Re: pgsql-server/src/interfaces/libpgtcl pgtclCmds ...

OK, patch backed out.  Please address Tom's suggestions and resubmit.
Thanks.


---------------------------------------------------------------------------

Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> >> I am beginning to think that patch must have a hex on it.
>
> > Oops.  Here it is, in mailbox format.
>
> Having looked it over, I'm not happy about it.  The two big problems are
>
> * hardwired use of "connection_closed" as a NOTIFY condition name.
> It might be considered unlikely that this condition name is already in
> use out there ... or it might not.
>
> * not removing pending notifies from queue when connection loss
> is detected.  This WILL break existing applications (note blithe
> reference to possible segfaults in notify scripts in his message).
> The reason we are killing those notifies is so that the app won't be
> fooled into trying to execute database operations because of receipt
> of a stale NOTIFY callback.  While a callback intended specifically
> for connection_closed could be expected not to try to do database
> operations, I think it's unreasonable to expect existing callbacks for
> normal NOTIFY conditions to be coded to guard against this.
>
> I'm also unhappy about the complete lack of documentation.
>
> I'd like to revert this patch and ask Gerhard to try again.
>
> The design I'd suggest is that there be a new command added to libpgtcl
> with a format along the lines of
>     pg_on_connection_loss dbHandle [ callbackCommand ]
> This would be essentially similar to pg_listen except for omitting the
> notifyName parameter, and could share a lot of the internal
> implementation.  By doing this we could avoid hardwiring an assumption
> about an unused notification name.
>
> Also, the code *has* to be rejiggered so that ordinary notify events
> are still dropped on connection loss.  And some documentation of this
> new command would be appropriate...
>
>             regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: if posting/reading through Usenet, please send an appropriate
> subscribe-nomail command to majordomo@postgresql.org so that your
> message can get through to the mailing list cleanly
>

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073