Efficient Distribution of Full-Fledged XQuery

Abstract-- We investigate techniques to automatically decompose any XQuery query into subqueries, that can be executed near their data sources; i.e., function-shipping. In this scenario, the subqueries being executed remotely may have XML nodevalued parameters or results, that must be shipped in some way. The main challenge addressed here is to ensure that the decomposed queries properly respect XML node identity and preserve structural properties, when (parts of) XML nodes are sent over the network, effectively copying them. We start by precisely characterizing the conditions, under which pass-by-value parameter passing causes semantic differences between remote execution of an XQuery expression and its local execution. We then formulate a conservative strategy that effectively avoids decomposition in such cases. To broaden the possibilities of query distribution, we extend the pass-byvalue semantics to a pass-by-fragment semantics, which keeps better track of node identities and stru...

• Type: Conference
• Year: 2009
• Where: ICDE
• Authors: Ying Zhang, Nan Tang, Peter A. Boncz
• Keywords: Database, Efficient Xquery Extension, ICDE 2009, XML Node Identity, XQuery Decomposition Techniques, XQuery Expression, XQuery Query