Dynamic load management for distributed continuous query systems

A distributed stream processing system must adapt to changes in environment parameters and servers' load. We believe a dynamic load management scheme is indispensable for the system to be scalable. In particular, we expect aggressive methods such as query operator migration during runtime to bring long term benefit (especially for long running continuous queries) even though they may incur some short term overhead. However, to date few complete and practical solutions have been proposed for this problem. In this paper, we offer our solution to the problem. More specifically we make the following contributions: We formally define a new metric, performance ratio (PR), to measure the relative performance of each query and the objective for the whole system. By building a new cost model, we identify the heuristics that can be used to approach the objective. We propose a complete and practical distributed load management scheme, which includes a static initial placement scheme for newly, initiated queries as well as a runtime dynamic scheme. We conducted an extensive experimental study that shows the effectiveness of our technique.