.. _enforce_engine:

========================
Enforcing Storage Engine
========================

|Percona Server| has implemented variable which can be used for enforcing the use of a specific storage engine.

When this variable is specified and a user tries to create a table using an explicit storage engine that is not the specified enforced engine, he will get either an error if the ``NO_ENGINE_SUBSTITUTION`` SQL mode is enabled or a warning if ``NO_ENGINE_SUBSTITUTION`` is disabled and the table will be created anyway using the enforced engine (this is consistent with the default |MySQL| way of creating the default storage engine if other engines aren't available unless ``NO_ENGINE_SUBSTITUTION`` is set).

In case user tries to enable :variable:`enforce_storage_engine` with engine that isn't available, system will not start.

.. note::
 
 If you're using :variable:`enforce_storage_engine`, you must either disable it before doing ``mysql_upgrade`` or perform ``mysql_upgrade`` with server started with :option:`--skip-grants-tables`.

Version Specific Information
============================

  * :rn:`5.5.24-26.0`
    Variable :variable:`enforce_storage_engine` implemented.

System Variables
================

.. variable:: enforce_storage_engine

     :cli: No
     :conf: Yes
     :scope: Global
     :dyn: No
     :vartype: String
     :default: NULL

.. note:: 

  This variable is not case sensitive.

Example
=======

Adding following option to :term:`my.cnf` will start the server with InnoDB as enforced storage engine. ::  

 enforce_storage_engine=InnoDB
