[Zope] Re: BTreeFolder

Shane Hathaway shane@zope.com
Mon, 15 Jul 2002 10:20:01 -0400

Toby Dickenson wrote:
> On Monday 15 Jul 2002 2:40 pm, Shane Hathaway wrote:
>>Magnus Heino wrote:
>>>Whats the reason for not using this instead of the current folder code,
>>>as default? Size?
>>Are you talking about making all folders hold their items in BTrees?
>>That's kind of hard for Zope 2 because of all the backward compatibility
>>issues, but I think it's on the plan for Zope 3.
> I dont think we would want to use BTrees for *every* folder; they have a 
> significant overhead compared to ordinary Folders which makes them 
> unattractive for folders that hold a small number of subobjects. I guess the 
> break-even point is around where the BTree doesnt all fit into one bucket, 
> which is several hundred items if I remember correctly.
> It would be nice to have Folders that automagically upgraded themselves to 
> BTreeFolders once some size threshold was exceeded.

Agreed.  We'll need to do measurements at some point to find out whether 
the overhead really is significant, and where the transition point 
should be (since we don't want to make end users think about such 
things. :-) )