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.linnakan...@enterprisedb.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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