Re: logical replication worker accesses catalogs in error context callback

On Sat, Jan 30, 2021 at 8:23 AM Andres Freund <andres@anarazel.de> wrote:
>
> Hi,
>
> On 2021-01-28 11:14:03 +0530, Amit Kapila wrote:
> > On Wed, Jan 27, 2021 at 9:38 AM Bharath Rupireddy
> > <bharath.rupireddyforpostgres@gmail.com> wrote:
> > >
> > > On Wed, Jan 27, 2021 at 7:48 AM Zhihong Yu <zyu@yugabyte.com> wrote:
> > >
> > > Thanks for pointing to the changes in the commit message. I corrected
> > > them. Attaching v4 patch set, consider it for further review.
> > >
> >
> > About 0001, have we tried to reproduce the actual bug here which means
> > when the error_callback is called we should face some problem? I feel
> > with the correct testcase we should hit the Assert
> > (Assert(IsTransactionState());) in SearchCatCacheInternal because
> > there we expect the transaction to be in a valid state. I understand
> > that the transaction is in a broken state at that time but having a
> > testcase to hit the actual bug makes it easy to test the fix.
>
> I think it's easy to hit - add a trivial DEBUG message to XLogWrite(),
> and run anything involving logical rep using a low enough log
> level. There might even be enough messages with a low enough level
> already somewhere in the relevant paths.

I'm not sure how adding a DEBUG message to XLogWrite() would ensure
the logical replication worker on the subscriber system enters
slot_store_error_callback and hits the Assert(IsTransactionState());?
Could you please elaborate? Or I may be missing something here to
understand.

With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com