3548e4220d
Summary: Improve the iterators performance when the user explicitly sets the readahead size via `ReadOptions.readahead_size`. 1. Stop creating new table readers when the user explicitly sets readahead size. 2. Make use of an internal buffer based on `FilePrefetchBuffer` instead of using `ReadaheadRandomAccessFileReader`, to handle the user readahead requests (for both buffered and direct io cases). 3. Add `readahead_size` to db_bench. **Benchmarks:** https://gist.github.com/sagar0/53693edc320a18abeaeca94ca32f5737 For 1 MB readahead, Buffered IO performance improves by 28% and Direct IO performance improves by 50%. For 512KB readahead, Buffered IO performance improves by 30% and Direct IO performance improves by 67%. **Test Plan:** Updated `DBIteratorTest.ReadAhead` test to make sure that: - no new table readers are created for iterators on setting ReadOptions.readahead_size - At least "readahead" number of bytes are actually getting read on each iterator read. TODO later: - Use similar logic for compactions as well. - This ties in nicely with #4052 and paves the way for removing ReadaheadRandomAcessFile later. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5246 Differential Revision: D15107946 Pulled By: sagar0 fbshipit-source-id: 2c1149729ca7d779e4e8b7710ba6f4e8cbfd3bea |
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| buckifier | ||
| build_tools | ||
| cache | ||
| cmake | ||
| coverage | ||
| db | ||
| docs | ||
| env | ||
| examples | ||
| hdfs | ||
| include/rocksdb | ||
| java | ||
| memtable | ||
| monitoring | ||
| options | ||
| port | ||
| table | ||
| third-party/gtest-1.7.0/fused-src/gtest | ||
| tools | ||
| util | ||
| utilities | ||
| .clang-format | ||
| .gitignore | ||
| .lgtm.yml | ||
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| AUTHORS | ||
| CMakeLists.txt | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| COPYING | ||
| DEFAULT_OPTIONS_HISTORY.md | ||
| DUMP_FORMAT.md | ||
| HISTORY.md | ||
| INSTALL.md | ||
| LANGUAGE-BINDINGS.md | ||
| LICENSE.Apache | ||
| LICENSE.leveldb | ||
| Makefile | ||
| README.md | ||
| ROCKSDB_LITE.md | ||
| TARGETS | ||
| USERS.md | ||
| Vagrantfile | ||
| WINDOWS_PORT.md | ||
| appveyor.yml | ||
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README.md
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/
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.