GRACE TECHNICAL REPORTS Context-Preserving XQuery Fusion
نویسندگان
چکیده
XQuery is a DBPL for querying XML databases. The semantics of XQuery is context sensitive and requires preservation of document order. In this paper, we propose, as far as we are aware, the first XQuery fusion that can deal with both the document order and the context of XQuery expressions. More specifically, we carefully design a context representation of XQuery expressions based on the Dewey order encoding, develop a context-preserving XQuery fusion for ordered trees by static emulation of the XML store, and prove that our fusion is correct. Our XQuery fusion has been implemented, and all the examples in this paper have passed the system.
منابع مشابه
Context-Preserving XQuery Fusion
XQuery is a DBPL for querying XML databases. The semantics of XQuery is context sensitive and requires preservation of document order. In this paper, we propose, as far as we are aware, the first XQuery fusion that can deal with both the document order and the context of XQuery expressions. More specifically, we carefully design a context representation of XQuery expressions based on the Dewey ...
متن کاملRewriting XQuery to Avoid Redundant Expressions based on Static Emulation of XML Store
Rewriting composite expressions based on eliminating intermediate results generated by redundant expressions is a traditional optimization technique (known as fusion) in both programming languages community and database community. In XQuery, composite expressions for node creation are typical in practice, for example, in data integration systems for XML with XQuery as schema mapping. We propose...
متن کاملConstructing Optimal Bushy Trees Possibly Containing Cross Products for Order Preserving Joins is in P
One of the main features of XQuery compared to traditional query languages like SQL, is that it preserves the input order—unless specified otherwise. As a consequence, order-preserving algebraic operators are needed to capture the semantics of XQuery correctly. One important algebraic operator is the orderpreserving join. The order-preserving join is associative but, in contrast to the traditio...
متن کاملSQL-AG: Querying structured documents using attribute grammars
Structured documents, such as program source texts, technical documentation, or XML data, comprise an important class of data in many applications. Structured documents are distinguished from flat text by their tree structure. In a program source text, this structure is the abstract syntax tree of the program. In a technical document, this structure is the division in chapters, sections, paragr...
متن کاملQuantifiers in XQuery
We present algebraic equivalences that allow to unnest nested algebraic expressions containing quantifiers for order-preserving algebraic operators. We illustrate how these equivalences can be applied successfully to unnest nested queries formulated in XQuery. Measurements illustrate the performance gains possible by unnesting.
متن کامل