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RocksDB v6.28.0 Release Notes

Release Date: 2021-12-17 // over 2 years ago

  • 🆕 New Features

    • 👍 Introduced 'CommitWithTimestamp' as a new tag. Currently, there is no API for user to trigger a write with this tag to the WAL. This is part of the efforts to support write-commited transactions with user-defined timestamps.
    • 🚤 Introduce SimulatedHybridFileSystem which can help simulating HDD latency in db_bench. Tiered Storage latency simulation can be enabled using -simulate_hybrid_fs_file (note that it doesn't work if db_bench is interrupted in the middle). -simulate_hdd can also be used to simulate all files on HDD.

    🐛 Bug Fixes

    • 🛠 Fixed a bug in rocksdb automatic implicit prefetching which got broken because of new feature adaptive_readahead and internal prefetching got disabled when iterator moves from one file to next.
    • Fixed a bug in TableOptions.prepopulate_block_cache which causes segmentation fault when used with TableOptions.partition_filters = true and TableOptions.cache_index_and_filter_blocks = true.
    • 🛠 Fixed a bug affecting custom memtable factories which are not registered with the ObjectRegistry. The bug could result in failure to save the OPTIONS file.
    • 🛠 Fixed a bug causing two duplicate entries to be appended to a file opened in non-direct mode and tracked by FaultInjectionTestFS.
    • Fixed a bug in TableOptions.prepopulate_block_cache to support block-based filters also.
    • 🚚 Block cache keys no longer use FSRandomAccessFile::GetUniqueId() (previously used when available), so a filesystem recycling unique ids can no longer lead to incorrect result or crash (#7405). For files generated by RocksDB >= 6.24, the cache keys are stable across DB::Open and DB directory move / copy / import / export / migration, etc. Although collisions are still theoretically possible, they are (a) impossible in many common cases, (b) not dependent on environmental factors, and (c) much less likely than a CPU miscalculation while executing RocksDB.
    • 🛠 Fixed a bug in C bindings causing iterator to return incorrect result (#9343).

    Behavior Changes

    • MemTableList::TrimHistory now use allocated bytes when max_write_buffer_size_to_maintain > 0(default in TrasactionDB, introduced in PR#5022) Fix #8371.

    Public API change

    • Extend WriteBatch::AssignTimestamp and AssignTimestamps API so that both functions can accept an optional checker argument that performs additional checking on timestamp sizes.
    • Introduce a new EventListener callback that will be called upon the end of automatic error recovery.
    • Add IncreaseFullHistoryTsLow API so users can advance each column family's full_history_ts_low seperately.
    • Add GetFullHistoryTsLow API so users can query current full_history_low value of specified column family.

    🐎 Performance Improvements

    • Replaced map property TableProperties::properties_offsets with uint64_t property external_sst_file_global_seqno_offset to save table properties's memory.
    • 🛠 Block cache accesses are faster by RocksDB using cache keys of fixed size (16 bytes).

    Java API Changes

    • ✂ Removed Java API TableProperties.getPropertiesOffsets() as it exposed internal details to external users.