Re: Informix 7 performance problems with PDQ

In article <856084002.8069@dejanews.com>, markc@osem.co.il writes >We have recently upgraded from INF5 to 7.2 We running on a HP UX 10.01 >system with 3cpu's and 384mb ram and 20gb disk. The system runs 3 >databases 2 client serevr and the other online 4gl prgs. We have the >PDQPriority set to 15 default. with a MAX of 70 in the onconfig. When a PDQ of 15 sounds high, try reducing it to 1 (parallel scans) and try again..then increase slowly.. As PDQ priority increases more threads are started and more CPU/memory is used. Also check OPTCOMPIND, 0=use indexes, 2 = use dyncamic hash joins (the default. Dynamic hash join = Built hash table resulting rows from smaller table, scan resulting rows from large table and check if each one is in the hash table. With 2 large tables this can use a lot of memory...up to 2 gigabytes has been heard of!. >user submits a heavy job it uses all 3 cpus until the job is finished >making the job work very fast, but the problem is when other users try to >work at the same time. The performance is terrible because all the cpu is >taken up running the first job. > >How can we limit a single job to not use more than say 50% cpu, or always >ensure a performance for other users. It is no good if one job uses >everything and nothing is left for anyone else until the job finshes. > Reduce PGQ priority. >Some users are getting over 30seconds responce times when this happens. > >If anybody can give any kind of help I would be grateful, informix does >not seem able to help us. > >In addition we have another problem. According to the book I should be >able to create a file called .informix in each users home dir and >individualy specify the PDQ here. But it doesn't work it ignores this >file. It only seems to read the PDQ when online is first brought up from >the informix.rc file and this is what it uses unless reset in a programe. >Their seems to be no dynamic way of doing it is .informix. > I thought the file was called .informixrc in the users home directory. >-------------------==== Posted via Deja News ====----------------------- > http://www.dejanews.com/ Search, Read, Post to Usenet -- David Williams