Re: timeouts on transactions etc?

On May 28, 2011, at 7:55 PM, Darren Duncan wrote:

> Does Postgres have any mechanisms where one can set an activity timeout, say either dynamically thru SQL to affect a current session, or alternately in a configuration file so to take effect globally?
>
> I mean for example so we can tell Postgres to automatically abort/rollback a current statement or transaction if it is still running after 5 seconds? It would return an error / throw an exception at the same time, as if there was a failure or constraint violation for some other reason, so the user would know.
>
> Or a generalization of this would be the DBMS enforcing particular resource limits, but I suspect that just clock time is a relatively easy one to do, as it could be implemented with ordinary timers and signals/interrupts.
>
> Purposes of this feature include coping with applications that are not well-behaved such as by failing to explicitly end transactions or by asking the DBMS to do too much at once.
>
> If so, where is this documented? If not, how much work might it be to add this?
>
> I'm looking for something enforced by the DBMS itself, not that an application or bridge layer should do.

You're looking for "statement_timeout", I think. You can set that globally, but it's better to set it just in the sessions where you want it.

http://www.postgresql.org/docs/9.0/static/runtime-config-client.html

There's also the ability to log long statements, so you can identify and fix bad queries without breaking functionality - log_min_duration_statement and friends.

Cheers,
Steve