2011/5/3 Merlin Moncure <mmoncure@xxxxxxxxx>: > On Tue, May 3, 2011 at 8:30 AM, raghu ram <raghuchennuru@xxxxxxxxx> wrote: >> On Tue, May 3, 2011 at 6:01 PM, Raghavendra >> <raghavendra.rao@xxxxxxxxxxxxxxxx> wrote: >>> >>> On Tue, May 3, 2011 at 5:37 PM, Simon Riggs <simon@xxxxxxxxxxxxxxx> wrote: >>>> >>>> On Tue, May 3, 2011 at 11:54 AM, raghu ram <raghuchennuru@xxxxxxxxx> >>>> wrote: >>>> >>>> > It may be a silly question, still out of curiosity I want to know, is >>>> > there >>>> > any possible way to flush the Postgres Shared Memory without restarting >>>> > the >>>> > cluster. >>>> > In Oracle, we can flush the SGA, can we get the same feature here.. >>>> > Thanks in Advance. >>>> >>>> >>>> The CHECKPOINT command will do this for you. >>> >>> >> >> According to PostgreSQL documentation, whenever you execute "CHECKPOINT" in >> the database,it will flush the modified data files presented in the Shared >> Buffers retuned to the Disk. >> http://www.postgresql.org/docs/9.0/static/sql-checkpoint.html >> Is this clears the entire shared memory cache and same time,if i execute >> fresh SQL statement, Data will be retuned from disk?? > > 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 > > merlin > > -- > Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-admin > -- Cédric Villemain 2ndQuadrant http://2ndQuadrant.fr/ ; PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
