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RocksDB v6.26.0 Release Notes

Release Date: 2021-10-20 // over 2 years ago

  • 🐛 Bug Fixes

    • 🛠 Fixes a bug in directed IO mode when calling MultiGet() for blobs in the same blob file. The bug is caused by not sorting the blob read requests by file offsets.
    • 🛠 Fix the incorrect disabling of SST rate limited deletion when the WAL and DB are in different directories. Only WAL rate limited deletion should be disabled if its in a different directory.
    • Fix DisableManualCompaction() to cancel compactions even when they are waiting on automatic compactions to drain due to CompactRangeOptions::exclusive_manual_compactions == true.
    • 🛠 Fix contract of Env::ReopenWritableFile() and FileSystem::ReopenWritableFile() to specify any existing file must not be deleted or truncated.
    • 🛠 Fixed bug in calls to IngestExternalFiles() with files for multiple column families. The bug could have introduced a delay in ingested file keys becoming visible after IngestExternalFiles() returned. Furthermore, mutations to ingested file keys while they were invisible could have been dropped (not necessarily immediately).
    • 🛠 Fixed a possible race condition impacting users of WriteBufferManager who constructed it with allow_stall == true. The race condition led to undefined behavior (in our experience, typically a process crash).
    • 🛠 Fixed a bug where stalled writes would remain stalled forever after the user calls WriteBufferManager::SetBufferSize() with new_size == 0 to dynamically disable memory limiting.
    • 👉 Make DB::close() thread-safe.
    • 🛠 Fix a bug in atomic flush where one bg flush thread will wait forever for a preceding bg flush thread to commit its result to MANIFEST but encounters an error which is mapped to a soft error (DB not stopped).
    • 🛠 Fix a bug in BackupEngine where some internal callers of GenericRateLimiter::Request() do not honor bytes <= GetSingleBurstBytes().

    🆕 New Features

    • Print information about blob files when using "ldb list_live_files_metadata"
    • 👍 Provided support for SingleDelete with user defined timestamp.
    • 🐎 Experimental new function DB::GetLiveFilesStorageInfo offers essentially a unified version of other functions like GetLiveFiles, GetLiveFilesChecksumInfo, and GetSortedWalFiles. Checkpoints and backups could show small behavioral changes and/or improved performance as they now use this new API.
    • Add remote compaction read/write bytes statistics: REMOTE_COMPACT_READ_BYTES, REMOTE_COMPACT_WRITE_BYTES.
    • Introduce an experimental feature to dump out the blocks from block cache and insert them to the secondary cache to reduce the cache warmup time (e.g., used while migrating DB instance). More information are in class CacheDumper and CacheDumpedLoader at rocksdb/utilities/cache_dump_load.h Note that, this feature is subject to the potential change in the future, it is still experimental.
    • Introduced a new BlobDB configuration option blob_garbage_collection_force_threshold, which can be used to trigger compactions targeting the SST files which reference the oldest blob files when the ratio of garbage in those blob files meets or exceeds the specified threshold. This can reduce space amplification with skewed workloads where the affected SST files might not otherwise get picked up for compaction.
    • ➕ Added EXPERIMENTAL support for table file (SST) unique identifiers that are stable and universally unique, available with new function GetUniqueIdFromTableProperties. Only SST files from RocksDB >= 6.24 support unique IDs.
    • ➕ Added GetMapProperty() support for "rocksdb.dbstats" (DB::Properties::kDBStats). As a map property, it includes DB-level internal stats accumulated over the DB's lifetime, such as user write related stats and uptime.

    Public API change

    • Made SystemClock extend the Customizable class and added a CreateFromString method. Implementations need to be registered with the ObjectRegistry and to implement a Name() method in order to be created via this method.
    • 🛠 Made SliceTransform extend the Customizable class and added a CreateFromString method. Implementations need to be registered with the ObjectRegistry and to implement a Name() method in order to be created via this method. The Capped and Prefixed transform classes return a short name (no length); use GetId for the fully qualified name.
    • Made FileChecksumGenFactory, SstPartitionerFactory, TablePropertiesCollectorFactory, and WalFilter extend the Customizable class and added a CreateFromString method.
    • 📇 Some fields of SstFileMetaData are deprecated for compatibility with new base class FileStorageInfo.
    • ➕ Add file_temperature to IngestExternalFileArg such that when ingesting SST files, we are able to indicate the temperature of the this batch of files.
    • If DB::Close() failed with a non aborted status, calling DB::Close() again will return the original status instead of Status::OK.
    • Add CacheTier to advanced_options.h to describe the cache tier we used. Add a lowest_used_cache_tier option to DBOptions (immutable) and pass it to BlockBasedTableReader. By default it is CacheTier::kNonVolatileBlockTier, which means, we always use both block cache (kVolatileTier) and secondary cache (kNonVolatileBlockTier). By set it to CacheTier::kVolatileTier, the DB will not use the secondary cache.
    • Even when options.max_compaction_bytes is hit, compaction output files are only cut when it aligns with grandparent files' boundaries. options.max_compaction_bytes could be slightly violated with the change, but the violation is no more than one target SST file size, which is usually much smaller.

    🐎 Performance Improvements

    • 👌 Improved CPU efficiency of building block-based table (SST) files (#9039 and #9040).

    Java API Changes