Re: Implementing RESET CONNECTION ...
Hans-Jürgen Schönig <postgres@cybertec.at>
From: Hans-Jürgen Schönig <postgres@cybertec.at>
To: Karel Zak <zakkr@zf.jcu.cz>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Oliver Jowett <oliver@opencloud.com>, Kris Jurka <books@ejurka.com>, eg@cybertec.at, List pgsql-patches <pgsql-patches@postgreSQL.org>
Date: 2005-01-04T09:01:28Z
Lists: pgsql-hackers
I completely agree with Karel. I think it is a bad idea to change the protocol for such a minor feature - i tend to call it overkill. I want to add one point to this discussion: There is not just JDBC - other connection pools or clients might want different behaviour (which can from my point of view only lead to a complete reset). If the JDBC driver prefers different behaviour (maybe for prepared statements) we should discuss further options for RESET. Now there is: RESET CONNECTION (cleaning entire connection), RESET ALL (cleaning GUCS only) and RESET some_guc. Maybe we want RESET LISTENER, RESET PREPARED, RESET CURSORS. Personally I think this is not a good idea. Regards, Hans Karel Zak wrote: > On Mon, 2005-01-03 at 20:27 -0500, Tom Lane wrote: > > >>I'm inclined to think that we'd have to add a protocol message that >>reports RESET CONNECTION to really answer objections of this type. >>That seems to bring the thing into the category of "stuff that forces >>a protocol version bump" :-( >> >>Perhaps RESET CONNECTION should be a protocol-level operation instead >>of a SQL command? That would prevent user-level code from causing it >>without the driver knowing. > > > I still don't see a big difference between DEALLOCATE and RESET -- both > can break the JDBC driver. I'm not sure if we need prevent bad usage of > PG tools (JDBC in this case). The DEALLOCATE/RESET usage is under user's > full control and everything can be described in docs. > > I think each PG command returns some status. For example in libpq it's > possible check by PQcmdStatus(). I think JDBC can checks this status (by > own PQcmdStatus() implementation) and if PG returns string "CONNECTION- > RESETED" it can deallocate internal stuff. This solution doesn't require > touch the protocol. > > Karel > -- Cybertec Geschwinde u Schoenig Schoengrabern 134, A-2020 Hollabrunn, Austria Tel: +43/660/816 40 77 www.cybertec.at, www.postgresql.at