Re: [Postgres-xc-developers] Patch correcting implicit 2-phase commit

[Michael P. <mic...@gm...>]

>
> I think we should try to minimize changes to CommitTransaction. Why not use
> the PrepareTransaction() to prepare the transaction instead of duplicating
> that code inside CommitTransaction ? Also, it would be nice if you can take
> away new code in a separate function and call that, something like
> AtEOXact_PGXC() or something like that.
>

Hi all,

I changed deeply the algorithm to avoid code duplication for implicit 2PC.
With the patch attached, Coordinator is prepared only if 2 Coordinators at
least are involved in a transaction (DDL case).
If only one Coordinator is involved in transaction or if transaction does
not contain any DDL, transaction is prepared on the involved nodes only.

To sum up:
1) for DDL transaction (more than 1 Coordinator and more than 1 Datanode
involved in a transaction)
- prepare on Coordinator (2PC file written)
- prepare on Nodes (2PC file written)
- Commit prepared on Coordinator
- Commit prepared on Datanodes
2) If no Coordinator, or only one Coordinator is involved in a transaction
- prepare on nodes
- commit on Coordinator
- Commit on Datanodes

Note: I didn' t put calls to implicit prepare functions in a separate
functions because modification of CommitTransaction() are really light.

Regards,

-- 
Michael Paquier
http://michaelpq.users.sourceforge.net