RE: PDQ

Albert, PDQ has nothing to do with index creation. You can not optimize these kind of tasks with PDQ resources. Performance degration during index creation is a consequence of allacation of PDQ resources that is supposed to used by that process. You can de-allocate PDQ resources (while index creation) dynamically by onmode -D 0 that is onmode <max PDQ priority allowed> Gursoy YERLI TMSSC, Informix DBA Brooks AFB, TX > -----Original Message----- > From: wisse [SMTP:wisse@kabelfoon.nl] > Sent: Monday, March 22, 1999 3:22 PM > To: informix-list@iiug.org > Subject: PDQ > > > --------------89105C2EC6E19702FDEFD42E > Content-Type: text/plain; charset=us-ascii > Content-Transfer-Encoding: 7bit > > I noticed a performance decrease instead of a performance increase > when > using PDQ with creating indexes. > > The create indexes are done one/with: > > * Informix 7.23.UC6 on Solaria 2.5.1. > * System: SUN E4000 with 6 CPU's and 5.3 GB internal memory. > * Informix has four CPU, NOAGE is set, AFFINITY is set for all 4 > Informix CPU's. > * Tables are fragmented round robbin on two dbspaces. > * Indexes has their own dbspace and disk/diskchannel > * All dbspaces are on raw devices > > During the creations of indexes nobody is using the system. When using > PDQ the index creation takes around 10% longer. That is not what I > want. > > Monitoring onstat -g mgm tells me hat I have PDQ resources enough. And > other measurements show me that the system has plenty of resources > left. > > The question is this a feature of Informix 7.23.UC6 or do I something > wrong. > > > Regards, > > Albert Wisse > > --------------89105C2EC6E19702FDEFD42E > Content-Type: text/html; charset=us-ascii > Content-Transfer-Encoding: 7bit > > <!doctype html public "-//w3c//dtd html 4.0 transitional//en"> > <html> > I noticed a performance decrease instead of a performance increase > when > using PDQ with creating indexes. > <p>The create indexes are done one/with: > <ul> > <li> > Informix 7.23.UC6 on Solaria 2.5.1.</li> > > <li> > System: SUN E4000 with 6 CPU's and 5.3 GB internal memory.</li> > > <li> > Informix has four CPU, NOAGE is set, AFFINITY is set for all 4 > Informix > CPU's.</li> > > <li> > Tables are fragmented round robbin on two dbspaces.</li> > > <li> > Indexes has their own dbspace and disk/diskchannel</li> > > <li> > All dbspaces are on raw devices</li> > </ul> > During the creations of indexes nobody is using the system. When using > PDQ the index creation takes around 10% longer. That is not what I > want. > <br>Monitoring onstat -g mgm tells me hat I have PDQ resources enough. > And other measurements show me that the system has plenty of resources > left. > <p>The question is this a feature of Informix 7.23.UC6 or do I > something > wrong. > <br>&nbsp; > <p>Regards, > <p>Albert Wisse</html> > > --------------89105C2EC6E19702FDEFD42E--

In article <7d5mro$55c$1@news.xmission.com>, "Yerli, Gursoy" <gursoy.yerli@tmssc.brooks.af.mil> wrote: > > Albert, > > PDQ has nothing to do with index creation. You can not optimize these > kind of tasks with PDQ resources. Performance degration during index > creation is a consequence of allacation of PDQ resources that is > supposed to used by that process. Ha ! PDQ has impact on the index builds - when PDQPRIORITY > 0. It's called vertical parallelism. Infx perform parallel scans, sorts and uses memory, allocated for PDQ for sorts. RTFM "Infx OnLine Dyn. Server Perfomance Tuning". > > > The question is this a feature of Informix 7.23.UC6 or do I something > > wrong. Here some advices about index builds : 1.PDQPRIORITY=100 2.DBSPACETEMP - as much as possible, on different disks and controllers. 3.PSORT_NPROCS - number of phys. CPUs, but 2< >10 4.SHMVIRTSIZE= about 75% of physical memory - cause sort threads tends to sort records in the virtual memory Some of the above (3,4) related to the very large indexes. With best regards, Juri Dovgart, Bank's "Ukraine" System Administrator. -----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own