On the optimal nesting order for computing N-relational joins
ACM Transactions on Database Systems (TODS)
Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
On the Complexity of Distributed Query Optimization
IEEE Transactions on Knowledge and Data Engineering
On the Complexity of Generating Optimal Left-Deep Processing Trees with Cross Products
ICDT '95 Proceedings of the 5th International Conference on Database Theory
Optimization of Nonrecursive Queries
VLDB '86 Proceedings of the 12th International Conference on Very Large Data Bases
Synopses for query optimization: a space-complexity perspective
PODS '04 Proceedings of the twenty-third ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Synopses for query optimization: A space-complexity perspective
ACM Transactions on Database Systems (TODS) - Special Issue: SIGMOD/PODS 2004
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In this work, we study the complexity of the problem of approximate query optimization. We show that, for any δ 0, the problem of finding a join order sequence whose cost is within a factor 2Θ(log1-δ(K)) of K, where K is the cost of the optimal join order sequence is NP-Hard. The complexity gap remains if the number of edges in the query graph is constrained to be a given function e(n) of the number of vertices n of the query graph, where n(n - 1)/2 - Θ(nτ) ≥ e(n) ≥ n + Θ(nτ) and τ is any constant between 0 and 1. These results show that, unless P=NP, the query optimization problem cannot be approximately solved by an algorithm that runs in polynomial time and has a competitive ratio that is within some polylogarithmic factor of the optimal cost.