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How do I lock a MySQL query?
LOCK TABLES works as follows:
- Sort all tables to be locked in an internally defined order (from the user standpoint the order is undefined).
- If a table is locked with a read and a write lock, put the write lock before the read lock.
- Lock one table at a time until the thread gets all locks.
Can we use Nolock in MySQL query?
The WITH (NOLOCK) table hint is used to override the default transaction isolation level of the table or the tables within the view in a specific query, by allowing the user to retrieve the data without being affected by the locks, on the requested data, due to another process that is changing it.
Can we use Nolock in MySQL?
Oracle, SQL Server and MySQL support isolation levels. When WITH (NOLOCK) is used with SQL Server, the statement does not place a lock nor honor exclusive locks on table. The MySQL nolock hint equivalent is READ UNCOMMITTED, also known as “dirty read” because it is the lowest level of isolation.
What are read and write locks in MySQL?
Read locks are “shared” locks which prevent a write lock is being acquired but not other read locks. Write locks are “exclusive ” locks that prevent any other lock of any kind. In this tutorial, you have learned how to lock and unlock tables for cooperating with the table accesses between sessions.
How do you lock a table in MySQL?
LOCK TABLES table_name [ READ | WRITE] In this syntax, you specify the name of the table that you want to lock after the LOCK TABLES keywords. In addition, you specify the type of lock, either READ or WRITE. MySQL allows you to lock multiple tables by specifying a list of comma-separated names of tables with lock types that you want to lock
What does the lock flag mean in MySQL?
A lock is a flag associated with a table. MySQL allows a client session to explicitly acquire a table lock for preventing other sessions from accessing the same table during a specific period.
What are the rules for lock acquisition in MySQL?
Rules for Lock Acquisition. If a table is to be locked with a read and a write lock, put the write lock request before the read lock request. Lock one table at a time until the session gets all locks. This policy ensures that table locking is deadlock free.