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Autoanalyze settings with zero scale factor

From: "Jeremy Haile" <jhaile(at)fastmail(dot)fm>
To: pgsql-performance(at)postgresql(dot)org
Subject: Autoanalyze settings with zero scale factor
Date: 2007-01-18 18:37:54
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
Some of my very large tables (10 million rows) need to be analyzed by
autovacuum on a frequent basis.  Rather than specifying this as a
percentage of table size + base threshold, I wanted to specify it as an
explicit number of rows.

I changed the table-specific settings so that the ANALYZE base threshold
was 5000 and the ANALYZE scale factor is 0.  According to the documented
formula: analyze threshold = analyze base threshold + analyze scale
factor * number of tuples, I assumed that this would cause the table to
be analyzed everytime 5000 tuples were inserted/updated/deleted.

However, the tables have been updated with tens of thousands of inserts
and the table has still not been analyzed (according to
pg_stat_user_tables).  Does a scale factor of 0 cause the table to never
be analyzed?  What am I doing wrong?

I'm using PG 8.2.1.

Jeremy Haile


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Next:From: Matthew T. O'ConnorDate: 2007-01-18 19:20:11
Subject: Re: Autoanalyze settings with zero scale factor
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Subject: Re: Configuration Advice

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