I was thinking of not considering these significant. Well, not in the initial version (I was thinking hashes rather than diffs ;-).

...but also the id and status columns are not qualified as "unsigned"...

I would consider those significant. Database engines might just change a flag in the format instead of updating each field: that's their business.

...you could always create a new table and load it from the old one, then rename the results...

That would be the database independent fallback. But since renaming a table is not standard SQL (is it, it would involve:

1. creating a temporary table
2. dumping the table data in there
3. drop the original table
4. create with new schema
5. copy the data back over
6. drop the temporary table

Liz