cs345-streams

cs345-streams - 1 Mining Data Streams The Stream Model...

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Unformatted text preview: 1 Mining Data Streams The Stream Model Sliding Windows Counting 1s 2 The Stream Model r Data enters at a rapid rate from one or more input ports. r The system cannot store the entire stream. r How do you make critical calculations about the stream using a limited amount of (secondary) memory? 3 Processor Limited Storage . . . 1, 5, 2, 7, 0, 9, 3 . . . a, r, v, t, y, h, b . . . 0, 0, 1, 0, 1, 1, 0 time Streams Entering Queries Output 4 Applications --- (1) r In general, stream processing is important for applications where R New data arrives frequently. R Important queries tend to ask about the most recent data, or summaries of data. 5 Applications --- (2) r Mining query streams. R Google wants to know what queries are more frequent today than yesterday. r Mining click streams. R Yahoo wants to know which of its pages are getting an unusual number of hits in the past hour. 6 Applications --- (3) r Sensors of all kinds need monitoring, especially when there are many sensors of the same type, feeding into a central controller, most of which are not sensing anything important at the moment. r Telephone call records summarized into customer bills. 7 Applications --- (4) r Intelligence-gathering. R Like evil-doers visit hotels at beginning of course, but much more data at a much faster rate. Who calls whom? Who accesses which Web pages? Who buys what where? 8 Sliding Windows r A useful model of stream processing is that queries are about a w i n d o w of length N--- the N most recent elements received....
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cs345-streams - 1 Mining Data Streams The Stream Model...

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