public function getAttributes( $includeParents = true )
    {
        if( !$this->columns ) {
            $this->columns = $this->catalog->pgAttributes->findByAttrelid( $this->oid )->sortByAttnum();
        }

        $output = $this->columns->copy();

        // include parents
        if( !$includeParents ) {
            $output->filter(
                function($attribute){
                    return !$attribute->isInherited();
                }
            );
        }

        return $output;
    }