My understanding is the when a dynamic file's *total* size exceeds the SPLIT.LOAD threshold, a group (almost certainly not the group you are writing to or just wrote to) will be split. The group(s) chosen to be split are controlled by some secret algorithm, but I don't believe that the largest groups are the ones first chosen to be split. This can be verified by doing a GROUP.STAT on a dynamic file (with poorly hashing keys) and noting that there are many empty groups as well as many overflowing groups. Dynamic files perform well on the total file (*average* group size) level, but still suffer from the same problems as static hashed files regarding poorly hashing keys when you get down to individual groups within the file. If this is not how the splitting process in dynamic files actually works, I would appreciate being enlightened.
/Scott Ballinger Pareto Corporation Edmonds WA USA 206 713 6006 On Thu, Apr 23, 2009 at 11:47 AM, Martin Phillips < [email protected]> wrote: > Hi Allen, > > If I know in advance that I'm adding a large number of records >> to a file, is there any way to force the file to "grow" in advance? >> > > You could do this with the MINIMUM.MODULUS parameter but the whole point of > dynamic files is that they do their own tuning. Although a dynamic file is > unlikely to be as good as a perfectly tuned static file, it will be a lot > better than a typical static file that has been left alone for a long while. > > Another important point is that a split affects only one (or arguably two) > groups unlike resizing a static file from modulo N to modulo N+1 which would > affect every group. > > My real point here is that it is usually best to let a dynamic file look > after itself. > > > Martin Phillips > Ladybridge Systems Ltd > 17b Coldstream Lane, Hardingstone, Northampton, NN4 6DB > +44-(0)1604-709200 ------- > > 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/
