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...