It would be nice to have ON COMMIT triggers for this use.

However you can emulate ON COMMIT triggers with a modification of the memcache update process :

        - A standard trigger sends the data to update to memcache
        - The trigger also sends the PID
        - Instead of being used immediately, this data is kept in a buffer
        - Notify is issued

        On commit :
        - postgres sends the NOTIFY signal
- the memcache updater reads the NOTIFY (which embeds the PID I believe) ; it finds the buffered data sent above and uses it to update memcached

        On rollback :
        - Interesting problem ;)))

        OK, it's a kludge. When can we get ON COMMIT triggers ?




On Tue, Apr 04, 2006 at 12:24:42AM -0700, C Storm wrote:
I was wondering if anyone on the list has a successful installation of
pgmemcache running
that uses LISTEN/NOTIFY to signal a successfully completed transaction,
i.e., to get around the fact
that TRIGGERS are transaction unaware.  Or perhaps any other
information regarding a successful
deployment of pgmemcache.

The problem with attempting that is that you'd have a window between
transaction commit and when the cache was invalidated. If that's
acceptable then it shouldn't be too difficult to set something up using
LISTEN/NOTIFY like you describe.



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