RE: Use of index in 7.0 vs 6.5

> -----Original Message-----
> From: Bruce Momjian [mailto:pgman@candle.pha.pa.us]
> 
> > Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > > That certainly would make sense.  We have hesitated to gather more
> > > statistics because of the time involved.  Fuller statistics 
> on just the
> > > indexed columns could be a big win and be done fairly quickly because
> > > the rows are already sorted in the index.
> > 
> > Yeah, a scan over just the index itself would be a perfect way to
> > gather stats.  The normal objection to it (can't tell whether entries
> > correspond to currently-valid tuples) doesn't apply, because we don't
> > really care whether the stats are perfectly accurate.
> > 
> > Should put this in TODO, along with something about splitting the
> > ANALYZE function out of VACUUM and making it invokable as a separate
> > statement.
> 
> Added:
> 
> * Remove ANALYZE from VACUUM so it can be run separately without locks
> * Gather more accurate statistics using indexes
>

Gathering statistics using indexes on-fly is best.
However VACUUM(without ANALYZE) already scans all indexes using
vc_scanoneind()/vc_vaconeind().  Isn't it availble anyway ?

Regards.

Hiroshi Inoue
Inoue@tpf.co.jp