MyRocks

[bohanjason]

1. add tpcc config file for MyRocks.
2. ddl and collectors were updated and committed before.
3. only finish TPCC for Myrocks, and run MySQL as a baseline, no other teammates.
   (Database extra credits)

[apavlo]

@bohanjason I don't think we need to merge this because you didn't make schema changes to make it work with MyRocks, right? It's just the regular MySQL DDL.

[bohanjason]

I copied MySQL DDL and removed the foreign key references for MyRocks tpcc DDL . This is because MyRocks does not support foreign keys. I think the changes have been merged before.