Re: Tablespaces and query planning - Mailing list pgsql-performance

From Albe Laurenz
Subject Re: Tablespaces and query planning
Date
Msg-id D960CB61B694CF459DCFB4B0128514C20800ADF1@exadv11.host.magwien.gv.at
Whole thread Raw
In response to Re: Tablespaces and query planning  (Cédric Villemain <cedric@2ndquadrant.com>)
List pgsql-performance
Cédric Villemain wrote:
> > - 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.

Thanks for the confirmationsand the clarification.  I hadn't thought of the
statistical entries in pg_class.

Yours,
Laurenz Albe

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