key_def length introspection

[TarantoolBot]

Related dev. issue(s): tarantool/tarantool#10111

Product: Tarantool
Since: 3.2
Root document: https://www.tarantool.io/en/doc/latest/reference/reference_lua/key_def/
SME: @ unera

Details

To check key_def length (parts count) there is a standard lua operator
# (__len metamethod).

Example:

function is_full_pkey(space, key)
    return #space.index[0].parts == #key
end

Requested by @ unera in tarantool/tarantool@90f3304.