[Zope3-Users] Modified IntId utility

[Maken Seteva]

On Sep 25, 2007, at 8:52 AM, Stefan H. Holek wrote:

> On 24. Sep 2007, at 18:53, Maken Seteva wrote:
>
>> Fellow Zopers.
>> I have made a slight modification to my intid util by inheriting  
>> from IntId and overriding _generateId().
>> I do this to be sure that all new created objects will have an  
>> incrementing number where
>> the first object created gets id 1, the next gets id 2 and so on.  
>> This way I get for "free" sorting by
>> oldest/newest.
>
> Please do not attach additional "meaning" to intids. The value of  
> an object's intid is (and should be) completely irrelevant.
>
> [snip]
>
>> What do you think about this? Is it "safe" to do this, or have i  
>> forgotten any unforseen oddities
>> that might occur in the future :O
>
> Your code looks like a conflict-magnet to me. I suggest you read up  
> on why counting in the ZODB is a bad idea.
>
> Stefan
>
>
> --
> It doesn't necessarily do it in chronological order, though.
>   --Douglas Adams
>
>

Hi Stefan,
Looks like a few others besides me actually are giving meaning to  
intids as well.. I base my choice of adding meaning to ids from this  
post (one approach  of reducing sort cost):

Quote (by Jim Fulton http://www.mail-archive.com/zodb-dev@zope.org/ 
msg02144.html):
Sort your results based on the "primary key" and therefore, pick your  
primary key to match your sort results. In terms of the Zope catalog  
framework, the primary keys are the document IDs, which are  
traditionally chosen randomly. You can pick your primary keys based  
on a desired sort order instead. A variation on this theme is to use  
multiple sets of document ids, storing multiple sets of ids in each  
index. Of course, this approach doesn't help with something like  
relevance ranks.
End quote


I *could* use, as the quote states, several ids but why not use the  
regular intid (that we already have) for this? As long as I resolve  
conflicts of course.

Not fully sure how to resolve conflicts though as I'm quite new to  
this. I saw a suggestion on BTrees.Length in another thread. So could  
I easily just replace the nextid in my code to use a Length instead?  
(and use Length.change to increment the counter).

My best regards
Seteva
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