Results 201 to 210 of about 327,421 (217)
Some of the next articles are maybe not open access.
Multiobjective query optimization
Proceedings of the twentieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems, 2001The optimization of queries in distributed database systems is known to be subject to delicate trade-offs. For example, the Mariposa database system allows users to specify a desired delay-cost tradeoff (that is, to supply a decreasing function u(d), specifying how much the user is willing to pay in order to receive the query results within time d ...
Christos H. Papadimitriou +1 more
openaire +2 more sources
Optimization of schemaSQL queries
Proceedings 2001 International Database Engineering and Applications Symposium, 2002We study the optimization of schemaSQL and schemaSQL-like languages. Our starting point is an extended relational algebra which can be used to implement schemaSQL and similar languages. We study transformation (rewrite) rules for the extended algebra which are used in a prototype cost-based optimizer for the rewriting of expressions into more efficient
K.B. Davis, F. Sadri
openaire +2 more sources
Query Optimization and Execution
2014SQL Server Query Processor is perhaps the least visible and least well-known part of SQL Server. It does not expose a large set of public features, and it allows very limited control in a documented and supported way. It accepts a query as input, compiles and optimizes it to generate the execution plan, and finally executes it.
openaire +2 more sources
Parallel SPARQL Query Optimization
2017 IEEE 33rd International Conference on Data Engineering (ICDE), 2017Existing parallel SPARQL query optimizers assume hash-based data partitioning and adopt plan enumeration algorithms with unnecessarily high complexity. Therefore, they cannot easily accommodate other partitioning methods and only consider an unnecessarily limited plan space.
Wu, Buwen +3 more
openaire +3 more sources
Query Evaluation and Optimization
2000Constraint Databases, Edité par G. Kuper, L.
Grumbach, Stéphane +3 more
openaire +3 more sources
2005
We propose and solve the optimal-location query in spatial databases. Given a set S of sites, a set O of weighted objects, and a spatial region Q, the optimal-location query returns a location in Q with maximum influence. Here the influence of a location l is the total weight of its RNNs, i.e.
Tian Xia, Donghui Zhang, Yang Du
openaire +2 more sources
We propose and solve the optimal-location query in spatial databases. Given a set S of sites, a set O of weighted objects, and a spatial region Q, the optimal-location query returns a location in Q with maximum influence. Here the influence of a location l is the total weight of its RNNs, i.e.
Tian Xia, Donghui Zhang, Yang Du
openaire +2 more sources
Journal of Algorithms, 1993
Abstract Let Γ0 be a set of n halfspaces in Ed (where the dimension d is fixed) and let m be a parameter, n ≤ m ≤ n⌊d/2⌋. We show that Γ0 can be preprocessed in time and space O(m1+δ) (for any fixed δ > 0) so that given a vector c ∈ Ed and another set Γq of additional halfspaces, the function c · x can be optimized over the intersection of the ...
openaire +2 more sources
Abstract Let Γ0 be a set of n halfspaces in Ed (where the dimension d is fixed) and let m be a parameter, n ≤ m ≤ n⌊d/2⌋. We show that Γ0 can be preprocessed in time and space O(m1+δ) (for any fixed δ > 0) so that given a vector c ∈ Ed and another set Γq of additional halfspaces, the function c · x can be optimized over the intersection of the ...
openaire +2 more sources
2006
Determining the best execution plan for a spatial query requires tools for measuring (more precisely, estimating) the number of (spatial) data items that are retrieved by a query as well as its cost, in terms of I/O and CPU effort. As in traditional databases, spatial query optimization tools include cost-based models, exploiting analytical formulae ...
Apostolos N. Papadopoulos +3 more
openaire +2 more sources
Determining the best execution plan for a spatial query requires tools for measuring (more precisely, estimating) the number of (spatial) data items that are retrieved by a query as well as its cost, in terms of I/O and CPU effort. As in traditional databases, spatial query optimization tools include cost-based models, exploiting analytical formulae ...
Apostolos N. Papadopoulos +3 more
openaire +2 more sources
Optimizing Phylogenetic Queries for Performance
IEEE/ACM Transactions on Computational Biology and Bioinformatics, 2018The vast majority of phylogenetic databases do not support declarative querying using which their contents can be flexibly and conveniently accessed and the template based query interfaces they support do not allow arbitrary speculative queries. They therefore also do not support query optimization leveraging unique phylogeny properties.
openaire +3 more sources
Configuring the Query Optimizer
2014The query optimizer is directly responsible for the performance of SQL statements. For this reason, it makes sense to take some time to configure it correctly. In fact, without an optimal configuration, the query optimizer may generate inefficient execution plans that lead to poor performance.
openaire +2 more sources