Summary:
Fix issues for reproducing synthetic ZippyDB workloads in the FAST20' paper using db_bench. Details changes as follows.
1, add a separate random mode in MixGraph to produce all_random workload.
2, fix power inverse function for generating prefix_dist workload.
3, make sure key_offset in prefix mode is always unsigned.
note: Need to carefully choose key_dist_a/b to avoid aliasing. Power inverse function range should be close to overall key space.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6795
Reviewed By: akankshamahajan15
Differential Revision: D21371095
Pulled By: zhichao-cao
fbshipit-source-id: 80744381e242392c8c7cf8ac3d68fe67fe876048
d9e170d82b