Heikki Linnakangas wrote:
> 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.

Are _all_ the indexes cached?  I would doubt that.  Also, for typical
table, what percentage is the size of all indexes combined?

  Bruce Momjian   [EMAIL PROTECTED]
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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TIP 9: In versions below 8.0, the planner will ignore your desire to
       choose an index scan if your joining column's datatypes do not

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