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Make query jumbling also squash PARAM_EXTERN params

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Commit 62d712ecfd made query jumbling squash lists of Consts as a
single element, but there's no reason not to treat PARAM_EXTERN
parameters the same.  For these purposes, these values are indeed
constants for any particular execution of a query.

In particular, this should make list squashing more useful for
applications using extended query protocol, which would use parameters
extensively.

A complication arises: if a query has both external parameters and
squashable lists, then the parameter number used as placeholder for the
squashed list might be inconsistent with regards to the parameter
numbers used by the query literal.  To reduce the surprise factor, all
parameters are renumbered starting from 1 in that case.

Author: Sami Imseih <samimseih@gmail.com>
Author: Dmitry Dolgov <9erthalion6@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAA5RZ0tRXoPG2y6bMgBCWNDt0Tn=unRerbzYM=oW0syi1=C1OA@mail.gmail.com
This commit is contained in:
Álvaro Herrera
2025-06-24 19:36:32 +02:00
parent debad29d22
commit c2da1a5d63
8 changed files with 199 additions and 99 deletions
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11
contrib/pg_stat_statements/sql/extended.sql
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@ -21,17 +21,26 @@ SELECT $1 \bind 'unnamed_val1' \g
SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
-- Various parameter numbering patterns
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
-- Unique query IDs with parameter numbers switched.
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
SELECT WHERE ($1::int, 7) IN ((8, $2::int), ($3::int, 9)) \bind '1' '2' '3' \g
SELECT WHERE ($2::int, 10) IN ((11, $3::int), ($1::int, 12)) \bind '1' '2' '3' \g
SELECT WHERE $1::int IN ($2::int, $3::int) \bind '1' '2' '3' \g
SELECT WHERE $2::int IN ($3::int, $1::int) \bind '1' '2' '3' \g
SELECT WHERE $3::int IN ($1::int, $2::int) \bind '1' '2' '3' \g
SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
-- Two groups of two queries with the same query ID.
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
SELECT WHERE '1'::int IN ($1::int, '2'::int) \bind '1' \g
SELECT WHERE '4'::int IN ($1::int, '5'::int) \bind '2' \g
SELECT WHERE $2::int IN ($1::int, '1'::int) \bind '1' '2' \g
SELECT WHERE $2::int IN ($1::int, '2'::int) \bind '3' '4' \g
SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
-- no squashable list, the parameters id's are kept as-is
SELECT WHERE $3 = $1 AND $2 = $4 \bind 1 2 1 2 \g
-- squashable list, so the parameter IDs will be re-assigned
SELECT WHERE 1 IN (1, 2, 3) AND $3 = $1 AND $2 = $4 \bind 1 2 1 2 \g
SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";