From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
---|---|
To: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Patch to improve performance of replay of AccessExclusiveLock |
Date: | 2017-03-22 14:39:57 |
Message-ID: | CANP8+jJ6n12+rMrYC3xm=u8pzJG-J79ddU+u+CJ3bGknLp9qeA@mail.gmail.com |
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Lists: | pgsql-hackers |
On 22 March 2017 at 13:19, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> wrote:
>> Given that, do you agree to me applying assign_aels_against_subxids.v1.patch
>> as well?
>
> Does applying assign_aels_against_subxids.v1.patch still need to keep
> the loop to release the subxacts? Won't this be gone already with the
> subxact commit/abort record replays?
No it is still required because aborts and commits might have
subcommitted subxids.
> This does possibly mean that we perform more loops over the
> RecoveryLockList even if the subxact does not have an AELs, but its
> parent xact does. Wonder if this is a good price to pay for releasing
> the locks earlier?
We'd be performing the same number of loops as we do now. It's just
now they would have a purpose.
But we aren't doing it at all unless the top level xid has at least
one AEL, so the bulk of the problem is gone.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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