From: Cédric Villemain <cedric@2ndquadrant.com>
To: pgsql-performance@postgresql.org
Cc: Albe Laurenz <laurenz.albe@wien.gv.at>
Subject: Re: Tablespaces and query planning
Date: Fri, 8 Jun 2012 12:36:03 +0200
Message-ID: <201206081236.08512.cedric@2ndquadrant.com> (raw)
In-Reply-To: <D960CB61B694CF459DCFB4B0128514C207F8154E@exadv11.host.magwien.gv.at>
References: <D960CB61B694CF459DCFB4B0128514C207F8154E@exadv11.host.magwien.gv.at>
> - The statistics gathered by ANALYZE are independent of the tablespace
> containing the table.
yes.
> - The tablespace containing the table has no influence on query planning
> unless seq_page_cost or random_page_cost has been set on the
> tablespace.
yes.
> - VACUUM ANALYZE does the same as VACUUM followed by ANALYZE.
no.
it is fine grained, but in the diffs there is:
VACUUM and ANALYSE do not update pg_class the same way for the
reltuples/relpages: for ex VACUUM is accurate for index, and ANALYZE is fuzzy
so if you issue a vacuum you have exact values, if you then run ANALYZE you
may change them to be less precise.
--
Cédric Villemain +33 (0)6 20 30 22 52
http://2ndQuadrant.fr/
PostgreSQL: Support 24x7 - Développement, Expertise et Formation
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To: pgsql-performance@postgresql.org
Cc: cedric@2ndquadrant.com, laurenz.albe@wien.gv.at
Subject: Re: Tablespaces and query planning
In-Reply-To: <201206081236.08512.cedric@2ndquadrant.com>
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