Features Not in LevelDB

RocksDB Features that are not in LevelDB

Performance

• Multithread compaction
• Multithread memtable inserts
• Reduced DB mutex holding
• Optimized level-based compaction style and universal compaction style
• Prefix bloom filter
• Memtable bloom filter
• Single bloom filter covering the whole SST file
• Write lock optimization
• Avoid data copying when possible
• Compression dictionary
• Improved Iter::Prev() performance
• Fewer comparator calls during SkipList searches
• Allocate memtable memory using huge page.

Features

• Column Families
• Transactions and WriteBatchWithIndex
• Backup and Checkpoints
• Merge Operators
• Compaction Filters
• RocksDB Java
• Manual Compactions Run in Parallel with Automatic Compactions
• Persistent Cache
• Bulk loading
• Forward Iterators/ Tailing iterator
• Single delete and range delete
• Pin iterator key/value

Alternative Data Structures And Formats

• Plain Table format for memory-only use cases
• vector-based and hash-based memtable format
• Clock-based cache
• Pluggable information log
• Annotate transaction log write with blob (for replication)

Tunability

• Rate limiting
• Tunable Slowdown and Stop threshold
• Option to keep all files open
• Option to keep all index and bloom filter blocks in block cache
• Multiple WAL recovery modes
• fadvise hints for readahead and to avoid caching in OS page cache
• option to pin L0 and L1 files in memory
• compression : zstd, zlib, dictionary encoding

Manageability

• Statistics
• Thread-local profiling
• More commands in command-line tools
• User-defined table properties
• Event listeners
• More DB Properties