If the table had a primary key, in case you ever face such a setup again (hopefully not!) then I think pt-online-schema-change to add the auto increment primary key while using ROW would probably be a better choice than the steps I mentioned in my first reply. It will rebuild the table anyway but at least it won’t block it while that happens.
If the table had a primary key, in case you ever face such a setup again (hopefully not!) then I think pt-online-schema-change to add the auto increment primary key while using ROW would probably be a better choice than the steps I mentioned in my first reply. It will rebuild the table anyway but at least it won’t block it while that happens.