How InnoDB Multi-Version Concurrency Control (MVCC) works

Abstract

Using a simple running example, we explain how non-locking reads, transaction rollback, and the purge of history works. More specifically, I am going to use a variation of this SQL from MDEV-24402:

CREATE TABLE t1 (a INT PRIMARY KEY, b INT NOT NULL, INDEX(b)) ENGINE=InnoDB;
BEGIN;
INSERT INTO t1 VALUES(5,4);
DELETE FROM t1 WHERE a=5;
COMMIT;
BEGIN;
INSERT INTO t1 VALUES(5,5);
ROLLBACK;
CHECK TABLE t1 EXTENDED;
DROP TABLE t1;

Date and time

• Thursday 17 November, 19:00 – 19:45 CET (UTC+1)

Presenter