Sample agg

This metric does a sampling, i.e. the first value to encounter is kept, the rest will just be collapsed into a single row.

Very useful for having a rough idea of what's going on in a super-high cardinality dimension w/o blowing space requirements.

Caveats: Missing specs, very grateful for a hit of how to best test this.

Or maybe you meant to say Shorts.SIZE (bytes to store data size) + SHORT.MAX_VALUE (bytes to store actual data)? that would make the most sense from reading the rest of the code.
Bonus points if you put actual comments to explain :)