Wrap all incoming migrations inside a single transaction

[mvgeny]

Every migration is wrapped in tx by default, but does it possible to wrap bunch of them? I had no success while implementing it by myself, because goose.Up accepts *sql.DB.

[mfridman]

It's not supported today, but it's something I'd like to add support for. Related #222

I'd like to call this "grouped migrations", where goose applies a group of separate migration files in a single transaction.

However, what should the behaviour be when one of those migration files cannot be executed within a transaction?

For example, say we have 6 new migrations: 11, 12, 13, 14, 15, 16 and migration 14 is marked with NO TRANSACTION. We cannot apply all 6 migrations in the same *sql.Tx.

The best we can do in this scenario (I think) is apply 11, 12, 13 in the same *sql.Tx and commit, then apply 14 with *sql.DB (or *sql.Conn) and then apply 15, 16 in another *sql.Tx and commit. It's a bit of an edge case, but it's something we have to account for.

Alternatively, we could do a look ahead and detect that you've opted in to "grouped migrations" and have a migration that cannot be applied in a transaction. I don't like this option though because it requires the user to modify goose.