Re: reasonable checkpoint interval

Stuart Cracraft wrote: > > What is considered a reasonable informix checkpoint interval? > > I'm currently investigating a problem on a system with the checkpoint, > as shown in /usr/informix/online.log, occuring every 6 minutes or so. > This is on a Unix box with Informix 7.12.UC1. > > Users on PC's have a GUI application to do queries into this Informix > Online SQL engine. Every few minutes, their PC's freezeup (all > simultaneously) for up to 5 minutes reducing their productivity by > orders of magnitude. > > What checkpoint intervals are considered reasonable? Is there > such a thing as having checkpoint intervals too close together? > What are the Informix defaults? > > Users of this system are doing a moderate number of queries typically > against extremely large tables all indexed and multiply so. Meanwhile > a large number of system batch jobs are running doing lots of table > queries. > > Thanks ahead. > > --Stuart There is no short answer on this. The rule of thumb is to increase LRU Writes and Decrease Chunk Writes (check out "onstat -F"). A good reference, besides the admin guide, is "Informix - OnLine Performance Tuning" by Elizabeth Suto, published by Prentice Hall PTR.