This document discusses several features that Alibaba is developing or contributing to MariaDB, including: 1. Time Machine/Flashback, which allows rolling databases back to snapshots by reversing DML operations in binary logs. 2. Double Sync Replication, which combines asynchronous and semi-synchronous replication to ensure the slave always knows the master's status. 3. Multi-source replication, which allows a single slave to replicate from multiple masters to support data sharding and backups across instances. 4. Thread Memory Monitor, which tracks memory usage by thread to identify which queries are using the most memory when the mysqld process exceeds limits.