Load test SQL scripts for ranking

[RodionGork]

User ranking recalculation is currently implemented like this:

we have tables taskstats and userstats and their corresponding views, from which they are filled. See
here for sql and here for update invocation.

It is very interesting (crucial) to know how this will work when we have many users and tasks.

So. Create some script to populate database with about 1000 tasks and 100000 users. Make each user solve at least 10 random tasks. Then invoke ranking recalculation. Check how much time it will take.