|From:||Arseny Sher <a(dot)sher(at)postgrespro(dot)ru>|
|To:||Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>|
|Cc:||Andres Freund <andres(at)anarazel(dot)de>, "Hsu\, John" <hsuchen(at)amazon(dot)com>, "pgsql-bugs\(at)lists(dot)postgresql(dot)org" <pgsql-bugs(at)lists(dot)postgresql(dot)org>|
|Subject:||Re: ERROR: subtransaction logged without previous top-level txn record|
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Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> writes:
>> Attached is raw version of isolation test triggering false
>> 'subtransaction logged without...' (case (1)).
> This didn't reproduce the desired error for me (tried without a
> patch). I think you need to add two more steps ("s2_checkpoint"
> "s2_get_changes") at the end of the test to set the restart_lsn at the
> appropriate location.
That's weird, it reliably fails with expected error for me. There are
already two s2_checkpoint's: first establishes potential (broken)
restart_lsn (serializes snapshot after first xl_xact_assignment of s0
xact, but before first record of s1 xact), the second ensures
s2_get_changes directly following it will actually advance the slot,
making that potential restart_lsn real.
I don't see how adding s2_checkpoint and s2_get_changes helps here. Do
they really provoke error in your setup? Could you check with pg_waldump
what's going on?
>> However, frankly I don't
>> see much value in it, so I'm dubious whether it should be included in
>> the patch.
> I think this will surely test some part of the system which was not
> tested before, mainly having some subxacts without top-xact getting
> decoded even though we don't need to send such a transaction. Can you
> prepare a complete patch (for
> Stop-demanding-that-top-xact-must-be-seen-before-sub) having this test
> as part of it?
Ok, will do.
-- cheers, arseny
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