virtual keyword doesn't seem to work in this cpp program

Question

Take a look at this small C++ program:

#include <iostream>

#define debugStream std::cout

struct Id {
    Id() {
        debugStream << this->getClassName() << " created\n";
    }

    virtual ~Id() {
        debugStream << this->getClassName() << " destroyed\n";
    }

    virtual std::string getClassName() {
        return "Id";
    }
};


struct D : public Id {
    std::string getClassName() {
        return "D";
    }
};

int main( int argc, const char *argv[] ) {
    Id* i = new D();
    return 0;
}

I expected this program to print:

D created
D destroyed

but instead it prints:

Id created
Id destroyed

virtual is working as expected for the destructor but not for the getClassName function. Why is it so?