public function drop_index($xmldb_table, $xmldb_intex) {
        if (!$this->table_exists($xmldb_table)) {
            throw new ddl_table_missing_exception($xmldb_table->getName());
        }

        // Check index exists
        if (!$this->index_exists($xmldb_table, $xmldb_intex)) {
            throw new ddl_exception('ddlunknownerror', null,
                      'Index ' . $xmldb_table->getName() . '->' . $xmldb_intex->getName() .
                      ' does not exist. Drop skipped');
        }

        if (!$sqlarr = $this->generator->getDropIndexSQL($xmldb_table, $xmldb_intex)) {
            throw new ddl_exception('ddlunknownerror', null, 'drop_index sql not generated');
        }

        $this->execute_sql_arr($sqlarr, array($xmldb_table->getName()));
    }