Hanno Schlichting wrote: > Jim Fulton wrote: >> On Nov 4, 2008, at 12:12 PM, Benji York wrote: >> >>> On Tue, Nov 4, 2008 at 12:01 PM, Jim Fulton <[EMAIL PROTECTED]> wrote: >>>> A few months back, there was a lot of discussion here about BTree >>>> performance. I got a sense that maximum BTree-node and bucket sizes >>>> should be increased. Does anyone have recommendations for new sizes? >>> It'd be cool if the bucket size could be dynamic (say governed by an >>> attribute on the BTree), but I suspect that is dramatically out of >>> scope >>> for what you were planning on doing. >> I have a list of projects I might try to do for 3.9. One would be to >> make BTrees subclassable >> and to modify BTrees to get these limits from class attributes. But >> whether I get to this or not, >> if there are more sensible defaults, it would make sense to use them. > > Personally I think the numbers for the integer BTree's could be > increased indeed, but for the object BTree's, a way to adjust the bucket > sizes would be more important. > > The problem for BTree's storing objects, is of course that you have no > idea how large those objects are going to be. Sometimes they might be > simple types with just a couple of bytes each, sometimes catalog brains > with one kilobyte, but sometimes they might be actual content-like > object of various megabyte in size. > > In general there is no way of knowing what you are going to use the > BTree's for. Making it possible for the application code to adjust the > values for the particular kind of data, is probably better than guessing > a better default value.
+1 The classic case here is comparing a catalogue metadata BTree with one containing persistent objects, where only the oid needs storing in the pickle. Laurence _______________________________________________ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev
