2011/5/3 Merlin Moncure <mmoncure@xxxxxxxxx>: > On Tue, May 3, 2011 at 8:55 AM, Cédric Villemain > <cedric.villemain.debian@xxxxxxxxx> wrote: >> 2011/5/3 Merlin Moncure <mmoncure@xxxxxxxxx>: >>> >>> no it will not, or at least there is no guarantee it will be. the >>> only way to reset the buffers in that sense is to restart the database >>> (and even then they might not be read from disk, because they could >>> sit in the o/s cache). to force a read from the drive you'd have to >>> reboot the server, or at least shut it down and use a lot of memory >>> for some other purpose. >> >> with linux, you can : "echo 3 > /proc/sys/vm/drop_caches" for the OS cache >> > > yeah -- good point. aside: does that also drop cache on the drive/raid card? no -- good point too ! (damn! how SAN users will do...maybe EMC or other are good enough to provide some control panel for that ? ) and as I read on the link provided by Tomas, it is better to issue a 'sync' before trying to drop cache (I do that sometime, but postgresql flush its write before shutdown, so I expected the dirty pages in OS cache not to be relative to postgresql files.) -- Cédric Villemain 2ndQuadrant http://2ndQuadrant.fr/ ; PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
