A Survey of Join-Processing in Datastreams

Stream join is a fundamental operation for relating information from different streams. For example, given two stream of packets seen by network monitors placed at two routers, people can join the streams on packet ids to identify those packets that flowed through both routers. As another example, an online auction system may generate two event streams: One signals opening of auctions and the other contains bids on the open auctions. A stream join is needed to relate bids with the corresponding open-auction events. As a third example, which involves a non-equality join, consider two data streams that arise in monitoring a cluster machine room, where one stream contains load information collected from different machines, and the other stream contains temperature readings from various sensors in the room.