RE: Fix for segfault in logical replication on master

On Thursday, June 17, 2021 1:31 PM Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com> wrote:
> In commit e7eea52b2d, you introduced a new function,
> RelationGetIdentityKeyBitmap(), which uses some odd logic for determining
> if a relation has a replica identity index. That code segfaults under certain
> conditions. A test case to demonstrate that is attached. Prior to patching
> the code, this new test gets stuck waiting for replication to finish, which never
> happens. You have to break out of the test and check
> tmp_check/log/021_no_replica_identity_publisher.log.
>
> I believe this bit of logic in src/backend/utils/cache/relcache.c:
>
> indexDesc = RelationIdGetRelation(relation->rd_replidindex);
> for (i = 0; i < indexDesc->rd_index->indnatts; i++)
>
> is unsafe without further checks, also attached.
>
> Would you mind taking a look?
Hi, Mark

Thanks for your reporting.
I started to analyze your report and
will reply after my idea to your modification is settled.

Best Regards,
Takamichi Osumi