On Sun, 2003-09-21 at 08:21, Ulrich Meis wrote: > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:pgsql-bugs- > > [EMAIL PROTECTED] On Behalf Of Jean-Luc Lachance > > Sent: Friday, September 19, 2003 4:44 PM > > To: Rod Taylor > > Cc: Ulrich Meis; [EMAIL PROTECTED] > > Subject: Re: [BUGS] select where id=random()*something returns two > results > > > > Rod, > > > > If the table has 100,000 tupples your query is generating 100,000 new > > tupples... > > Try: > > > > select * from quotes where id = ( > > select int8( 1 + random() * ( > > select id from quotes order by id desc limit 1))); > > > > How about > > select * from quotes where id=1+int8((select random())*(select max(id) > from quotes)); > > It works, but is it more or less efficient?
Run EXPLAIN ANALYZE on them both and you tell me which is more efficient. Efficiency of a query tends to change with the data that it is being executed on.
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