TY - GEN
T1 - Nested mappings
T2 - 32nd International Conference on Very Large Data Bases, VLDB 2006
AU - Fuxman, Ariel
AU - Hernandez, Mauricio A.
AU - Ho, Howard
AU - Miller, Renee J.
AU - Papotti, Paolo
AU - Popa, Lucian
PY - 2006
Y1 - 2006
N2 - Many problems in information integration rely on specifications, called schema mappings, that model the relationships between schémas. Schema mappings for both relational and nested data are well-known. In this work, we present a new formalism for schema mapping that ex-tends these existing formalisms in two significant ways. First, our nested mappings allow for nesting and correlation of mappings. This results in a natural programming paradigm that often yields more accurate specifications. In particular, we show that nested mappings can naturally preserve correlations among data that existing mapping formalisms cannot. We also show that using nested mappings for pur-Poses of exchanging data from a source to a target will result in less redundancy in the target data. The second extension to the mapping formalism is the ability to express, in a declarative way, grouping and data merging semantics. This semantics can be easily changed and customized to the integration task at hand. We present a new algorithm for the automatic generation of nested mappings from schema matchings (that is, simple element-to-element correspondences beween schemas). We have implemented this algorithm, along with algorithms for the generation of transformation queries (e.g., XQuery) ased on the nested mapping specification. We show that the generation algorithms scale well to large, highly nested schemas. We also show that using nested mappings in data exchange can drastically re-uce the execution cost of producing a target instance, particularly over large data sources, and can also dramatically improve the qual-ity of the generated data.
AB - Many problems in information integration rely on specifications, called schema mappings, that model the relationships between schémas. Schema mappings for both relational and nested data are well-known. In this work, we present a new formalism for schema mapping that ex-tends these existing formalisms in two significant ways. First, our nested mappings allow for nesting and correlation of mappings. This results in a natural programming paradigm that often yields more accurate specifications. In particular, we show that nested mappings can naturally preserve correlations among data that existing mapping formalisms cannot. We also show that using nested mappings for pur-Poses of exchanging data from a source to a target will result in less redundancy in the target data. The second extension to the mapping formalism is the ability to express, in a declarative way, grouping and data merging semantics. This semantics can be easily changed and customized to the integration task at hand. We present a new algorithm for the automatic generation of nested mappings from schema matchings (that is, simple element-to-element correspondences beween schemas). We have implemented this algorithm, along with algorithms for the generation of transformation queries (e.g., XQuery) ased on the nested mapping specification. We show that the generation algorithms scale well to large, highly nested schemas. We also show that using nested mappings in data exchange can drastically re-uce the execution cost of producing a target instance, particularly over large data sources, and can also dramatically improve the qual-ity of the generated data.
UR - http://www.scopus.com/inward/record.url?scp=84893842937&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84893842937&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84893842937
SN - 1595933859
SN - 9781595933850
T3 - VLDB 2006 - Proceedings of the 32nd International Conference on Very Large Data Bases
SP - 67
EP - 78
BT - VLDB 2006 - Proceedings of the 32nd International Conference on Very Large Data Bases
PB - Association for Computing Machinery
Y2 - 12 September 2006 through 15 September 2006
ER -