Incomplete Information in Relational Databases
Journal of the ACM (JACM)
Implementing imprecision in information systems
Information Sciences: an International Journal - Special issue on expert systems
Optimization of nested SQL queries revisited
SIGMOD '87 Proceedings of the 1987 ACM SIGMOD international conference on Management of data
Fuzzy querying with SQL: extensions and implementation aspects
Fuzzy Sets and Systems - Mathematical Modelling
An extended version of the fuzzy relational database model
Information Sciences: an International Journal
Aggregates in possibilistic databases
VLDB '89 Proceedings of the 15th international conference on Very large data bases
FastSort: a distributed single-input single-output external sort
SIGMOD '90 Proceedings of the 1990 ACM SIGMOD international conference on Management of data
Measuring properties of fuzzy sets: a general technique and its use in fuzzy query evaluation
Fuzzy Sets and Systems - On fuzzy information and database systems
A fuzzy Prolog database system
A fuzzy Prolog database system
On the representation and querying of sets of possible worlds
Selected papers of the workshop on Deductive database theory
Query optimisation in distributed object-oriented database systems
The Computer Journal - Special issue on database programming paradigms
Query evaluation techniques for large databases
ACM Computing Surveys (CSUR)
Fuzzy relational algebra for possibility-distribution-fuzzy-relational model of fuzzy data
Journal of Intelligent Information Systems
On optimizing an SQL-like nested query
ACM Transactions on Database Systems (TODS)
Extending the database relational model to capture more meaning
ACM Transactions on Database Systems (TODS)
Principles and Applications
An Efficient Evaluation of a Fuzzy Equi-Join Using Fuzzy Equality Indicators
IEEE Transactions on Knowledge and Data Engineering
The Adaptive-Hash Join Algorithm for a Hypercube Multicomputer
IEEE Transactions on Parallel and Distributed Systems
Efficient Evaluation of the Valid-Time Natural Join
Proceedings of the Tenth International Conference on Data Engineering
Design, Implementation and Evaluation of SCORE (a System for COntent based REtrieval of Pictures)
ICDE '95 Proceedings of the Eleventh International Conference on Data Engineering
Extending the Algebraic Framework of Query Processing to Handle Outerjoins
VLDB '84 Proceedings of the 10th International Conference on Very Large Data Bases
Optimization of Nested Queries in a Distributed Relational Database
VLDB '84 Proceedings of the 10th International Conference on Very Large Data Bases
VLDB '87 Proceedings of the 13th International Conference on Very Large Data Bases
An Evaluation of Non-Equijoin Algorithms
VLDB '91 Proceedings of the 17th International Conference on Very Large Data Bases
Improved Unnesting Algorithms for Join Aggregate SQL Queries
VLDB '92 Proceedings of the 18th International Conference on Very Large Data Bases
ACM SIGMOD Record
SQLf: a relational database language for fuzzy querying
IEEE Transactions on Fuzzy Systems
Managing Uncertainties in Image Databases: A Fuzzy Approach
Multimedia Tools and Applications
Rewriting Rules To Permeate Complex Similarity and Fuzzy Queries within a Relational Database System
IEEE Transactions on Knowledge and Data Engineering
Maintaining consistency of vague databases using data dependencies
Data & Knowledge Engineering
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In a fuzzy relational database where a relation is a fuzzy set of tuples and ill-known data are represented by possibility distributions, nested fuzzy queries can be expressed in the Fuzzy SQL language. Although it provides a very convenient way for users to express complex queries, a nested fuzzy query may be very inefficient to process with the naive evaluation method based on its semantics. In conventional databases, nested queries are unnested to improve the efficiency of their evaluation. In this paper, we extend the unnesting techniques to process several types of nested fuzzy queries. An extended merge-join is used to evaluate the unnested fuzzy queries. As shown by both theoretical analysis and experimental results, the unnesting techniques with the extended merge-join significantly improve the performance of evaluating nested fuzzy queries.