On Mar 24, 2005, at 4:13 PM, Peter Fein wrote:

> On 03/21/05 01:04 PM CST, David Binger 
> sayeth:
>>
>> On Mar 21, 2005, at 11:38 AM, Thomas Güttler wrote:
>>
>>> Am Montag, 21. März 2005 16:56 schrieb David Binger:
>>>> http://www.python.org/pycon/2005/papers/17/
>>>
>>> Thank you very much for this paper.
>>>
>>> Do Btrees know their size? Or is getting the size of a btree
>> no
>>> expensive, becaus it needs to traverse all nodes?
>> yes
>
> I use a BTree to underly one of my data structures.  I originally
> developed it using a dict, and added a member to keep track of length
> during modify operations.  Perhaps the same could be done for BTrees
> natively? Sorry for the non-patch suggestion, but we're moving away
> from
> Durus for scalability reasons & I don't have time ATM.

I'm a little reluctant to add persistent information that is derived
from other
persistent information.

One interesting feature that may not be obvious is that iterating over
all of
the instances in the BTree does not, by itself, actually load the
pickles of
any of the (Persistent) instances stored as values in the tree.  It
does force
the loading of the BNodes, but that is much less data.

Could you characterize the scalability requirements of your application?