Re: hyrax vs. RelationBuildPartitionDesc

I wrote:
> I recall having noticed someplace where I thought the relcache partition
> support was simply failing to make provisions for cleaning up a cached
> structure at relcache entry drop, but I didn't have time to pursue it
> right then.  Let me see if I can reconstruct what I was worried about.

Ah, here we are: it was rel->rd_partcheck.  I'm not sure exactly how
complicated that structure can be, but I'm pretty sure that this is
a laughably inadequate method of cleaning it up:

    if (relation->rd_partcheck)
        pfree(relation->rd_partcheck);

Having it be loose data in CacheMemoryContext, which is the current state
of affairs, is just not going to be practical to clean up.  I suggest that
maybe it could be copied into rd_partkeycxt or rd_pdcxt, so that it'd go
away as a byproduct of freeing those.  If there's a reason it has to be
independent of both, it'll have to have its own small context.

Dunno if that's related to hyrax's issue, though.

            regards, tom lane