Return error when attempting to revert a migration if no down block is defined

[benjamin-thomas]

v1.10.0

Hello,

Is there a way to ensure no rollback ever occurs. I tried removing the migrate:down keyword but rolling back then succeeds, which I don't want

For the moment, this seems to do the trick. Do you see a better way?

-- migrate:up
CREATE ROLE whatever;

-- migrate:down
SELECT 1/0

[amacneil]

What are you trying to achieve? If you don't define a down migration (or add a no-op statement as you propose) then I believe dbmate will still remove record of that migration but will not make any changes to the database.

[benjamin-thomas]

Yes that's the problem :)

If there is no migrate:down instruction, it'd be useful if that record wouldn't be removed.

Otherwise the migration is marked "pending" via the CLI and will be ran once more on dbmate migrate, but then fails as it was meant to be ran once.

I gave an example of a non idempotent command but that migration could be anything, cleanup data, changing a db design that should never be reversed, etc..

Using a division by zero does the trick for me, I just wondered if that was something handled and not documented.

[amacneil]

Let's keep this issue open, I think it would be nice to explicitly fail when attempting to rollback a migration if no down migration is defined, rather than pretending that something happened.

Of course, it's still entirely up to the developer to ensure that a down migration is the inverse of an up migration, and/or that the up migration is idempotent if desired.

[gregwebs]

I have a PR #434 where you can specify specific migrations to do or to rollback: #434. It seems like that would solve this issue?