Hitachi, Ltd.

Itatu Nishizawa

Tsuneyuki Imaki

A query parser that converts query definition into a query graph and decides the execution order of operators is installed, a set of consecutive operators in the execution order is called a stage, the total of calculation costs of operators configuring each stage is called a calculation cost of the stage, the query graph is divided into multiple stages such that the calculation cost of each stage becomes a value less than a value dividing the total cost of all operators by the number of calculation cores, and each calculation core extracts tuples one by one from an input stream, and, when taking charge of and executing processing of the tuples from the entrance to exit of the query graph, before the execution of each stage, confirms whether processing of the stage is completed for a tuple previous to a charge tuple.

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Tokyo, Japan

Itatu Nishizawa