From: Giuseppe Broccolo <giuseppe.broccolo@2ndquadrant.it>
To: pgsql-performance@postgresql.org
Subject: Re: pg_statio_all_tables columns
Date: Mon, 30 Sep 2013 16:40:49 +0200
Message-ID: <52498D71.8010002@2ndquadrant.it> (raw)
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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
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To: pgsql-performance@postgresql.org
Cc: giuseppe.broccolo@2ndquadrant.it
Subject: Re: pg_statio_all_tables columns
In-Reply-To: <52498D71.8010002@2ndquadrant.it>
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