| 摘要 |
A database system and methodology for generalized order optimization is described. In one embodiment, for example, in a database system, a method of the present invention is described for optimizing a query requesting data from a database in an ordered form, the method comprises steps of: generating a plurality of partial access plans for obtaining data requested by the query; constructing generalized orders representing requirements of the query for ordering of data, each generalized order representing a set of simple orders; creating generalized orders representing order properties of the partial access plans; intersecting the generalized orders representing requirements of the query for ordering of data with the generalized orders representing order properties of the partial access plans to determine partial access plans having favorable orderings; and building a query execution plan for obtaining and ordering the data requested by the query based, at least in part, on selecting partial access plans having favorable orderings.
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