[DB-SIG] Two-phase commit API proposal (was Re: Any standard for two phase commit APIs?)

[James Henstridge]

On 25/01/2008, Dieter Maurer <dieter at handshake.de> wrote:
> This description suggests that the TM provides the "main" transaction
> identifier and the resource manager could add the branch part.

I guess the reason why the TM generally assigns the branch qualifiers
in XA systems is that it is in the best place to do so: it can simply
issue sequential numbers to each resource that joins the transaction.
An RM has no knowledge of what other branch qualifiers have been used
so would need to do something more comlpex.

Now whether the TM or RM generates the branch qualifier, I'd expect
that the TM needs to know all the full transaction IDs if it is to
properly handle recovery.  If the RM is generating the ID, then the TM
would now need some way to retrieve that ID.

James.