| 摘要 |
A method, apparatus and article of manufacture for utilizing an abstract derived entity are disclosed. An abstract derived entity is a data object present in an abstract data model that may be referenced by other entities in the abstract data model as though it were a relational table present in a physical data source. In one embodiment, an abstract data model provides data access independent of the manner in which the data is physically represented in a set of physical data sources. In addition, an abstract derived entity may be used to provide aggregate data joined with other non-aggregate data. Aggregate data values are calculated from the column of a relational table, or other sets of input data. In one embodiment, an abstract derived entity may describe a describe relational table comprising a set of aggregate data used to form a column of the relational table joined to other columns formed from the sets of input data specified by the abstract derived entity. The resulting abstract derived table may be queried as though it were an actual relational table stored in a physical data source.
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