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How are transactions implemented in MySQL?
2 Answers. MySQL only supports transactions in the table type is InnoDB. Otherwise, you have to do all the rollbacks and retries in code. Doing it in code can be really difficult since you may lose the connection to the server, then you can’t roll back in a timely manner.
How MySQL transactions work internally?
In fact, MySQL’s default storage engine InnoDB uses transactions for everything whether you request it or not. But most people use a mode called autocommit, where each statement implicitly starts a transaction and implicitly commits as soon as the statement finishes.
What is use of transaction in MySQL?
A transaction in MySQL is a sequential group of statements, queries, or operations such as select, insert, update or delete to perform as a one single work unit that can be committed or rolled back. Or, all modifications are undone when the transaction is rollback.
What does transaction do in MySQL?
A transaction is a sequential group of database manipulation operations, which is performed as if it were one single work unit. In other words, a transaction will never be complete unless each individual operation within the group is successful.
Do transactions only support DCL?
Transactions apply only to the Data Manipulation Language (DML) portion of the SQL language (such as INSERT, UPDATE, and DELETE). Transactions do not apply to the Data Control Language (DCL) or Data Definition Language (DDL) portions (such as CREATE, DROP, ALTER, and so on) of the SQL language.
Which is the START TRANSACTION statement in MySQL?
MySQL transaction statements. MySQL provides us with the following important statement to control transactions: To start a transaction, you use the START TRANSACTION statement. The BEGIN or BEGIN WORK are the aliases of the START TRANSACTION. To commit the current transaction and make its changes permanent, you use the COMMIT statement.
When does a transaction end in MySQL server?
A transaction ends when it is committed or rolled back, either explicitly with a COMMIT or ROLLBACK statement or implicitly when a DDL (Data Definition Language (DDL) is used to manage table and index structure and CREATE, ALTER, RENAME, DROP and TRUNCATE statements are to name a few data definition elements) statement is issued.
What happens if there is no open transaction in MySQL?
There is no open transaction, MySQL will rollback the transaction upon disconnect. You cannot commit the transaction (IFAIK). It will not help you, because you cannot commit a transaction from a broken connection.
When to not commit a transaction in MySQL?
ALTER TABLE, CREATE TABLE, and DROP TABLE do not commit a transaction if the TEMPORARY keyword is used. Statements that implicitly use or modify tables in the MySQL database. CREATE USER, DROP USER, GRANT, RENAME USER, REVOKE, SET PASSWORD. Transaction-control and locking statements.