async_query (PGconn)

    /*
     * call-seq:
     *    conn.async_query(sql)
     *
     * Sends an asynchronous SQL query request specified by _sql_ to the PostgreSQL.
     * Returns an Array as the resulting tuple on success.
     * On failure, it returns +nil+, and the error details can be obtained by #error.
     */
    static VALUE
    pgconn_async_query(obj, str)
        VALUE obj, str;
    {
        return pgresult_result_with_clear(pgconn_async_exec(obj, str));
    }