Dynamic query switching for complex event processing on FPGAs

This paper presents an FPGA event processing system which can dynamically switch queries with the following features. (1) The switch can be performed without a need for a server shutdown. (2) The output stream includes results of the old query just until the new query starts producing results. (3) The old results and new results are not disordered in the output stream. Switching queries is essential to maintain reliability, availability, and serviceability and to increase business profit. We propose (i) a query management mechanism which makes both a new and old query run in parallel and (ii) a network which selects and send out proper result data from mixed result data. We have validated the design on a FPGA board with financial trading queries and shown the feasibility of the query switch with 32 queries running simultaneously, each of which is fed input events of 20Gbps throughput.