Re: REL_12_STABLE crashing with assertion failure in ExtractReplicaIdentity

I wrote:
> As far as 4) goes, I think the code in ExtractReplicaIdentity is pretty
> duff anyway, because it doesn't bother to check for the defined failure
> return for RelationIdGetRelation. But if we're concerned about the
> cost of recalculating this stuff per-row, couldn't we cache it a little
> better? It should be safe to assume the set of index columns isn't
> changing intra-query.
> ... in fact, isn't all the infrastructure for that present already?
> Why is this code looking directly at the index at all, rather than
> using the relcache's rd_idattr bitmap?

Here's a proposed patch along those lines. It fixes Hadi's original
crash case and passes check-world.

I'm a bit suspicious of the exclusion for idattrs being empty, but
if I remove that, some of the contrib/test_decoding test results
change. Anybody want to comment on that? If that's actually an
expected situation, why is there an elog(DEBUG) in that path?

regards, tom lane