Re: Support for 2-Phase Commit protocol

on 2004-03-29 19:43 Freddy Villalba Arias wrote:

> I'm currently envolved in a Project requiring v7.4 (7.4.2?). I won't
> be using distributed transaction, but transactions that span multiple
> objects (all of them on the same JVM). Therefore, as I understood it
> from reading the JTA spec, I should not need to use the XA "objects"
> (XAConnection...) but just "plain JDBC"'s ones (Connection,
> Statement...).

What do you mean by multiple objects? Sounds like you have multiple
transactions on a single back end that all need to complete atomically
-- more related to nested transactions and savepoints than to
two-phase commits.

> Then, the following question arises: does the fact that 2-Phase commit
> isn't yet supported imply that I cannot use JTA?

It's been a while since I read the JTA spec, but even if the
transaction manager did not require XA support from the driver, it
still would not be able to glue your transactions together using a
two-phase commit, which is what you want. So the TM would commit each
transaction individually, but it would not be able to roll them back
in the case of mid-point failure.

The point of the XA interfaces is to encapsulate the two-phase
protocol, allowing local transactions to be prepared before they are
committed. Without the XA support, JTA is basically a standard
interface to a transaction manager and X/Open-style transaction semantics.

I assume Bruce is talking either about this patch:

http://archives.postgresql.org/pgsql-patches/2003-10/msg00273.php

or this work:

http://snaga.org/pgsql/

Alexander.

on 2004-03-29 19:43 Freddy Villalba Arias wrote:

> I'm currently envolved in a Project requiring v7.4 (7.4.2?). I won't
> be using distributed transaction, but transactions that span multiple
> objects (all of them on the same JVM). Therefore, as I understood it
> from reading the JTA spec, I should not need to use the XA "objects"
> (XAConnection...) but just "plain JDBC"'s ones (Connection,
> Statement...).
>
> Then, the following question arises: does the fact that 2-Phase commit
> isn't yet supported imply that I cannot use JTA? Are these to issues
> unrelated?
>
> I'll look forward for your feedback.
>
> -----Mensaje original-----
> De: Bruce Momjian [mailto:pgman(at)candle(dot)pha(dot)pa(dot)us]
> Enviado el: lunes, 29 de marzo de 2004 18:36
> Para: Alexander Staubo
> CC: Freddy Villalba Arias; PostgreSQL JDBC Mailing List
> Asunto: Re: [JDBC] Support for 2-Phase Commit protocol
>
>
> Someone has a 2-phase commit patch and we are looking to get it into
> 7.5.
>
>
>
------------------------------------------------------------------------
> ---
>
> Alexander Staubo wrote:
>
>>This is on the PostgreSQL todo list:
>>
>> http://developer.postgresql.org/todo.php
>>
>>However, as far as I know it's not something people are working
>>actively on, or at least not to the extent that we will see a release
>>in the near term. I would like to be wrong, though.
>>
>>Seeing as this is a server issue and not specifically a JDBC issue,
>>the pgsql-hackers list is probably the place to ask about the
>>development status of future features.
>>
>>To my knowledge, Firebird (http://www.firebirdsql.org/) is the only
>>open-source database that supports two-phase commits; its JDBC driver
>>comes with JTA support. You may have better luck with that. Firebird
>>is itself a decent database, but is going to feel like a step back
>>into the '80s once you've gotten used to PostgreSQL's sleek, modern
>>facilities [*].
>>
>>[*] Variable-length "text" data type that does not need a pre-declared
>
>
>>size, virtually unlimited row sizes, online alter/drop/rename for
>>tables/columns/etc., ability to index fields declared as >250 chars
>>long, SQL shell with proper readline support, intelligible error
>>messages, mature documentation, I could go on.
>>
>>Alexander.
>>
>>on 2004-03-29 17:19 Freddy Villalba Arias wrote:
>>
>>
>>>Hi everybody,
>>>
>>>
>>>
>>>I forgot to include this other question (also urgent, sorry if I?m
>>>stressing you up): does anybody know what is PostgreSQL?s current
>
> status
>
>>>regarding ?Two Phase Commit Protocol Support??
>>>
>>>
>>>
>>>Again, thanx.
>>>
>>>
>>>
>>>Regards,
>>>
>>>Freddy.
>>>
>>
>>
>>---------------------------(end of
>
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>
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>