Introduction In database systems, transaction durability is the most critical part of the ACID feature. It promises that once a transaction is successfully committed, the modified data will take effect permanently, and the data will not be lost even if the system crashes or hardware fails. However, the realization of this promise is not as simple as it seems. Will the data really not be lost after the transaction is committed? This depends on the database's internal log mechanism, persistence strategy, distributed architecture design, and hardware redundancy capabilities. This article will start from a single...

1. MVCC Architecture Design and Implementation Principles 1.1 Storage Engine Layer Architecture InnoDB uses a layered storage architecture to implement the MVCC mechanism: Memory structure: Buffer Pool: Data page cache pool (default 128MB) Undo Log Buffer: Transaction rollback log cache (default 16MB) Change Buffer: Non-unique index update buffer Disk structure: Clustered index B+ tree (primary key index) Secondary index B+ tree Undo...