Julien:

I would need to store the value of each key in the separate variables

static int parserUrl_handler(request_rec *r)
{ 
    ap_add_cgi_vars(r); 

    const char *value = apr_table_get(r->subprocess_env, "QUERY_STRING");
    ap_rprintf(r, "QUERY_STRING : %s\n", value);

    return OK;
}