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How do you lock a table in a transaction?
The correct way to use LOCK TABLES and UNLOCK TABLES with transactional tables, such as InnoDB tables, is to begin a transaction with SET autocommit = 0 (not START TRANSACTION ) followed by LOCK TABLES , and to not call UNLOCK TABLES until you commit the transaction explicitly.
Is UNION all faster than UNION?
UNION ALL is faster and more optimized than UNION. But we cannot use it in all scenarios. UNION ALL with SELECT DISTINCT is not equivalent to UNION.
Does a Select lock a table?
Yes, select locks the table until reads completes which conflicts with Insert/Delete/Updates lock mode. Generally Select should be used with WITH (NOLOCK) to avoid blocking the dml operations but it will result in dirty reads. You will need to weigh between concurrency and data consistency.
How to solve table locking issues in Business Central?
In Business Central / Dynamics NAV, the SQL Server uses Row Level Locking, which means two Users can modify the data in the same table simultaneously but cannot modify the same data (rows). Note: LockTable, FindSet (ForUpdate: true) statements also apply Row Level Locks.
What happens when a table is locked in SQL Server?
When a Transaction tries to access the data that is being Locked by another Transaction, SQL Server blocks that Transaction. And when a Transaction is blocked for more than 10 seconds (Lock Time-out), it will be terminated automatically with the “Table was Locked by another User” error.
Can a session that holds the read lock write to the table?
The session that holds the READ lock can only read data from the table, but cannot write. And other sessions cannot write data to the table until the READ lock is released. The write operations from another session will be put into the waiting states until the READ lock is released.
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