Re: Overcoming 7.12 vs. 5.05 performance gap

F. Fernandez wrote: > > Hi! > > We have a customer working with OnLine 5.05UC2 in an DEC Alpha with > 2 processors and 256 Mb RAM. They have a 7.12 UC1 but don't want > to use it since it's 30% slower in some critical programs. > > We already have been jugling with several parameters, including > disabling multiprocessor, altering CPU VP#, etc. Every time we > compare we get almost the same results. > > We did not yet tried to fragment tables since we only have 3 > disks and the database is only a couple of hundred megabytes. > > I would like to know if anyone has already worked out a solution > for this kind of problems or if you just admit the performance > loss and get on with it... > > Another option would be to upgrade directly to 7.2x, but I don't > know if there are significant performance gains from 7.1x to 7.2x > on alpha platforms. Anyone tested this? > I had a similar experience from the programmer end when my former company went from 5.03 to 7.10/7.11. Run times for DSS reports shot way up. At first, I thought that the indexes were corrupted during the conversion. Tried to recreate them, to no avail. Suddenly, voila! Problem solved, everythings running smoothly. The sys admin says he upped the # of memory buffers (by a factor of 10). The read cache hit ratio moved up to 95%. Shared memory was too small for our needs. Memory buffers (I think the config variable is "BUFSIZE") are but one of many tunable parameters in 7.1x. The default value may be too low for a medium to large database with a lot of processes running against it in parallel. In our case, it made a major difference. After that, without much more tuning (our sys admin was not a tinkerer), we experienced about a 20% improvement in speed over 5.03.