它通过统一的检索界面同时对多个网络数据库进行检索，并将检索结果归并，一起提供给用户。

Many network databases were searched at the same time through the uniform search interface, and the search results were merged to offer to users.

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本文考虑在并行数据库系统中基于归并排序的分组操作和集函数计算。

This paper considers SQL Group-By and aggregation based on merge-sort in parallel database systems.

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