Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions - Mailing list pgsql-hackers

On Mon, Jul 6, 2020 at 11:31 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Sun, Jul 5, 2020 at 4:47 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> >
> > On Sat, Jul 4, 2020 at 11:35 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > >
> >
> > > 9.
> > > +ReorderBufferHandleConcurrentAbort(ReorderBuffer *rb, ReorderBufferTXN *txn,
> > > {
> > > ..
> > > + ReorderBufferToastReset(rb, txn);
> > > + if (specinsert != NULL)
> > > + ReorderBufferReturnChange(rb, specinsert);
> > > ..
> > > }
> > >
> > > Why do we need to do these here when we wouldn't have been done for
> > > any exception other than ERRCODE_TRANSACTION_ROLLBACK?
> >
> > Because we are handling this exception "ERRCODE_TRANSACTION_ROLLBACK"
> > gracefully and we are continuing with further decoding so we need to
> > return this change back.
> >
>
> Okay, then I suggest we should do these before calling stream_stop and
> also move ReorderBufferResetTXN after calling stream_stop  to follow a
> pattern similar to try block unless there is a reason for not doing
> so.  Also, it would be good if we can initialize specinsert with NULL
> after returning the change as we are doing at other places.

Okay

> > > 10.  I have got the below failure once.  I have not investigated this
> > > in detail as the patch is still under progress.  See, if you have any
> > > idea?
> > > #   Failed test 'check extra columns contain local defaults'
> > > #   at t/013_stream_subxact_ddl_abort.pl line 81.
> > > #          got: '2|0'
> > > #     expected: '1000|500'
> > > # Looks like you failed 1 test of 2.
> > > make[2]: *** [check] Error 1
> > > make[1]: *** [check-subscription-recurse] Error 2
> > > make[1]: *** Waiting for unfinished jobs....
> > > make: *** [check-world-src/test-recurse] Error 2
> >
> > Even I got the failure once and after that, it did not reproduce.  I
> > have executed it multiple time but it did not reproduce again.  Are
> > you able to reproduce it consistently?
> >
>
> No, I am also not able to reproduce it consistently but I think this
> can fail if a subscriber sends the replay_location before actually
> replaying the changes.  First, I thought that extra send_feedback we
> have in apply_handle_stream_commit might have caused this but I guess
> that can't happen because we need the commit time location for that
> and we are storing the same at the end of apply_handle_stream_commit
> after applying all messages.  I am not sure what is going on here.  I
> think we somehow need to reproduce this or some variant of this test
> consistently to find the root cause.

And I think it appeared first time for me,  so maybe either induced
from past few versions so some changes in the last few versions might
have exposed it.  I have noticed that almost 50% of the time I am able
to reproduce after the clean build so I can trace back from which
version it started appearing that way it will be easy to narrow down.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com