The isFixedWidth for all of the array types should be false. The reason is that the array itself will not be fixed length, since even with an upper bound, there may be less elements than that. This really comes into play too when down the road we allow arrays to be put in the row key. In this case, we'll need to do some type conversion because the element types will need to be variable length (we do the same thing for our index row key). The reason is that variable length types have a representation of null, while fixed length types don't.