no way to disable transactions in knex 0.8.0+ migrations

[jurko-gospodnetic]

knex 0.8.0 started wrapping all knex migration steps in separate transactions, and there seems to be no way to turn this behaviour off.

Problem with that is that there are some databases and some commands that just can not be run under an active database transaction. For example, running a ALTER TYPE ... ADD VALUE command on Postgres will fail in such scenario (http://www.postgresql.org/docs/9.4/static/sql-altertype.html).

This is also related to a problem of knex reporting such failures by just logging an end-user warning message and not reporting it on as a regular promise rejection, but I'll log that as a separate issue.

I have not yet tested whether and how I can manually stop and restart knex's database transaction around such problematic commands, but since the whole migration steps can not in theory be safely run under a transaction, there really should be a way to turn this behaviour off.

[tgriesser]

Ah wow, that's interesting - didn't realize you couldn't do that. Did a little digging and this seems to be how rails fixed it - via disabling ddl transactions on a per-migration basis

I'll look to get something in there to turn this off... would you prefer a flag to have them disabled for all migrations or one which disables on a per-file basis?

[jurko-gospodnetic]

Well, for easy backward compatibility, it would definitely be good to be able to disable them all together.

Allowing disabling them for specific files seems like a logical next step, but is not really something I need at this moment so haven't given much thought to how the interface for that would function.

[tgriesser]

Should now be able to add a disableTransactions option in the migration config and it will not try to wrap things in a transaction.

[jurko-gospodnetic]

Thanks, will give this a try!

Commit's a b*tch to review though, thanks to overwhelming ES5 --> ES6 code changes. :-)

[tgriesser]

Sorry about that, only real functional change was here