236d4c67e9
Summary: In one deployment we saw high latencies (presumably from slow iterator operations) and a lot of CPU time reported by perf with this stack: ``` rocksdb::MergingIterator::Next rocksdb::DBIter::FindNextUserEntryInternal rocksdb::DBIter::Seek ``` I think what's happening is: 1. we create a snapshot iterator, 2. we do lots of Put()s for the same key x; this creates lots of entries in memtable, 3. we seek the iterator to a key slightly smaller than x, 4. the seek walks over lots of entries in memtable for key x, skipping them because of high sequence numbers. CC IslamAbdelRahman Closes https://github.com/facebook/rocksdb/pull/1413 Differential Revision: D4083879 Pulled By: IslamAbdelRahman fbshipit-source-id: a83ddae |
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|---|---|---|
| arcanist_util | ||
| build_tools | ||
| cmake/modules | ||
| coverage | ||
| db | ||
| docs | ||
| examples | ||
| hdfs | ||
| include/rocksdb | ||
| java | ||
| memtable | ||
| port | ||
| table | ||
| third-party | ||
| tools | ||
| util | ||
| utilities | ||
| .arcconfig | ||
| .clang-format | ||
| .gitignore | ||
| .travis.yml | ||
| appveyor.yml | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| DEFAULT_OPTIONS_HISTORY.md | ||
| DUMP_FORMAT.md | ||
| HISTORY.md | ||
| INSTALL.md | ||
| LANGUAGE-BINDINGS.md | ||
| LICENSE | ||
| Makefile | ||
| PATENTS | ||
| README.md | ||
| ROCKSDB_LITE.md | ||
| src.mk | ||
| thirdparty.inc | ||
| USERS.md | ||
| Vagrantfile | ||
| WINDOWS_PORT.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/