Pessimistic lock

Shared lock

To acquire a shared lock on the queried rows, assign PESSIMISTIC_READ to the lockMode field of the PageQuery class. This will generate an SQL statement with a FOR SHARE clause, allowing other transactions to read the same rows but preventing them from updating or deleting them until the current transaction is complete.

UserQuery testQuery = UserQuery.builder().id(1).lockMode(LockMode.PESSIMISTIC_READ).build();
List<UserEntity> lockedUsers = userService.query(userQuery);
// SQL: SELECT * FROM t_user t WHERE id = ? FOR SHARE

Exclusive lock

To acquire an exclusive lock on queried rows, assign PESSIMISTIC_WRITE to the lockMode field of the PageQuery class. This appends a FOR UPDATE clause to the SQL query, locking the selected rows for the duration of the transaction and preventing concurrent access by other transactions.

UserQuery testQuery = UserQuery.builder().id(1).lockMode(LockMode.PESSIMISTIC_WRITE).build();
List<UserEntity> lockedUsers = userService.query(userQuery);
// SQL: SELECT * FROM t_user t WHERE id = ? FOR UPDATE