Re: Broken O(n^2) avoidance in wal segment recycling.

From: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Broken O(n^2) avoidance in wal segment recycling.
Date: 2017-06-23 06:25:38
Message-ID: CAB7nPqQPrFefK2fj8Y0WSG4rf9LaigD0ithEeabtb2fvhDQ3+g@mail.gmail.com
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On Thu, Jun 22, 2017 at 6:10 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> We've not heard any complaints about this afaik, but it's not something
> that's easily diagnosable as being a problem. Therefore I suspect we
> should fix and backpatch this?

Agreed. I have just poked at this problem and have finished with the
attached. Logically it is not complicated at the argument values used
by the callers of RemoveXlogFile() are never updated when scanning
pg_wal. Surely this patch needs an extra pair of eyes.
--
Michael

Attachment Content-Type Size
fix-wal-recycle-perf.patch text/x-patch 4.6 KB

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