Yeah in Postgres you can check for the existence of a column in a table. If it exists/doesn't exist you can drop/add the column. Obviously "ALTER TABLE x ADD CO

Yeah in Postgres you can check for the existence of a column in a table. If it exists/doesn't exist you can drop/add the column. Obviously "ALTER TABLE x ADD COLUMN y" isn't idempotent, but the whole SQL statement around it can be idempotent.