Concurrent UPDATE in the Same Table

Transaction T1:

START TRANSACTION;
UPDATE test SET address='test1234' WHERE name='test1';
COMMIT;

Transaction T2:

START TRANSACTION;
UPDATE test SET address='test1234' WHERE name='test2';
COMMIT;

Transaction T3:

START TRANSACTION;
UPDATE test SET address='test1234' WHERE name='test1';
COMMIT;

Scenario 1:

T1 is started but not committed. At this time, T2 is started. UPDATE of T1 and then T2 starts, and both of them succeed. This is because the UPDATE operations use row-level locks and do not conflict when they update different rows.

Scenario 2:

T1 is started but not committed. At this time, T3 is started. UPDATE of T1 and then T3 starts, and UPDATE of T1 succeeds. UPDATE of T3 times out. This is because T1 and T3 update the same row and the lock is held by T1 at the time of the update.