Re: wal_buffers

On Mon, Feb 20, 2012 at 4:10 AM, Fujii Masao <masao.fujii@gmail.com> wrote:
> On Mon, Feb 20, 2012 at 3:08 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>> On Sun, Feb 19, 2012 at 9:46 AM, Euler Taveira de Oliveira
>> <euler@timbira.com> wrote:
>>> On 19-02-2012 02:24, Robert Haas wrote:
>>>> I have attached tps scatterplots.  The obvious conclusion appears to
>>>> be that, with only 16MB of wal_buffers, the buffer "wraps around" with
>>>> some regularity
>>>>
>>> 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?
>
> There is no existing statistics view suitable to include such information.
> What about defining pg_stat_xlog or something?

Perhaps pg_stat_perf so we don't need to find a new home every time.

Thinking about it, I think renaming pg_stat_bgwriter would make more sense.

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