From: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Thom Brown <thom(at)linux(dot)com>, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de> |
Subject: | Re: Proposal: "Causal reads" mode for load balancing reads without stale data |
Date: | 2016-03-29 21:47:53 |
Message-ID: | CAEepm=1C0tZKKFscPDN_4N2YuKfZ-7Z=DsL3xoiAXhdNFS6LSQ@mail.gmail.com |
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Lists: | pgsql-hackers |
On Wed, Mar 30, 2016 at 6:04 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Tue, Mar 29, 2016 at 3:17 AM, Michael Paquier
> <michael(dot)paquier(at)gmail(dot)com> wrote:
>> OK, so I am switching this patch as "Ready for committer", for 0001.
>> It is in better shape now.
>
> Well... I have a few questions yet.
>
> The new argument to SyncRepWaitForLSN is called "bool commit", but
> RecordTransactionAbortPrepared passes true. Either it should be
> passing false, or the parameter is misnamed or at the least in need of
> a better comment.
>
> I don't understand why this patch is touching the abort paths at all.
> XactLogAbortRecord sets XACT_COMPLETION_SYNC_APPLY_FEEDBACK, and
> xact_redo_abort honors it. But surely it makes no sense to wait for
> an abort to become visible.
You're right, that was totally unnecessary. Here is a version that
removes that (ie XactLogAbortRecord doesn't request apply feedback
from the standby, xact_redo_abort doesn't send apply feedback to the
primary and RecordTransactionAbortPrepared now passes false to
SyncRepWaitForLSN so it doesn't wait for apply feedback from the
standby). Also I fixed a silly bug in SyncRepWaitForLSN when capping
the mode. I have also renamed XACT_COMPLETION_SYNC_APPLY_FEEDBACK to
the more general XACT_COMPLETION_APPLY_FEEDBACK, because the later
0004 patch will use it for a more general purpose than
synchronous_commit.
--
Thomas Munro
http://www.enterprisedb.com
Attachment | Content-Type | Size |
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0001-remote-apply-v10.patch | application/octet-stream | 24.1 KB |
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