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I am trying to experiment a bit with the isolation level of MySQL in a test environment.
I do the following:

mysql> set @@session.tx_isolation='READ-UNCOMMITED';
ERROR 1231 (42000): Variable 'tx_isolation' can't be set to the value of 'READ-UNCOMMITED'

This also fails:

mysql> update information_schema.session_variables set variable_value='READ-UNCOMMITED' where variable_name='TX_ISOLATION';
ERROR 1044 (42000): Access denied for user 'root'@'localhost' to database 'information_schema' 

What am I doing wrong here? I am root. So it should not be a rights issue.

share|improve this question
up vote 5 down vote accepted

You need to try

SET tx_isolation = 'READ-UNCOMMITTED';



You could also declare it at the start of the transaction


Give it a Try !!!


Please note that you misspelled READ-UNCOMMITED (Missing T). It should be READ-UNCOMMITTED

You cannot change tx_isolation in the INFORMATION_SCHEMA database because it is an in-memory read-only database.

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+1 for finding the spelling mistake. Nevertheless set @@session.tx_isolation='READ-UNCOMMITTED' is a valid statement. – Shlomi Noach Sep 29 '13 at 13:36
@ShlomiNoach you are right. That set is the type of syntax used in the header of mysqldumps. – RolandoMySQLDBA Sep 30 '13 at 20:00

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