[ZODB-Dev] ZODB idioms
Jeremy Hylton
jeremy@zope.com
Mon, 24 Jun 2002 11:40:35 -0400
>>>>> "CD" == Casey Duncan <casey@zope.com> writes:
CD> Hmmm, I thought the B stood for "Balanced". Isn't that false
CD> advertising? ;^) Unless of course it stands for binary...
No one knows what the B stands for. The inventors of the BTree (Bayer
and McCreight) aren't telling.
I assume that it was just too hard / too much work to get rebalancing
implemented.
CD> This could make FieldIndexes of sequencial values rather
CD> unfortunate....
The particular problem of sequential keys is unfortunate, but hardly
catastrophic. The BTree uses twice as much space as it would under
ideal conditions.
I think the much worse problems come when there are deletions from the
BTree, but I'll have to leave that for a BTree expert like Tim.
I think it's safe to say, though, that we have no idea what effect
unbalanced BTrees have in real life.
Jeremy