From: | jesus(at)omniti(dot)com |
---|---|
To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
Cc: | PostgreSQL-development Development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: question about implementing XA-ish functions |
Date: | 2009-12-18 19:24:07 |
Message-ID: | 38889E8E-126E-4FB2-8CF5-6379E8008FA1@omniti.com |
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Lists: | pgsql-hackers |
This is perfect. It fires on both commit and rollback? And I can
determine which? The system I'm interfacing with has 2PC so it should
be a pretty tight fit. Thanks a ton Heikki!
--
Theo Schlossnagle (mobile)
http://omniti.com/is/theo-schlossnagle
On Dec 18, 2009, at 10:34 AM, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com
> wrote:
> Theo Schlossnagle wrote:
>> I'm trying to implement a function that has some XA like properties.
>>
>> Is it possible to write a postgres extension function that fires
>> when called within a pg transaction... however, the actions it
>> takes need to be later committed or rolled back based on the
>> containing transactions commital or not. Not having looked to
>> deeply into this, I'm wondering if this is possible. Naively, my
>> first hookpoint would be something like:
>>
>> allocate something in the transactions memory context and register
>> a cleanup.... do my work.
>>
>> when the transaction memory context is cleaned up, my cleanup
>> handler fires, I detect whether the txn was committed or rolledback
>> and rightly mark my work as committed or rolled back.
>
> See RegisterXactCallback(). And then there's the ResourceOwners, that
> you can use to register custom resources for cleanup.
>
> Of course, you'll never be able to make it atomic without 2PC. The
> callbacks are executed very soon after after the commit record has
> been
> flushed to disk, so the window is small but it's there.
>
> --
> Heikki Linnakangas
> EnterpriseDB http://www.enterprisedb.com
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