AutoCE: An Accurate and Efficient Model Advisor for Learned Cardinality Estimation

TL;DR

AutoCE is a learning-based model advisor that adaptively selects the most suitable cardinality estimation model for diverse datasets, significantly improving accuracy and efficiency in database query optimization.

Contribution

It introduces a novel deep metric learning approach with incremental learning for effective model selection across varied datasets.

Findings

AutoCE achieves 27% better performance in query optimization.

It outperforms baselines with 2.1x higher accuracy.

Demonstrates robustness and efficiency in PostgreSQL integration.

Abstract

Cardinality estimation (CE) plays a crucial role in many database-related tasks such as query generation, cost estimation, and join ordering. Lately, we have witnessed the emergence of numerous learned CE models. However, no single CE model is invincible when it comes to the datasets with various data distributions. To facilitate data-intensive applications with accurate and efficient cardinality estimation, it is important to have an approach that can judiciously and efficiently select the most suitable CE model for an arbitrary dataset. In this paper, we study a new problem of selecting the best CE models for a variety of datasets. This problem is rather challenging as it is hard to capture the relationship from various datasets to the performance of disparate models. To address this problem, we propose a model advisor, named AutoCE, which can adaptively select the best model for a dataset. The main contribution of AutoCE is the learning-based model selection, where deep metric learning is used to learn a recommendation model and incremental learning is proposed to reduce the labeling overhead and improve the model robustness. We have integrated AutoCE into PostgreSQL and evaluated its impact on query optimization. The results showed that AutoCE achieved the best performance (27% better) and outperformed the baselines concerning accuracy (2.1 times better) and efficacy (4.2 times better).