| From: | Cédric Villemain <cedric(at)2ndquadrant(dot)com> |
|---|---|
| To: | pgsql-performance(at)postgresql(dot)org |
| Cc: | "Albe Laurenz" <laurenz(dot)albe(at)wien(dot)gv(dot)at> |
| Subject: | Re: Tablespaces and query planning |
| Date: | 2012-06-08 10:36:03 |
| Message-ID: | 201206081236.08512.cedric@2ndquadrant.com |
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| Lists: | pgsql-performance |
> - 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/
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