On Mon, Jun 13, 2022 at 8:29 AM Masahiko Sawada <sawada.m...@gmail.com> wrote: > > On Tue, Jun 7, 2022 at 9:32 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > On Mon, May 30, 2022 at 11:13 AM Masahiko Sawada <sawada.m...@gmail.com> > > wrote: > > > > > > On Wed, May 25, 2022 at 12:11 PM Masahiko Sawada <sawada.m...@gmail.com> > > > wrote: > > > > > > > > > > poc_add_regression_tests.patch adds regression tests for this bug. The > > > regression tests are required for both HEAD and back-patching but I've > > > separated this patch for testing the above two patches easily. > > > > > Thank you for the comments. > > > > > Few comments on the test case patch: > > =============================== > > 1. > > +# For the transaction that TRUNCATEd the table tbl1, the last decoding > > decodes > > +# only its COMMIT record, because it starts from the RUNNING_XACT > > record emitted > > +# during the first checkpoint execution. This transaction must be marked > > as > > +# catalog-changes while decoding the COMMIT record and the decoding > > of the INSERT > > +# record must read the pg_class with the correct historic snapshot. > > +permutation "s0_init" "s0_begin" "s0_savepoint" "s0_truncate" > > "s1_checkpoint" "s1_get_changes" "s0_commit" "s0_begin" "s0_insert" > > "s1_checkpoint" "s1_get_changes" "s0_commit" "s1_get_changes" > > > > Will this test always work? What if we get an additional running_xact > > record between steps "s0_commit" and "s0_begin" that is logged via > > bgwriter? You can mimic that by adding an additional checkpoint > > between those two steps. If we do that, the test will pass even > > without the patch because I think the last decoding will start > > decoding from this new running_xact record. > > Right. It could pass depending on the timing but doesn't fail > depending on the timing. I think we need to somehow stop bgwriter to > make the test case stable but it seems unrealistic. >
Agreed, in my local testing for this case, I use to increase LOG_SNAPSHOT_INTERVAL_MS to avoid such a situation but I understand it is not practical via test. > Do you have any > better ideas? > No, I don't have any better ideas. I think it is better to add some information related to this in the comments because it may help to improve the test in the future if we come up with a better idea. -- With Regards, Amit Kapila.
