Hey,
are you saying that the table schema changes during the active lifetime of your rails application? If not then I've misunderstood you and the rest of this response is not relevant.
My first reaction would be to avoid messing with the underlying schema at runtime... It's not an informed reaction, it just strikes me as bad news.
If schema changes happen so frequently that you can't afford the downtime of a deploy I'd suggest you were abusing the relational model - time to rethink your design.
If schema changes are not happening that frequently then things will be a lot more stable if you redeploy with each schema change. Of course, that's just one guy's opinion.
However, if changing the schema is what you're set on doing then you *might* have some success calling Model.reset_column_information as you think is required - however, rails autogenerates methods based on the schema and I don't know enough about that end of things to be able to say whether it'll work at all - just a suggestion.
Regards, Trevor