Hello Giuseppe, do you actually mean I have a *poorly-cached *database? Should this ratio stay low even in the case of a write-heavy table?
On Mon, Sep 30, 2013 at 5:40 PM, Giuseppe Broccolo < giuseppe.brocc...@2ndquadrant.it> wrote: > Hi Xenofon, > > Il 30/09/2013 14:45, Xenofon Papadopoulos ha scritto: > > I am trying to understand the heap_blks_read and heap_blks_hit of >> pg_statio_all_tables in 9.2 >> Do the numbers refer only to SELECT, or they take INSERT into account? >> > > heap_blks_read and heap_blks_hit refer to number of blocks read from disk > layer and from page cache respectively during table usage, independently if > insert, select, delete, update operations are involved. > > > Would a heap_blks_read / ( heap_blks_read + heap_blks_hit ) ration of >> over 55% combined with a heap_blks_read value of over 50M indicate an issue >> with the queries affecting that table, or it is normal if the table is >> heavily written to? >> > > High values of this ratio mean you have a well-cached database, since disk > blocks reads slow down database operations. You can performe it increasing > the cache available to your database. > > > Giuseppe. > > -- > Giuseppe Broccolo - 2ndQuadrant Italy > PostgreSQL Training, Services and Support > giuseppe.broccolo@2ndQuadrant.**it | www.2ndQuadrant.it > > > > -- > Sent via pgsql-performance mailing list (pgsql-performance@postgresql.** > org <pgsql-performance@postgresql.org>) > To make changes to your subscription: > http://www.postgresql.org/**mailpref/pgsql-performance<http://www.postgresql.org/mailpref/pgsql-performance> >
