Making post views as sortable

I am using custom field on wordpress admin posts page by adding the following code and then trying to sort the posts based on post views but the sorting does isn’t working. Here is the code I have added in functions.php:

add_filter('manage_posts_columns', 'posts_column_views');
add_action('manage_posts_custom_column', 'posts_custom_column_views',5,2);
function posts_column_views($defaults){
    $defaults['post_views'] = __('Views');
    return $defaults;
}
function posts_custom_column_views($column_name, $id){
    if($column_name === 'post_views'){
        echo getPostViews(get_the_ID());
    }
}

// Register the column as sortable
function posts_column_register_sortable( $columns ) {
$columns['post_views'] = 'post_views';

return $columns;
}
add_filter( 'manage_edit-post_sortable_columns', 'posts_column_register_sortable' );


function posts_column_orderby( $vars ) {
if ( isset( $vars['orderby'] ) && 'post_views_count' == $vars['orderby'] ) {
    $vars = array_merge( $vars, array(
        'meta_key' => 'post_views',
        'orderby' => 'meta_value_num'
    ) );
}

return $vars;
}
add_filter( 'request', 'posts_column_orderby' );


function getPostViews($postID){
    $count_key = 'post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if($count==''){
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
        return "0";
    }
    return $count;
}
function setPostViews($postID) {
if (!current_user_can('level_7') ) :
    $count_key = 'post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if($count==''){
        $count = 0;
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
    }else{
        $count++;
        update_post_meta($postID, $count_key, $count);
    }
endif;
}

Now the problem is that I can see the post views in the wordpress admin edit.php page and the volumn Views is also sortable but clicking on Views column doesn’t sort the posts based on views.

Please help me to solve this problem.