Efficient distributed query processing for autonomous RDF databases
Proceedings of the 15th International Conference on Extending Database Technology
Opening the black boxes in data flow optimization
Proceedings of the VLDB Endowment
On the correct and complete enumeration of the core search space
Proceedings of the 2013 ACM SIGMOD International Conference on Management of Data
Using similarity distance for performance prediction of the query optimization process
Proceedings of the Sixth International Workshop on Testing Database Systems
Counter strike: generic top-down join enumeration for hypergraphs
Proceedings of the VLDB Endowment
| Hi-index | 0.00 |
Finding an optimal execution order of join operations is a crucial task in every cost-based query optimizer. Since there are many possible join trees for a given query, the overhead of the join (tree) enumeration algorithm per valid join tree should be minimal. In the case of a clique-shaped query graph, the best known top-down algorithm has a complexity of Θ(n2) per join tree, where n is the number of relations. In this paper, we present an algorithm that has an according O(1) complexity in this case. We show experimentally that this more theoretical result has indeed a high impact on the performance in other non-clique settings. This is especially true for cyclic query graphs. Further, we evaluate the performance of our new algorithm and compare it with the best top-down and bottom-up algorithms described in the literature.