Re: BUG #19420: Zombie FK exists after partition is detached.

I'm thinking about that too, but I wanted to make sure there wasn't a
better solution first.

pt., 27 lut 2026 o 15:45 Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> napisał(a):

> On Fri, 2026-02-27 at 09:09 +0000, PG Bug reporting form wrote:
> > Logged by: Agnieszka Chodkowska
> > PostgreSQL version: 16.6
> > Operating system: Linux, Debian 12.2.0 64 bit
> >
> > I have child table with FK defined as folllows
> >
> > ALTER TABLE IF EXISTS tst.child_test_1
> > ADD CONSTRAINT child_test_1_parent_id_parent_part_by_fkey FOREIGN KEY
> > (parent_id, parent_part_by)
> > REFERENCES tst.maintenance_test_1_p20260218 (id, part_by) MATCH
> SIMPLE
> > ON UPDATE NO ACTION
> > ON DELETE CASCADE;
>
> This is a table partition with a foreign key to another table partition,
> correct?
>
> > I updated configuration according to documentation as follows:
> > retention_keep_table=false ,
> > retention_keep_index = false
>
> These are not PostgreSQL configuration parameters...
>
> > Somehow postgresql retains the foreign keys of the detached/dropped
> > partitions, to the parent table partitions.
>
> That is as expected. partitions are tables in their own right and can
> entertain foreign key constraints to other tables, independent of their
> role as partitions of a partitioned table.
>
> > I try the following methods:
> > partman.run_maintenance('tst.child_test_1')
> > partman.run_maintenance()
> > ALTER TABLE tst.child_test_1 DETACH PARTITION <child_test_p_20260218>
> >
> > The error persisted regardless of the method used.
>
> I'd say that you have to drop the foreign key constraint explicitly.
>
> Yours,
> Laurenz Albe
>

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