[DB-SIG] DBAPI two phase commit implementation in psycopg2

[Daniele Varrazzo]

On Fri, Sep 24, 2010 at 9:48 AM, M.-A. Lemburg <mal at egenix.com> wrote:

> I'd also look around to check how other tools that interoperate with
> PG in two-phase commits handle this. XA is a widely used standard
> in the industry, so I assume the problem must have popped up
> elsewhere as well.

MySQL uses a XA model, so the mapping is direct. Other high profile
databases hide the commands they use under tons of APIs and I've not
been able to find implementation details.

I've found instead the JDBC implementation of the XA - PG mapper [1]:
it is probably a good idea to use the same format to allow some form
of interoperation between tools. They use str(format_id) + '_' +
Base64(gtrid) + '_' + Base64(bqual) and on recover they refuse to work
on anything that doesn't follow this model. I don't agree on the
latter point because I think the driver should allow the user to
leverage everything the database permits, so I will probably find a
way to parse back a generic string into a XID. But I guess this is an
implementation detail better discussed on the psycopg mailing lists.

Thank you very much. Have a nice weekend.

-- Daniele

[1]: http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/jdbc/pgjdbc/org/postgresql/xa/RecoveredXid.java?rev=1.3&content-type=text/x-cvsweb-markup