> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:pgsql-hackers- > [EMAIL PROTECTED] On Behalf Of Tom Lane > Sent: Thursday, November 17, 2005 4:17 PM > To: Simon Riggs > Cc: Kevin Grittner; pgsql-hackers@postgresql.org > Subject: Re: [HACKERS] Improving count(*) > > Simon Riggs <[EMAIL PROTECTED]> writes: > > From here, another proposal. We have a GUC called count_uses_estimate > > that is set to off by default. If set to true, then a count(*) will use > > the planner logic to estimate number of rows in the table and return > > that as the answer, rather than actually count the row. > > Ugh. Why not just provide a function to retrieve the planner estimate, > but *not* call it count(*)? It would fit nicely with the contrib/dbsize > stuff (or I should say, the stuff formerly in dbsize...)
An estimate of the number of rows would be nice to have. A function called cardinality_estimate() or something of that nature seems more natural than count(*) ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
