Re: sysptprof: bufreads, pagreads and isreads ?

In article <6ckfgs$s36$1@news.xmission.com>, Georg Winkens <georg@cyberdude.com> writes > >Dear Informix Community, > >Who can help me to get a clearer picture about the figures in the >sysptprof table (also provided by onstat -p)? > >What is the relationship between the figures for the ISAM calls and the >figures for the Buffer Reads/Writes? > No real relationship. one ISAN call may access >1 buffer. E.g. varchar with a forward pointer. >How can it happen that the number of bufreads goes down but the number >of isreads goes up when a different index is used by a query? This would be because the new index was not in memory. Hence more disk reads are needed. > >How is it possible that I sometimes have iswrites but no bufwrites and >pagwrites? (I am the only one using the server) Because Online is doing write caching? > >Is it a good approach to try to minimize the bufreads (knowing all data >is in cache) when tuning a query? Or should I focus more on the ISAM >calls? I normally try to minimize both. Start with onstat -u and if the session has >1000 reads look to see what it is doing and use set explain on. > >Looking forward to hearing from you (and to see hopefully more clearer). >Cheers, > Georg -- David Williams Maintainer of the Informix FAQ Primary site (Beta Version) http://www.smooth1.demon.co.uk Official site http://www.iiug.org/techinfo/faq/faq_top.html I see you standin', Standin' on your own, It's such a lonely place for you, For you to be If you need a shoulder, Or if you need a friend, I'll be here standing, Until the bitter end... So don't chastise me Or think I, I mean you harm... All I ever wanted Was for you To know that I care