A data stream is a real-time, continuous, ordered sequence of items. Some examples include sensor data, Internet traffic, financial tickers, on-line auctions, and transaction logs such as Web usage logs and telephone call records. Likewise, queries over streams run continuously over a period of time and incrementally return new results as new data arrives. For example, a temperature detection system of a factory warehouse may run queries like the following. Query-1: “Every five minutes, retrieve the maximum temperature over the past five minutes.” 
Query-2: “Return the average temperature measured on each floor over the past 10 minutes.” 继续阅读【UVA1203】Argus(优先队列)