Addition on - post table custom column

/*
* first paste: http://pastebin.com/wuSwHjjg
*/

//enable newly added column ordering
add_filter( 'manage_edit-post_sortable_columns', 'dct_table_sorting' ); //use manage_edit-{post_type}_sortable_columns for custom post type
function dct_table_sorting( $columns ) {
  $columns['column1'] = 'column1';
  $columns['column2'] = 'column2';
  return $columns;
}

add_filter( 'request', 'dct_column1_orderby' );
function dct_column1_orderby( $vars ) {
    if ( isset( $vars['orderby'] ) && 'column1' == $vars['orderby'] ) {
        $vars = array_merge( $vars, array(
            'meta_key' => 'column1_meta_key',
            'orderby' => 'meta_value'
        ) );
    }

    return $vars;
}

add_filter( 'request', 'dct_column2_orderby' );
function dct_column2_orderby( $vars ) {
    if ( isset( $vars['orderby'] ) && 'column2' == $vars['orderby'] ) {
        $vars = array_merge( $vars, array(
            'meta_key' => 'column2_meta_key',
            'orderby' => 'meta_value'
        ) );
    }

    return $vars;
}


/*
*re-arranging table columns
*lets add these two columns before date (date is the last column of the list by default)
*if we want to do this, then we need to add following codes inside function "dct_table_head" (see paste: http://pastebin.com/wuSwHjjg) before returning.
*/
$key = 'date'; //name of the "date" column key
$offset = array_search($key, array_keys($defaults));
$result = array_merge
    (
        array_slice($defaults, 0, $offset),
        array('column1' => 'Column1', 'column2' => 'Column2'),
        array_slice($defaults, $offset, null)
    );
//we will then return $result, instead of $defaults