Cockroach keys are arbitrary byte arrays. If textual data is used in keys, utf8 encoding is recommended (this helps for cleaner display of values in debugging tools). User-supplied keys are encoded using an ordered code. System keys are either prefixed with null characters (\0 or \0\0) for system tables, or take the form of to sort user-key-range specific system keys immediately after the user keys they refer to. Null characters are used in system key prefixes to guarantee that they sort first.