[Grok-dev] Performance of OrderedContainer

[Gary Poster]

On Jun 17, 2008, at 6:05 AM, Sebastian Ware wrote:

> I was looking at the trunk of grok because I need to use  
> OrderedContainer. But, if I add say 1 million objects to an  
> OrderedContainer, won't it become very slow due to the  
> implementation with PersistentList? Say that I want to show the last  
> 100 of the objects, I would have to return all 1 million keys.

Big ordered mappings are one of the use cases for zc.blist.  The  
following is a description, including the mechanism.

http://svn.zope.org/zc.blist/trunk/src/zc/blist/README.txt?view=auto

The set of edge cases is very large, and so the tests are primarily of  
the "run random operations for hours to try and find a problem".  I've  
run them for four or five hours now without any bugs.  I intend to  
release 1.0 soon, and some internal ZC projects will be using it soon.

It can be a drop in replacement for PersistentList in an ordered  
mapping implementation.  The only potential incompatibility I can  
think of is that getting a slice returns an iterator rather than a list.

Gary