public function fetchColumn($fieldIndex): array
    {
        $this->checkFieldIndex($fieldIndex);
        if (is_string($fieldIndex)) {
            $fieldIndex = $this->namesHash[$fieldIndex];
        }

        $result = [];
        for ($i = 0; $i < $this->numRows; $i++) {
            $result[] = $this->converters[$fieldIndex]->input(
                pg_fetch_result($this->resource, $i, $fieldIndex)
            );
        }
        return $result;
    }