am 10.03.2006, um 10:46:39 -0500 mailte Emi Lu folgendes: > Hello, > > postgresql 8.0.1, in a plpgsql function > > To update columns' values in a table (without OID), if I ran: > 1. "update table1 set col1 = ..., col2 = ... ... col100 =" > > or > 2. > "update table1 set col1 = " > ... > "update table1 set col100 = " > > way 1 only has one disk I/O, right? While way 2 is more time consuming > since there is disk I/O when a update is ran. Because of MVCC every UPDATE is practical a DELETE + INSERT. Way1: you have only one DELETE+INSERT, Way2 one hundred, and you have 100 dead rows until the next VACUUM. HTH, Andreas -- Andreas Kretschmer (Kontakt: siehe Header) Heynitz: 035242/47215, D1: 0160/7141639 GnuPG-ID 0x3FFF606C http://wwwkeys.de.pgp.net === Schollglas Unternehmensgruppe ===
