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Cardinality estimation has long been grounded in statistical tools for density estimation. To capture the rich multivariate distributions of relational tables, we propose the use of a new type of high-capacity statistical model: deep…

Cardinality estimation is a key component of database query optimization. Recent studies have demonstrated that learned cardinality estimation techniques can surpass traditional methods in accuracy. However, a significant barrier to their…

Databases · Computer Science 2025-12-30 Lyu Yi , Weiqi Feng , Yuanbiao Wang , Yuhong Kan

We introduce Deep Sketches, which are compact models of databases that allow us to estimate the result sizes of SQL queries. Deep Sketches are powered by a new deep learning approach to cardinality estimation that can capture correlations…

Cardinality estimation (CardEst) still remains a challenging problem for DBMS. Recent years have witnessed the success of ML-based cardinality estimators in outperforming traditional methods. However, these solutions suffer from poor…

Databases · Computer Science 2026-03-31 Liangzu Liu , Yiyan Wang , Yinjun Wu , Runze Su , Zhuo Chang , Peizhi Wu , Jianjun Chen , Fuxin Jiang , Rui Shi , Bin Cui , Tieying Zhang

We present FasCo, a simple yet effective learning-based estimator for the cost of executing a database query plan. FasCo uses significantly shorter training time and a lower inference cost than the state-of-the-art approaches, while…

Databases · Computer Science 2023-03-22 Weiping Yu , Siqiang Luo

Cardinality estimation is one of the most fundamental and challenging problems in query optimization. Neither classical nor learning-based methods yield satisfactory performance when estimating the cardinality of the join queries. They…

Databases · Computer Science 2022-12-13 Ziniu Wu , Parimarjan Negi , Mohammad Alizadeh , Tim Kraska , Samuel Madden

Cardinality estimation (CardEst) is a critical aspect of query optimization. Traditionally, it leverages statistics built directly over the data. However, organizational policies (e.g., regulatory compliance) may restrict global data…

Databases · Computer Science 2025-06-23 Peizhi Wu , Rong Kang , Tieying Zhang , Jianjun Chen , Ryan Marcus , Zachary G. Ives

The containment rate of query Q1 in query Q2 over database D is the percentage of Q1's result tuples over D that are also in Q2's result over D. We directly estimate containment rates between pairs of queries over a specific database. For…

Databases · Computer Science 2019-08-22 Rojeh Hayek , Oded Shmueli

Cardinality estimation is a fundamental functionality in database systems. Most existing cardinality estimators focus on handling predicates over numeric or categorical data. They have largely omitted an important data type, set-valued…

Databases · Computer Science 2025-03-20 Yufan Sheng , Xin Cao , Kaiqi Zhao , Yixiang Fang , Jianzhong Qi , Wenjie Zhang , Christian S. Jensen

Estimating the cardinality of the output of a query is a fundamental problem in database query processing. In this article, we overview a recently published contribution that casts the cardinality estimation problem as linear optimization…

Databases · Computer Science 2025-05-13 Mahmoud Abo Khamis , Vasileios Nakos , Dan Olteanu , Dan Suciu

Traditional query optimization relies on cost-based optimizers that estimate execution cost (e.g., runtime, memory, and I/O) using predefined heuristics and statistical models. Improving these heuristics requires substantial engineering…

Databases · Computer Science 2026-02-12 Mehmet Hamza Erol , Xiangpeng Hao , Federico Bianchi , Ciro Greco , Jacopo Tagliabue , James Zou

Join ordering is a key factor in query performance, yet traditional cost-based optimizers often produce sub-optimal plans due to inaccurate cardinality estimates in multi-predicate, multi-join queries. Existing alternatives such as…

Databases · Computer Science 2025-08-26 David Justen , Matthias Boehm

In query optimisation accurate cardinality estimation is essential for finding optimal query plans. It is especially challenging for RDF due to the lack of explicit schema and the excessive occurrence of joins in RDF queries. Existing…

Databases · Computer Science 2018-01-22 Xin Wang , Eugene Siow , Aastha Madaan , Thanassis Tiropanis

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…

Databases · Computer Science 2024-09-25 Jintao Zhang , Chao Zhang , Guoliang Li , Chengliang Chai

Cardinality estimation has long been crucial for cost-based database optimizers in identifying optimal query execution plans, attracting significant attention over the past decades. While recent advancements have significantly improved the…

Databases · Computer Science 2025-10-20 Renrui Li , Qingzhi Ma , Jiajie Xu , Lei Zhao , An Liu

Query optimizer is at the heart of the database systems. Cost-based optimizer studied in this paper is adopted in almost all current database systems. A cost-based optimizer introduces a plan enumeration algorithm to find a (sub)plan, and…

Databases · Computer Science 2021-01-06 Hai Lan , Zhifeng Bao , Yuwei Peng

Cardinality estimation is the problem of estimating the size of the output of a query, without actually evaluating the query. The cardinality estimator is a critical piece of a query optimizer, and is often the main culprit when the…

Databases · Computer Science 2025-02-11 Haozhe Zhang , Christoph Mayer , Mahmoud Abo Khamis , Dan Olteanu , Dan Suciu

Cardinality estimation (CE), the task of predicting the result size of queries is a critical component of query optimization. Accurate estimates are essential for generating efficient query execution plans. Recently, machine learning…

Databases · Computer Science 2025-12-16 Lankadinee Rathuwadu , Guanli Liu , Christopher Leckie , Renata Borovica-Gajic

Learned cardinality estimation methods have achieved high precision compared to traditional methods. Among learned methods, query-driven approaches have faced the workload drift problem for a long time. Although both data-driven and hybrid…

Databases · Computer Science 2023-12-04 Kaixin Zhang , Hongzhi Wang , Yabin Lu , Ziqi Li , Chang Shu , Yu Yan , Donghua Yang

Despite of decades of work, query optimizers still make mistakes on "difficult" queries because of bad cardinality estimates, often due to the interaction of multiple predicates and correlations in the data. In this paper, we propose a…

Databases · Computer Science 2016-01-22 Wentao Wu , Jeffrey F. Naughton , Harneet Singh