Re: Cannot dump foreign key constraints on partitioned table

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: amul sul <sulamul(at)gmail(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Cannot dump foreign key constraints on partitioned table
Date: 2018-07-12 03:48:14
Message-ID: 20180712034814.GB7352@paquier.xyz
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On Wed, Jul 11, 2018 at 03:49:59PM +0530, amul sul wrote:
> On the master head, getConstraints() function skips FK constraints for
> a partitioned table because of tbinfo->hastriggers is false.
>
> While creating FK constraints on the partitioned table, the FK triggers are only
> created on leaf partitions and skipped for the partitioned tables.

Oops. Good catch.

> To fix this, either bypass the aforementioned condition of getConstraints() or
> set pg_class.relhastriggers to true for the partitioned table which doesn't seem
> to be the right solution, IMO. Thoughts?

Changing pg_class.relhastriggers is out of scope because as far as I
know partitioned tables have no triggers, so the current value is
correct, and that would be a catalog change at this stage which would
cause any existing deployments of v11 to complain about the
inconsistency. I think that this should be fixed client-side as the
attached does.

I have just stolen this SQL set from Alvaro to check the consistency of
the dumps created:
create table prim (a int primary key);
create table partfk (a int references prim) partition by range (a);
create table partfk1 partition of partfk for values from (0) to (100);
create table partfk2 partition of partfk for values from (100) to (200);

Thoughts?
--
Michael

Attachment Content-Type Size
dump-partition-fk.patch text/x-diff 636 bytes

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