Performs a bitwise `xor` operation. If the existing value in the
database is not present or shorter than `param`, it is first extended
to the length of `param` with zero bytes. If `param` is shorter than
the existing value in the database, the existing value is truncated to
match the length of `param`.
Performs a bitwise `xor` operation. If the existing value in the database is not present or shorter than `param`, it is first extended to the length of `param` with zero bytes. If `param` is shorter than the existing value in the database, the existing value is truncated to match the length of `param`.