RocksDB 4.0 发布，更新内容如下： 新特性 Added support for transactions. See include/rocksdb/utilities/transaction.h for more info. DB::GetProperty() now accepts "rocksdb.aggregated-table-properties" and "rocksdb.aggregated-table-properties-at-levelN", in which case it returns aggregated table properties of the target column family, or the aggregated table properties of the specified level N if the "at-level" version is used. Add compression option kZSTDNotFinalCompression for people to experiment ZSTD although its format is not finalized. We removed the need for LATEST_BACKUP file in BackupEngine. We still keep writing it when we create new backups (because of backward compatibility), but we don't read it anymore. 公共 API 变化 Removed class Env::RandomRWFile and Env::NewRandomRWFile(). Renamed DBOptions.num_subcompactions to DBOptions.max_subcompactions to make the name better match the actual functionality of the option. Added Equal() method to the Comparator interface that can optionally be overwritten in cases where equality comparisons can be done more efficiently than three-way comparisons. Previous 'experimental' OptimisticTransaction class has been replaced by Transaction class. 下载页面：RocksDB 4.0 RocksDB 是一个来自 facebook 的可嵌入式的支持持久化的 key-value 存储系统，也可作为 C/S 模式下的存储数据库，但主要目的还是嵌入式。RocksDB 基于 LevelDB 构建。关于 RocksDB 的性能说明。 RocksDB 4.0 发布，key-value 存储系统下载地址
