如何向Mondrian描述OLAP多维数据集

<Schema name="MyOLAPSchema">
  <Cube name="SalesCube" defaultMeasure="SalesAmount">
    <Table name="sales_fact">
      <!-- 列出事实表的列 -->
      <Column name="product_id" type="Numeric"/>
      <Column name="time_id" type="Numeric"/>
      <Column name="sales_amount" type="Numeric"/>
    </Table>
    <Dimension name="Product">
      <!-- 列出维度表的列 -->
      <Hierarchy name="ProductHierarchy" hasAll="true">
        <Table name="product_dim"/>
        <Level name="Category" column="category_name" uniqueMembers="true"/>
        <Level name="Subcategory" column="subcategory_name" uniqueMembers="true"/>
        <Level name="Product" column="product_name" uniqueMembers="true"/>
      </Hierarchy>
    </Dimension>
    <Dimension name="Time">
      <!-- 列出维度表的列 -->
      <Hierarchy name="TimeHierarchy" hasAll="true">
        <Table name="time_dim"/>
        <Level name="Year" column="year" uniqueMembers="true"/>
        <Level name="Quarter" column="quarter" uniqueMembers="false"/>
        <Level name="Month" column="month" uniqueMembers="false"/>
      </Hierarchy>
    </Dimension>
    <Measure name="SalesAmount" column="sales_amount" aggregator="sum" formatString="$#,##0.00"/>
  </Cube>
</Schema>