faster run_sql with shared database connection

[lovasoa]

see #338

[lovasoa]

@vlasky @guspower : this ended up being a larger change than expected... Would any of you be available to test this on your applications before I release the change for everyone ? I would like to make sure the change does not have any unexpected consequences.

[guspower]

@lovasoa yes I can take it for a spin tomorrow and let you know.

[guspower]

FYI I cloned better_run_sql_management yesterday and ran the release build against a reasonable size app - no issues functionally. I was going to cook up a performance test to compare against the previous release but I see you've merged in so I'll hold off for now.

[lovasoa]

Great to hear it works. And I actually would be very interested in the numbers you get on your application in a performance test.

[guspower]

Me too! First I am going to set up a functional check using spider and then figure out how to run a perf test (which is always a pain :) ) I doubt I'll get one running this week due to workload, but when I do I will share.