Optimal timeout growth factor

Determine the value of the timeout growth factor \(\theta>1\) that minimizes the total evaluation time of the generalized round-robin timeout mechanism for candidate query plans.

Background

The round-robin timeout mechanism increases its execution-time limit geometrically across rounds. The paper generalizes the doubling schedule to δr=θδr−1\delta_r=\theta\delta_{r-1} for any θ>1\theta>1, derives corresponding bounds on total evaluation time, and leaves the choice of the best growth factor unresolved.

References

It is an interesting question to select the $\theta$ that minimizes $T{\roundrobin}$, which we leave for future work.

— Query Performance Tuning with Optimal Exploration of Optimizer Cost Model Parameter Space  (2610.02607 - Wu et al., 2 Oct 2026) in Remark following Theorem 2.4, Section 3.1.1