protected function addIndexes(Table $table)
    {
        $stmt = $this->dbh->query("SELECT INDEX_NAME, COLUMN_NAME FROM USER_IND_COLUMNS WHERE TABLE_NAME = '" . $table->getName() . "' ORDER BY COLUMN_NAME");

        $indices = [];
        while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
            $indices[$row['INDEX_NAME']][]= $row['COLUMN_NAME'];
        }

        foreach ($indices as $indexName => $columnNames) {
            $index = new Index($indexName);
            foreach ($columnNames as $columnName) {
                // Oracle deals with complex indices using an internal reference, so...
                // let's ignore this kind of index
                if ($table->hasColumn($columnName)) {
                    $index->addColumn($table->getColumn($columnName));
                }
            }
            // since some of the columns are pruned above, we must only add an index if it has columns
            if ($index->hasColumns()) {
                $table->addIndex($index);
            }
        }
    }