Global-as-View(GAv (Previous approaches Mapping Mediated schema CD: ASIN, Title, Genre Artist: AsIN, name Source Source Source Source Source R1 R2 R3 R4 R5
Global-as-View (GAV) (Previous approaches) Source Source Source Source Source R1 R2 R3 R4 R5 CD: ASIN, Title, Genre,… Artist: ASIN, name, … Mediated Schema Mapping:
Local-as-View LAV Mapping Mediated schema CD: ASIN, Title, Genre, Year Artist. As IN Name, Mediated Mediated Mediated Mediated Mediated View View View View View Source Source Source Source Source R1 R2 R3 R4 R5
Local-as-View (LAV) Source Source Source Source Source R1 R2 R3 R4 R5 CD: ASIN, Title, Genre, Year Artist: ASIN, Name, … Mediated Schema Mapping: Mediated View Mediated View Mediated View Mediated View Mediated View
benefits of lav Describing information sources became easier a data integration system could accommodate new sources easily The descriptions of the information sources could be more precise describe precise constraints on the contents of the sources become easier
benefits of LAV ◼ Describing information sources became easier a data integration system could accommodate new sources easily ◼ The descriptions of the information sources could be more precise describe precise constraints on the contents of the sources become easier
Query reformulation Mediated schema A query CD: ASIN, Title, Genre posed over CD(A, T,G) a set of queries on the data sources CDs Books Album Authors ASIN ISBN ISBN Price FirstName DiscountPrice DiscountPrice LastName Studio Edition Artists ASIN CDCategories Bookcategories ArtistName ASIN ISBN GroupName Category Category
Query reformulation Books Title ISBN Price DiscountPrice Edition CDs Album ASIN Price DiscountPrice Studio BookCategories ISBN Category CDCategories ASIN Category Artists ASIN ArtistName GroupName Authors ISBN FirstName LastName CD: ASIN, Title, Genre,… Mediated Schema A query posed over CD(A,T,G) a set of queries on the data sources
Query Answering in LAV Answering queries using vieWS(AQUv a problem which was earlier considered in the context of query optimization Given a set of views Vi,,Vn And a query Q, Can we answer Q using only the answers to
Query Answering in LAV = Answering queries using views (AQUV) ◼ a problem which was earlier considered in the context of query optimization Given a set of views V1 ,…,Vn , And a query Q, Can we answer Q using only the answers to V1 ,…,Vn?