smart shutdown at end of transaction (was: Default mode for shutdown)

On Wed, Dec 15, 2010 at 10:11 AM, Alvaro Herrera
<alvherre@commandprompt.com> wrote:
> It occurs to me that we may need a new mode, which disconnects sessions
> that are not in a transaction (or as soon as they are) but leaves
> in-progress transactions alone; this could be the new default.  Of
> course, this is much more difficult to implement than the current modes.

This idea appeared to have some support.  I'd like to suggest that we
take this a step further.  Instead of adding a fourth mode, I'd like
to suggest that we redefine "smart" to have the behavior described
above.  This is based on the theory that (1) people who like smart
shutdown like it because it allows currently-running transactions to
complete without error, and will find it acceptable to have idle
transactions terminated immediately and other sessions terminated
after the command completes; and (2) people who dislike smart shutdown
(such as me) dislike it primarily because a completely idle session
that someone's forgotten to close can prevent shutdown indefinitely.
Either part of this theory could be wrong, of course, although I'm
pretty sure #2 holds for me personally at the least.

Patch is attached.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company