Re: Reac-Cache-Rate of a Data Warehousing System
From: leekb@bigfoot.com > >Have a couple questions here, > >In the Informix Performance Guide, a >95% read cache rate is normal and >definitely achievable in a transactional system/environment. In a *transactional* environment, yes. >Considering the vast amount of data read/written in a data warehousing >system, is it practical having the BUFFERS the size of the huge amount >data read by a query statement? Probably not. You'd probably want to reduce your buffers and make use of PDQ memory instead. >On the same light, is achieving >95% read cache rate on such a system >practical? Probably not. It might be possible, but it probably isn't desirable. ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com
I'm wondering why achieving >95% read cache rate in a data warehouse would be considered undesirable? Suppose you had several GB of shared memory. You might be able to cache whole tables, or in a small warehouse, maybe even cache the whole thing. Light scans are fast, but isn't reading from memory even faster? Curious, David Grove Obnoxio The Clown <obnoxio@hotmail.com> wrote in message news:7tab13$t1s$1@news.xmission.com... > > From: leekb@bigfoot.com > > > >Have a couple questions here, > > > >In the Informix Performance Guide, a >95% read cache rate is normal and > >definitely achievable in a transactional system/environment. > > In a *transactional* environment, yes. > > >Considering the vast amount of data read/written in a data warehousing > >system, is it practical having the BUFFERS the size of the huge amount > >data read by a query statement? > > Probably not. You'd probably want to reduce your buffers and make use of PDQ > memory instead. > > >On the same light, is achieving >95% read cache rate on such a system > >practical? > > Probably not. It might be possible, but it probably isn't desirable. > > ______________________________________________________ > Get Your Private, Free Email at http://www.hotmail.com