SQL update with %IGNOREINDEX

I'm in a tricky situation where a new required property is being added to a class, along with an index on it. The existing data has nulls, so the index build fails. I can't run a query to update the rows where there are nulls, because it tries to use the index, which hasn't been built yet.

I realize that a valid workaround would be to remove the index, add the property, run the query to do the update, then re-add the index, but this feels overly messy (and doesn't fit well with my logic for incremental deployment). It would be nice if there was instead some way to make the update not use the index, but I'm not seeing that in the documentation. Any thoughts?