An array is basically a set of homogeneous fields indexed by number, which are probably accessed in constant-time. A relational table is a completely different

An array is basically a set of homogeneous fields indexed by number, which are probably accessed in constant-time. A relational table is a completely different beast. Even after disregarding performance (which might be an abysmal difference in many use cases) it's not obvious how to access by index without "hacks". And if you consider multidimensional data, things get tougher without arrays...