On Wed, Jun 9, 2021 at 12:06 AM Jeremy Schneider <schnj...@amazon.com> wrote: > > On 6/4/21 23:42, Amit Kapila wrote: > > On 2021-Jun-04, Jeremy Schneider wrote: > > ERROR: XX000: could not open relation with OID 0 > LOCATION: ReorderBufferToastReplace, reorderbuffer.c:305 > > Even, if this fixes the issue, I guess it is better to find why this > happens? I think the reason why the code is giving an error is that > after toast insertions we always expect the insert on the main table > of toast table, but if there happens to be a case where after toast > insertion, instead of getting the insertion on the main table we get > an insert in some other table then you will see this error. I think > this can happen for speculative insertions where insertions lead to a > toast table insert, then we get a speculative abort record, and then > insertion on some other table. The main thing is currently decoding > code ignores speculative aborts due to which such a problem can occur. > Now, there could be other cases where such a problem can happen but if > my theory is correct then the patch we are discussing in the thread > [1] should solve this problem. > > Jeremy, is this problem reproducible? Can we get a testcase or > pg_waldump output of previous WAL records? > > [1] - > https://www.postgresql.org/message-id/CAExHW5sPKF-Oovx_qZe4p5oM6Dvof7_P%2BXgsNAViug15Fm99jA%40mail.gmail.com > > > It's unclear to me whether or not we'll be able to catch the repro on the > actual production system. It seems that we are hitting this somewhat > consistently, but at irregular and infrequent intervals. If we are able to > catch it and walk the WAL records then I'll post back here. >
Okay, one thing you can check is if there is a usage of Insert .. On Conflict .. statement in the actual production system? > FYI, Bertrand was able to replicate the exact error message with pretty much > the same repro that's in the other email thread which is linked above. > > Separately, would there be any harm in adding the relation OID to the error > message? Personally, I just think the error message is generally more useful > if it shows the main relation OID (since we know that the toast OID can be > 0). Not a big deal though. > I don't think that is a bad idea. However, I think it might be better to propose that as a separate patch in a new thread. -- With Regards, Amit Kapila.
