On Tue, Oct 12, 2010 at 1:07 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Anyway, if anyone is hot to make COUNT(*) faster, that's where to look. > I don't think any of the previous discussion in this thread is on-point > at all, except for the parts where people suggested avoiding it.
I kind of hope that index-only scans help with this, too. If you have a wide table and a narrow (but not partial) index, and if the visibility map bits are mostly set, it ought to be cheaper to read the index than the table - certainly in the case where any disk I/O is involved, and maybe even if it isn't. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
