Re: Autoanalyze settings with zero scale factor

Jeremy Haile wrote:
> 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.

That is right, and exactly how the scaling factor / base value are
supposed to work, so this should be fine.

> 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.

No a scaling factor of 0 shouldn't stop the table from being analyzed.

Unless it's just a bug, my only guess is that autovacuum may be getting
busy at times (vacuuming large tables for example) and hasn't had a
chance to even look at that table for a while, and by the time it gets
to it, there have been tens of thousands of inserts.  Does that sounds
plausible?

Also, are other auto-vacuums and auto-analyzes showing up in the
pg_stats table?  Maybe it's a stats system issue.