| 摘要 |
A method and apparatus is provided in a parallel database system having a plurality of nodes for computing a moving aggregate of an attribute of a relation having multiple tuples. Portions of the relation are distributed across the plurality of nodes of the database system. For each node i, the database system identifies one or more other nodes that contain tuples of the relation which are covered by a moving window of each tuple of the relation at node i. For each such identified node, a value representing an aggregate of the tuples at each such identified node is communicated to node i. The moving aggregate is then calculated using at least tuples of the relation at node i as well as the value from each of the identified one or more nodes.
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