Database Reference
In-Depth Information
Tatarinov, I., & Halevy, A. Y. (2004). Efficient query reformulation in peer-data management systems. In
G. Weikum, A.C. König & S. Deßloch (Eds.),
Proceedings of the ACM SIGMOD International Confer-
ence on Management of Data,
(pp. 539-550). Paris, France, June 13-18, 2004. ACM.
Tatarinov, I., & Ives, Z. G. (2003). The Piazza peer data management project.
SIGMOD Record
,
32
(3),
47-52. doi:10.1145/945721.945732
XPath. (2006).
XML path language 2.0
. Retrieved from www.w3.org/TR/xpath20
XQuery. (2002).
XQuery 1.0: An XML query language
. W3C Working Draft. Retrieved from www.
w3.org/TR/ xquery
Xu, W., & Ozsoyoglu, Z. M. (2005). Rewriting XPath queries using materialized views. In K. Böhm, et
al. (Eds.),
Proceedigns of the 31st International Conference on Very Large Data Bases,
(pp. 121-132).
Trondheim, Norway, August 30 - September 2, 2005, ACM.
Yu, C., & Popa, L. (2004). Constraint-based XML query rewriting for data integration. In G. Weikum,
A.C. König, & S. Deßloch (Eds.),
Proceedings of the ACM SIGMOD International Conference on
Management of Data,
(pp. 371-382). Paris, France, June 13-18, 2004. ACM.
KEY TERMS AND DEFINITIONS
Data Integration:
Data integration consists in combining data from different sources into a uni-
fied format. The goal of data integration is to enable rapid development of new applications requiring
information from multiple sources. In particular, in P2P integration when an answer is issued against an
arbitrarily chosen peer then the answer should consist of data stored in the queried peer as well as data
stored in its direct and indirect partners (acquaintances) .
Schema Mapping:
Schema mapping is a specification defining how data structured under one schema
(the
source schema
) is to be transformed into data structured under another schema (the
target schema
).
The specification is based on source-to-target dependences involving atomic relational formulas (relat-
ing to relational data) or tree-pattern formulas (relating to XML data).
Tree Pattern:
Tree pattern is an expression defining a part of an XML tree; a branch in the tree is
denoted by square brackets ([ ]), a node-to-child relationship is denoted by slash (/), a node-to-descendant
relationship is denoted by double slash (//), nodes are denoted by labels (
l
denotes nodes labeled with
l
) or
by wildcard (*) that denotes a node labeled with any label. Depending on the set of permitted operators
we have different classes of tree patterns. (In this chapter, operators // and * have not been considered).
A tree pattern can be treated as a kind of a variable-free XPath query.
Tree-Pattern Formula:
A tree-pattern formula is created from a tree pattern after assigning variables
to some symbols representing nodes (i.e. to labels or to wildcards). Variables assigned to text and at-
tribute nodes are text-valued variables. Otherwise, they are node-valued variables. Values of variables
constrain trees matching the pattern. A TPF can be understood as a simple query defining the answer
by means of the underlying tree pattern and values of variables. (In this chapter we considered only
text-valued variables).
XML Functional Dependency (XFD):
An XML functional dependency is a constraint saying that
a path value (i.e. a node or a text value denoted by the path) is functionally determined by a set of text
