Public API Change

  • Users of Statistics::getHistogramString() will see fewer histogram buckets and different bucket endpoints.
  • Slice::compare and BytewiseComparator Compare no longer accept Slices containing nullptr.
  • Transaction::Get and Transaction::GetForUpdate variants with PinnableSlice added.

New Features

  • Add Iterator::Refresh(), which allows users to update the iterator state so that they can avoid some initialization costs of recreating iterators.
  • Replace dynamic_cast<> (except unit test) so people can choose to build with RTTI off. With make, release mode is by default built with -fno-rtti and debug mode is built without it. Users can override it by setting USE_RTTI=0 or 1.
  • Universal compactions including the bottom level can be executed in a dedicated thread pool. This alleviates head-of-line blocking in the compaction queue, which cause write stalling, particularly in multi-instance use cases. Users can enable this feature via Env::SetBackgroundThreads(N, Env::Priority::BOTTOM), where N > 0.
  • Allow merge operator to be called even with a single merge operand during compactions, by appropriately overriding MergeOperator::AllowSingleOperand.
  • Add DB::VerifyChecksum(), which verifies the checksums in all SST files in a running DB.
  • Block-based table support for disabling checksums by setting BlockBasedTableOptions::checksum = kNoChecksum.

Bug Fixes

  • Fix wrong latencies in rocksdb.db.get.micros, rocksdb.db.write.micros, and
  • Fix incorrect dropping of deletions during intra-L0 compaction.
  • Fix transient reappearance of keys covered by range deletions when memtable prefix bloom filter is enabled.
  • Fix potentially wrong file smallest key when range deletions separated by snapshot are written together.