The Clio project: managing heterogeneity
ACM SIGMOD Record
DTDs versus XML schema: a practical study
Proceedings of the 7th International Workshop on the Web and Databases: colocated with ACM SIGMOD/PODS 2004
Locally consistent transformations and query answering in data exchange
PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Schema mappings, data exchange, and metadata management
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Data exchange: semantics and query answering
Theoretical Computer Science - Database theory
Composing schema mappings: Second-order dependencies to the rescue
ACM Transactions on Database Systems (TODS) - Special Issue: SIGMOD/PODS 2004
Conjunctive queries over trees
Journal of the ACM (JACM)
Representing and querying XML with incomplete information
ACM Transactions on Database Systems (TODS)
Data exchange and incomplete information
Proceedings of the twenty-fifth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Model management 2.0: manipulating richer mappings
Proceedings of the 2007 ACM SIGMOD international conference on Management of data
CWA-solutions for data exchange settings with target dependencies
Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
Simple off the shelf abstractions for XML schema
ACM SIGMOD Record
XML data exchange: Consistency and query answering
Journal of the ACM (JACM)
Answering aggregate queries in data exchange
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Data exchange and schema mappings in open and closed worlds
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Optimizing Conjunctive Queries over Trees Using Schema Information
MFCS '08 Proceedings of the 33rd international symposium on Mathematical Foundations of Computer Science
Query languages for data exchange: beyond unions of conjunctive queries
Proceedings of the 12th International Conference on Database Theory
Logical foundations of relational data exchange
ACM SIGMOD Record
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
XML with incomplete information: models, properties, and query answering
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Data exchange: On the complexity of answering queries with inequalities
Information Processing Letters
Conjunctive query containment over trees
DBPL'07 Proceedings of the 11th international conference on Database programming languages
Certain answers for XML queries
Proceedings of the twenty-ninth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Tractable XML data exchange via relations
Proceedings of the 20th ACM international conference on Information and knowledge management
Using an inference mechanism for helping the data integration
Proceedings of the 15th Symposium on International Database Engineering & Applications
Between tree patterns and conjunctive queries: is there tractability beyond acyclicity?
MFCS'12 Proceedings of the 37th international conference on Mathematical Foundations of Computer Science
XML data exchange with target constraints
Information Processing and Management: an International Journal
Query processing under GLAV mappings for relational and graph databases
Proceedings of the VLDB Endowment
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In XML data exchange, a schema mapping specifies rules for restructuring a source document under the target schema, and queries over the target document must be answered in a way consistent with the source information. Mapping rules and queries in this scenario are typically based on various kinds of tree patterns. Patterns with downward navigation have been studied, and tractable classes of mappings and queries have been isolated. In this paper we extend schema mappings and queries with general tree patterns that include horizontal navigation and data-value comparisons, and study their impact on the tractability of the query answering problem. Our main results state that, in the nutshell, extending the tractable cases for downward patterns with expressive schema mappings is harmless, but adding new features to queries quickly leads to intractability even for very simple schema mapping.