Re: BUG #16840: Rows not found in table partitioned by hash when not all partitions exists

Argh! I pasted the wrong value of volume_id in my examples. Number 1 should
be replaced with 2 so correct insert should look like this:

INSERT INTO dir (volume_id, path) VALUES
(2, 'abc'),
(2, 'def'),
(2, 'ghi');

And queries:
SELECT * FROM dir WHERE volume_id=2 AND path='abc';
SELECT * FROM dir WHERE volume_id=2 AND (path='abc' OR path='def');
SELECT * FROM dir_part_2 WHERE volume_id=2 AND (path='abc' or path='def');

Sorry for creating unnecessary confusion.

Michał Albrycht

śr., 27 sty 2021 o 18:03 PG Bug reporting form <noreply(at)postgresql(dot)org>
napisał(a):

> The following bug has been logged on the website:
>
> Bug reference: 16840
> Logged by: Michał Albrycht
> Email address: michalalbrycht(at)gmail(dot)com
> PostgreSQL version: 13.1
> Operating system: Ubuntu 18
> Description:
>
> Lets create a table partitioned by hash:
>
> CREATE TABLE dir (
> id SERIAL,
> volume_id BIGINT,
> path TEXT
> ) PARTITION BY HASH (volume_id);
>
>
> Now let's create just one partition:
>
> CREATE TABLE dir_part_2 PARTITION OF dir FOR VALUES WITH (modulus 3,
> remainder 2);
>
> Insert sample value:
>
> INSERT INTO dir (volume_id, path) VALUES
> (1, 'abc'),
> (1, 'def'),
> (1, 'ghi');
>
> Queries to verify db state:
> SELECT * FROM dir WHERE volume_id=1 AND path='abc'; -- returns 1 row - OK
> SELECT * FROM dir WHERE volume_id=1 AND (path='abc' OR path='def') --
> returns 0 rows - NOT OK!
> SELECT * FROM dir_part_2 WHERE volume_id=1 AND (path='abc' or path='def')
> --
> returns 2 rows - OK
>
> Now lets add missing partitions:
> CREATE TABLE dir_part_0 PARTITION OF dir FOR VALUES WITH (modulus 3,
> remainder 0);
> CREATE TABLE dir_part_1 PARTITION OF dir FOR VALUES WITH (modulus 3,
> remainder 1);
>
> And run problematic query one more time:
> SELECT * FROM dir WHERE volume_id=1 AND (path='abc' OR path='def') --
> returns 2 rows - OK
>
>
> So Postgres silently fails to find a rows, and does not throw any error
> when
> not all hash partitions are present.
>
>