On Wed, May 26, 2010 at 5:25 AM, Cédric Villemain < cedric.villemain.deb...@gmail.com> wrote:
> 2010/5/25 Chirag Dave <cd...@ca.afilias.info>: > > > > > > On Tue, May 25, 2010 at 1:48 PM, Balkrishna Sharma <b...@hotmail.com> > wrote: > >> > >> Hi, > >> I am increasing the shared_buffer size in postgresql.conf and want to > >> measure its effect on READ. In essence I want to know if the SELECT > queries > >> I am firing repeatedly is reading from the buffer or going directly to > the > >> disk. > >> I am expecting the first SELECT to go to disk and the subsequent call of > >> the same SELECT to read from buffer . > >> Right now I am just looking at execution time of the SELECTs and trying > to > >> conclude. But there should be a direct way to see where the SELECT reads > >> from. > > > > You can also use pg_stat_database view. you can compute cache reads > > percentage of the total number of reads (cache and physical) between the > two > > snapshots using pg_stat_database.blks_hit and > pg_stat_database.blks_read. > > views does not reflect this exact behavior : hit and read are relative > to hit shared buffers and request a block (from OS page cache or from > disk). > > Correct, thats where pgFincore will be usefull. > > > > > Chirag Dave 416-673-4102 > > Database Administrator, Afilias Canada Corp. > > cd...@ca.afilias.info > > > > > >> > >> How can I accomplish this ? > >> Thanks > >> Bala > >> ________________________________ > >> The New Busy think 9 to 5 is a cute idea. Combine multiple calendars > with > >> Hotmail. Get busy. > > > > > > -- > Cédric Villemain 2ndQuadrant > http://2ndQuadrant.fr/ PostgreSQL : Expertise, Formation et Support >
