Code review comment for lp:~blake-rouse/maas/add-boot-type-to-node

We just hit trouble with this migration: http://paste.ubuntu.com/7841190/

I suspect the error may be because the migration updates a field on the model which, in the schema revision the migration works on, hasn't actually been added yet.

If it weren't for that, I think the migration would still fail for an additional reason: as it turns out you can't add a column to a database table and then start populating that column in the same transaction. You either do it right away by setting a default, or you do it in a separate transaction. (A migration runs as a transaction, of course.)

On a final nitpick, do we know that updating every node individually and querying the tags table for each will perform sufficiently well on very large numbers of nodes?