On 19.04.2008, at 19:04, Scott Marlowe wrote:
No, that will certainly NOT just affect write performance; if the
postmaster is busy writing out checkpoints, that will block SELECT
queries that are accessing whatever is being checkpointed.
What I meant is if there are no INSERT's or UPDATE's going on it
shouldn't
affect SELECT queries, or am I wrong?
But checkpoints only occur every 10 seconds because of a high insert /
update rate. So, there ARE inserts and updates going on, and a lot of
them, and they are blocking your selects when checkpoint hits.
While adjusting your background writer might be called for, and might
provide you with some relief, you REALLY need to find out what's
pushing so much data into your db at once that it's causing a
checkpoint storm.
that's correct, there are nightly (at least at the moment) processes
that
insert around 2-3 mio rows and delete about the same amount. I can see
that
those 'checkpoints are occurring too frequently' messages are only
logged
during that timeframe.
I assume that it's normal that so many INSERT's and DELETE's cause the
background writer to choke a little bit. I guess I really need to
adjust the
processes to INSERT and DELETE rows in a slower pace if I want to do
other
queries during the same time.
cheers,
tom
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