Temporal database systems extend traditional relational database systems. One important such extension is to support time-varying aggregation.
时态数据库扩展了传统的关系数据库，其中一个重要的扩展就是对于时态聚集查询的支持。
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In the whole process flow, data aggregation is the key stage to realize parallel importing. The aggregation method of temporal data is described in detail.