Re: Informix help needed

Timity Coldenhoff (ecs50145@zach.fit.edu) writes: > I have set up On-Line to use one 400M disk as a primary dbspace, and a > separate 400M drive to be a mirror. I have another disk, approx. 200M of > which is used as a different space, which is also mirrored to another > drive. When I try to get the status of either of these spaces, tbmonitor > tells me that a fraction of the primary is used (which I expect) and that > ALL of the mirror is used (which I am confused about). After going over > the docs many times, I cannot find any reference to this particular > situation. Does Informix actually go out and grab the entire mirror space? Referencing our configuration (AT&T 3B2 600/G), the answer would be an unqualified "yes". Online wants the entire mirror drive available: it is a true mirroring system, that is, it is an exact duplicate of the other drive. > Second question: I need to perform a large number of selects on a fairly > large table in a very short period of time. The very basic numbers here > are 5000 selects on a table with 250,000 rows, each row having 60 bytes. > One unique composite index set up on three columns. Each select returns > exactly one tuple. Essentially, I have the following: > $ select * > into $host_var > from table_x > where ((col1 = $hv1) and (col2 = $hv2) and (col3 = $hv3)); > which is done 5000 times, getting a different row each time. This needs > to be done within two minutes. I haven't been able to do it in less than > three. I have set up shared memory to no swapping, with 4500 buffers > which forces a large amount of the data to be cached. > So, are there any weird quirks, kludges, or even simple advice to eek > out a few milliseconds? That time constraint is critical, and any and all > suggestions, no matter how simple are appreciated. I am contemplating > going into the pre-processed code and trying to trim that down also... > would I be wasting my time? I don't know exactly how you're executing that SQL statement, but what we have found at this site is that DECLAREing a cursor and using FETCH NEXT inside a WHILE loop is intrinsically faster than any number of individual SELECT statements. (Of course, this presupposes you at least have RDS or I4GL available.) > Final question: Are you still with me? There is very little technical > information provided in the Informix manuals. Sad, but true. > For instance, how are shared memory buffers managed? . . . Well, now you're beyond me - I'm not a techie type, just a good, old-fashioned programmer/analyst. Good luck! Bill Williams ------------------------------------------------------------------------------ Milnet (Internet) address: bwilliams@aqlan.ssc.af.mil --------------------------- D I S C L A I M E R ------------------------------ The opinions expressed here do not reflect the views of the US Air Force, the Department of Defense, the US Government, or anyone else but ME. So there. ------------------------------------------------------------------------------ A 4GL "CUTTING EDGE" TECHNOLOGY SITE: AT&T 3B2 WITH ONLINE (*GASP!*) ------------------------------------------------------------------------------