Message-Id: <1169145474.20103.1169962769@webmail.messagingengine.com>
From: "Jeremy Haile" <jhaile@fastmail.fm>
To: pgsql-performance@postgresql.org
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Subject: Autoanalyze settings with zero scale factor
Date: Thu, 18 Jan 2007 13:37:54 -0500

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.

Thanks,
Jeremy Haile