Constraint checking with partial information
PODS '94 Proceedings of the thirteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Containment of conjunctive queries: beyond relations as sets
ACM Transactions on Database Systems (TODS)
Equivalences Among Relational Expressions with the Union and Difference Operators
Journal of the ACM (JACM)
A formal semantics of patterns in XSLT and XPath
Markup Languages
Containment for XPath Fragments under DTD Constraints
ICDT '03 Proceedings of the 9th International Conference on Database Theory
Queries Independent of Updates
VLDB '93 Proceedings of the 19th International Conference on Very Large Data Bases
XPath Containment in the Presence of Disjunction, DTDs, and Variables
ICDT '03 Proceedings of the 9th International Conference on Database Theory
Tree pattern query minimization
The VLDB Journal — The International Journal on Very Large Data Bases
Answering queries using views: A survey
The VLDB Journal — The International Journal on Very Large Data Bases
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
Containment and equivalence for a fragment of XPath
Journal of the ACM (JACM)
ACM SIGMOD Record
The complexity of query containment in expressive fragments of XPath 2.0
Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
On testing satisfiability of tree pattern queries
VLDB '04 Proceedings of the Thirtieth international conference on Very large data bases - Volume 30
Contained Rewritings of XPath Queries Using Views Revisited
WISE '08 Proceedings of the 9th international conference on Web Information Systems Engineering
On tree pattern query rewriting using views
WISE'07 Proceedings of the 8th international conference on Web information systems engineering
On equivalence and rewriting of XPath queries using views under DTD constraints
DEXA'11 Proceedings of the 22nd international conference on Database and expert systems applications - Volume Part II
Union rewritings for XPath fragments
Proceedings of the 15th Symposium on International Database Engineering & Applications
Hi-index | 0.00 |
In this paper, we address the containment problem for unions of XPath queries with and without schema. We find the problem can be always reduced into containment problem between one single query and a union of queries. When schema is not available, the problem can be further reduced into checking containment between pairwise queries (each from one union), but this only holds for some XPath subsets, such as XP { /,//,[] } , but not for XP { /,//,[],* } . We then show the problem is still solvable in XP { /,//,[],* } , though no efficient algorithm exists. When schema is at hand, we propose a strategy to rewrite a query into a union of simplified queries based on schema information, and then apply methods developed when schema is not taken into account. The problem is then reduced into checking containment between unions of queries in XP { /,[] } without schema.