Re: Table statistics definitions

---- you wrote: > I'm trying to interpret the table level statistics (sysptprof in sysmaster) > and we are having a debate about the meaning of some of the columns. Can > someone please define the difference between the following: > > Isreads > Bufreads > Pagreads > > I believe isreads stands for ISAM-reads which refers to direct I/O from > disk, bufreads would be stuff that is read from the Informix buffers, and I > think pagreads refers to read-ahead pages read from disk. If this is > correct, how does the reading of indexes play into isam reads? If you read > an index for a table to get to a particular data value, does it count the > index reads and the table reads in the isreads column for that table? I > assume sequential scans are also included in isreads? > > Please enlighten us and help us end our debate! I will leave it to the gurus to enlighten you, but I can continue the debate Dude. I had a different take on these values. Isreads - Read requests at the ISAM level Bufreads - Buffer reads from the cache Pagreads - Actual disk IO If isreads is actual IO, then the systems I work on have a serious problem, because they are huge! I took this to be the number of requested reads. The other values then tell you how they were satisfied. Also, isrewrites (updates) and isdeletes also add to isreads, because each operation requires a read. But I could be wrong, I am just a blonde. I'm sure Art will enlighten us. AB ---------------------------------------------------------------- Get your free email from AltaVista at http://altavista.iname.com