197 lines
5.8 KiB
PL/PgSQL
197 lines
5.8 KiB
PL/PgSQL
--
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-- LIMIT
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-- Check the LIMIT/OFFSET feature of SELECT
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--
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SELECT ''::text AS two, unique1, unique2, stringu1
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FROM onek WHERE unique1 > 50
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ORDER BY unique1 LIMIT 2;
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SELECT ''::text AS five, unique1, unique2, stringu1
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FROM onek WHERE unique1 > 60
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ORDER BY unique1 LIMIT 5;
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SELECT ''::text AS two, unique1, unique2, stringu1
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FROM onek WHERE unique1 > 60 AND unique1 < 63
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ORDER BY unique1 LIMIT 5;
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SELECT ''::text AS three, unique1, unique2, stringu1
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FROM onek WHERE unique1 > 100
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ORDER BY unique1 LIMIT 3 OFFSET 20;
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SELECT ''::text AS zero, unique1, unique2, stringu1
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FROM onek WHERE unique1 < 50
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ORDER BY unique1 DESC LIMIT 8 OFFSET 99;
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SELECT ''::text AS eleven, unique1, unique2, stringu1
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FROM onek WHERE unique1 < 50
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ORDER BY unique1 DESC LIMIT 20 OFFSET 39;
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SELECT ''::text AS ten, unique1, unique2, stringu1
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FROM onek
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ORDER BY unique1 OFFSET 990;
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SELECT ''::text AS five, unique1, unique2, stringu1
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FROM onek
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ORDER BY unique1 OFFSET 990 LIMIT 5;
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SELECT ''::text AS five, unique1, unique2, stringu1
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FROM onek
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ORDER BY unique1 LIMIT 5 OFFSET 900;
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-- Test null limit and offset. The planner would discard a simple null
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-- constant, so to ensure executor is exercised, do this:
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select * from int8_tbl limit (case when random() < 0.5 then null::bigint end);
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select * from int8_tbl offset (case when random() < 0.5 then null::bigint end);
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-- Test assorted cases involving backwards fetch from a LIMIT plan node
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begin;
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declare c1 cursor for select * from int8_tbl limit 10;
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fetch all in c1;
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fetch 1 in c1;
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fetch backward 1 in c1;
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fetch backward all in c1;
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fetch backward 1 in c1;
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fetch all in c1;
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declare c2 cursor for select * from int8_tbl limit 3;
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fetch all in c2;
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fetch 1 in c2;
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fetch backward 1 in c2;
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fetch backward all in c2;
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fetch backward 1 in c2;
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fetch all in c2;
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declare c3 cursor for select * from int8_tbl offset 3;
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fetch all in c3;
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fetch 1 in c3;
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fetch backward 1 in c3;
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fetch backward all in c3;
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fetch backward 1 in c3;
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fetch all in c3;
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declare c4 cursor for select * from int8_tbl offset 10;
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fetch all in c4;
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fetch 1 in c4;
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fetch backward 1 in c4;
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fetch backward all in c4;
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fetch backward 1 in c4;
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fetch all in c4;
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declare c5 cursor for select * from int8_tbl order by q1 fetch first 2 rows with ties;
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fetch all in c5;
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fetch 1 in c5;
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fetch backward 1 in c5;
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fetch backward 1 in c5;
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fetch all in c5;
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fetch backward all in c5;
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fetch all in c5;
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fetch backward all in c5;
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rollback;
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-- Stress test for variable LIMIT in conjunction with bounded-heap sorting
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SELECT
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(SELECT n
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FROM (VALUES (1)) AS x,
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(SELECT n FROM generate_series(1,10) AS n
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ORDER BY n LIMIT 1 OFFSET s-1) AS y) AS z
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FROM generate_series(1,10) AS s;
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--
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-- Test behavior of volatile and set-returning functions in conjunction
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-- with ORDER BY and LIMIT.
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--
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create temp sequence testseq;
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explain (verbose, costs off)
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select unique1, unique2, nextval('testseq')
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from tenk1 order by unique2 limit 10;
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select unique1, unique2, nextval('testseq')
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from tenk1 order by unique2 limit 10;
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select currval('testseq');
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explain (verbose, costs off)
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select unique1, unique2, nextval('testseq')
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from tenk1 order by tenthous limit 10;
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select unique1, unique2, nextval('testseq')
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from tenk1 order by tenthous limit 10;
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select currval('testseq');
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explain (verbose, costs off)
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select unique1, unique2, generate_series(1,10)
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from tenk1 order by unique2 limit 7;
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select unique1, unique2, generate_series(1,10)
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from tenk1 order by unique2 limit 7;
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explain (verbose, costs off)
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select unique1, unique2, generate_series(1,10)
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from tenk1 order by tenthous limit 7;
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select unique1, unique2, generate_series(1,10)
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from tenk1 order by tenthous limit 7;
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-- use of random() is to keep planner from folding the expressions together
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explain (verbose, costs off)
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select generate_series(0,2) as s1, generate_series((random()*.1)::int,2) as s2;
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select generate_series(0,2) as s1, generate_series((random()*.1)::int,2) as s2;
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explain (verbose, costs off)
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select generate_series(0,2) as s1, generate_series((random()*.1)::int,2) as s2
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order by s2 desc;
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select generate_series(0,2) as s1, generate_series((random()*.1)::int,2) as s2
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order by s2 desc;
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-- test for failure to set all aggregates' aggtranstype
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explain (verbose, costs off)
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select sum(tenthous) as s1, sum(tenthous) + random()*0 as s2
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from tenk1 group by thousand order by thousand limit 3;
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select sum(tenthous) as s1, sum(tenthous) + random()*0 as s2
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from tenk1 group by thousand order by thousand limit 3;
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--
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-- FETCH FIRST
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-- Check the WITH TIES clause
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--
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SELECT thousand
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FROM onek WHERE thousand < 5
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ORDER BY thousand FETCH FIRST 2 ROW WITH TIES;
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SELECT thousand
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FROM onek WHERE thousand < 5
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ORDER BY thousand FETCH FIRST ROWS WITH TIES;
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SELECT thousand
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FROM onek WHERE thousand < 5
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ORDER BY thousand FETCH FIRST 1 ROW WITH TIES;
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SELECT thousand
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FROM onek WHERE thousand < 5
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ORDER BY thousand FETCH FIRST 2 ROW ONLY;
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-- should fail
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SELECT ''::text AS two, unique1, unique2, stringu1
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FROM onek WHERE unique1 > 50
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FETCH FIRST 2 ROW WITH TIES;
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-- test ruleutils
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CREATE VIEW limit_thousand_v_1 AS SELECT thousand FROM onek WHERE thousand < 995
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ORDER BY thousand FETCH FIRST 5 ROWS WITH TIES OFFSET 10;
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\d+ limit_thousand_v_1
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CREATE VIEW limit_thousand_v_2 AS SELECT thousand FROM onek WHERE thousand < 995
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ORDER BY thousand OFFSET 10 FETCH FIRST 5 ROWS ONLY;
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\d+ limit_thousand_v_2
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CREATE VIEW limit_thousand_v_3 AS SELECT thousand FROM onek WHERE thousand < 995
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ORDER BY thousand FETCH FIRST NULL ROWS WITH TIES; -- fails
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CREATE VIEW limit_thousand_v_3 AS SELECT thousand FROM onek WHERE thousand < 995
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ORDER BY thousand FETCH FIRST (NULL+1) ROWS WITH TIES;
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\d+ limit_thousand_v_3
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CREATE VIEW limit_thousand_v_4 AS SELECT thousand FROM onek WHERE thousand < 995
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ORDER BY thousand FETCH FIRST NULL ROWS ONLY;
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\d+ limit_thousand_v_4
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-- leave these views
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