From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-committers(at)postgresql(dot)org, Gerhard Hintermayer <g(dot)hintermayer(at)inode(dot)at> |
Subject: | Re: pgsql-server/src/interfaces/libpgtcl pgtclCmds ... |
Date: | 2002-08-18 01:40:03 |
Message-ID: | 200208180140.g7I1e3715924@candle.pha.pa.us |
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Thread: | |
Lists: | pgsql-committers |
OK, patch backed out. Please address Tom's suggestions and resubmit.
Thanks.
---------------------------------------------------------------------------
Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)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
>
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--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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