On Thu, 9 Feb 2006, Kris Jurka wrote:
> On Thu, 9 Feb 2006, Xavier Bugaud wrote:
>
>> Currently, the last JDBC driver is not fully XA compliant as it does not
>> support transaction interleaving and suspend/resume.
>>
>> I can't see on the todo list anything about XA improvement. Is it
>> planned to implement the missing XA features ?
>
> It is possible to fake these to some extent in the driver, but we've decided
> not to do that and wait for full support from the backend. There isn't a
> whole lot of interest from backend developers to do this though and I don't
> know of anyone working on it. Their goal was to implement two phase commit,
> but XA is more than that. I'm not sure they knew this at the time and seemed
> a little put out when the goalposts were moved after they completed the
> design and implementation.
Many other big JDBC implementations don't support it either,
or fake it, or support it only partially. Therefore no transaction
coordinator implementation can rely on transaction interleaving or
suspend/resume anyway, or at least have to provide a flag to work around
it. Therefore there's very little practical value in actually
implementing them, beside being able to tick the "fully XA-compliant"
checkbox in marketing material.
See earlier discussion on the subject:
http://archives.postgresql.org/pgsql-jdbc/2005-06/msg00165.php
Implementing transaction interleaving and suspend resume would be a very
invasive change to the backend. Frankly I doubt it will never be
implemented.
(BTW: this should be added a FAQ. Preferably with instructions on
configuring various application servers to work with our implementation)
- Heikki