Thread: pgsql: Test decoding of two-phase transactions during the build of a co
Test decoding of two-phase transactions during the build of a consistent snapshot. Commit a271a1b50e added the capability to allow decoding at prepare time. This adds an isolation testcase to test that decoding happens at commit time when the consistent snapshot state is reached after prepare but before commit prepared. Author: Ajin Cherian Reviewed-by: Amit Kapila Discussion: https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru https://postgr.es/m/CAMGcDxeqEpWj3fTXwqhSwBdXd2RS9jzwWscO-XbeCfso6ts3+Q@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/5a3574d7b33480de51692962e6fd25d00c05718a Modified Files -------------- contrib/test_decoding/Makefile | 3 +- .../test_decoding/expected/twophase_snapshot.out | 41 +++++++++++++++++ contrib/test_decoding/specs/twophase_snapshot.spec | 53 ++++++++++++++++++++++ 3 files changed, 96 insertions(+), 1 deletion(-)
Amit Kapila <akapila@postgresql.org> writes: > Test decoding of two-phase transactions during the build of a consistent snapshot. It seems this test case isn't 100% stable: https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=chipmunk&dt=2021-01-08%2023%3A56%3A57 ========================== output_iso/regression.diffs ================ diff -U3 /home/pgbfarm/buildroot/HEAD/pgsql.build/contrib/test_decoding/expected/twophase_snapshot.out /home/pgbfarm/buildroot/HEAD/pgsql.build/contrib/test_decoding/output_iso/results/twophase_snapshot.out --- /home/pgbfarm/buildroot/HEAD/pgsql.build/contrib/test_decoding/expected/twophase_snapshot.out 2021-01-07 02:49:30.231809843+0200 +++ /home/pgbfarm/buildroot/HEAD/pgsql.build/contrib/test_decoding/output_iso/results/twophase_snapshot.out 2021-01-0904:01:26.730510078 +0200 @@ -26,6 +26,8 @@ data BEGIN +COMMIT +BEGIN table public.do_write: INSERT: id[integer]:2 COMMIT step s2cp: COMMIT PREPARED 'test1'; @@ -33,6 +35,10 @@ data BEGIN +COMMIT +BEGIN +COMMIT +BEGIN table public.do_write: INSERT: id[integer]:1 PREPARE TRANSACTION 'test1' COMMIT PREPARED 'test1' I think we've seen this extra-transactions symptom before, but I don't recall the details at this late hour. regards, tom lane
On Sat, Jan 9, 2021 at 11:17 AM Tom Lane <tgl@sss.pgh.pa.us> wrote: > > Amit Kapila <akapila@postgresql.org> writes: > > Test decoding of two-phase transactions during the build of a consistent snapshot. > > It seems this test case isn't 100% stable: > > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=chipmunk&dt=2021-01-08%2023%3A56%3A57 > > ========================== output_iso/regression.diffs ================ > diff -U3 /home/pgbfarm/buildroot/HEAD/pgsql.build/contrib/test_decoding/expected/twophase_snapshot.out /home/pgbfarm/buildroot/HEAD/pgsql.build/contrib/test_decoding/output_iso/results/twophase_snapshot.out > --- /home/pgbfarm/buildroot/HEAD/pgsql.build/contrib/test_decoding/expected/twophase_snapshot.out 2021-01-07 02:49:30.231809843+0200 > +++ /home/pgbfarm/buildroot/HEAD/pgsql.build/contrib/test_decoding/output_iso/results/twophase_snapshot.out 2021-01-0904:01:26.730510078 +0200 > @@ -26,6 +26,8 @@ > data > > BEGIN > +COMMIT > +BEGIN > table public.do_write: INSERT: id[integer]:2 > COMMIT > step s2cp: COMMIT PREPARED 'test1'; > @@ -33,6 +35,10 @@ > data > > BEGIN > +COMMIT > +BEGIN > +COMMIT > +BEGIN > table public.do_write: INSERT: id[integer]:1 > PREPARE TRANSACTION 'test1' > COMMIT PREPARED 'test1' > > I think we've seen this extra-transactions symptom before, > but I don't recall the details at this late hour. > I'll look into it. -- With Regards, Amit Kapila.
On Sat, Jan 9, 2021 at 12:18 PM Amit Kapila <amit.kapila16@gmail.com> wrote: > > On Sat, Jan 9, 2021 at 11:17 AM Tom Lane <tgl@sss.pgh.pa.us> wrote: > > > > > > I think we've seen this extra-transactions symptom before, > > but I don't recall the details at this late hour. > > > > I'll look into it. > I think I know whats going on here. I have responded to the thread on pgsql-hackers [1]. [1] - https://www.postgresql.org/message-id/CAA4eK1J5onGc-sHLj3moS247rJK6KpvM_wAfiOHs6YFnHHs3%2Bw%40mail.gmail.com -- With Regards, Amit Kapila.
Amit Kapila <amit.kapila16@gmail.com> writes:
> I think I know whats going on here. I have responded to the thread on
> pgsql-hackers [1].
Ah, yeah, the autovacuum theory fits the facts: chipmunk is pretty
slow, and it's not failed 100% of the time.
regards, tom lane
On Sat, Jan 9, 2021 at 1:09 PM Tom Lane <tgl@sss.pgh.pa.us> wrote: > > Amit Kapila <amit.kapila16@gmail.com> writes: > > I think I know whats going on here. I have responded to the thread on > > pgsql-hackers [1]. > > Ah, yeah, the autovacuum theory fits the facts: chipmunk is pretty > slow, and it's not failed 100% of the time. > I have pushed the fix. It is difficult to reproduce the exact case but I have reproduced it with a parallel empty xact and pushed the fix. -- With Regards, Amit Kapila.