Esc: An Early-stopping Checker for Budget-aware Index Tuning

TL;DR

This paper introduces Esc, an early-stopping checker for budget-aware index tuning that reduces the number of costly optimizer calls by stopping the process when the projected index quality loss is within a user-defined threshold, without sacrificing much accuracy.

Contribution

The paper proposes Esc, a low-overhead early-stopping mechanism that improves budget-aware index tuning efficiency by predicting when to stop tuning based on quality loss thresholds.

Findings

Esc significantly reduces the number of optimizer calls.

It maintains index quality with minimal overhead.

Experimental results show effectiveness on industrial benchmarks.

Abstract

Index tuning is a time-consuming process. One major performance bottleneck in existing index tuning systems is the large amount of "what-if" query optimizer calls that estimate the cost of a given pair of query and index configuration without materializing the indexes. There has been recent work on budget-aware index tuning that limits the amount of what-if calls allowed in index tuning. Existing budget-aware index tuning algorithms, however, typically make fast progress early on in terms of the best configuration found but slow down when more and more what-if calls are allocated. This observation of "diminishing return" on index quality leads us to introduce early stopping for budget-aware index tuning, where user specifies a threshold on the tolerable loss of index quality and we stop index tuning if the projected loss with the remaining budget is below the threshold. We further propose Esc, a low-overhead early-stopping checker that realizes this new functionality. Experimental evaluation on top of both industrial benchmarks and real customer workloads demonstrate that Esc can significantly reduce the number of what-if calls made during budget-aware index tuning while incur little or zero improvement loss and little extra computational overhead compared to the overall index tuning time.