On Wednesday 28 July 2004 23:28, you wrote:

> You may need a fair amount of memory.  I tried creating
> PersistentDict that contained 500000 Persistent instances.  It took
> 172 seconds to commit it and the resident size of the client went up
> to about 250 MB.  The underlying filestorage is about 50 MB.
> Setting _p_changed on the PersistentDict and commiting it takes
> about 25 seconds and adds about 16 MB to the filestorage.
>
> Using a PersistentDict with that many entries would be highly
> suboptimal if you needed to add and remove entries frequently.

I got a similar performance figures. Do you think BTrees are really what I
need here?

> > 2) is there any intention or need at MEMS to implement BTrees like ZODB?
> > Would anyone hazard a guess at how difficult/easy it would be?
>
> Implementing BTrees should not be too difficult.  David is toying
> with them right now.  He has also implemented a linked list data
> structure.

Given that using a PersistentDict seems pretty bad for this number of objects,
do you have a performance figure for same number of things in the BTree
prototype? Will they be released?

In ZODB parlance I think what I need is an at a IOBTree.

>
>   Neil