YCSB legacy code in db_bench?

[xxks-kkk]

I go through db_bench.cc, and I notice that code ships with some code related to YCSB. I'm curious what's the status of this part of the code? --benchmarks doesn't expose ycsb option and when I manually enable this option, core dump happens.

Also, it seems db_bench.cc is somewhat broken when I run the benchmark by default

$ ./db_bench
LevelDB:    version 1.17
Date:       Tue Apr 17 18:12:07 2018
CPU:        1 * Intel(R) Core(TM) i5-2435M CPU @ 2.40GHz
CPUCache:   3072 KB
Keys:       16 bytes each
Values:     1024 bytes each (512 bytes after compression)
Entries:    1000000
RawSize:    991.8 MB (estimated)
FileSize:   503.5 MB (estimated)
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
fillseq      :     197.156 micros/op;    5.0 MB/s
fillsync     :    4347.880 micros/op;    0.2 MB/s (1000 ops)
fillrandom   :     234.785 micros/op;    4.2 MB/s
overwrite    :     285.580 micros/op;    3.5 MB/s
readrandom   :      61.021 micros/op; (1000000 of 1000000 found)
readrandom   :      58.686 micros/op; (1000000 of 1000000 found)
readseq      :       7.205 micros/op;  137.7 MB/s
readreverse  :      16.426 micros/op;   60.4 MB/s
lt-db_bench: ./db/dbformat.h:111: leveldb::Slice leveldb::ExtractUserKey(const leveldb::Slice&): Assertion `internal_key.size() >= 8' failed.
Aborted (core dumped)