Terry Jones wrote:
I've just read the ZODB/ZEO Programming Guide (Release 3.6.0,
A.M. Kuchling, January 5, 2006) and I'd like to ask a few questions.

Are the following all correct?

You may have more joy with these questions on the zodb-dev@zope.org mailing list...

 - The BTrees supported by ZODB have nothing to do with Berkeley DB Btrees
   (apart from the fact that they're both implementations of BTrees).

Correct. And I think the ZODB ones are a variant of BTree...

 - ZODB BTrees do not allow duplicate keys (a la bsddb).


 - ZODB BTrees do not allow you to set up secondary keys (a la bsddb).

Dunno what that means. I think you're just use two BTrees for this...

 - Is the byValue() ZODB BTree method officially deprecated? Scheduled for
   deprecation / removal?

Never used it, no idea...

Assuming the first three above are correct, and that I would like both
duplicate keys

What do you mean by duplicate keys? This sounds like a fairly screwy concept for a mapping... Do you mean you want to map one key to a set of values or that you want to map more than one key to the same value?

and secondary keys

Again, you need to explain what you mean by secondary keys...

 1. Use both ZODB and bsddb in the same application, dealing with things
    like locking and transactions across both object types in a somewhat
    manual way.

Oooo.. feel the pain...

    This would have the additional major downside of making it harder to
    use ZEO for storage, right? (Yes, I could pickle the entire bsddb
    databases and hand them to ZEO, but that's not really what I had in

That would be insane ;-)

 2. Try to add support for bsddb BTrees (with duplicate keys) to ZODB.

Doubt you'd want to do that ;-)

 3. Redesign what I'm doing so as to only need ZODB BTrees. This is quite
    far from optimal (in terms of space and time), but might be the
    quickest to implement.

I think there are things that you can do with BTrees and their Set objects that will solve any problems you have. You need to explain what it is you're trying to do and we can help you...

If someone with more knowledge of ZODB and the BTrees therein and bsddb
feels like confirming, correcting, or commenting on the above summary, and
options, that would be great.

Take a look at the code in ZCatalog and PluginIndexes. I think you'll find everything you're looking for...



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