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pg_stat_statements: Fix handling of duplicate constant locations

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Two or more constants can have the same location.  We handled this
correctly for non squashed constants, but failed to do it if squashed
(resulting in out-of-bounds memory access), because the code structure
became broken by commit 0f65f3eec4: we failed to update 'last_loc'
correctly when skipping these squashed constants.

The simplest fix seems to be to get rid of 'last_loc' altogether -- in
hindsight, it's quite pointless.  Also, when ignoring a constant because
of this, make sure to fulfill fill_in_constant_lengths's duty of setting
its length to -1.

Lastly, we can use == instead of <= because the locations have been
sorted beforehand, so the < case cannot arise.

Co-authored-by: Sami Imseih <samimseih@gmail.com>
Co-authored-by: Dmitry Dolgov <9erthalion6@gmail.com>
Reported-by: Konstantin Knizhnik <knizhnik@garret.ru>
Backpatch-through: 18
Discussion: https://www.postgresql.org/message-id/2b91e358-0d99-43f7-be44-d2d4dbce37b3%40garret.ru
This commit is contained in:
Álvaro Herrera
2025-10-29 12:35:02 +01:00
parent a92bbffbc3
commit b1635c1666
3 changed files with 123 additions and 16 deletions
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26
contrib/pg_stat_statements/sql/squashing.sql
View File

@@ -291,6 +291,30 @@ select where '1' IN ('1'::int::text, '2'::int::text);
select where '1' = ANY (array['1'::int::text, '2'::int::text]);
SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
-- composite function with row expansion
create table test_composite(x integer);
CREATE FUNCTION composite_f(a integer[], out x integer, out y integer) returns
record as $$ begin
x = a[1];
y = a[2];
end;
$$ language plpgsql;
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
SELECT ((composite_f(array[1, 2]))).* FROM test_composite;
SELECT ((composite_f(array[1, 2, 3]))).* FROM test_composite;
SELECT ((composite_f(array[1, 2, 3]))).*, 1, 2, 3, ((composite_f(array[1, 2, 3]))).*, 1, 2
FROM test_composite
WHERE x IN (1, 2, 3);
SELECT ((composite_f(array[1, $1, 3]))).*, 1 FROM test_composite \bind 1
;
-- ROW() expression with row expansion
SELECT (ROW(ARRAY[1,2])).*;
SELECT (ROW(ARRAY[1, 2], ARRAY[1, 2, 3])).*;
SELECT 1, 2, (ROW(ARRAY[1, 2], ARRAY[1, 2, 3])).*, 3, 4;
SELECT (ROW(ARRAY[1, 2], ARRAY[1, $1, 3])).*, 1 \bind 1
;
SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
--
-- cleanup
--
@@ -300,3 +324,5 @@ DROP TABLE test_squash_numeric;
DROP TABLE test_squash_bigint;
DROP TABLE test_squash_cast CASCADE;
DROP TABLE test_squash_jsonb;
DROP TABLE test_composite;
DROP FUNCTION composite_f;