RE: update statistics slowing system
Glen, I forgot to mention, that 'update statistics' intensively replaces data/index pages in the common buffer cache, and this can also effect performance of applications working with any database on the same server ------------------------------------------ Alexey Sonkin Senior Database Administrator > -----Original Message----- > From: Glen Johnson [mailto:glen@csisoft.com] > Sent: Wednesday, November 12, 2003 6:20 PM > To: Alexey Sonkin > Subject: Re: update statistics slowing system > > > Thank you, So other than normal disk contention problems, running undate > statistics on a table should not effect the performance of other Informix > applications accessing other databases. > > > ----- Original Message ----- > From: "Alexey Sonkin" <alexeis@grandvirtual.com> > To: "'Glen Johnson'" <glen@csisoft.com>; <informix-list@iiug.org> > Sent: Wednesday, November 12, 2003 5:02 PM > Subject: RE: update statistics slowing system > > > > Glen, > > > > 'Update statistics' is usually disk-bottlenecked > > and doesn't execute at more then 1 CPU. > > > > If You have poor distribution of data across physical > > hard drive, 'statistics' can dramatically affect the overall > > system performance - no matter what database particular > > application is working with. > > > > In the case You are using RAID 10 (or even RAID 5) > > this effect should be much smaller then with single drives, > > unless Your logical log is on the same drive as data > > for 'update statistics' and Your database is UNBUFFERED or > > ANSI and Your application is write-intensive > > > > ------------------------------------------ > > Alexey Sonkin > > Senior Database Administrator > > > > > > > -----Original Message----- > > > From: Glen Johnson [mailto:glen@csisoft.com] > > > Sent: Wednesday, November 12, 2003 3:10 PM > > > To: informix-list@iiug.org > > > Subject: update statistics slowing system > > > > > > Should doing an update statistics on a table in one database affect > the > > > preformance of users in a totally separate database. Does it lock > some > > > global tables? I don't think it is a CPU problem since this is on a 6 > > > processor Linux system. sending to informix-list