rocksdb

fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph

Sagar Vemuri 7103559f49 Improve direct IO range scan performance with readahead (#3884 ) Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see 4.5X performance improvement in seekrandom benchmark doing long range scans, when using direct reads, on flash. Description: This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. Implementation Details: - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. Constraints: - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. Benchmarks: I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb		7 years ago
buckifier	Update buckifier and TARGETS	7 years ago
build_tools	Pass -latomic to linker when using clang	7 years ago
cache	Fix LRUCache missing null check on destruct	7 years ago
cmake	Search paths provided by intel's "tbbvars.sh".	7 years ago
coverage	Suppress lint in old files	7 years ago
db	Add file name info to SequentialFileReader. (#4026 )	7 years ago
docs	Adding blog post for 5.10.2 release	7 years ago
env	Build and tests fixes for Solaris Sparc (#4000 )	7 years ago
examples	Pinnableslice examples and blog post	7 years ago
hdfs	Comment out unused variables	7 years ago
include/rocksdb	Add kOptionsStatistics to GetProperty() (#3966 )	7 years ago
java	zLinux build error with gcc and IBM Java headers (#4013 )	7 years ago
memtable	Remove tests from ROCKSDB_VALGRIND_RUN	7 years ago
monitoring	Build and tests fixes for Solaris Sparc (#4000 )	7 years ago
options	PersistRocksDBOptions() to use WritableFileWriter	7 years ago
port	Add file name info to SequentialFileReader. (#4026 )	7 years ago
table	Improve direct IO range scan performance with readahead (#3884 )	7 years ago
third-party	fix some text in comments.	7 years ago
tools	Add file name info to SequentialFileReader. (#4026 )	7 years ago
util	Improve direct IO range scan performance with readahead (#3884 )	7 years ago
utilities	Add file name info to SequentialFileReader. (#4026 )	7 years ago
.clang-format	A script that automatically reformat affected lines	11 years ago
.gitignore	Remove leftover references to phutil_module_cache	7 years ago
.travis.yml	travis: osx install zstd lz4 snappy xz (#3893 )	7 years ago
AUTHORS	Update RocksDB Authors File	7 years ago
CMakeLists.txt	Provide a way to override windows memory allocator with jemalloc for ZSTD	7 years ago
CODE_OF_CONDUCT.md	Add Code of Conduct	7 years ago
CONTRIBUTING.md	Add Code of Conduct	7 years ago
COPYING	Add GPLv2 as an alternative license.	8 years ago
DEFAULT_OPTIONS_HISTORY.md	options.delayed_write_rate use the rate of rate_limiter by default.	8 years ago
DUMP_FORMAT.md	First version of rocksdb_dump and rocksdb_undump.	10 years ago
HISTORY.md	Improve direct IO range scan performance with readahead (#3884 )	7 years ago
INSTALL.md	Enable compilation on OpenBSD	7 years ago
LANGUAGE-BINDINGS.md	Add Nim to the list of language bindings	7 years ago
LICENSE.Apache	Change RocksDB License	8 years ago
LICENSE.leveldb	Add back the LevelDB license file	8 years ago
Makefile	Extend existing unit tests to run with WriteUnprepared as well	7 years ago
README.md	Add dual-license info to README.md	7 years ago
ROCKSDB_LITE.md	Fix some typos in comments and docs.	7 years ago
TARGETS	Provide a way to override windows memory allocator with jemalloc for ZSTD	7 years ago
USERS.md	Added ProfaneDB	7 years ago
Vagrantfile	Adding CentOS 7 Vagrantfile & build script	7 years ago
WINDOWS_PORT.md	Commit both PR and internal code review changes	10 years ago
appveyor.yml	Upgrade Appveyor to VS2017	7 years ago
issue_template.md	Add a template for issues	7 years ago
src.mk	Provide a way to override windows memory allocator with jemalloc for ZSTD	7 years ago
thirdparty.inc	Provide a way to override windows memory allocator with jemalloc for ZSTD	7 years ago

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.