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24c19e9f66
create_merge_append_plan failed to honor the CP_EXACT_TLIST flag:
it would generate the expected targetlist but then it felt free to
add resjunk sort targets to it. This demonstrably leads to assertion
failures in v11 and HEAD, and it's probably just accidental that we
don't see the same in older branches. I've not looked into whether
there would be any real-world consequences in non-assert builds.
In HEAD, create_append_plan has sprouted the same problem, so fix
that too (although we do not have any test cases that seem able to
reach that bug). This is an oversight in commit 3fc6e2d7f which
invented the CP_EXACT_TLIST flag, so back-patch to 9.6 where that
came in.
convert_subquery_pathkeys would create pathkeys for subquery output
values if they match any EquivalenceClass known in the outer query
and are available in the subquery's syntactic targetlist. However,
the second part of that condition is wrong, because such values might
not appear in the subquery relation's reltarget list, which would
mean that they couldn't be accessed above the level of the subquery
scan. We must check that they appear in the reltarget list, instead.
This can lead to dropping knowledge about the subquery's sort
ordering, but I believe it's okay, because any sort key that the
outer query actually has any interest in would appear in the
reltarget list.
This second issue is of very long standing, but right now there's no
evidence that it causes observable problems before 9.6, so I refrained
from back-patching further than that. We can revisit that choice if
somebody finds a way to make it cause problems in older branches.
(Developing useful test cases for these issues is really problematic;
fixing convert_subquery_pathkeys removes the only known way to exhibit
the create_merge_append_plan bug, and neither of the test cases added
by this patch causes a problem in all branches, even when considering
the issues separately.)
The second issue explains bug #15795 from Suresh Kumar R ("could not
find pathkey item to sort" with nested DISTINCT queries). I stumbled
across the first issue while investigating that.
Discussion: https://postgr.es/m/15795-fadb56c8e44ee73c@postgresql.org
442 lines
12 KiB
PL/PgSQL
442 lines
12 KiB
PL/PgSQL
--
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-- UNION (also INTERSECT, EXCEPT)
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--
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-- Simple UNION constructs
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SELECT 1 AS two UNION SELECT 2 ORDER BY 1;
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SELECT 1 AS one UNION SELECT 1 ORDER BY 1;
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SELECT 1 AS two UNION ALL SELECT 2;
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SELECT 1 AS two UNION ALL SELECT 1;
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SELECT 1 AS three UNION SELECT 2 UNION SELECT 3 ORDER BY 1;
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SELECT 1 AS two UNION SELECT 2 UNION SELECT 2 ORDER BY 1;
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SELECT 1 AS three UNION SELECT 2 UNION ALL SELECT 2 ORDER BY 1;
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SELECT 1.1 AS two UNION SELECT 2.2 ORDER BY 1;
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-- Mixed types
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SELECT 1.1 AS two UNION SELECT 2 ORDER BY 1;
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SELECT 1 AS two UNION SELECT 2.2 ORDER BY 1;
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SELECT 1 AS one UNION SELECT 1.0::float8 ORDER BY 1;
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SELECT 1.1 AS two UNION ALL SELECT 2 ORDER BY 1;
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SELECT 1.0::float8 AS two UNION ALL SELECT 1 ORDER BY 1;
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SELECT 1.1 AS three UNION SELECT 2 UNION SELECT 3 ORDER BY 1;
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SELECT 1.1::float8 AS two UNION SELECT 2 UNION SELECT 2.0::float8 ORDER BY 1;
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SELECT 1.1 AS three UNION SELECT 2 UNION ALL SELECT 2 ORDER BY 1;
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SELECT 1.1 AS two UNION (SELECT 2 UNION ALL SELECT 2) ORDER BY 1;
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--
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-- Try testing from tables...
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--
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SELECT f1 AS five FROM FLOAT8_TBL
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UNION
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SELECT f1 FROM FLOAT8_TBL
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ORDER BY 1;
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SELECT f1 AS ten FROM FLOAT8_TBL
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UNION ALL
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SELECT f1 FROM FLOAT8_TBL;
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SELECT f1 AS nine FROM FLOAT8_TBL
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UNION
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SELECT f1 FROM INT4_TBL
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ORDER BY 1;
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SELECT f1 AS ten FROM FLOAT8_TBL
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UNION ALL
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SELECT f1 FROM INT4_TBL;
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SELECT f1 AS five FROM FLOAT8_TBL
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WHERE f1 BETWEEN -1e6 AND 1e6
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UNION
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SELECT f1 FROM INT4_TBL
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WHERE f1 BETWEEN 0 AND 1000000
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ORDER BY 1;
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SELECT CAST(f1 AS char(4)) AS three FROM VARCHAR_TBL
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UNION
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SELECT f1 FROM CHAR_TBL
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ORDER BY 1;
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SELECT f1 AS three FROM VARCHAR_TBL
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UNION
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SELECT CAST(f1 AS varchar) FROM CHAR_TBL
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ORDER BY 1;
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SELECT f1 AS eight FROM VARCHAR_TBL
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UNION ALL
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SELECT f1 FROM CHAR_TBL;
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SELECT f1 AS five FROM TEXT_TBL
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UNION
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SELECT f1 FROM VARCHAR_TBL
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UNION
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SELECT TRIM(TRAILING FROM f1) FROM CHAR_TBL
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ORDER BY 1;
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--
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-- INTERSECT and EXCEPT
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--
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SELECT q2 FROM int8_tbl INTERSECT SELECT q1 FROM int8_tbl ORDER BY 1;
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SELECT q2 FROM int8_tbl INTERSECT ALL SELECT q1 FROM int8_tbl ORDER BY 1;
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SELECT q2 FROM int8_tbl EXCEPT SELECT q1 FROM int8_tbl ORDER BY 1;
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SELECT q2 FROM int8_tbl EXCEPT ALL SELECT q1 FROM int8_tbl ORDER BY 1;
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SELECT q2 FROM int8_tbl EXCEPT ALL SELECT DISTINCT q1 FROM int8_tbl ORDER BY 1;
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SELECT q1 FROM int8_tbl EXCEPT SELECT q2 FROM int8_tbl ORDER BY 1;
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SELECT q1 FROM int8_tbl EXCEPT ALL SELECT q2 FROM int8_tbl ORDER BY 1;
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SELECT q1 FROM int8_tbl EXCEPT ALL SELECT DISTINCT q2 FROM int8_tbl ORDER BY 1;
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SELECT q1 FROM int8_tbl EXCEPT ALL SELECT q1 FROM int8_tbl FOR NO KEY UPDATE;
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-- nested cases
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(SELECT 1,2,3 UNION SELECT 4,5,6) INTERSECT SELECT 4,5,6;
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(SELECT 1,2,3 UNION SELECT 4,5,6 ORDER BY 1,2) INTERSECT SELECT 4,5,6;
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(SELECT 1,2,3 UNION SELECT 4,5,6) EXCEPT SELECT 4,5,6;
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(SELECT 1,2,3 UNION SELECT 4,5,6 ORDER BY 1,2) EXCEPT SELECT 4,5,6;
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-- exercise both hashed and sorted implementations of INTERSECT/EXCEPT
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set enable_hashagg to on;
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explain (costs off)
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select count(*) from
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( select unique1 from tenk1 intersect select fivethous from tenk1 ) ss;
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select count(*) from
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( select unique1 from tenk1 intersect select fivethous from tenk1 ) ss;
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explain (costs off)
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select unique1 from tenk1 except select unique2 from tenk1 where unique2 != 10;
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select unique1 from tenk1 except select unique2 from tenk1 where unique2 != 10;
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set enable_hashagg to off;
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explain (costs off)
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select count(*) from
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( select unique1 from tenk1 intersect select fivethous from tenk1 ) ss;
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select count(*) from
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( select unique1 from tenk1 intersect select fivethous from tenk1 ) ss;
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explain (costs off)
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select unique1 from tenk1 except select unique2 from tenk1 where unique2 != 10;
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select unique1 from tenk1 except select unique2 from tenk1 where unique2 != 10;
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reset enable_hashagg;
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--
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-- Mixed types
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--
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SELECT f1 FROM float8_tbl INTERSECT SELECT f1 FROM int4_tbl ORDER BY 1;
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SELECT f1 FROM float8_tbl EXCEPT SELECT f1 FROM int4_tbl ORDER BY 1;
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--
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-- Operator precedence and (((((extra))))) parentheses
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--
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SELECT q1 FROM int8_tbl INTERSECT SELECT q2 FROM int8_tbl UNION ALL SELECT q2 FROM int8_tbl ORDER BY 1;
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SELECT q1 FROM int8_tbl INTERSECT (((SELECT q2 FROM int8_tbl UNION ALL SELECT q2 FROM int8_tbl))) ORDER BY 1;
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(((SELECT q1 FROM int8_tbl INTERSECT SELECT q2 FROM int8_tbl ORDER BY 1))) UNION ALL SELECT q2 FROM int8_tbl;
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SELECT q1 FROM int8_tbl UNION ALL SELECT q2 FROM int8_tbl EXCEPT SELECT q1 FROM int8_tbl ORDER BY 1;
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SELECT q1 FROM int8_tbl UNION ALL (((SELECT q2 FROM int8_tbl EXCEPT SELECT q1 FROM int8_tbl ORDER BY 1)));
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(((SELECT q1 FROM int8_tbl UNION ALL SELECT q2 FROM int8_tbl))) EXCEPT SELECT q1 FROM int8_tbl ORDER BY 1;
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--
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-- Subqueries with ORDER BY & LIMIT clauses
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--
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-- In this syntax, ORDER BY/LIMIT apply to the result of the EXCEPT
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SELECT q1,q2 FROM int8_tbl EXCEPT SELECT q2,q1 FROM int8_tbl
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ORDER BY q2,q1;
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-- This should fail, because q2 isn't a name of an EXCEPT output column
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SELECT q1 FROM int8_tbl EXCEPT SELECT q2 FROM int8_tbl ORDER BY q2 LIMIT 1;
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-- But this should work:
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SELECT q1 FROM int8_tbl EXCEPT (((SELECT q2 FROM int8_tbl ORDER BY q2 LIMIT 1))) ORDER BY 1;
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--
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-- New syntaxes (7.1) permit new tests
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--
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(((((select * from int8_tbl)))));
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--
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-- Check behavior with empty select list (allowed since 9.4)
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--
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select union select;
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select intersect select;
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select except select;
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-- check hashed implementation
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set enable_hashagg = true;
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set enable_sort = false;
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explain (costs off)
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select from generate_series(1,5) union select from generate_series(1,3);
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explain (costs off)
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select from generate_series(1,5) intersect select from generate_series(1,3);
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select from generate_series(1,5) union select from generate_series(1,3);
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select from generate_series(1,5) union all select from generate_series(1,3);
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select from generate_series(1,5) intersect select from generate_series(1,3);
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select from generate_series(1,5) intersect all select from generate_series(1,3);
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select from generate_series(1,5) except select from generate_series(1,3);
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select from generate_series(1,5) except all select from generate_series(1,3);
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-- check sorted implementation
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set enable_hashagg = false;
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set enable_sort = true;
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explain (costs off)
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select from generate_series(1,5) union select from generate_series(1,3);
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explain (costs off)
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select from generate_series(1,5) intersect select from generate_series(1,3);
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select from generate_series(1,5) union select from generate_series(1,3);
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select from generate_series(1,5) union all select from generate_series(1,3);
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select from generate_series(1,5) intersect select from generate_series(1,3);
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select from generate_series(1,5) intersect all select from generate_series(1,3);
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select from generate_series(1,5) except select from generate_series(1,3);
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select from generate_series(1,5) except all select from generate_series(1,3);
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reset enable_hashagg;
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reset enable_sort;
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--
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-- Check handling of a case with unknown constants. We don't guarantee
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-- an undecorated constant will work in all cases, but historically this
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-- usage has worked, so test we don't break it.
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--
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SELECT a.f1 FROM (SELECT 'test' AS f1 FROM varchar_tbl) a
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UNION
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SELECT b.f1 FROM (SELECT f1 FROM varchar_tbl) b
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ORDER BY 1;
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-- This should fail, but it should produce an error cursor
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SELECT '3.4'::numeric UNION SELECT 'foo';
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--
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-- Test that expression-index constraints can be pushed down through
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-- UNION or UNION ALL
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--
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CREATE TEMP TABLE t1 (a text, b text);
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CREATE INDEX t1_ab_idx on t1 ((a || b));
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CREATE TEMP TABLE t2 (ab text primary key);
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INSERT INTO t1 VALUES ('a', 'b'), ('x', 'y');
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INSERT INTO t2 VALUES ('ab'), ('xy');
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set enable_seqscan = off;
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set enable_indexscan = on;
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set enable_bitmapscan = off;
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explain (costs off)
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SELECT * FROM
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(SELECT a || b AS ab FROM t1
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UNION ALL
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SELECT * FROM t2) t
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WHERE ab = 'ab';
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explain (costs off)
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SELECT * FROM
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(SELECT a || b AS ab FROM t1
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UNION
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SELECT * FROM t2) t
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WHERE ab = 'ab';
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--
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-- Test that ORDER BY for UNION ALL can be pushed down to inheritance
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-- children.
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--
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CREATE TEMP TABLE t1c (b text, a text);
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ALTER TABLE t1c INHERIT t1;
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CREATE TEMP TABLE t2c (primary key (ab)) INHERITS (t2);
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INSERT INTO t1c VALUES ('v', 'w'), ('c', 'd'), ('m', 'n'), ('e', 'f');
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INSERT INTO t2c VALUES ('vw'), ('cd'), ('mn'), ('ef');
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CREATE INDEX t1c_ab_idx on t1c ((a || b));
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set enable_seqscan = on;
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set enable_indexonlyscan = off;
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explain (costs off)
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SELECT * FROM
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(SELECT a || b AS ab FROM t1
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UNION ALL
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SELECT ab FROM t2) t
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ORDER BY 1 LIMIT 8;
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SELECT * FROM
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(SELECT a || b AS ab FROM t1
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UNION ALL
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SELECT ab FROM t2) t
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ORDER BY 1 LIMIT 8;
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reset enable_seqscan;
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reset enable_indexscan;
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reset enable_bitmapscan;
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-- This simpler variant of the above test has been observed to fail differently
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create table events (event_id int primary key);
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create table other_events (event_id int primary key);
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create table events_child () inherits (events);
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explain (costs off)
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select event_id
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from (select event_id from events
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union all
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select event_id from other_events) ss
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order by event_id;
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drop table events_child, events, other_events;
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reset enable_indexonlyscan;
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-- Test constraint exclusion of UNION ALL subqueries
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explain (costs off)
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SELECT * FROM
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(SELECT 1 AS t, * FROM tenk1 a
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UNION ALL
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SELECT 2 AS t, * FROM tenk1 b) c
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WHERE t = 2;
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-- Test that we push quals into UNION sub-selects only when it's safe
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explain (costs off)
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SELECT * FROM
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(SELECT 1 AS t, 2 AS x
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UNION
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SELECT 2 AS t, 4 AS x) ss
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WHERE x < 4
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ORDER BY x;
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SELECT * FROM
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(SELECT 1 AS t, 2 AS x
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UNION
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SELECT 2 AS t, 4 AS x) ss
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WHERE x < 4
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ORDER BY x;
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explain (costs off)
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SELECT * FROM
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(SELECT 1 AS t, generate_series(1,10) AS x
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UNION
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SELECT 2 AS t, 4 AS x) ss
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WHERE x < 4
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ORDER BY x;
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SELECT * FROM
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(SELECT 1 AS t, generate_series(1,10) AS x
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UNION
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SELECT 2 AS t, 4 AS x) ss
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WHERE x < 4
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ORDER BY x;
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explain (costs off)
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SELECT * FROM
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(SELECT 1 AS t, (random()*3)::int AS x
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UNION
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SELECT 2 AS t, 4 AS x) ss
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WHERE x > 3
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ORDER BY x;
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SELECT * FROM
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(SELECT 1 AS t, (random()*3)::int AS x
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UNION
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SELECT 2 AS t, 4 AS x) ss
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WHERE x > 3
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ORDER BY x;
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-- Test cases where the native ordering of a sub-select has more pathkeys
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-- than the outer query cares about
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explain (costs off)
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select distinct q1 from
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(select distinct * from int8_tbl i81
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union all
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select distinct * from int8_tbl i82) ss
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where q2 = q2;
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select distinct q1 from
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(select distinct * from int8_tbl i81
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union all
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select distinct * from int8_tbl i82) ss
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where q2 = q2;
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explain (costs off)
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select distinct q1 from
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(select distinct * from int8_tbl i81
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union all
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select distinct * from int8_tbl i82) ss
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where -q1 = q2;
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select distinct q1 from
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(select distinct * from int8_tbl i81
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union all
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select distinct * from int8_tbl i82) ss
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where -q1 = q2;
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-- Test proper handling of parameterized appendrel paths when the
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-- potential join qual is expensive
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create function expensivefunc(int) returns int
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language plpgsql immutable strict cost 10000
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as $$begin return $1; end$$;
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create temp table t3 as select generate_series(-1000,1000) as x;
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create index t3i on t3 (expensivefunc(x));
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analyze t3;
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explain (costs off)
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select * from
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(select * from t3 a union all select * from t3 b) ss
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join int4_tbl on f1 = expensivefunc(x);
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select * from
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(select * from t3 a union all select * from t3 b) ss
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join int4_tbl on f1 = expensivefunc(x);
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drop table t3;
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drop function expensivefunc(int);
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-- Test handling of appendrel quals that const-simplify into an AND
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explain (costs off)
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select * from
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(select *, 0 as x from int8_tbl a
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union all
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select *, 1 as x from int8_tbl b) ss
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where (x = 0) or (q1 >= q2 and q1 <= q2);
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select * from
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(select *, 0 as x from int8_tbl a
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union all
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select *, 1 as x from int8_tbl b) ss
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where (x = 0) or (q1 >= q2 and q1 <= q2);
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