Reads one back, or undefined when nothing readable is there. Undefined, not zeros: "no row yet" makes the caller look for legacy keys and carry the lifetime serve total forward, while a zero row is a day that served nothing.
Reads one back, or undefined when nothing readable is there. Undefined, not zeros: "no row yet" makes the caller look for legacy keys and carry the lifetime serve total forward, while a zero row is a day that served nothing.