Method and system for efficiently performing database table aggregation using an aggregation index

摘要

A method and system for efficiently performing database table aggregation is provided. In a preferred embodiment, an aggregation facility efficiently aggregates a source table using indices on an aggregated column of the source table and a grouping column of the source table. The facility uses the index on the aggregated column to identify the contents of the aggregated column in each row of the source table. The facility further uses information derived from the index on the grouping column to identify the contents of the grouping column in each row of the source table. For each row of the source table, the facility aggregates the identified aggregated column contents into a result value for the identified grouping column contents. In a further preferred embodiment, the facility generates a relation mapping from source table row to grouping column, which the facility uses to identify the contents of the grouping column in each row of the source table. In a further preferred embodiment, the facility may be used to perform multiple-level aggregations, as well as aggregations in which there are multiple grouping columns, multiple aggregated columns, and/or multiple result columns.