Re: Huge number of disk writes after migration to 8.1

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Tom Lane wrote:
>> Looking at the code, stats entries for dropped tables are cleaned out
>> only when a VACUUM command is done; which is something we probably ought
>> to change.

> I was going to ask if you were confusing pgstat_vacuum_tabstat with a
> VACUUM command, when I noticed that only in vacuum() is that function
> called!  This surprised me and I agree that it should be changed.  I'm
> not sure what would be a more appropiate place to call it, however.

I don't have a problem with that.  What I'm thinking is that a DROP
TABLE command should issue a tabpurge message for the specific table
(or index) being zapped.  We still need vacuum_tabstat as a backstop
in case the tabpurge message gets lost, though.

Another thought is that in autovacuum, pgstat_vacuum_tabstat is really
called too often: once per autovac cycle would be sufficient, but
instead it's repeated for each table we vacuum.

            regards, tom lane