Window-Oblivious Join: A Data-Driven Memory Management Scheme for Stream Join

Memory management is a critical issue in stream processing involving stateful operators such as join. Traditionally, the memory requirement for a stream join is query-driven: a query has to explicitly define a window for each (potentially unbounded) input. The window essentially bounds the size of the buffer allocated for that stream. However, outputs produced by such approach may not be desirable (if the window size is not part of the intended query semantic) due to the volatile input characteristics. The authors discover that when streams are ordered or partially ordered, it is possible to use a data-driven memory management scheme for improved performance.