Re: Database-wide vacuum can take a long time, duringwhich tables are not being analyzed

On Wed, 2006-11-01 at 14:15 -0500, Steven Flatt wrote:
> Here is a potential problem with the auto-vacuum daemon, and I'm
> wondering if anyone has considered this.  To avoid transaction ID
> wraparound, the auto-vacuum daemon will periodically determine that it
> needs to do a DB-wide vacuum, which takes a long time.  On our system,
> it is on the order of a couple of weeks.  (The system is very busy and
> there is a lot of I/O going on pretty much 24/7).  During this period
> of time, there is nothing to automatically analyze any of the tables,
> leading to further performance problems.  What are your thoughts on
> having the DB-wide vacuum running on a separate thread so that the
> daemon can concurrently wake up and take care of analyzing tables?

Yes, do it.

Every couple of weeks implies a transaction rate of ~~500tps, so I'd be
interested to hear more about your system.

--
  Simon Riggs
  EnterpriseDB   http://www.enterprisedb.com