rocksdb

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

Andrew Kryczka 504fe4de80 Avoid allocations/copies for large `GetMergeOperands()` results (#10458 ) Summary: This PR avoids allocations and copies for the result of `GetMergeOperands()` when the average operand size is at least 256 bytes and the total operands size is at least 32KB. The `GetMergeOperands()` already included `PinnableSlice` but was calling `PinSelf()` (i.e., allocating and copying) for each operand. When this optimization takes effect, we instead call `PinSlice()` to skip that allocation and copy. Resources are pinned in order for the `PinnableSlice` to point to valid memory even after `GetMergeOperands()` returns. The pinned resources include a referenced `SuperVersion`, a `MergingContext`, and a `PinnedIteratorsManager`. They are bundled into a `GetMergeOperandsState`. We use `SharedCleanablePtr` to share that bundle among all `PinnableSlice`s populated by `GetMergeOperands()`. That way, the last `PinnableSlice` to be `Reset()` will cleanup the bundle, including unreferencing the `SuperVersion`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10458 Test Plan: - new DB level test - measured benefit/regression in a number of memtable scenarios Setup command: ``` $ ./db_bench -benchmarks=mergerandom -merge_operator=StringAppendOperator -num=$num -writes=16384 -key_size=16 -value_size=$value_sz -compression_type=none -write_buffer_size=1048576000 ``` Benchmark command: ``` ./db_bench -threads=$threads -use_existing_db=true -avoid_flush_during_recovery=true -write_buffer_size=1048576000 -benchmarks=readrandomoperands -merge_operator=StringAppendOperator -num=$num -duration=10 ``` Worst regression is when a key has many tiny operands: - Parameters: num=1 (implying 16384 operands per key), value_sz=8, threads=1 - `GetMergeOperands()` latency increases 682 micros -> 800 micros (+17%) The regression disappears into the noise (<1% difference) if we remove the `Reset()` loop and the size counting loop. The former is arguably needed regardless of this PR as the convention in `Get()` and `MultiGet()` is to `Reset()` the input `PinnableSlice`s at the start. The latter could be optimized to count the size as we accumulate operands rather than after the fact. Best improvement is when a key has large operands and high concurrency: - Parameters: num=4 (implying 4096 operands per key), value_sz=2KB, threads=32 - `GetMergeOperands()` latency decreases 11492 micros -> 437 micros (-96%). Reviewed By: cbi42 Differential Revision: D38336578 Pulled By: ajkr fbshipit-source-id: 48146d127e04cb7f2d4d2939a2b9dff3aba18258		2 years ago
.circleci	Run new benchmark script in branch. (#10303 )	2 years ago
.github/workflows	Use released clang-format instead of the one from dev branch (#9646 )	3 years ago
buckifier	Use optimized folly DistributedMutex in LRUCache when available (#10179 )	3 years ago
build_tools	Run new benchmark script in branch. (#10303 )	2 years ago
cache	Split cache to minimize internal fragmentation (#10287 )	2 years ago
cmake	gcc-11 and cmake related cleanup (#9286 )	3 years ago
coverage	Fix commit_prereq and other targets (#9797 )	3 years ago
db	Avoid allocations/copies for large `GetMergeOperands()` results (#10458 )	2 years ago
db_stress_tool	Stop operating on DB in a stress test background thread (#10373 )	2 years ago
docs	Bump tzinfo from 1.2.9 to 1.2.10 in /docs (#10400 )	2 years ago
env	increase buffer size in PosixFileSystem::GetAbsolutePath to PATH_MAX (#10413 )	2 years ago
examples	Add a simple example of backup and restore (#10054 )	3 years ago
file	Provide support for direct_reads with async_io (#10197 )	2 years ago
fuzz	Fix compilation errors and add fuzzers to CircleCI (#9420 )	3 years ago
include/rocksdb	Avoid allocations/copies for large `GetMergeOperands()` results (#10458 )	2 years ago
java	Revert "Add a blob-specific cache priority (#10309 )" (#10434 )	2 years ago
logging	Use EnvLogger instead of PosixLogger (#10436 )	2 years ago
memory	Revert "Add a blob-specific cache priority (#10309 )" (#10434 )	2 years ago
memtable	Fix a bug in hash linked list (#10401 )	2 years ago
microbench	Avoid allocations/copies for large `GetMergeOperands()` results (#10458 )	2 years ago
monitoring	Use EnvLogger instead of PosixLogger (#10436 )	2 years ago
options	Fix race conditions in GenericRateLimiter (#10374 )	2 years ago
plugin	Add initial CMake support to plugin (#9214 )	3 years ago
port	Use EnvLogger instead of PosixLogger (#10436 )	2 years ago
table	Fix cache metrics update when secondary cache is used (#10440 )	2 years ago
test_util	Add seqno to time mapping (#10338 )	2 years ago
third-party	Meta-internal folly integration with F14FastMap (#9546 )	3 years ago
tools	Avoid allocations/copies for large `GetMergeOperands()` results (#10458 )	2 years ago
trace_replay	Use std::numeric_limits<> (#9954 )	3 years ago
util	db_bench -use_stderr_info_logger to print timestamp (#10435 )	2 years ago
utilities	Fix serious FSDirectory use-after-Close bug (missing fsync) (#10460 )	2 years ago
.clang-format	A script that automatically reformat affected lines	11 years ago
.gitignore	Snapshots with user-specified timestamps (#9879 )	3 years ago
.lgtm.yml	Create lgtm.yml for LGTM.com C/C++ analysis (#4058 )	7 years ago
.watchmanconfig	Added .watchmanconfig file to rocksdb repo (#5593 )	6 years ago
AUTHORS	Update RocksDB Authors File	7 years ago
CMakeLists.txt	Fix the error path of PLUGIN_ROOT (#10446 )	2 years ago
CODE_OF_CONDUCT.md	Adopt Contributor Covenant	5 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	Add Options::DisableExtraChecks, clarify force_consistency_checks (#9363 )	3 years ago
DUMP_FORMAT.md	First version of rocksdb_dump and rocksdb_undump.	10 years ago
HISTORY.md	Split cache to minimize internal fragmentation (#10287 )	2 years ago
INSTALL.md	Update supported VS versions in INSTALL.md (#9823 )	3 years ago
LANGUAGE-BINDINGS.md	Update branch name to "main" in README/LANGUAGE_BINDINGS (#8727 )	3 years ago
LICENSE.Apache	Change RocksDB License	8 years ago
LICENSE.leveldb	Add back the LevelDB license file	8 years ago
Makefile	Add seqno to time mapping (#10338 )	2 years ago
PLUGINS.md	Add pmem-rocksdb-plugin link in PLUGINs.md (#9934 )	3 years ago
README.md	Remove Travis CI (#10407 )	2 years ago
ROCKSDB_LITE.md	Fix remaining uses of "backupable" (#9792 )	3 years ago
TARGETS	Charge blob cache usage against the global memory limit (#10321 )	2 years ago
USERS.md	Add Solana's RocksDB use case in USERS.md (#9558 )	3 years ago
Vagrantfile	Adding CentOS 7 Vagrantfile & build script	7 years ago
WINDOWS_PORT.md	Update branch name in WINDOWS_PORT.md (#8745 )	3 years ago
common.mk	Clean up variables for temporary directory (#9961 )	3 years ago
crash_test.mk	Clean up variables for temporary directory (#9961 )	3 years ago
issue_template.md	Add Google Group to Issue Template	5 years ago
rocksdb.pc.in	build: fix pkg-config file generation (#9953 )	3 years ago
src.mk	Charge blob cache usage against the global memory limit (#10321 )	2 years ago
thirdparty.inc	Fix build jemalloc api (#5470 )	6 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 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.