Patent ID: 8112438

Claim:
A coordinator server that is configured to be connected to a plurality of parallelized database servers each storing data and that performs a pipeline processing, comprising: a first transmitting unit that transmits a processing command to the database servers in response to a query request for requesting a data acquisition from a client; a buffer unit that buffers data sets transmitted from the database servers as a result of a processing according to the processing command; an integrating unit that integrates the data sets buffered in the buffer unit to obtain a merged data set; a second transmitting unit that transmits the merged data set to the client; a first determining unit that determines a transmission start or a transmission suspend of the data sets from the database servers based on a data size of the data sets buffered in the buffer unit; and a third transmitting unit that transmits a control command instructing the transmission start or the transmission suspend of the data sets to the database servers based on a result of determination by the first determining unit.