Since three queries process three different data rows, InnoDB will initiate all queries at the same time while locking only the data rows that tied to each query: Finish the 3rd query, unlock the table.Initiate the 3rd query and lock the entire table.Initiate the 2nd query and lock the entire table.Initiate the 1st query and lock the entire table.UPDATE `employees`.`employees` SET `email` = ' ' WHERE `emp_no` = '10004' Īnd suppose we need them to execute altogether in a batch. UPDATE `employees`.`employees` SET `email` = ' ' WHERE `emp_no` = '10003' UPDATE `employees`.`employees` SET `email` = ' ' WHERE `emp_no` = '10001' We have a table employees with 5 data rows: emp_no So even when this query is not finished yet, user still can access other data records using different queries. InnoDB implements the row-level locking which locks only the records being modified or deleted, while the other records are set free. So any attempt to access this table data during this time will be blocked. It means when one or more data cell is modified or deleted, MySQL locks the entire table until it finishes. In MyISAM, the locking method is called table-locking. MyISAM and InnoDB have two different locking methods. This way, data integrity is always protected. In a simple term, when there’s a running query that modifies or deletes data from the data table, MySQL blocks access to data from any other queries until the query finishes. Locking is a database integrity practice implemented in MySQL to ensure the accuracy of the data being processed. The biggest difference between MyISAM and InnoDB is that InnoDB implements row-level locking while MyISAM uses table-level locking. We can’t really compare them but we can see the difference and explain why MyISAM is better for some situations, while InnoDB will be more preferred in some other cases. MyISAM and InnoDB are the two most popular storage engines used in MySQL.
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