[ZODB-Dev] ZODB4 project plan

[Magnus Lycka]

At 11:22 2002-11-27 -0500, Phillip J. Eby wrote:
>Speaking of YAGNI's and ZODB4, does anybody have any actual use cases for 
>nested transactions?  I notice that's listed on the project plan, but I 
>thought that discussion on the Persistence-SIG suggested them to be overkill.

While it's currently not a concrete issue for us, I've been wondering
about how to use undo in our app SystemSpecifyer (now at sourceforge)
when we make it a multi user application.

I'd like to be able to combine multi user functionality with a fine
grained undo feature (as in a word processor), and I planned to use
ZODB undo.

If I commit a transaction to ZEO and some other user commits another
transaction after that, I suppose I can't undo my changes without
undoing the other user's changes.

I've been wondering if either subtransactions or versions would be
helpful there, but it's just thoughts. We have a lot of other things
to fix before we actually start working on multi user issues.

Typically, different users don't change the same objects, so I guess
I could use versions (but it's just been a thought). Then I guessed
(without having investigated this) that changes in subtransactions
aren't written to ZEO until the main tranaction commits, and then I
suppose I could use this for my fine grained undo, but if both
features go away, I don't quite know how to solve this.


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Magnus Lycka, Thinkware AB
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