PostgreSQL zero-downtime migration of a primary key from int to bigint (with Ruby on Rails specific notes) “90% what?” “I said this table is at 90%.” “Of what?” “Of int values for its primary key.” “That .. doesn’t sound good.” “No, if it gets to 100% we’re down.” “That’s not good.” “No, captain obvious.” “So what do we do?” “We have to migrate it to