Re: Proposed patch: Smooth replication during VACUUM FULL

Gabriele Bartolini <gabriele.bartolini@2ndquadrant.it>

From: Gabriele Bartolini <gabriele.bartolini@2ndQuadrant.it>

To: Simon Riggs <simon@2ndQuadrant.com>

Cc: Tom Lane <tgl@sss.pgh.pa.us>, Greg Stark <gsstark@mit.edu>, Jaime Casanova <jaime@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>

Date: 2011-05-02T17:15:11Z

Lists: pgsql-hackers

Attachments

vacuum_full_delay-v2.png (image/png)
vacuum_full_delay-v2.patch (text/plain) patch v2

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
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