Re: pg_restore causing deadlocks on partitioned tables

On Tue, Sep 15, 2020 at 7:28 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I wrote:
> > However, the deadlock report suggests, and manual experimentation
> > confirms, that
>
> > (1) TRUNCATE on a partition tries to get AccessShareLock on the parent;
>
> The reason for this is that
>
> (a) ExecuteTruncateGuts calls InitResultRelInfo, because it might
> need that to fire TRUNCATE triggers for the child relation.
>
> (b) InitResultRelInfo calls RelationGetPartitionQual, which
> of course(?) must access the parent table.
>
> AFAICS, it is utterly silly for InitResultRelInfo to be forcing
> a partition qual to be computed when we might not need it.
> We could flush ResultRelInfo.ri_PartitionCheck altogether and
> have anything that was reading it instead do
> RelationGetPartitionQual(ResultRelInfo.ri_RelationDesc).
>
> Actually it looks like most of the places reading it are
> just interested in non-nullness; can't those be nuked from
> orbit in favor of testing rel->rd_rel->relispartition?

Yeah, makes sense. Please see attached a patch to do that.

--
Amit Langote
EnterpriseDB: http://www.enterprisedb.com