[ZODB-Dev] Newbie questions; indexes; non-Zope example code?

[John J Lee]

I've played around with ZODB before, but looking at it again I find I have
a few big questions:

-What happens when this occurs?

 1. Two transactions (I suppose in separate threads) start at around the
 same time.
 2. One transaction starts and finishes its commit.
 3. The other transaction commits.

 Doesn't this lead to the second commit being based on stale data?


-Am I correct in remembering from somewhere that undo doesn't work well
 with indexes that are kept up-to-date when objects change?

 Questions:

 Why? (I saw an explanation, but can't remember where...)
 Is this true of all Storages?
 Is there any way around it, now or in future?
 Does this apply to versions as well as to undo?


-Is IndexedCatalog the only non-Zope entangled index that keeps indexes
 up-to-date when objects change?


-Does anybody have any open source non-Zope ZODB code -- especially
 involving indexes?  I'd like to get a feel for how people use ZODB.


-What's the timescale for the final ZODB 4 release?


Thanks in advance for any help


John