What Is a Data Lock in MySQL

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What Is a Data Lock in MySQL?

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A

MySQL uses two types of data locks at two levels to provide you the transaction isolation level you need:

Share Lock at Row Level (S) - A data row is locked by a transaction for reading.
Exclusive Lock at Row Level (X) - A data row is locked by a transaction for updating and deleting.
Intention Share Lock at Table Level (IS): A data table is locked by a transaction for placing share locks at row level.
Intention Exclusive Lock at Table Level (IX): A data table is locked by a transaction for placing exclusive lock at row level.

⇒ Experiment with Data Locks in MySQL

⇐ Change Transaction Isolation Level in MySQL

⇑ Transaction Management: Commit or Rollback in MySQL

⇑⇑ MySQL Database Tutorials

2017-04-28, 2865🔥, 0💬

Change Transaction Isolation Level in MySQL
How To View and Change the Current Transaction Isolation Level in MySQL? If you want to view or change the current transaction isolation level, you can use the following commands: SELECT @@TX_ISOLATION FROM DUAL; -- Viewing the current transaction isolation level. SET TRANSACTION ISOLATION LEVEL lev... 2017-08-08, 3931🔥, 0💬

Transaction Isolation Levels in MySQL
What Are Transaction Isolation Levels in MySQL? There are 4 transaction isolation levels defined by SQL-1992 standard: READ UNCOMMITTED - The SELECT statements in one transaction will read uncommitted data changes from transactions of all connected sessions. In this level, "dirty read" could happen,... 2017-08-03, 3599🔥, 0💬

Transaction Roll Back when Session Killed in MySQL
What Happens to the Current Transaction If the Session Is Killed in MySQL? If a session is killed by the DBA, the current transaction in that session will be rolled back and ended. All the database changes made in the current transaction will be removed. This is called an implicit rollback when sess... 2017-08-03, 3264🔥, 0💬

What Is a Data Lock in MySQL
What Is a Data Lock in MySQL? MySQL uses two types of data locks at two levels to provide you the transaction isolation level you need: Share Lock at Row Level (S) - A data row is locked by a transaction for reading. Exclusive Lock at Row Level (X) - A data row is locked by a transaction for updatin... 2017-04-28, 2866🔥, 0💬

Read Consistency Support in MySQL in MySQL
How Does MySQL Handle Read Consistency in MySQL? Read consistency is a concept that describes how consistent the output will be on two subsequent read operations. A read operation is usually a stand alone SELECT statement or a SELECT subquery in a parent statement. A database server can support up t... 2017-08-03, 2809🔥, 0💬

Transaction Waiting for a Data Lock in MySQL
How Long a Transaction Will Wait for a Data Lock in MySQL? If you issue a UPDATE or DELETE statement on a row that has an exclusive lock owned by another session, your statement will be blocked to wait for the other session to release the lock. But the wait will be timed out after the predefined inn... 2017-04-28, 2797🔥, 0💬

What Is a Dead Lock in MySQL
What Is a Dead Lock in MySQL? A dead lock is phenomenon happens between two transactions with each of them holding a lock that blocks the other transaction as shown in the following diagram: (transaction 1) (transaction 2) update row X to create lock 1 update row Y to create lock 2 update row X (blo... 2017-04-28, 2781🔥, 0💬

Experiment with Data Locks in MySQL
How To Experiment Data Locks in MySQL? If you want to have some experience with data locks, you can create two windows running two mysql transactions in two sessions. In session 1, you can run a UPDATE statement with REPEATABLE READ transaction isolation level to create an exclusive lock. Before com... 2017-04-28, 2715🔥, 0💬

Transaction Roll Back when Session Ended in MySQL
What Happens to the Current Transaction If the Session Is Ended in MySQL? If a session is ended, the current transaction in that session will be rolled back and ended. All the database changes made in the current transaction will be removed. This is called an implicit rollback when session is ended.... 2017-08-03, 2691🔥, 0💬

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