You can also join customers and orders in a query by forming the cross-product and retrieving all the relative bits of data as one large projection.

您还可以在查询中联接客户和订单，方法是构建叉积并将所有相关数据位作为一个大型投影检索出来。

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Building bitmap join indexes of dimension tables and fact tables directly may bring a large number of useless index items that affect query efficiency.

直接建立维度表与事实表的位图连接索引会产生大量无用的索引项，影响查询效率。

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Query optimization for large join queries is one of the key factors to improving the performance of database systems.

多连接查询优化是提高数据库性能的关键问题之一。

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