Re: Proposed patch: Smooth replication during VACUUM FULL

From: Gabriele Bartolini <gabriele(dot)bartolini(at)2ndQuadrant(dot)it>
To: Simon Riggs <simon(at)2ndQuadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Stark <gsstark(at)mit(dot)edu>, Jaime Casanova <jaime(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Proposed patch: Smooth replication during VACUUM FULL
Date: 2011-05-02 17:15:11
Message-ID: 4DBEE69F.9010602@2ndQuadrant.it
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Il 02/05/11 18:20, Simon Riggs ha scritto:
> I'm sure Gabriele can add those things as well - that also looks like
> another 1 line change.

Yes, today we have performed some tests with that patch as well
(attached is version 2). The version 2 of the patch (which includes the
change Tom suggested on Saturday), smooths the process even more.

You can look at the attached graph for now - even though we are
currently relaunching a test with all 3 different versions from scratch
(unpatched, patch v1 and patch v2), with larger data in order to confirm
this behaviour.

> I'm just observing that the patch as-is appears effective and I feel
> it is important.

Exactly. One thing also important to note as well is that with the
vacuum delay being honoured, "vacuum full" operations in a SyncRep
scenario take less time as well - as the load is more distributed over time.

You can easily spot in the graphs the point where VACUUM FULL
terminates, then it is just a matter of flushing the WAL delay for
replication.

Anyway, I hope I can give you more detailed information tomorrow. Thanks.

Cheers,
Gabriele

--
Gabriele Bartolini - 2ndQuadrant Italia
PostgreSQL Training, Services and Support
gabriele(dot)bartolini(at)2ndQuadrant(dot)it | www.2ndQuadrant.it

Attachment Content-Type Size
image/png 9.3 KB
vacuum_full_delay-v2.patch text/plain 692 bytes

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