Overview of MySQL Transaction, Lock, and Undo Modules – Article Index

Author's Note

Author: Cao Shengchun, technical expert at iKexing, author of the public account "Yi Shu Yi Xi", focusing on MySQL and OceanBase source code analysis. The series has been running for a year, completing three major modules with plans for MVCC and Redo.

1. Transaction Module

Articles 01‑15 explore the fundamentals of transaction processing in InnoDB, including transaction pool and manager initialization, the effect of BEGIN statements, transaction object allocation, transaction start preparation, read/write transaction variations, binlog handling before commit, the three‑phase of two‑phase commit (prepare, commit, flush/sync/commit sub‑phases), savepoint creation and rollback, and a final transaction summary.

2. Lock Module

Articles 16‑32 cover InnoDB lock mechanisms: table locks, row lock types and modes, lock structures in memory, global lock object attributes, procedures for acquiring table and row locks (fast and slow paths), lock waiting and timeout handling, deadlock detection and resolution (pre‑work, detection, and solving), lock release timing for row and AUTO‑INC locks, and detailed explanations of lock‑related logs such as deadlock logs and implicit locks.

3. Undo Module

Articles 44‑54 discuss the undo subsystem, introducing undo tablespace, rollback segments, undo segment allocation, and undo page structures. They detail how undo segments are allocated from the insert_undo_cached and update_undo_cached caches, the format of undo logs generated by INSERT, UPDATE, and DELETE statements, and the procedures for rolling back these operations. The series also explains how undo logs are handled during transaction commit.

The series is produced by the iKexing open‑source community and is intended for readers interested in deep MySQL/InnoDB internals.