Re: BUG #18402: Attaching a new partition doesn't reuse the prebuilt index on said partition

Hello,

is there a week retention before this report is delivered to the mailing list ?

Regards
Gilles

----- Mail original -----
> De: "PG Bug reporting form" <noreply(at)postgresql(dot)org>
> À: "pgsql-bugs" <pgsql-bugs(at)lists(dot)postgresql(dot)org>
> Cc: "gparc" <gparc(at)online(dot)fr>
> Envoyé: Mercredi 20 Mars 2024 15:29:14
> Objet: BUG #18402: Attaching a new partition doesn't reuse the prebuilt index on said partition

> The following bug has been logged on the website:
>
> Bug reference: 18402
> Logged by: Gilles PARC
> Email address: gparc(at)online(dot)fr
> PostgreSQL version: 16.2
> Operating system: Linux
> Description:
>
> Example :
>
> First I create a list partitioned table and fill it
> CREATE TABLE master
> (
> id integer NOT NULL,
> millesime varchar(4) NOT NULL,
> CONSTRAINT master_pk PRIMARY KEY (id, millesime)
> ) partition by list (millesime);
>
> CREATE TABLE master_2022 PARTITION OF master FOR VALUES IN ('2022');
> CREATE TABLE master_2023 PARTITION OF master FOR VALUES IN ('2023');
> CREATE TABLE master_2024 PARTITION OF master FOR VALUES IN ('2024');
> CREATE TABLE master_2025 PARTITION OF master FOR VALUES IN ('2025');
>
> DO
> $do$
> BEGIN
> FOR i IN 2022..2025 LOOP
> INSERT INTO master VALUES (generate_series(1,100000), i::varchar);
> END LOOP;
> END
> $do$;
>
> I now list the created indexes:
> \diS+ master*
> List of relations
> Schema | Name | Type | Owner | Table |
> Persistence | Access method | Size | Description
> --------+------------------+-------------------+----------+-------------+-------------+---------------+---------+-------------
> public | master_2022_pkey | index | postgres | master_2022 |
> permanent | btree | 3088 kB |
> public | master_2023_pkey | index | postgres | master_2023 |
> permanent | btree | 3088 kB |
> public | master_2024_pkey | index | postgres | master_2024 |
> permanent | btree | 3088 kB |
> public | master_2025_pkey | index | postgres | master_2025 |
> permanent | btree | 3088 kB |
> public | master_pk | partitioned index | postgres | master |
> permanent | btree | 0 bytes |
> (5 rows)
>
>
> Now I prepare a new 2026 partition with correct constraints and indexes and
> attach it :
>
> CREATE TABLE master_2026 (LIKE master INCLUDING DEFAULTS INCLUDING
> CONSTRAINTS);
> ALTER TABLE master_2026 ADD CONSTRAINT master_2026_ck CHECK (millesime =
> '2026');
> DO
> $do$
> BEGIN
> INSERT INTO master_2026 VALUES (generate_series(1,100000), '2026');
> END
> $do$;
> CREATE UNIQUE INDEX CONCURRENTLY master_2026_pkey ON master_2026 (id,
> millesime);
> ALTER TABLE master ATTACH PARTITION master_2026 FOR VALUES IN ('2026');
> ALTER TABLE master_2026 DROP CONSTRAINT master_2026_ck;
>
> But now, when I list the indexes again, I see that my unique index above is
> not considered to use
> and a new one is created (master_2026_pkey1).
> \diS+ master*
> Schema | Name | Type | Owner | Table |
> Persistence | Access method | Size | Description
> --------+-------------------+-------------------+----------+-------------+-------------+---------------+---------+-------------
> public | master_2022_pkey | index | postgres | master_2022 |
> permanent | btree | 3088 kB |
> public | master_2023_pkey | index | postgres | master_2023 |
> permanent | btree | 3088 kB |
> public | master_2024_pkey | index | postgres | master_2024 |
> permanent | btree | 3088 kB |
> public | master_2025_pkey | index | postgres | master_2025 |
> permanent | btree | 3088 kB |
> public | master_2026_pkey | index | postgres | master_2026 |
> permanent | btree | 3104 kB |
> public | master_2026_pkey1 | index | postgres | master_2026 |
> permanent | btree | 3104 kB |
> public | master_pk | partitioned index | postgres | master |
> permanent | btree | 0 bytes |
> (7 rows)
>
> why is it so ?
>
> Bug or Feature ?
> Regards
> Gilles