Обсуждение: 8.3 Autovacuum Questions

I just have a couple of quick questions about 8.3 and Autovacuum.

1.  When autovacuum chooses to vacuum a table, the entire table is vacuumed, and not just a specified percentage of the table.  Correct?

2.  There is no way, without turning autovacuum off, of excluding vacuum/analyze during a specific period of time (say during a known peak usage period).

3.  If I have a PostgreSQL cluster with 10 databases, does autovacuum_max_workers=3 mean I have a possibility of 3 total workers or 30 workers (i.e. autovacuum_max_workers * number of db's)?

Thanks,

Chris

Chris Hoover escribió:
> I just have a couple of quick questions about 8.3 and Autovacuum.
>
> 1.  When autovacuum chooses to vacuum a table, the entire table is vacuumed,
> and not just a specified percentage of the table.  Correct?

Yes.

> 2.  There is no way, without turning autovacuum off, of excluding
> vacuum/analyze during a specific period of time (say during a known peak
> usage period).

Nope, no way.  (You could have a script to update the
pg_autovacuum.enabled flag, and change it using cron.)

> 3.  If I have a PostgreSQL cluster with 10 databases, does
> autovacuum_max_workers=3 mean I have a possibility of 3 total workers or 30
> workers (i.e. autovacuum_max_workers * number of db's)?

3 workers total.

--
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

Alvaro,

Thanks a bunch for the concise answers.  That is exactly what we needed to confirm.

Chris