Re: [HACKERS] Autovacuum Improvements

Russell Smith wrote:
> 2. Index cleanup is the most expensive part of vacuum.  So doing a
> partial vacuum actually means more I/O as you have to do index cleanup
> more often.

I don't think that's usually the case. Index(es) are typically only a
fraction of the size of the table, and since 8.2 we do index vacuums in
a single scan in physical order. In fact, in many applications the index
is be mostly cached and the index scan doesn't generate any I/O at all.

I believe the heap scans are the biggest issue at the moment.

--
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com