Re: wal_buffers - Mailing list pgsql-hackers

From Tom Lane
Subject Re: wal_buffers
Date
Msg-id 28916.1329676391@sss.pgh.pa.us
Whole thread Raw
In response to Re: wal_buffers  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: wal_buffers  (Simon Riggs <simon@2ndQuadrant.com>)
List pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> On Sun, Feb 19, 2012 at 9:46 AM, Euler Taveira de Oliveira
> <euler@timbira.com> wrote:
>> Isn't it useful to print some messages on the log when we have "wrap around"?
>> In this case, we have an idea that wal_buffers needs to be increased.

> I was thinking about that.  I think that what might be more useful
> than a log message is a counter somewhere in shared memory.  Logging
> imposes a lot of overhead, which is exactly what we don't want here,
> and the volume might be quite high on a system that is bumping up
> against this problem.  Of course then the question is... how would we
> expose the counter value?

Why do you need a counter, other than the current LSN?  Surely the
number of WAL buffer ring cycles can be deduced directly from that.
        regards, tom lane


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