doug@xxxxxxxxxxxxxxxxx (Douglas J Hunley) writes: > Subject about says it all. Should I be more concerned about checkpoints > happening 'frequently' or lasting 'longer'? In other words, is it ok to > checkpoint say, every 5 minutes, if it only last a second or three or better > to have checkpoints every 10 minutes that last half a minute? Stupid examples > probably, but you get my point I hope :) Well, with the (new-in-8.1) background writer, you should be able to have whatever combination might appear attractive, as the point of the background writer is to push out dirty pages. Pre-8.1, your choice would be either to: a) Flush frequently, and so have the checkpoints be of short duration, or b) Flush infrequently, so that the checkpoint flushes would have a long duration. Now, if you have reasonable settings (I'm not sure how well its tuning is documented :-(), checkpoint "flushes" should be able to be short, however infrequent they may be. In effect, the "oops, the database got blocked by checkpoint flushing" issue should now be gone... The issue that then remains is whether to checkpoint often, in which case crash recovery will tend to be be quicker, or whether to checkpoint seldom, in which case crash recovery will have fewer checkpoints to choose from, and hence will run somewhat longer. If your systems don't crash much, and recovery time isn't a big deal, then this probably doesn't much matter... -- (reverse (concatenate 'string "ofni.sesabatadxunil" "@" "enworbbc")) http://linuxfinances.info/info/sap.html "I don't plan to maintain it, just to install it." -- Richard M. Stallman -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your Subscription: http://mail.postgresql.org/mj/mj_wwwusr?domain=postgresql.org&extra=pgsql-performance
