Re: C-ISAM indexes

In article <8f9ei0$2n$1@lore.csc.com>, "P Travis" <ptravis@csc.com> wrote: > > <mars1972@my-deja.com> wrote in message news:8f93f8$14c$1@nnrp1.deja.com... > > I just spoke with tech support and they told me something I'm having > > problems believing. > > > > We have a 7.24UC1 SE database using C-ISAM programs to access the > > database. For three weeks in a row, we have had performance problems. > > The first problem showed up on April 20th and lasted through April 21st. > > To fix that problem, we tried rebuilding the indexes on April 23rd. > > The problem went away until April 28th. We ran secheck on April 30th. > > The problem went away until May 5th, even though secheck reported no > > errors. We didn't do anything this last weekend and the problem has > > continued through today. The actual problem is that physical IO goes to > > between 90 and 100 percent, causing some serious response problems. As > > you may notice, the problem is starting at the end of the week, > > Thursday on the first week, Friday on the next two. We've looked for > > all sorts of things. No program has changed, no new cron jobs are > > running, no extra users, no users running abnormal processes. > > > > I called tech support again today and they mention that SE indexes and > > C-ISAM indexes were separate. An index built using CREATE INDEX in > > dbaccess was not used by C-ISAM. For an index to be used by C-ISAM, it > > had to be created using isaddindex(). I have a hard time believing > > this, because, while I don't know that much about C-ISAM, we've been > > running this way for more than 6 months. Why would any problem show up > > now, and why would recreating or sechecking the index fix anything? I > > would have expected some serious performance problems before now if this > > were true. Also, why would the call to select the index (isstart, I > > believe) succeed if C-ISAM couldn't use it? > > > > An answer to either problem would be greatly appreciated. > > > > -- > > # unrm / > > ksh: unrm: not found > > # man cpio > > > > > > Sent via Deja.com http://www.deja.com/ > > Before you buy. > > Do you insert/update/delete large amounts of data ? Have you tried running > update statistics ?> > Update statistics can have a huge impact on the speed of the database.> > Update statistics is run monthly. Unfortunately, those statistics are not used by C-ISAM to my knowledge, because the engine is being bypassedby C-ISAM. Data and index files are begin referenced directly. -- # unrm / ksh: unrm: not found # man cpio Sent via Deja.com http://www.deja.com/ Before you buy.