1a130fa3c1
Summary: This is for https://github.com/facebook/rocksdb/issues/9737 I have wasted more than a few hours running db_bench benchmarks where --seed was not set and getting better than expected results because cache hit rates are great because multiple invocations of db_bench used the same value for --seed or did not set it, and then all used 0. The result is that all see the same sequence of keys. Others have done the same. The problem is worse in that it is easy to miss and the result is a benchmark with results that are misleading. A good way to avoid this is to set it to the equivalent of gettimeofday() when either --seed is not set or it is set to 0 (the default). With this change the actual seed is printed when it was 0 at process start: Set seed to 1647992570365606 because --seed was 0 Pull Request resolved: https://github.com/facebook/rocksdb/pull/9740 Test Plan: Perf results: ./db_bench --benchmarks=fillseq,readrandom --num=1000000 --reads=4000000 readrandom : 6.469 micros/op 154583 ops/sec; 17.1 MB/s (4000000 of 4000000 found) ./db_bench --benchmarks=fillseq,readrandom --num=1000000 --reads=4000000 --seed=0 readrandom : 6.565 micros/op 152321 ops/sec; 16.9 MB/s (4000000 of 4000000 found) ./db_bench --benchmarks=fillseq,readrandom --num=1000000 --reads=4000000 --seed=1 readrandom : 6.461 micros/op 154777 ops/sec; 17.1 MB/s (4000000 of 4000000 found) ./db_bench --benchmarks=fillseq,readrandom --num=1000000 --reads=4000000 --seed=2 readrandom : 6.525 micros/op 153244 ops/sec; 17.0 MB/s (4000000 of 4000000 found) Reviewed By: jay-zhuang Differential Revision: D35145361 Pulled By: mdcallag fbshipit-source-id: 2b35b153ccec46b27d7c9405997523555fc51267 |
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| DEFAULT_OPTIONS_HISTORY.md | ||
| DUMP_FORMAT.md | ||
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| LICENSE.Apache | ||
| LICENSE.leveldb | ||
| Makefile | ||
| PLUGINS.md | ||
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| README.md | ||
| ROCKSDB_LITE.md | ||
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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 especially suitable for storing multiple terabytes of data in a single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/main/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.
Questions and discussions are welcome on the RocksDB Developers Public Facebook group and email list on Google Groups.
License
RocksDB is dual-licensed under both the GPLv2 (found in the COPYING file in the root directory) and Apache 2.0 License (found in the LICENSE.Apache file in the root directory). You may select, at your option, one of the above-listed licenses.