  The knob tuning aims to optimize database performance by searching for the
most effective knob configuration under a certain workload. Existing works
suffer two significant problems. On the one hand, there exist multiple similar
even useless evaluations of knob tuning even with the diverse searching methods
because of the different sensitivities of knobs on a certain workload. On the
other hand, the single evaluation of knob configurations may bring
overestimation or underestimation because of the query uncertainty performance.
To solve the above problems, we propose a decoupled query uncertainty-aware
knob classifier, called KnobCF, to enhance the knob tuning. Our method has
three significant contributions: (1) We propose a novel concept of the
uncertainty-aware knob configuration estimation to enhance the knob tuning
process. (2) We provide an effective few-shot uncertainty knob estimator
without extra time consumption in training data collection, which has a high
time efficiency in practical tuning tasks. (3) Our method provides a general
framework that could be easily deployed in any knob tuning task because we make
no changes to the knob tuners and the database management system. Our
experiments on four open-source benchmarks demonstrate that our method
effectively reduces useless evaluations and improves the tuning results.
Especially in TPCC, our method achieves competitive tuning results with only
60% to 70% time consumption compared to the full workload evaluations.
