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Several layers of information.

Multi-layered Databases for Intelligent Query Answering in Mobile Environments (Sanjay Madria and Y. Fu, madrias@umr.edu). Several layers of information. Lowest layer corresponding to the primitive information stored in a conventional database.

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Several layers of information.

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  1. Multi-layered Databases for Intelligent Query Answering in Mobile Environments (Sanjay Madria and Y. Fu, madrias@umr.edu) • Several layers of information. • Lowest layer corresponding to the primitive information stored in a conventional database. • Higher layers storing more general information extracted from lower layers. • A multi-layered database (MLDB) consists of 4 major components: <S, O, C, D> • S: a database schema; • O: a set of generalization operators; • C: a set of integrity constraints; • D: a set of database relations. • Selection or sampling. • Resolution. • Transformation. • Concept hierarchy climbing. • Categorization. • Aggregation. • Discoloration. • Deletion.

  2. An MLDB Example Layer 3 attraction3(id, name, address, open_times, admission_price, summary). hotel3(…) restaurant3(…) • Layer 0 attraction(id, name, address, open_times, admission_price, description, map, picture, video) hotel(…) restaurant(…) • Layer 1 attraction1(id, name, address, open_times, admission_price, description, coarse_map, thumbnail_picture, still_video_image). hotel1(…) restaurant1(…) • Layer 2 attraction2(id, name, address, open_times, admission_price, description, directions, picture_title, video_title). hotel2(…) restaurant2(…)

  3. Intelligent Query Answering in an MLDB • Answer a query with the highest layer relations possible to reduce the communication cost. • Determine the highest layer relations which are able to answer the query: • For each condition in query condition, decide the highest layer relation in which it can be evaluated. • For each attribute in query result, decide the highest layer relation in which it exists. • For each relation involved, select its lowest layer from the first two steps.

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