The talk given at the FOSDEM conference in 2023 was about the TIDB, a distributed SQL database developed by PingCap. The speaker discussed the challenges of online schema changes in a distributed database and proposed a solution using schema versioning. They explained the various states a schema transition goes through and how it affects transactions and data propagation. The speaker also talked about the architecture of TIDB, including its three main components: PD, the placement driver, the SQL layer, and the storage layer. They mentioned the performance improvements made in TIDB, including a 10 times speed increase in the backfill process using the lightning import tool. The talk also covered other tools and features of TIDB, such as data migration, backup and restore, and the chaos mesh for testing system resilience. Finally, there was a Q&A session where participants asked questions about various aspects of TIDB, such as data storage, transaction support, and compatibility with the MySQL client protocol.