37921b4997
Summary: Introduce parameter -read_random_exp_range in db_bench to provide some key skewness in readrandom and multireadrandom benchmarks. It will helpful to cover block cache better. Test Plan: Run benchmarks with this new parameter. I can clearly see block cache hit rate change while I increase this value (DB size is about 66MB): ./db_bench --benchmarks=readrandom -statistics -use_existing_db -cache_size=5000000 --read_random_exp_range=0.0 rocksdb.block.cache.data.miss COUNT : 958418 rocksdb.block.cache.data.hit COUNT : 41582 ./db_bench --benchmarks=readrandom -statistics -use_existing_db -cache_size=5000000 --read_random_exp_range=5.0 rocksdb.block.cache.data.miss COUNT : 819518 rocksdb.block.cache.data.hit COUNT : 180482 ./db_bench --benchmarks=readrandom -statistics -use_existing_db -cache_size=5000000 --read_random_exp_range=10.0 rocksdb.block.cache.data.miss COUNT : 450479 rocksdb.block.cache.data.hit COUNT : 549521 ./db_bench --benchmarks=readrandom -statistics -use_existing_db -cache_size=5000000 --read_random_exp_range=20.0 rocksdb.block.cache.data.miss COUNT : 223192 rocksdb.block.cache.data.hit COUNT : 776808 Reviewers: MarkCallaghan, kradhakrishnan, yhchiang, rven, igor Reviewed By: igor Subscribers: leveldb, dhruba Differential Revision: https://reviews.facebook.net/D34629
RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
RocksDB is developed and maintained by Facebook Database Engineering Team. It is built on earlier work on LevelDB by Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)
This code is a library that forms the core building block for a fast key value server, especially suited for storing data on flash drives. It has a Log-Structured-Merge-Database (LSM) design with flexible tradeoffs between Write-Amplification-Factor (WAF), Read-Amplification-Factor (RAF) and Space-Amplification-Factor (SAF). It has multi-threaded compactions, making it specially suitable for storing multiple terabytes of data in a single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/master/examples
See the github wiki for more explanation.
The public interface is in include/. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Design discussions are conducted in https://www.facebook.com/groups/rocksdb.dev/