am Tue, dem 29.08.2006, um 16:55:11 +0200 mailte Willo van der Merwe folgendes: > >>4 1/2 seconds for a count(*) ? This seems a bit rough - is there anything > >>else > >> > > > >Because of MVCC. > >http://www.thescripts.com/forum/thread173678.html > >http://www.varlena.com/GeneralBits/120.php > >http://www.varlena.com/GeneralBits/49.php > > > > > >Andreas > > > Hi Andreas, > > Thanks for your prompt reply. I understand why this is a sequential > scan, I'm just a bit perturbed that it takes 4.5 seconds to execute said > scan. The table is only 750,000 records big. What happens when this > table 7 million records big? Will this query then take 45 seconds to > execute?
How often do you need a 'select count(*) from big_table'? I assume, not frequently. And if you need realy this, you can write a trigger or read the statistics for the table. Andreas -- Andreas Kretschmer Kontakt: Heynitz: 035242/47215, D1: 0160/7141639 (mehr: -> Header) GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net ---------------------------(end of broadcast)--------------------------- 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 match
