Whether the update operation in MySQL will lock the table is an issue worthy of attention, because this will affect concurrency performance and system response speed. This article will explore this issue from two aspects: one is when there is no index, and the other is when MySQL turns on automatic transaction submission and manual submission of transactions.
First, without an index, MySQL's update operation will lock the entire table. This is because there is a mechanism in the database called "pessimistic locking", that is, by default, MySQL will think that other transactions will update the table at any time, so it will first lock the entire table and then perform modification operations to ensure the consistency and integrity of the data. sex.
However, if an index is created on a field of the table, MySQL will use the "optimistic locking" mechanism, which only locks the rows that need to be modified, rather than the entire table. This is because indexes allow MySQL to quickly locate rows that need to be modified without scanning the entire table, thereby reducing the cost of locking the table.
Secondly, MySQL's transaction submission method will also affect whether the update operation will lock the table. When MySQL turns on automatic transaction submission, each SQL statement will automatically open and submit a transaction, which will frequently lock the table, resulting in slow system response. When manually submitting a transaction, we need to manually open the transaction before performing the modification operation, and then manually submit the transaction after the execution is completed. This can minimize the time of locking the table and improve the system concurrency performance.
In general, whether the update operation in MySQL will lock the table depends on whether the table has an index and the transaction submission method. If there is no index or auto-commit transactions are enabled, the update operation will lock the entire table; if there is an index or transactions are manually enabled, the update operation will only lock the rows that need to be modified, not the entire table. Therefore, in actual development, we should choose the optimal solution according to the specific situation to improve system performance and response speed.