Revision a0e9ee5965dc773bd92f5b3fffd1a0c602ec135c authored by Igor Canadi on 15 May 2014, 23:07:05 UTC, committed by Igor Canadi on 15 May 2014, 23:07:05 UTC
Summary: This diff adds rapidjson (https://code.google.com/p/rapidjson/) to RocksDB repository. First step to adding JSON is to add a JSON parser :) I'm not sure if rapidjson is the right choice. I only considered folly as an alternative. Using folly JSON parser has serious downsides. I tried extracting folly::json from the folly library. However, it depends on folly::dynamic, which basically depends on everything else. I would prefer to avoid adding complete folly library as RocksDB dependency. Folly has a lot of its own dependencies (https://github.com/facebook/folly) and also looks like open source world has some trouble installing it (https://groups.google.com/forum/#!forum/facebook-folly -- 60% of the posts are compile errors). We can discuss this if you think otherwise. RapidJSON does not have any dependencies whatsoever. No boost, no STL. We don't need to compile it since it's all header files. The performance results are also impressive: https://code.google.com/p/rapidjson/wiki/Performance. However, I'll make sure to write code in a way that we can easily switch JSON implementations going forward. Quora thread has some alternatives: http://www.quora.com/What-is-the-best-C-JSON-library Test Plan: none Reviewers: dhruba, haobo, yhchiang, sdong, jamesgpearce Reviewed By: haobo CC: leveldb Differential Revision: https://reviews.facebook.net/D18729
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HISTORY.md
# Rocksdb Change Log
## Unreleased (3.1.0)
### Public API changes
* Replaced ColumnFamilyOptions::table_properties_collectors with ColumnFamilyOptions::table_properties_collector_factories
### New Features
* Hash index for block-based table will be materialized and reconstructed more efficiently. Previously hash index is constructed by scanning the whole table during every table open.
## 3.0.0 (05/05/2014)
### Public API changes
* Added _LEVEL to all InfoLogLevel enums
* Deprecated ReadOptions.prefix and ReadOptions.prefix_seek. Seek() defaults to prefix-based seek when Options.prefix_extractor is supplied. More detail is documented in https://github.com/facebook/rocksdb/wiki/Prefix-Seek-API-Changes
* MemTableRepFactory::CreateMemTableRep() takes info logger as an extra parameter.
### New Features
* Column family support
* Added an option to use different checksum functions in BlockBasedTableOptions
* Added ApplyToAllCacheEntries() function to Cache
## 2.8.0 (04/04/2014)
* Removed arena.h from public header files.
* By default, checksums are verified on every read from database
* Change default value of several options, including: paranoid_checks=true, max_open_files=5000, level0_slowdown_writes_trigger=20, level0_stop_writes_trigger=24, disable_seek_compaction=true, max_background_flushes=1 and allow_mmap_writes=false
* Added is_manual_compaction to CompactionFilter::Context
* Added "virtual void WaitForJoin()" in class Env. Default operation is no-op.
* Removed BackupEngine::DeleteBackupsNewerThan() function
* Added new option -- verify_checksums_in_compaction
* Changed Options.prefix_extractor from raw pointer to shared_ptr (take ownership)
Changed HashSkipListRepFactory and HashLinkListRepFactory constructor to not take SliceTransform object (use Options.prefix_extractor implicitly)
* Added Env::GetThreadPoolQueueLen(), which returns the waiting queue length of thread pools
* Added a command "checkconsistency" in ldb tool, which checks
if file system state matches DB state (file existence and file sizes)
* Separate options related to block based table to a new struct BlockBasedTableOptions.
* WriteBatch has a new function Count() to return total size in the batch, and Data() now returns a reference instead of a copy
* Add more counters to perf context.
* Supports several more DB properties: compaction-pending, background-errors and cur-size-active-mem-table.
### New Features
* If we find one truncated record at the end of the MANIFEST or WAL files,
we will ignore it. We assume that writers of these records were interrupted
and that we can safely ignore it.
* A new SST format "PlainTable" is added, which is optimized for memory-only workloads. It can be created through NewPlainTableFactory() or NewTotalOrderPlainTableFactory().
* A new mem table implementation hash linked list optimizing for the case that there are only few keys for each prefix, which can be created through NewHashLinkListRepFactory().
* Merge operator supports a new function PartialMergeMulti() to allow users to do partial merges against multiple operands.
* Now compaction filter has a V2 interface. It buffers the kv-pairs sharing the same key prefix, process them in batches, and return the batched results back to DB. The new interface uses a new structure CompactionFilterContext for the same purpose as CompactionFilter::Context in V1.
* Geo-spatial support for locations and radial-search.
## 2.7.0 (01/28/2014)
### Public API changes
* Renamed `StackableDB::GetRawDB()` to `StackableDB::GetBaseDB()`.
* Renamed `WriteBatch::Data()` `const std::string& Data() const`.
* Renamed class `TableStats` to `TableProperties`.
* Deleted class `PrefixHashRepFactory`. Please use `NewHashSkipListRepFactory()` instead.
* Supported multi-threaded `EnableFileDeletions()` and `DisableFileDeletions()`.
* Added `DB::GetOptions()`.
* Added `DB::GetDbIdentity()`.
### New Features
* Added [BackupableDB](https://github.com/facebook/rocksdb/wiki/How-to-backup-RocksDB%3F)
* Implemented [TailingIterator](https://github.com/facebook/rocksdb/wiki/Tailing-Iterator), a special type of iterator that
doesn't create a snapshot (can be used to read newly inserted data)
and is optimized for doing sequential reads.
* Added property block for table, which allows (1) a table to store
its metadata and (2) end user to collect and store properties they
are interested in.
* Enabled caching index and filter block in block cache (turned off by default).
* Supported error report when doing manual compaction.
* Supported additional Linux platform flavors and Mac OS.
* Put with `SliceParts` - Variant of `Put()` that gathers output like `writev(2)`
* Bug fixes and code refactor for compatibility with upcoming Column
Family feature.
### Performance Improvements
* Huge benchmark performance improvements by multiple efforts. For example, increase in readonly QPS from about 530k in 2.6 release to 1.1 million in 2.7 [1]
* Speeding up a way RocksDB deleted obsolete files - no longer listing the whole directory under a lock -- decrease in p99
* Use raw pointer instead of shared pointer for statistics: [5b825d](https://github.com/facebook/rocksdb/commit/5b825d6964e26ec3b4bb6faa708ebb1787f1d7bd) -- huge increase in performance -- shared pointers are slow
* Optimized locking for `Get()` -- [1fdb3f](https://github.com/facebook/rocksdb/commit/1fdb3f7dc60e96394e3e5b69a46ede5d67fb976c) -- 1.5x QPS increase for some workloads
* Cache speedup - [e8d40c3](https://github.com/facebook/rocksdb/commit/e8d40c31b3cca0c3e1ae9abe9b9003b1288026a9)
* Implemented autovector, which allocates first N elements on stack. Most of vectors in RocksDB are small. Also, we never want to allocate heap objects while holding a mutex. -- [c01676e4](https://github.com/facebook/rocksdb/commit/c01676e46d3be08c3c140361ef1f5884f47d3b3c)
* Lots of efforts to move malloc, memcpy and IO outside of locks
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