How to turn off hbm2ddl?

Just omitting hibernate.hbm2ddl.auto defaults to Hibernate not doing anything. From the reference documentation:

1.1.4. Hibernate configuration

The hbm2ddl.auto option turns on automatic generation of database schemas directly into the database. This can also be turned off by removing the configuration option, or redirected to a file with the help of the SchemaExport Ant task.

Setting hbm2ddl.auto to none (undocumented) might generate a warning, such as: org.hibernate.cfg.SettingsFactory - Unrecognized value for "hibernate.hbm2ddl.auto": none

To get this one clear, one should look into the source of org.hibernate.cfg.SettingsFactory (you might see something else depending on the version used):

String autoSchemaExport = properties.getProperty( AvailableSettings.HBM2DDL_AUTO );
if ( "validate".equals(autoSchemaExport) ) {
    settings.setAutoValidateSchema( true );
}
else if ( "update".equals(autoSchemaExport) ) {
    settings.setAutoUpdateSchema( true );
}
else if ( "create".equals(autoSchemaExport) ) {
    settings.setAutoCreateSchema( true );
}
else if ( "create-drop".equals( autoSchemaExport ) ) {
    settings.setAutoCreateSchema( true );
    settings.setAutoDropSchema( true );
}
else if ( !StringHelper.isEmpty( autoSchemaExport ) ) {
    LOG.warn( "Unrecognized value for \"hibernate.hbm2ddl.auto\": " + autoSchemaExport );
}

In the org.hibernate.cfg.Settings class those variables are initialized as:

private boolean autoCreateSchema;
private boolean autoDropSchema;
private boolean autoUpdateSchema;
private boolean autoValidateSchema;

so these default to false.

Omitting the hibernate.hbm2ddl.auto setting should switch off the HBM2DDL_AUTO functionality as would suggested hibernate.hbm2ddl.auto = none, but on the latter case you get a warning in the log.

You can switch it off by :

hibernate.hbm2ddl.auto=none

It's undocumented but priceless !