Using acceptors as transducers
Theoretical Computer Science
Algorithmics and applications of tree and graph searching
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Multi-level operator combination in XML query processing
Proceedings of the eleventh international conference on Information and knowledge management
Knowledge-Based Image Retrieval with Spatial and Temporal Constructs
IEEE Transactions on Knowledge and Data Engineering
The Case for Enhanced Abstract Data Types
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
What Do Those Weird XML Types Want, Anyway?
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
How to Make SQL Stand for String Query Language
DBPL '99 Revised Papers from the 7th International Workshop on Database Programming Languages: Research Issues in Structured and Semistructured Database Programming
DBPL '01 Revised Papers from the 8th International Workshop on Database Programming Languages
MIL primitives for querying a fragmented world
The VLDB Journal — The International Journal on Very Large Data Bases
Enhanced abstract data types in object-relational databases
The VLDB Journal — The International Journal on Very Large Data Bases
Design and implementation of a string database query language
Information Systems - Special issue: Data management in bioinformatics
DUMAX: a dual mode algebra for XML queries
Proceedings of the 2nd international conference on Scalable information systems
Safety, translation and evaluation of alignment calculus
ADBIS'97 Proceedings of the First East-European conference on Advances in Databases and Information systems
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Relational database systems and most object-oriented database systems provide support for queries. Usually these queries represent retrievals over sets or multisets. Many new applications for databases, such as multimedia systems and digital libraries, need support for queries on complex bulk types such as lists and trees. In this paper we describe an object-oriented query algebra called AQUA (= A Query Algebra) for lists and trees. The operators in the algebra preserve the ordering between the elements of a list or tree, even when the result list or tree contains an arbitrary set of nodes from the original tree. We also present predicate languages for lists and trees which allow order-sensitive queries because they use pattern matching to examine groups of list or tree nodes rather than individual nodes. The ability to decompose predicate patterns enables optimizations that make use of indices.