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A Dynamic Mapping Strategy In Top-k Queries Over Relational Databases

Posted on:2008-08-14Degree:MasterType:Thesis
Country:ChinaCandidate:M J ShenFull Text:PDF
GTID:2178360272968585Subject:Computer software and theory
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Vague queries are vey popular in daily lives.In many applications, users specify target values for certain attributes, without requiring exact matches to these values in return. Instead, the result to such queries is typically a rank of the"Top k"tuples that best match the given attribute values.The internet provides a good platform for vague queries,many engines in the internet provides the ability in vague queries.The queries for numbers are very important in vague queries. The queries for numbers maintain the basis feathers of vague queries.Because the number is easy to manipulate and compare,it's convinient to manipulate it wih math's mathod.The research in Top-k queries rank in these kinds:the first way is finding the nearest neighbors of a multidimensional data point, which are not yet effectively supported by most RDBMSs. The second way is mapping a multiattribute Top-k selection query on a relational database to a traditional selection query,it's important to find the domain.There are also many particular Top-k queries ways.Because the second way can be supported by RDBMS, it can automatically benefit from advanced multidimensional access methods. The static mapping strategy is useful to determin the domain in a single query.But for a lot of queries,dynamic mapping strategy is more useful than static mapping strategy.There are many parameters to determin in dynamic mapping strategy.Improve the parameters will be very helpful to improve the effect for queries.
Keywords/Search Tags:Multidimensional histograms, rank query, Top-k query processing
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