rocksdb/docs/_posts/2017-09-28-rocksdb-5-8-released.markdown at d3296260c220195552023142edfca09c11e5f1bf

title	layout	author	category
RocksDB 5.8 Released!	post	maysamyabandeh	blog

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.

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.

Fix wrong latencies in rocksdb.db.get.micros, rocksdb.db.write.micros, and rocksdb.sst.read.micros.
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.