On Jul 7, 2012, at 8:54 AM, Magnus Hagander <mag...@hagander.net> wrote: > On Sat, Jul 7, 2012 at 3:52 PM, Robert Haas <robertmh...@gmail.com> wrote: >> On Jul 7, 2012, at 9:07 AM, Euler Taveira <eu...@timbira.com> wrote: >>> On 07-07-2012 09:00, Satoshi Nagayasu wrote: >>>> I've created new patch to get/reset statistics of WAL buffer >>>> writes (flushes) caused by WAL buffer full. >>>> >>> This new statistic doesn't solve your problem (tune wal_buffers). It doesn't >>> give you the wal_buffers value. It only says "hey, I needed more buffers so >>> I >>> write those dirty ones". It doesn't say how many. I would like to have >>> something that says "hey, you have 1000 buffers available and you are using >>> 100 buffers (10%)". This new statistic is only useful for decreasing the >>> WALWriteLock contention. >> >> The number of WAL buffers that you are using is going to change so quickly >> as to be utterly meaningless. I don't really see that there's any statistic >> we could gather that would tell us how many WAL buffers are needed. This >> patch seems like it's on the right track, at least telling you how often >> you're running out. > > We could keep a high watermark of "what's the largest percentage we've > used", perhaps?
Sure, but I doubt that would be as informative as this. It's no big deal if you hit 100% every once in a while; what you really want to know is whether it's happening once per second or once per week. ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
