Re: Cancelling idle in transaction state

On Sun, Dec 6, 2009 at 4:23 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> We are using NOTICE, not NOTIFY, assuming that we use anything at all
> (which I still regard as unnecessary).  Please stop injecting confusion
> into the discussion.

Attached is a minimal POC patch that allows to cancel an idle
transaction with SIGINT. The HS patch also allows this in its current
form but as Simon points out the client gets out of sync with it.

The proposal is to send an additional NOTICE to the client and abort
all open transactions and subtransactions (this is what I got from the
previous discussion).

I had to write an additional function AbortAnyTransaction() which
aborts all transactions and subtransactions and leaves the transaction
in the aborted state, is there an existing function to do this?

We'd probably want to add a timeout for idle transactions also (which
is a wishlist item since quite some time) and could also offer user
functions like pg_cancel_idle_transaction(). Along this we might need
to add internal reasons like we do for SIGUSR1 because we are now
multiplexing different functionality onto the SIGINT signal. One might
want to cancel an idle transaction only and not a running query,
without keeping track of internal reasons one risks to cancel a
legitimate query if that backend has started to work on a query again.

Comments?


Joachim