299 lines
10 KiB
PL/PgSQL
299 lines
10 KiB
PL/PgSQL
-- only use parallelism when explicitly intending to do so
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SET max_parallel_maintenance_workers = 0;
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SET max_parallel_workers = 0;
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-- A table with contents that, when sorted, triggers abbreviated
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-- key aborts. One easy way to achieve that is to use uuids that all
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-- have the same prefix, as abbreviated keys for uuids just use the
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-- first sizeof(Datum) bytes.
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CREATE TEMP TABLE abbrev_abort_uuids (
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id serial not null,
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abort_increasing uuid,
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abort_decreasing uuid,
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noabort_increasing uuid,
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noabort_decreasing uuid);
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INSERT INTO abbrev_abort_uuids (abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing)
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SELECT
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('00000000-0000-0000-0000-'||to_char(g.i, '000000000000FM'))::uuid abort_increasing,
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('00000000-0000-0000-0000-'||to_char(20000 - g.i, '000000000000FM'))::uuid abort_decreasing,
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(to_char(g.i % 10009, '00000000FM')||'-0000-0000-0000-'||to_char(g.i, '000000000000FM'))::uuid noabort_increasing,
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(to_char(((20000 - g.i) % 10009), '00000000FM')||'-0000-0000-0000-'||to_char(20000 - g.i, '000000000000FM'))::uuid noabort_decreasing
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FROM generate_series(0, 20000, 1) g(i);
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-- and a few NULLs
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INSERT INTO abbrev_abort_uuids(id) VALUES(0);
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INSERT INTO abbrev_abort_uuids DEFAULT VALUES;
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INSERT INTO abbrev_abort_uuids DEFAULT VALUES;
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-- add just a few duplicates
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INSERT INTO abbrev_abort_uuids (abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing)
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SELECT abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
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FROM abbrev_abort_uuids
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WHERE (id < 10 OR id > 19990) AND id % 3 = 0 AND abort_increasing is not null;
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----
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-- Check sort node uses of tuplesort wrt. abbreviated keys
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----
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-- plain sort triggering abbreviated abort
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SELECT abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_increasing OFFSET 20000 - 4;
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SELECT abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_decreasing NULLS FIRST OFFSET 20000 - 4;
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-- plain sort not triggering abbreviated abort
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SELECT noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_increasing OFFSET 20000 - 4;
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SELECT noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing NULLS FIRST OFFSET 20000 - 4;
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-- bounded sort (disables abbreviated keys)
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SELECT abort_increasing, noabort_increasing FROM abbrev_abort_uuids ORDER BY abort_increasing LIMIT 5;
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SELECT abort_increasing, noabort_increasing FROM abbrev_abort_uuids ORDER BY noabort_increasing NULLS FIRST LIMIT 5;
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----
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-- Check index creation uses of tuplesort wrt. abbreviated keys
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----
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-- index creation using abbreviated keys successfully
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CREATE INDEX abbrev_abort_uuids__noabort_increasing_idx ON abbrev_abort_uuids (noabort_increasing);
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CREATE INDEX abbrev_abort_uuids__noabort_decreasing_idx ON abbrev_abort_uuids (noabort_decreasing);
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-- verify
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EXPLAIN (COSTS OFF)
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SELECT id, noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_increasing LIMIT 5;
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SELECT id, noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_increasing LIMIT 5;
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EXPLAIN (COSTS OFF)
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SELECT id, noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing LIMIT 5;
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SELECT id, noabort_increasing, noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing LIMIT 5;
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-- index creation using abbreviated keys, hitting abort
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CREATE INDEX abbrev_abort_uuids__abort_increasing_idx ON abbrev_abort_uuids (abort_increasing);
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CREATE INDEX abbrev_abort_uuids__abort_decreasing_idx ON abbrev_abort_uuids (abort_decreasing);
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-- verify
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EXPLAIN (COSTS OFF)
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SELECT id, abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_increasing LIMIT 5;
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SELECT id, abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_increasing LIMIT 5;
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EXPLAIN (COSTS OFF)
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SELECT id, abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_decreasing LIMIT 5;
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SELECT id, abort_increasing, abort_decreasing FROM abbrev_abort_uuids ORDER BY abort_decreasing LIMIT 5;
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----
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-- Check CLUSTER uses of tuplesort wrt. abbreviated keys
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----
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-- when aborting, increasing order
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BEGIN;
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SET LOCAL enable_indexscan = false;
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CLUSTER abbrev_abort_uuids USING abbrev_abort_uuids__abort_increasing_idx;
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-- head
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SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
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FROM abbrev_abort_uuids
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ORDER BY ctid LIMIT 5;
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-- tail
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SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
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FROM abbrev_abort_uuids
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ORDER BY ctid DESC LIMIT 5;
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ROLLBACK;
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-- when aborting, decreasing order
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BEGIN;
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SET LOCAL enable_indexscan = false;
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CLUSTER abbrev_abort_uuids USING abbrev_abort_uuids__abort_decreasing_idx;
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-- head
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SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
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FROM abbrev_abort_uuids
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ORDER BY ctid LIMIT 5;
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-- tail
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SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
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FROM abbrev_abort_uuids
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ORDER BY ctid DESC LIMIT 5;
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ROLLBACK;
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-- when not aborting, increasing order
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BEGIN;
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SET LOCAL enable_indexscan = false;
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CLUSTER abbrev_abort_uuids USING abbrev_abort_uuids__noabort_increasing_idx;
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-- head
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SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
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FROM abbrev_abort_uuids
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ORDER BY ctid LIMIT 5;
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-- tail
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SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
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FROM abbrev_abort_uuids
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ORDER BY ctid DESC LIMIT 5;
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ROLLBACK;
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-- when no aborting, decreasing order
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BEGIN;
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SET LOCAL enable_indexscan = false;
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CLUSTER abbrev_abort_uuids USING abbrev_abort_uuids__noabort_decreasing_idx;
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-- head
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SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
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FROM abbrev_abort_uuids
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ORDER BY ctid LIMIT 5;
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-- tail
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SELECT id, abort_increasing, abort_decreasing, noabort_increasing, noabort_decreasing
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FROM abbrev_abort_uuids
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ORDER BY ctid DESC LIMIT 5;
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ROLLBACK;
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----
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-- test forward and backward scans for in-memory and disk based tuplesort
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----
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-- in-memory
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BEGIN;
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SET LOCAL enable_indexscan = false;
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-- unfortunately can't show analyze output confirming sort method,
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-- the memory used output wouldn't be stable
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EXPLAIN (COSTS OFF) DECLARE c SCROLL CURSOR FOR SELECT noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing;
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DECLARE c SCROLL CURSOR FOR SELECT noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing;
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-- first and second
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FETCH NEXT FROM c;
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FETCH NEXT FROM c;
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-- scroll beyond beginning
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FETCH BACKWARD FROM c;
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FETCH BACKWARD FROM c;
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FETCH BACKWARD FROM c;
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FETCH BACKWARD FROM c;
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FETCH NEXT FROM c;
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-- scroll beyond end
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FETCH LAST FROM c;
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FETCH BACKWARD FROM c;
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FETCH NEXT FROM c;
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FETCH NEXT FROM c;
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FETCH NEXT FROM c;
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FETCH BACKWARD FROM c;
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FETCH NEXT FROM c;
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COMMIT;
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-- disk based
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BEGIN;
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SET LOCAL enable_indexscan = false;
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SET LOCAL work_mem = '100kB';
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-- unfortunately can't show analyze output confirming sort method,
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-- the memory used output wouldn't be stable
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EXPLAIN (COSTS OFF) DECLARE c SCROLL CURSOR FOR SELECT noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing;
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DECLARE c SCROLL CURSOR FOR SELECT noabort_decreasing FROM abbrev_abort_uuids ORDER BY noabort_decreasing;
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-- first and second
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FETCH NEXT FROM c;
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FETCH NEXT FROM c;
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-- scroll beyond beginning
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FETCH BACKWARD FROM c;
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FETCH BACKWARD FROM c;
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FETCH BACKWARD FROM c;
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FETCH BACKWARD FROM c;
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FETCH NEXT FROM c;
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-- scroll beyond end
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FETCH LAST FROM c;
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FETCH BACKWARD FROM c;
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FETCH NEXT FROM c;
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FETCH NEXT FROM c;
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FETCH NEXT FROM c;
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FETCH BACKWARD FROM c;
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FETCH NEXT FROM c;
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COMMIT;
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----
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-- test tuplesort using both in-memory and disk sort
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---
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-- memory based
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SELECT
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-- fixed-width by-value datum
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(array_agg(id ORDER BY id DESC NULLS FIRST))[0:5],
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-- fixed-width by-ref datum
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(array_agg(abort_increasing ORDER BY abort_increasing DESC NULLS LAST))[0:5],
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-- variable-width datum
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(array_agg(id::text ORDER BY id::text DESC NULLS LAST))[0:5],
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-- fixed width by-value datum tuplesort
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percentile_disc(0.99) WITHIN GROUP (ORDER BY id),
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-- ensure state is shared
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percentile_disc(0.01) WITHIN GROUP (ORDER BY id),
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-- fixed width by-ref datum tuplesort
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percentile_disc(0.8) WITHIN GROUP (ORDER BY abort_increasing),
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-- variable width by-ref datum tuplesort
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percentile_disc(0.2) WITHIN GROUP (ORDER BY id::text),
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-- multi-column tuplesort
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rank('00000000-0000-0000-0000-000000000000', '2', '2') WITHIN GROUP (ORDER BY noabort_increasing, id, id::text)
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FROM (
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SELECT * FROM abbrev_abort_uuids
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UNION ALL
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SELECT NULL, NULL, NULL, NULL, NULL) s;
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-- disk based (see also above)
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BEGIN;
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SET LOCAL work_mem = '100kB';
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SELECT
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(array_agg(id ORDER BY id DESC NULLS FIRST))[0:5],
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(array_agg(abort_increasing ORDER BY abort_increasing DESC NULLS LAST))[0:5],
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(array_agg(id::text ORDER BY id::text DESC NULLS LAST))[0:5],
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percentile_disc(0.99) WITHIN GROUP (ORDER BY id),
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percentile_disc(0.01) WITHIN GROUP (ORDER BY id),
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percentile_disc(0.8) WITHIN GROUP (ORDER BY abort_increasing),
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percentile_disc(0.2) WITHIN GROUP (ORDER BY id::text),
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rank('00000000-0000-0000-0000-000000000000', '2', '2') WITHIN GROUP (ORDER BY noabort_increasing, id, id::text)
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FROM (
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SELECT * FROM abbrev_abort_uuids
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UNION ALL
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SELECT NULL, NULL, NULL, NULL, NULL) s;
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ROLLBACK;
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----
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-- test tuplesort mark/restore
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---
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CREATE TEMP TABLE test_mark_restore(col1 int, col2 int, col12 int);
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-- need a few duplicates for mark/restore to matter
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INSERT INTO test_mark_restore(col1, col2, col12)
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SELECT a.i, b.i, a.i * b.i FROM generate_series(1, 500) a(i), generate_series(1, 5) b(i);
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BEGIN;
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SET LOCAL enable_nestloop = off;
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SET LOCAL enable_hashjoin = off;
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SET LOCAL enable_material = off;
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-- set query into variable once, to avoid repetition of the fairly long query
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SELECT $$
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SELECT col12, count(distinct a.col1), count(distinct a.col2), count(distinct b.col1), count(distinct b.col2), count(*)
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FROM test_mark_restore a
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JOIN test_mark_restore b USING(col12)
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GROUP BY 1
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HAVING count(*) > 1
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ORDER BY 2 DESC, 1 DESC, 3 DESC, 4 DESC, 5 DESC, 6 DESC
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LIMIT 10
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$$ AS qry \gset
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-- test mark/restore with in-memory sorts
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EXPLAIN (COSTS OFF) :qry;
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:qry;
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-- test mark/restore with on-disk sorts
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SET LOCAL work_mem = '100kB';
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EXPLAIN (COSTS OFF) :qry;
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:qry;
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COMMIT;
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