A Proof Procedure for Data Dependencies
Journal of the ACM (JACM)
Graph minors. V. Excluding a planar graph
Journal of Combinatorial Theory Series B
The monadic second-order logic of graphs. I. recognizable sets of finite graphs
Information and Computation
Easy problems for tree-decomposable graphs
Journal of Algorithms
On the estimation of join result sizes
EDBT '94 Proceedings of the 4th international conference on extending database technology: Advances in database technology
Answering queries using views (extended abstract)
PODS '95 Proceedings of the fourteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Selectivity and cost estimation for joins based on random sampling
Journal of Computer and System Sciences
An overview of query optimization in relational systems
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
All structured programs have small tree width and good register allocation
Information and Computation
The theory of joins in relational databases
ACM Transactions on Database Systems (TODS)
Testing implications of data dependencies
ACM Transactions on Database Systems (TODS)
Query Optimization in Database Systems
ACM Computing Surveys (CSUR)
Communications of the ACM
Data integration: a theoretical perspective
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Query evaluation via tree-decompositions
Journal of the ACM (JACM)
Data Exchange: Semantics and Query Answering
ICDT '03 Proceedings of the 9th International Conference on Database Theory
Random Sampling from Database Files: A Survey
Proceedings of the 5th International Conference SSDBM on Statistical and Scientific Database Management
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
Schema mappings, data exchange, and metadata management
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Constraint solving via fractional edge covers
SODA '06 Proceedings of the seventeenth annual ACM-SIAM symposium on Discrete algorithm
Query reformulation with constraints
ACM SIGMOD Record
A logical approach to multicut problems
Information Processing Letters
Information Theory and Network Coding
Information Theory and Network Coding
Size Bounds and Query Plans for Relational Joins
FOCS '08 Proceedings of the 2008 49th Annual IEEE Symposium on Foundations of Computer Science
Size and treewidth bounds for conjunctive queries
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Efficient datalog abduction through bounded treewidth
AAAI'07 Proceedings of the 22nd national conference on Artificial intelligence - Volume 2
A non-Shannon-type conditional inequality of information quantities
IEEE Transactions on Information Theory
On characterization of entropy function via information inequalities
IEEE Transactions on Information Theory
Two Constructions on Limits of Entropy Functions
IEEE Transactions on Information Theory
Networks, Matroids, and Non-Shannon Information Inequalities
IEEE Transactions on Information Theory
Skew strikes back: new developments in the theory of join algorithms
ACM SIGMOD Record
Hi-index | 0.00 |
This article provides new worst-case bounds for the size and treewith of the result Q(D) of a conjunctive query Q applied to a database D. We derive bounds for the result size |Q(D)| in terms of structural properties of Q, both in the absence and in the presence of keys and functional dependencies. These bounds are based on a novel “coloring” of the query variables that associates a coloring number C(Q) to each query Q. Intuitively, each color used represents some possible entropy of that variable. Using this coloring number, we derive tight bounds for the size of Q(D) in case (i) no functional dependencies or keys are specified, and (ii) simple functional dependencies (keys) are given. These results generalize recent size-bounds for join queries obtained by Atserias et al. [2008]. In the case of arbitrary (compound) functional dependencies, we use tools from information theory to provide lower and upper bounds, establishing a close connection between size bounds and a basic question in information theory. Our new coloring scheme also allows us to precisely characterize (both in the absence of keys and with simple keys) the treewidth-preserving queries---the queries for which the treewidth of the output relation is bounded by a function of the treewidth of the input database. Finally, we give some results on the computational complexity of determining the size bounds, and of deciding whether the treewidth is preserved.