Re: [PATCHES] Implementing RESET CONNECTION ...

OK, what would people like done with this patch? Our TODO list has:

* -Add RESET CONNECTION command to reset all session state

This would include resetting of all variables (RESET ALL), dropping of
temporary tables, removing any NOTIFYs, cursors, open transactions,
prepared queries, currval()s, etc. This could be used for connection
pooling. We could also change RESET ALL to have this functionality.
The difficult of this features is allowing RESET ALL to not affect
changes made by the interface driver for its internal use. One idea
is for this to be a protocol-only feature. Another approach is to
notify the protocol when a RESET CONNECTION command is used.

This patch does everything except reset currval(), but the big missing
item is that it doesn't handle the protocol issues outlined in the TODO
item. However, there also has been very little discussion on exactly
how the protocol stuff would work.

Should we add it for 8.2 and see if we get any problem reports?

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

> I have backed out the patch until there is more discussion.
>
> I now see that the CC list had an incorrect entry for the patches list,
> so I am unsure if others have seen this patch thoroughly.

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

Hans-Jrgen Schnig wrote:
> We have implemented a patch which can be used by connection pools for
> instance.
> RESECT CONNECTION cleans up a backend so that it can be reused.
> Temp tables, LISTEN / NOTIFY stuff, WITH HOLD cursors, open
> transactions, prepared statements and GUCs are cleaned up.
> I hope we have not missed important per-backend information.
>
> test=# BEGIN;
> BEGIN
> test=# RESET CONNECTION;
> RESET
> test=# COMMIT;
> WARNING: there is no transaction in progress
> COMMIT
> test=# PREPARE myplan(int, int) AS SELECT $1 + $2;
> PREPARE
> test=# RESET CONNECTION;
> RESET
> test=# EXECUTE myplan(1, 2);
> ERROR: prepared statement "myplan" does not exist
> test=#
> test=# DECLARE mycur CURSOR WITH HOLD FOR SELECT relname FROM pg_class;
> DECLARE CURSOR
> test=# FETCH NEXT FROM mycur;
> relname
> ---------
> views
> (1 row)
>
> test=# RESET CONNECTION;
> RESET
> test=# FETCH NEXT FROM mycur;
> ERROR: cursor "mycur" does not exist
> test=# CREATE TEMP TABLE mytmp (id int4);
> CREATE TABLE
> test=# RESET CONNECTION;
> RESET
> test=# INSERT INTO mytmp VALUES (10);
> ERROR: relation "mytmp" does not exist
>
>
> All regression tests passed.
> It would be nice if we had this in 8.1.
>
> Best regards,
>
> Hans
>
>
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>

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--
Bruce Momjian http://candle.pha.pa.us
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