rocksdb/index.html
2013-11-15 11:34:04 -08:00

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<title>RocksDB | A persistent key-value store for fast storage environments</title>
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<a href='index.html'><h1>RocksDB</h1></a>
<ul>
<li><a href='overview.html'>Overview</a></li>
<li><a href='https://github.com/facebook/rocksdb/wiki/_pages'>Wiki</a></li>
<li><a href='https://github.com/facebook/rocksdb'>GitHub</a>
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<h1>
A persistent key-value store for fast storage environments
</h1>
<a class='button' href='overview.html'>Get Started</a>
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<article>
<h2>What is RocksDB?</h2>
<p>
RocksDB is an embeddable persistent key-value store for fast storage. RocksDB
can also be the foundation for a client-server database but our current focus is
on embedded workloads.
</p>
<p>
RocksDB builds on <a href='https://code.google.com/p/leveldb/'>LevelDB</a> to be
scalable to run on servers with many CPU cores, to efficiently use fast storage,
to support IO-bound, in-memory and write-once workloads, and to be flexible to
allow for innovation.
</p>
<p>For more background on RocksDB, see <a href="intro.pdf">Dhruba Borthakur's
introductory talk</a> from the Data @ Scale 2013 conference.</p>
<h2>How does performance compare?</h2>
<p>
We benchmarked LevelDB and found that it was unsuitable for our server
workloads. The <a
href='http://leveldb.googlecode.com/svn/trunk/doc/benchmark.html'> benchmark
results</a> look awesome at first sight, but we quickly realized that those
results were for a database whose size was smaller than the size of RAM on the
test machine - where the entire database could fit in the OS page cache. When we
performed the same benchmarks on a database that was at least 5 times larger
than main memory, the performance results were dismal.
</p>
<p>
By contrast, we've published the <a
href='https://github.com/facebook/rocksdb/wiki/Performance-Benchmarks'> RocksDB
benchmark results</a> for server side workloads on Flash. We also measured the
performance of LevelDB on these server-workload benchmarks and found that
RocksDB solidly outperforms LevelDB for these IO bound workloads. We found that
LevelDB's single-threaded compaction process was insufficient to drive server
workloads. We saw frequent write-stalls with LevelDB that caused 99-percentile
latency to be tremendously large. We found that mmap-ing a file into the OS
cache introduced performance bottlenecks for reads. We could not make LevelDB
consume all the IOs offered by the underlying Flash storage.
</p>
<h2>What is RocksDB suitable for?</h2>
<p>
RocksDB can be used by applications that need low latency database accesses. A
user-facing application that stores the viewing history and state of users of a
website can potentially store this content on RocksDB. A spam detection
application that needs fast access to big data sets can use RocksDB. A
graph-search query that needs to scan a data set in realtime can use RocksDB.
RocksDB can be used to cache data from Hadoop, thereby allowing applications to
query Hadoop data in realtime. A message-queue that supports a high number of
inserts and deletes can use RocksDB.
</p>
<h2>Why is RocksDB open sourced?</h2>
<p>
We are open sourcing this project <a
href='http://github.com/facebook/rocksdb'>on GitHub</a> because we think it will
be useful beyond Facebook. We are hoping that software programmers and database
developers will use, enhance, and customize RocksDB for their use-cases. We
would also like to engage with the academic community on topics related to
efficiency for modern database algorithms.
</p>
</article>
<aside>
<h3>Quick links</h3>
<ul>
<li><a href='overview.html'>Overview</a></li>
<li><a href='https://github.com/facebook/rocksdb/wiki/_pages'>Wiki</a></li>
<li><a href='https://github.com/facebook/rocksdb'>GitHub</a>
</ul>
<h3>Community</h3>
<ul>
<li><a href='https://github.com/facebook/rocksdb/issues'>Report an issue</a></li>
<li><a href='https://www.facebook.com/rocksdb'>Facebook Page</a></li>
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<h3>Open source</h3>
<ul>
<li><a href='https://github.com/facebook/rocksdb/blob/master/LICENSE'>BSD license</a></li>
<li><a href='https://github.com/facebook/rocksdb/blob/master/CONTRIBUTING.md'>Contributing</a></li>
<li><a href='https://github.com/facebook/rocksdb/blob/master/PATENTS'>Patent grant</a></li>
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