Allow performance checking on SQL queries

[Manfred]

• As a developer I want to run a raw SQL query against a production-like database so I can optimize it

Allow a developer to run SQL queries against the PerfCheck database so they can test performance and get EXPLAIN output without having to SSH into a PerfCheck server and get access to the database.

[Manfred]

Optionally we could make EXPLAIN really nice.

[sudara]

This is a pretty interesting idea. Currently wondering if it's "enough" to deter console access, as I know that many are often ssh'ing in to:

1. Open a console to inspect which customer has most X records
2. Running the queries via the rails console

However, I think some of that could be mitigated with some in-app guidance.

[sudara]

Also, in the case that triggered this — I followed up with the dev, and the reason a normal perf check job wasn't run is still because

1. the perception of the db state was in question and
2. It's currently difficult to run a successful job, so much so that people aren't trying.

So we should probably wait on this to see if this resurfaces as a need once we are more stable and the majority of the jobs people run succeed instead of fail. (We never had people with this need on the old daemon)

Related — we used to provide a link rack mini profiler results which contained more information about each query. Instead of providing granular access to the db, we could surface those results again if rack-mini-profiler is installed.

[Manfred]

I guess any time someone feels the needs to access the console is an indication of missing performance or debugging tools.