[ZODB-Dev] ZODB idioms

[Jeremy Hylton]

>>>>> "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