So you talk to a database, doing transactions. What happens actually, behind the scenes? Let’s have a look. There is a test table, and we write data into it inside a transaction: CREATE TABLE t ( id serial, data varbinary(255) ) START TRANSACTION READ WRITE INSERT INTO t ( id, data ) VALUES (NULL, RANDOM_BYTES(255)) COMMIT The MySQL test instance we are talking to is running on a Linux machine, an