> As Greg commented upthread, we seem to be getting forced to the > conclusion that the initial buffer scan in BufferSync() is somehow > causing this. There are a couple of things it'd be useful to try > here: > > * see how the size of the hiccup varies with shared_buffers; I tried decreasing shared buffers - both 25MB and 50MB were too small for my load - I had slow queries at all times. So then I increased it from what I was using - 100MB - to 500MB - and the hiccup roughly doubles in length. At 100MB, the hiccup is about 2-3 seconds long. At 500MB, the hiccup is about 6 seconds long. > > * try inserting a delay into that scan loop, as per attached > quick-and-dirty patch. (Numbers pulled from the air, but > we can worry about tuning after we see if this is really > where the problem is.) > After finally getting this particular system into a state where I could build postgres (I was using the binary install) I built a 8.3.4, using your patch - but I didn't see any change in the behaviour. I see hiccups that appear to be the same length as I saw on the binary build of 8.3.4. Thanks, Dan -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
