rocksdb/HISTORY.md

Rocksdb Change Log

Unreleased (will be released in 3.0)

• By default, max_background_flushes is 1 and flush process is removed from background compaction process. Flush process is now always executed in high priority thread pool.

Unreleased (will be relased in 2.8)

Unreleased

Public API changes

• Removed arena.h from public header files.
• By default, checksums are verified on every read from database
• Added is_manual_compaction to CompactionFilter::Context

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
• Implemented TailingIterator, 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 -- huge increase in performance -- shared pointers are slow
• Optimized locking for Get() -- 1fdb3f -- 1.5x QPS increase for some workloads
• Cache speedup - e8d40c3
• 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
• Lots of efforts to move malloc, memcpy and IO outside of locks