Ddl

The article discusses the necessity of ACID properties for database DDL operations, challenges in traditional systems, and how PolarDB-X implements transactional DDL, ensuring atomicity, consistency, isolation, and durability to enhance reliability and operational flexibility.

Database schema evolution (DDL) poses unique challenges in ensuring concurrency with transactions while maintaining ACID properties. Traditional approaches use metadata locks (MDLs) to serialize DDL and DML/DQL, but this can severely impact performance. This blog discusses the issues and explores solutions like multi-version concurrency control to enable highly concurrent non-blocking schema changes.