Re: ERROR: subtransaction logged without previous top-level txn record - Mailing list pgsql-bugs

From Arseny Sher
Subject Re: ERROR: subtransaction logged without previous top-level txn record
Date
Msg-id 87lfp9u4kp.fsf@ars-thinkpad
Whole thread Raw
In response to Re: ERROR: subtransaction logged without previous top-level txn record  (Amit Kapila <amit.kapila16@gmail.com>)
Responses Re: ERROR: subtransaction logged without previous top-level txn record
Re: ERROR: subtransaction logged without previous top-level txn record
List pgsql-bugs
Amit Kapila <amit.kapila16@gmail.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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