[Grok-dev] ZODB and storing, retrieving, deleting, use of ID

[Christian Theune]

On Fri, 2008-10-10 at 20:15 -0700, Kevin Teague wrote:
> When doing autogeneration of primary keys in a relational database,
> there is usually a separate Sequence object which tracks the value of
> the next id to use, when a new record is inserted the Sequence object
> is updated by one. It's possible to implement this directly in Grok,
> but Laurences suggestions of randomised keys for efficiency may be
> preferable.

Those Sequences work differently in a way that the ZODB doesn't support.
They are implemented in a manner that allows them to look "around"
transactions to retrieve a globally unique value with little conflicts
but consistency. ZODB doesn't support that. Either you can create a
perfect serial (but get conflicts), resolve the conflicts (and get
broken serials) or use a non-serial approach (like randomization).

Christian

-- 
Christian Theune · ct at gocept.com
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http://gocept.com · tel +49 345 1229889 7 · fax +49 345 1229889 1
Zope and Plone consulting and development
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