Detect long-running Queries

[nunziotocci]

Envelope should keep track of what queries it's running and when they started so that if it takes a certain amount of time it issues a log.

This would be configurable by the config parameter log_queries_over=<seconds>. If set to zero, don't issue logs.

Also, these logs should be issued no matter what the log_level is.

It would be interesting if you could attach a custom action to this handler, but that would need to be discussed.

[justintocci]

it would be cool to call a database function when this happens, because then it would be a piece of cake to notify the sysadmin of the long running query via text or email.

[nunziotocci]

Ok, I'll add a log_queries_over_action_name=<pg_function> parameter and Envelope will pass the PID of the process to the function.