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RocksDB v6.20.0 Release Notes

Release Date: 2021-04-16 // about 3 years ago

  • Behavior Changes

    • ColumnFamilyOptions::sample_for_compression now takes effect for creation of all block-based tables. Previously it only took effect for block-based tables created by flush.
    • CompactFiles() can no longer compact files from lower level to up level, which has the risk to corrupt DB (details: #8063). The validation is also added to all compactions.
    • 🛠 Fixed some cases in which DB::OpenForReadOnly() could write to the filesystem. If you want a Logger with a read-only DB, you must now set DBOptions::info_log yourself, such as using CreateLoggerFromOptions().
    • get_iostats_context() will never return nullptr. If thread-local support is not available, and user does not opt-out iostats context, then compilation will fail. The same applies to perf context as well.
    • ➕ Added support for WriteBatchWithIndex::NewIteratorWithBase when overwrite_key=false. Previously, this combination was not supported and would assert or return nullptr.
    • 👌 Improve the behavior of WriteBatchWithIndex for Merge operations. Now more operations may be stored in order to return the correct merged result.

    🐛 Bug Fixes

    • 👉 Use thread-safe strerror_r() to get error messages.
    • 🛠 Fixed a potential hang in shutdown for a DB whose Env has high-pri thread pool disabled (Env::GetBackgroundThreads(Env::Priority::HIGH) == 0)
    • 📚 Made BackupEngine thread-safe and added documentation comments to clarify what is safe for multiple BackupEngine objects accessing the same backup directory.
    • 🛠 Fixed crash (divide by zero) when compression dictionary is applied to a file containing only range tombstones.
    • 🛠 Fixed a backward iteration bug with partitioned filter enabled: not including the prefix of the last key of the previous filter partition in current filter partition can cause wrong iteration result.
    • Fixed a bug that allowed DBOptions::max_open_files to be set with a non-negative integer with ColumnFamilyOptions::compaction_style = kCompactionStyleFIFO.

    🐎 Performance Improvements

    • 🐎 On ARM platform, use yield instead of wfe to relax cpu to gain better performance.

    Public API change

    • Added TableProperties::slow_compression_estimated_data_size and TableProperties::fast_compression_estimated_data_size. When ColumnFamilyOptions::sample_for_compression > 0, they estimate what TableProperties::data_size would have been if the "fast" or "slow" (see ColumnFamilyOptions::sample_for_compression API doc for definitions) compression had been used instead.
    • ⚡️ Update DB::StartIOTrace and remove Env object from the arguments as its redundant and DB already has Env object that is passed down to IOTracer::StartIOTrace
    • ➕ Added FlushReason::kWalFull, which is reported when a memtable is flushed due to the WAL reaching its size limit; those flushes were previously reported as FlushReason::kWriteBufferManager. Also, changed the reason for flushes triggered by the write buffer manager to FlushReason::kWriteBufferManager; they were previously reported as FlushReason::kWriteBufferFull.
    • Extend file_checksum_dump ldb command and DB::GetLiveFilesChecksumInfo API for IntegratedBlobDB and get checksum of blob files along with SST files.

    🆕 New Features

    • Added the ability to open BackupEngine backups as read-only DBs, using BackupInfo::name_for_open and env_for_open provided by BackupEngine::GetBackupInfo() with include_file_details=true.
    • ➕ Added BackupEngine support for integrated BlobDB, with blob files shared between backups when table files are shared. Because of current limitations, blob files always use the kLegacyCrc32cAndFileSize naming scheme, and incremental backups must read and checksum all blob files in a DB, even for files that are already backed up.
    • ➕ Added an optional output parameter to BackupEngine::CreateNewBackup(WithMetadata) to return the BackupID of the new backup.
    • ➕ Added BackupEngine::GetBackupInfo / GetLatestBackupInfo for querying individual backups.
    • 👍 Made the Ribbon filter a long-term supported feature in terms of the SST schema(compatible with version >= 6.15.0) though the API for enabling it is expected to change.