Efficient method of updating multiple records

[malikoth]

There needs to be an efficient way to modify all records matching a QuerySet.

I would imagine this would best be implemented as an update method on the QuerySet, that combines the QuerySet's filter_clauses with a set_clause to issue an UPDATE statement.

It would also be useful to have something like Django's bulk_update for a way to efficiently perform more targeted updates, though I have less of a concept of either how Django does it, or how I think it should be done here. I think this is lower priority than just getting update implemented in the first place.