I've always been curious why someone hasn't (or why I haven't heard of someone) prototyping an improvement to MySQL's query cache to invalidate the cache less f

I've always been curious why someone hasn't (or why I haven't heard of someone) prototyping an improvement to MySQL's query cache to invalidate the cache less frequently and get more dependable usage. Currently it invalidates when any table referenced by the query changes. It seems like you could improve this algorithm without too much trouble. For example, it feels like if the query was located solely through indexes, it should be able to do cache invalidation on an update to those index hits rather than on the entire table. I'll have to look through the code one day and see why this makes no sense.