We consider data exchange for XML documents： given source and target schemas, a mapping between them, and a document conforming to the source schema, construct a target document and answer target queries in a way tha...We consider data exchange for XML documents： given source and target schemas, a mapping between them, and a document conforming to the source schema, construct a target document and answer target queries in a way that is consistent with the source information. The problem has pri- marily been studied in the relational context, in which data- exchange systems have also been built. Since many XML documents are stored in relations, it is natural to consider using a relational system for XML data exchange. However, there is a complexity mismatch between query answering in relational and in XML data exchange. This indicates that to make the use of relational systems pos- sible, restrictions have to be imposed on XML schemas and mappings, as well as on XML shredding schemes. We isolate a set of five requirements that must be ful- filled in order to have a faithful representation of the XML data-exchange problem by a relational translation. We then demonstrate that these requirements naturally suggest the in- lining technique for data-exchange tasks. Our key contribu- tion is to provide shredding algorithms for schemas, docu- ments, mappings and queries, and demonstrate that they en- able us to correctly perform XML data-exchange tasks using a relational system.展开更多
文摘We consider data exchange for XML documents： given source and target schemas, a mapping between them, and a document conforming to the source schema, construct a target document and answer target queries in a way that is consistent with the source information. The problem has pri- marily been studied in the relational context, in which data- exchange systems have also been built. Since many XML documents are stored in relations, it is natural to consider using a relational system for XML data exchange. However, there is a complexity mismatch between query answering in relational and in XML data exchange. This indicates that to make the use of relational systems pos- sible, restrictions have to be imposed on XML schemas and mappings, as well as on XML shredding schemes. We isolate a set of five requirements that must be ful- filled in order to have a faithful representation of the XML data-exchange problem by a relational translation. We then demonstrate that these requirements naturally suggest the in- lining technique for data-exchange tasks. Our key contribu- tion is to provide shredding algorithms for schemas, docu- ments, mappings and queries, and demonstrate that they en- able us to correctly perform XML data-exchange tasks using a relational system.
