| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Euler Taveira de Oliveira <euler(at)timbira(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: wal_buffers |
| Date: | 2012-02-19 18:33:11 |
| Message-ID: | 28916.1329676391@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Sun, Feb 19, 2012 at 9:46 AM, Euler Taveira de Oliveira
> <euler(at)timbira(dot)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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