[ZODB-Dev] Re: [Zope-DB] ZODB transaction level is Read Repeatable?

[Paolo Losi]

Tim Peters wrote:
> You can say anything you want, the trick is to get others to agree <wink>.

:-)

> In ZODB 3.3, by default it's a little different, because "multiversion
> concurrency control" (MVCC) is the default in 3.3 (and not available
> before 3.3).  The short course is that MVCC takes away the
> ReadConflictError case:  a transaction under MVCC always sees the
> state that _was_ current at the time the current transaction began.


WOW. I'm impressed.
How do I switch MVCC off/on?
Is there any recent paper/doc explaining mvcc internals/invalidation
mechanisms... is http://zope.org/Wikis/ZODB/MultiVersionConcurrencyControl
still relevant?

> B: read anything not touched by A (i.e., some transaction in B starts before
>    A commits 64)

The first transaction start with DB.open(), right?
Thank you very much for the helpful explanation...

	Paolo