-- tail
SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
FROM abbrev_abort_uuids
ORDER BY ctid DESC LIMIT 5;
id | abort_increasing | abort_decreasing | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------+--------------------------------------+--------------------------------------
0 | | | |
20002 | | | |
20003 | | | |
10009 | 00000000-0000-0000-0000-000000010008 | 00000000-0000-0000-0000-000000009992 | 00010008-0000-0000-0000-000000010008 | 00009992-0000-0000-0000-000000009992
10008 | 00000000-0000-0000-0000-000000010007 | 00000000-0000-0000-0000-000000009993 | 00010007-0000-0000-0000-000000010007 | 00009993-0000-0000-0000-000000009993
(5 rows)
ROLLBACK;
-- when no aborting, decreasing order
BEGIN;
SET LOCAL enable_indexscan = false;
CLUSTER abbrev_abort_uuids USING abbrev_abort_uuids__noabort_decreasing_idx;
-- head
SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
FROM abbrev_abort_uuids
ORDER BY ctid LIMIT 5;
id | abort_increasing | abort_decreasing | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------+--------------------------------------+--------------------------------------
20010 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
20001 | 00000000-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000 | 00009991-0000-0000-0000-000000020000 | 00000000-0000-0000-0000-000000000000
9992 | 00000000-0000-0000-0000-000000009991 | 00000000-0000-0000-0000-000000010009 | 00009991-0000-0000-0000-000000009991 | 00000000-0000-0000-0000-000000010009
20000 | 00000000-0000-0000-0000-000000019999 | 00000000-0000-0000-0000-000000000001 | 00009990-0000-0000-0000-000000019999 | 00000001-0000-0000-0000-000000000001
9991 | 00000000-0000-0000-0000-000000009990 | 00000000-0000-0000-0000-000000010010 | 00009990-0000-0000-0000-000000009990 | 00000001-0000-0000-0000-000000010010
(5 rows)
-- tail
SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
FROM abbrev_abort_uuids
ORDER BY ctid DESC LIMIT 5;
id | abort_increasing | abort_decreasing | noabort_increasing | noabort_decreasing
-------+--------------------------------------+--------------------------------------+--------------------------------------+--------------------------------------
0 | | | |
20003 | | | |
20002 | | | |
9993 | 00000000-0000-0000-0000-000000009992 | 00000000-0000-0000-0000-000000010008 | 00009992-0000-0000-0000-000000009992 | 00010008-0000-0000-0000-000000010008
9994 | 00000000-0000-0000-0000-000000009993 | 00000000-0000-0000-0000-000000010007 | 00009993-0000-0000-0000-000000009993 | 00010007-0000-0000-0000-000000010007
(5 rows)
ROLLBACK;
----
-- test sorting of large datums VALUES
----
-- Ensure the order is correct and values look intact
SELECT LEFT(a,10),b FROM
(VALUES(REPEAT('a', 512 * 1024),1),(REPEAT('b', 512 * 1024),2)) v(a,b)
ORDER BY v.a DESC;
left | b
------------+---
bbbbbbbbbb | 2
aaaaaaaaaa | 1
(2 rows)
----
-- test forward and backward scans for in-memory and disk based tuplesort
----
-- in-memory
BEGIN;
SET LOCAL enable_indexscan = false;
-- unfortunately can't show analyze output confirming sort method,
-- the memory used output wouldn't be stable
EXPLAIN (COSTS OFF) DECLARE c SCROLL CURSOR FOR SELECT noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing;
QUERY PLAN
--------------------------------------
Sort
Sort Key: noabort_decreasing
-> Seq Scan on abbrev_abort_uuids
(3 rows)
DECLARE c SCROLL CURSOR FOR SELECT noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing;
-- first and second
FETCH NEXT FROM c;
noabort_decreasing
--------------------------------------
00000000-0000-0000-0000-000000000000
(1 row)
FETCH NEXT FROM c;
noabort_decreasing
--------------------------------------
00000000-0000-0000-0000-000000000000
(1 row)
-- scroll beyond beginning
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------------------------
00000000-0000-0000-0000-000000000000
(1 row)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH NEXT FROM c;
noabort_decreasing
--------------------------------------
00000000-0000-0000-0000-000000000000
(1 row)
-- scroll beyond end
FETCH LAST FROM c;
noabort_decreasing
--------------------
(1 row)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(1 row)
FETCH NEXT FROM c;
noabort_decreasing
--------------------
(1 row)
FETCH NEXT FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH NEXT FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(1 row)
FETCH NEXT FROM c;
noabort_decreasing
--------------------
(0 rows)
COMMIT;
-- disk based
BEGIN;
SET LOCAL enable_indexscan = false;
SET LOCAL work_mem = '100kB';
-- unfortunately can't show analyze output confirming sort method,
-- the memory used output wouldn't be stable
EXPLAIN (COSTS OFF) DECLARE c SCROLL CURSOR FOR SELECT noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing;
QUERY PLAN
--------------------------------------
Sort
Sort Key: noabort_decreasing
-> Seq Scan on abbrev_abort_uuids
(3 rows)
DECLARE c SCROLL CURSOR FOR SELECT noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing;
-- first and second
FETCH NEXT FROM c;
noabort_decreasing
--------------------------------------
00000000-0000-0000-0000-000000000000
(1 row)
FETCH NEXT FROM c;
noabort_decreasing
--------------------------------------
00000000-0000-0000-0000-000000000000
(1 row)
-- scroll beyond beginning
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------------------------
00000000-0000-0000-0000-000000000000
(1 row)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH NEXT FROM c;
noabort_decreasing
--------------------------------------
00000000-0000-0000-0000-000000000000
(1 row)
-- scroll beyond end
FETCH LAST FROM c;
noabort_decreasing
--------------------
(1 row)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(1 row)
FETCH NEXT FROM c;
noabort_decreasing
--------------------
(1 row)
FETCH NEXT FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH NEXT FROM c;
noabort_decreasing
--------------------
(0 rows)
FETCH BACKWARD FROM c;
noabort_decreasing
--------------------
(1 row)
FETCH NEXT FROM c;
noabort_decreasing
--------------------
(0 rows)
COMMIT;
----
-- test tuplesort using both in-memory and disk sort
---
-- memory based
SELECT
-- fixed-width by-value datum
(array_agg(id ORDER BY id DESC NULLS FIRST))[0:5],
-- fixed-width by-ref datum
(array_agg(abort_increasing ORDER BY abort_increasing DESC NULLS LAST))[0:5],
-- variable-width datum
(array_agg(id::text ORDER BY id::text DESC NULLS LAST))[0:5],
-- fixed width by-value datum tuplesort
percentile_disc(0.99) WITHIN GROUP (ORDER BY id),
-- ensure state is shared
percentile_disc(0.01) WITHIN GROUP (ORDER BY id),
-- fixed width by-ref datum tuplesort
percentile_disc(0.8) WITHIN GROUP (ORDER BY abort_increasing),
-- variable width by-ref datum tuplesort
percentile_disc(0.2) WITHIN GROUP (ORDER BY id::text),
-- multi-column tuplesort
rank('00000000-0000-0000-0000-000000000000', '2', '2') WITHIN GROUP (ORDER BY noabort_increasing, id, id::text)
FROM (
SELECT * FROM abbrev_abort_uuids
UNION ALL
SELECT NULL, NULL, NULL, NULL, NULL) s;
array_agg | array_agg | array_agg | percentile_disc | percentile_disc | percentile_disc | percentile_disc | rank
--------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------+-----------------+-----------------+--------------------------------------+-----------------+------
{NULL,20010,20009,20008,20007} | {00000000-0000-0000-0000-000000020000,00000000-0000-0000-0000-000000020000,00000000-0000-0000-0000-000000019999,00000000-0000-0000-0000-000000019998,00000000-0000-0000-0000-000000019997} | {9999,9998,9997,9996,9995} | 19810 | 200 | 00000000-0000-0000-0000-000000016003 | 136 | 2
(1 row)
-- disk based (see also above)
BEGIN;
SET LOCAL work_mem = '100kB';
SELECT
(array_agg(id ORDER BY id DESC NULLS FIRST))[0:5],
(array_agg(abort_increasing ORDER BY abort_increasing DESC NULLS LAST))[0:5],
(array_agg(id::text ORDER BY id::text DESC NULLS LAST))[0:5],
percentile_disc(0.99) WITHIN GROUP (ORDER BY id),
percentile_disc(0.01) WITHIN GROUP (ORDER BY id),
percentile_disc(0.8) WITHIN GROUP (ORDER BY abort_increasing),
percentile_disc(0.2) WITHIN GROUP (ORDER BY id::text),
rank('00000000-0000-0000-0000-000000000000', '2', '2') WITHIN GROUP (ORDER BY noabort_increasing, id, id::text)
FROM (
SELECT * FROM abbrev_abort_uuids
UNION ALL
SELECT NULL, NULL, NULL, NULL, NULL) s;
array_agg | array_agg | array_agg | percentile_disc | percentile_disc | percentile_disc | percentile_disc | rank
--------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------+-----------------+-----------------+--------------------------------------+-----------------+------
{NULL,20010,20009,20008,20007} | {00000000-0000-0000-0000-000000020000,00000000-0000-0000-0000-000000020000,00000000-0000-0000-0000-000000019999,00000000-0000-0000-0000-000000019998,00000000-0000-0000-0000-000000019997} | {9999,9998,9997,9996,9995} | 19810 | 200 | 00000000-0000-0000-0000-000000016003 | 136 | 2
(1 row)
ROLLBACK;
----
-- test tuplesort mark/restore
---
CREATE TEMP TABLE test_mark_restore(col1 int, col2 int, col12 int);
-- need a few duplicates for mark/restore to matter
INSERT INTO test_mark_restore(col1, col2, col12)
SELECT a.i, b.i, a.i * b.i FROM generate_series(1, 500) a(i), generate_series(1, 5) b(i);
BEGIN;
SET LOCAL enable_nestloop = off;
SET LOCAL enable_hashjoin = off;
SET LOCAL enable_material = off;
-- set query into variable once, to avoid repetition of the fairly long query
SELECT $$
SELECT col12, count(distinct a.col1), count(distinct a.col2), count(distinct b.col1), count(distinct b.col2), count(*)
FROM test_mark_restore a
JOIN test_mark_restore b USING(col12)
GROUP BY 1
HAVING count(*) > 1
ORDER BY 2 DESC, 1 DESC, 3 DESC, 4 DESC, 5 DESC, 6 DESC
LIMIT 10
$$ AS qry \gset
-- test mark/restore with in-memory sorts
EXPLAIN (COSTS OFF) :qry;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
-> Sort
Sort Key: (count(DISTINCT a.col1)) DESC, a.col12 DESC, (count(DISTINCT a.col2)) DESC, (count(DISTINCT b.col1)) DESC, (count(DISTINCT b.col2)) DESC, (count(*)) DESC
-> GroupAggregate
Group Key: a.col12
Filter: (count(*) > 1)
-> Incremental Sort
Sort Key: a.col12 DESC, a.col1
Presorted Key: a.col12
-> Merge Join
Merge Cond: (a.col12 = b.col12)
-> Sort
Sort Key: a.col12 DESC
-> Seq Scan on test_mark_restore a
-> Sort
Sort Key: b.col12 DESC
-> Seq Scan on test_mark_restore b
(17 rows)
:qry;
col12 | count | count | count | count | count
-------+-------+-------+-------+-------+-------
480 | 5 | 5 | 5 | 5 | 25
420 | 5 | 5 | 5 | 5 | 25
360 | 5 | 5 | 5 | 5 | 25
300 | 5 | 5 | 5 | 5 | 25
240 | 5 | 5 | 5 | 5 | 25
180 | 5 | 5 | 5 | 5 | 25
120 | 5 | 5 | 5 | 5 | 25
60 | 5 | 5 | 5 | 5 | 25
960 | 4 | 4 | 4 | 4 | 16
900 | 4 | 4 | 4 | 4 | 16
(10 rows)
-- test mark/restore with on-disk sorts
SET LOCAL work_mem = '100kB';
EXPLAIN (COSTS OFF) :qry;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
-> Sort
Sort Key: (count(DISTINCT a.col1)) DESC, a.col12 DESC, (count(DISTINCT a.col2)) DESC, (count(DISTINCT b.col1)) DESC, (count(DISTINCT b.col2)) DESC, (count(*)) DESC
-> GroupAggregate
Group Key: a.col12
Filter: (count(*) > 1)
-> Incremental Sort
Sort Key: a.col12 DESC, a.col1
Presorted Key: a.col12
-> Merge Join
Merge Cond: (a.col12 = b.col12)
-> Sort
Sort Key: a.col12 DESC
-> Seq Scan on test_mark_restore a
-> Sort
Sort Key: b.col12 DESC
-> Seq Scan on test_mark_restore b
(17 rows)
:qry;
col12 | count | count | count | count | count
-------+-------+-------+-------+-------+-------
480 | 5 | 5 | 5 | 5 | 25
420 | 5 | 5 | 5 | 5 | 25
360 | 5 | 5 | 5 | 5 | 25
300 | 5 | 5 | 5 | 5 | 25
240 | 5 | 5 | 5 | 5 | 25
180 | 5 | 5 | 5 | 5 | 25
120 | 5 | 5 | 5 | 5 | 25
60 | 5 | 5 | 5 | 5 | 25
960 | 4 | 4 | 4 | 4 | 16
900 | 4 | 4 | 4 | 4 | 16
(10 rows)
COMMIT;
|
