# Automatic Transaction Commit Mode

__*AUTOCOMMIT*__

+ By default, the TiDB cluster runs in the**AUTOCOMMIT** mode
  + As long as you execute DML, they will be automatically committed
  + Each statement is treated as a transaction
+ Check the autocommit settings: `SELECT @@autocommit;`  
+ Disable autocommit mode: 
  + `SET autocommit = 0;`  
  + `BEGIN;`  
  + You should end the transaction in the following way:
    + `COMMIT;` 
    + `ROLLBACK;` 
------------------------------------------------------------

By default, autocommit mode is enabled.

Due to the limitations of the underlying storage engine, TiDB requires a single row to be no more than 6 MB. All columns of a row are converted to bytes according to their data types and summed up to estimate the size of a single row.

By default, TiDB sets the total size of a single transaction to no more than 100 MB.

More details in course 201.5 Developing on TiDB Best Practices.