1
0
mirror of https://github.com/postgres/postgres.git synced 2025-06-08 22:02:03 +03:00
Michael Paquier 7e8b44f4e0 pg_stat_statements: Fix parameter number gaps in normalized queries
pg_stat_statements anticipates that certain constant locations may be
recorded multiple times and attempts to avoid calculating a length for
these locations in fill_in_constant_lengths().

However, during generate_normalized_query() where normalized query
strings are generated, these locations are not excluded from
consideration.  This could increment the parameter number counter for
every recorded occurrence at such a location, leading to an incorrect
normalization in certain cases with gaps in the numbers reported.

For example, take this query:
SELECT WHERE '1' IN ('2'::int, '3'::int::text)
Before this commit, it would be normalized like that, with gaps in the
parameter numbers:
SELECT WHERE $1 IN ($3::int, $4::int::text)
However the correct, less confusing one should be like that:
SELECT WHERE $1 IN ($2::int, $3::int::text)

This commit fixes the computation of the parameter numbers to track the
number of constants replaced with an $n by a separate counter instead of
the iterator used to loop through the list of locations.

The underlying query IDs are not changed, neither are the normalized
strings for existing PGSS hash entries.  New entries with fresh
normalized queries would automatically get reshaped based on the new
parameter numbering.

Issue discovered while discussing a separate problem for HEAD, but this
affects all the stable branches.

Author: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/CAA5RZ0tzxvWXsacGyxrixdhy3tTTDfJQqxyFBRFh31nNHBQ5qA@mail.gmail.com
Backpatch-through: 13
2025-05-29 11:26:27 +09:00

158 lines
4.3 KiB
PL/PgSQL

--
-- SELECT statements
--
CREATE EXTENSION pg_stat_statements;
SET pg_stat_statements.track_utility = FALSE;
SET pg_stat_statements.track_planning = TRUE;
SELECT pg_stat_statements_reset();
--
-- simple and compound statements
--
SELECT 1 AS "int";
SELECT 'hello'
-- multiline
AS "text";
SELECT 'world' AS "text";
-- transaction
BEGIN;
SELECT 1 AS "int";
SELECT 'hello' AS "text";
COMMIT;
-- compound transaction
BEGIN \;
SELECT 2.0 AS "float" \;
SELECT 'world' AS "text" \;
COMMIT;
-- compound with empty statements and spurious leading spacing
\;\; SELECT 3 + 3 \;\;\; SELECT ' ' || ' !' \;\; SELECT 1 + 4 \;;
-- non ;-terminated statements
SELECT 1 + 1 + 1 AS "add" \gset
SELECT :add + 1 + 1 AS "add" \;
SELECT :add + 1 + 1 AS "add" \gset
-- set operator
SELECT 1 AS i UNION SELECT 2 ORDER BY i;
-- ? operator
select '{"a":1, "b":2}'::jsonb ? 'b';
-- cte
WITH t(f) AS (
VALUES (1.0), (2.0)
)
SELECT f FROM t ORDER BY f;
-- prepared statement with parameter
PREPARE pgss_test (int) AS SELECT $1, 'test' LIMIT 1;
EXECUTE pgss_test(1);
DEALLOCATE pgss_test;
SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
SELECT pg_stat_statements_reset();
-- normalization of constants and parameters, with constant locations
-- recorded one or more times.
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
SELECT WHERE '1' IN ('1'::int, '3'::int::text);
SELECT WHERE (1, 2) IN ((1, 2), (2, 3));
SELECT WHERE (3, 4) IN ((5, 6), (8, 7));
SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
--
-- queries with locking clauses
--
CREATE TABLE pgss_a (id integer PRIMARY KEY);
CREATE TABLE pgss_b (id integer PRIMARY KEY, a_id integer REFERENCES pgss_a);
SELECT pg_stat_statements_reset();
-- control query
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id;
-- test range tables
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_a;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_b;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_a, pgss_b; -- matches plain "FOR UPDATE"
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_b, pgss_a;
-- test strengths
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR NO KEY UPDATE;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR SHARE;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR KEY SHARE;
-- test wait policies
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE NOWAIT;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE SKIP LOCKED;
SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C";
DROP TABLE pgss_a, pgss_b CASCADE;
--
-- access to pg_stat_statements_info view
--
SELECT pg_stat_statements_reset();
SELECT dealloc FROM pg_stat_statements_info;
-- FROM [ONLY]
CREATE TABLE tbl_inh(id integer);
CREATE TABLE tbl_inh_1() INHERITS (tbl_inh);
INSERT INTO tbl_inh_1 SELECT 1;
SELECT * FROM tbl_inh;
SELECT * FROM ONLY tbl_inh;
SELECT COUNT(*) FROM pg_stat_statements WHERE query LIKE '%FROM%tbl_inh%';
-- WITH TIES
CREATE TABLE limitoption AS SELECT 0 AS val FROM generate_series(1, 10);
SELECT *
FROM limitoption
WHERE val < 2
ORDER BY val
FETCH FIRST 2 ROWS WITH TIES;
SELECT *
FROM limitoption
WHERE val < 2
ORDER BY val
FETCH FIRST 2 ROW ONLY;
SELECT COUNT(*) FROM pg_stat_statements WHERE query LIKE '%FETCH FIRST%';
-- GROUP BY [DISTINCT]
SELECT a, b, c
FROM (VALUES (1, 2, 3), (4, NULL, 6), (7, 8, 9)) AS t (a, b, c)
GROUP BY ROLLUP(a, b), rollup(a, c)
ORDER BY a, b, c;
SELECT a, b, c
FROM (VALUES (1, 2, 3), (4, NULL, 6), (7, 8, 9)) AS t (a, b, c)
GROUP BY DISTINCT ROLLUP(a, b), rollup(a, c)
ORDER BY a, b, c;
SELECT COUNT(*) FROM pg_stat_statements WHERE query LIKE '%GROUP BY%ROLLUP%';
-- GROUPING SET agglevelsup
SELECT (
SELECT (
SELECT GROUPING(a,b) FROM (VALUES (1)) v2(c)
) FROM (VALUES (1,2)) v1(a,b) GROUP BY (a,b)
) FROM (VALUES(6,7)) v3(e,f) GROUP BY ROLLUP(e,f);
SELECT (
SELECT (
SELECT GROUPING(e,f) FROM (VALUES (1)) v2(c)
) FROM (VALUES (1,2)) v1(a,b) GROUP BY (a,b)
) FROM (VALUES(6,7)) v3(e,f) GROUP BY ROLLUP(e,f);
SELECT COUNT(*) FROM pg_stat_statements WHERE query LIKE '%SELECT GROUPING%';
SELECT pg_stat_statements_reset();