private function _getPrimaryKey($tableName)
{
$primaryKey = Db::getInstance()->query("SELECT pg_attribute.attname\n FROM pg_index, pg_class, pg_attribute\n WHERE\n pg_class.oid = '{$tableName}'::REGCLASS AND\n indrelid = pg_class.oid AND\n pg_attribute.attrelid = pg_class.oid AND\n pg_attribute.attnum = ANY(pg_index.indkey)\n AND indisprimary;\n ")->fetch();
if ($primaryKey) {
return Arrays::getValue($primaryKey, 'attname');
} else {
return '';
}
}