[Grok-dev] Performance of OrderedContainer

Gary Poster gary at zope.com
Tue Jun 17 13:58:36 EDT 2008

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.


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.


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