Description: ------------ Currently MDB2_Schema doesn't handle schemas with multiple keys defined as a primary key (one being an auto increment field) because MDB2 lack the necessary tool to change a primary key. Please take a look at Bug #12154. Instead of a new method changeConstraint() another approach would be to detect inside createConstraint() when we are trying to create a PRIMARY KEY when one already exists, in this case MDB could assume that we want to replace this key. Expected result: ---------------- Ability to perform such query: ALTER TABLE `wp_options` DROP PRIMARY KEY , ADD PRIMARY KEY ( `option_id` , `blog_id` , `option_name` )