Database system providing optimization of group by operator over a union all
A database system providing improved methods for optimization and execution of queries aggregating information from multiple database tables is described. The improved method breaks serial operations into a group of child operations that can be individually optimized and processed in parallel. A query including a grouping operator over a union node is split by pushing the grouping operation down into each input arm of the union node. Specifically, grouping operators are inserted into each child arm of qualifying union nodes, enabling separate physical database tables to be summarized in parallel. Each of the child grouping operators concurrently groups data and generates summary results in parallel, taking advantage of capabilities of available parallel processing hardware. The aggregate operators of the original master grouping operator are modified to accept and correctly synthesize sub-aggregated results generated by each of the child grouping operators. The method also enables individual optimization of operations on each database table, including use of advantageous index-only execution plans.
Sybase, Inc.
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inventional additional additional inventional
Xiqing Steven A. Roger D.
Li Kirk MacNicol