Heya, Thinking about data types and serialization. I think null support is an important characteristic for the serialized representations, especially when considering the compound type. However, doing so in directly incompatible with fixed-width representations for numerics. For instance, if we want to have a fixed-width signed long stored on 8-bytes, where do you put null? float and double types can cheat a little by folding negative and positive NaN's into a single representation (this isn't strictly correct!), leaving a place to represent null. In the long example case, the obvious choice is to reduce MAX_VALUE or increase MIN_VALUE by one. This will allocate an additional encoding which can be used for null. My experience working with scientific data, however, makes me wince at the idea.
The variable-width encodings have it a little easier. There's already enough going on that it's simpler to make room. Remember, the final goal is to support order-preserving serialization. This imposes some limitations on our encoding strategies. For instance, it's not enough to simply encode null, it really needs to be encoded as 0x00 so as to sort lexicographically earlier than any other value. What do you think? Any ideas, experiences, etc? Thanks, Nick
