My example was having one or more translates in the dicts used. That was the basis for breaking it up.
----- Original Message ----- From: "Timothy Snyder" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, November 11, 2004 11:34 AM Subject: RE: [U2] broken up SELECTS > "Adrian Matthews" <[EMAIL PROTECTED]> wrote on 11/11/2004 > 10:26:48 AM: > > > It's something I've always done over the last twenty years. The select > > processor in theory should apply optimisiation but I always break my > > statements down to reduce the working record set and to increase > readability. > > > > Makes very little difference on smaller amount of records but makes a > huge > > difference when record counts get into the millions, especially on > distributed > > files or selects which work on a mixture of non-indexed and indexed > fields. > > Of course, like so many things in the MV world (and life in general) this > is an "it depends" scenario. If you're selecting based on three fields > that reside in the record, the additional overhead of comparing them will > be negligible compared to making a second pass through. It also depends on > whether one of the criteria would be expected to reduce the working set of > records significantly. If so, a second pass may be worth it. If you can > reduce the working set significantly by selecting on a resident field, and > save a nasty translate for a small percentage of the entire file, a > two-pass approach is almost a no-brainer. But if the resident field only > pares out 10% of the records, you'll be passing through 90% of the file > twice, and you have to determine whether the second pass is saving work or > creating more. With a particularly nasty dictionary item, it may be worth > it. > > > Tim Snyder > IBM Information Management > Consulting I/T Specialist , U2 Professional Services > ------- > u2-users mailing list > [EMAIL PROTECTED] > To unsubscribe please visit http://listserver.u2ug.org/ ------- u2-users mailing list [EMAIL PROTECTED] To unsubscribe please visit http://listserver.u2ug.org/
