_setupPrimaryKey example

    public function info($key = null)
    {
        $this->_setupPrimaryKey();

        $info = array(
            self::SCHEMA           => $this->_schema,
            self::NAME             => $this->_name,
            self::COLS             => $this->_getCols(),
            self::PRIMARY          => (array) $this->_primary,
            self::METADATA         => $this->_metadata,
            self::ROW_CLASS        => $this->getRowClass(),
            self::ROWSET_CLASS     => $this->getRowsetClass(),
            self::REFERENCE_MAP    => $this->_referenceMap,
            self::DEPENDENT_TABLES => $this->_dependentTables,