A library that provides an embeddable, persistent key-value store for fast storage.
c34271a5a5
Summary: The way counters/statistics are implemented in rocksdb demands that enum Tickers and TickerNameMap follow the same order, otherwise statistics exposed from fbcode/rocks get out-of-sync. 2 counters for prefix had violated this order and when I built counters for fbcode/mcrocksdb, statistics for sequence number were appearing out-of-sync. The other change is to record sequence-number using setTickerCount only and not recordTick. This is because of difference in statistics as understood by rocks/utils which uses ServiceData::statistics function and rocksdb statistics. In rocksdb there is just 1 counter for a countername. But in ServiceData there are 4 independent buckets for every countername-Count, Sum, Average and Rate. SetTickerCount and RecordTick update the same variable in rocksdb but different buckets in ServiceData. Therefore, I had to choose one consistent function from RecordTick or SetTickerCount for sequence number in rocksdb. I chose SetTickerCount because the statistics object in options passed during rocksdb-open is user-dependent and SetTickerCount makes sense there. There will be a corresponding diff to mcorcksdb in fbcode shortly. Test Plan: make all check; check ticker value using fprintfs Reviewers: dhruba Reviewed By: dhruba CC: leveldb Differential Revision: https://reviews.facebook.net/D12669 |
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build_tools | ||
coverage | ||
db | ||
doc | ||
hdfs | ||
helpers/memenv | ||
include | ||
java | ||
linters/src | ||
port | ||
scribe | ||
snappy | ||
table | ||
thrift | ||
tools | ||
util | ||
utilities | ||
.arcconfig | ||
.gitignore | ||
LICENSE | ||
Makefile | ||
README | ||
README.fb |
rocksdb: A persistent key-value store for flash storage Authors: * The Facebook Database Engineering Team * Build 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 an Log-Stuctured-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. The core of this code has been derived from open-source leveldb. The code under this directory implements a system for maintaining a persistent key/value store. See doc/index.html for more explanation. See doc/impl.html for a brief overview of the implementation. The public interface is in include/*.h. 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. Guide to header files: include/db.h Main interface to the DB: Start here include/options.h Control over the behavior of an entire database, and also control over the behavior of individual reads and writes. include/comparator.h Abstraction for user-specified comparison function. If you want just bytewise comparison of keys, you can use the default comparator, but clients can write their own comparator implementations if they want custom ordering (e.g. to handle different character encodings, etc.) include/iterator.h Interface for iterating over data. You can get an iterator from a DB object. include/write_batch.h Interface for atomically applying multiple updates to a database. include/slice.h A simple module for maintaining a pointer and a length into some other byte array. include/status.h Status is returned from many of the public interfaces and is used to report success and various kinds of errors. include/env.h Abstraction of the OS environment. A posix implementation of this interface is in util/env_posix.cc include/table_builder.h Lower-level modules that most clients probably won't use directly include/cache.h An API for the block cache. include/compaction_filter.h An API for a application filter invoked on every compaction. include/filter_policy.h An API for configuring a bloom filter. include/memtablerep.h An API for implementing a memtable. include/statistics.h An API to retrieve various database statistics. include/transaction_log_iterator.h An API to retrieve transaction logs from a database.