LEO - DB2's LEarning Optimizer

Summary: LEO, DB2's LEarning Optimizer, uses a feedback loop to repair cardinality estimates by comparing forecasts with actuals at each QEP step. Online or offline, incremental or batched, it updates costs and statistics across operators (joins, DISTINCT, GROUP BY) with low overhead and large potential gains. (summarized by gpt-5-nano on Feb 09 2026)

Paper ID: 8726
Venue: VLDB
Year: 2001
Pagerank: 0.00036962631
Overall Rank: 182 | 98.74%
DOI: -

Incoming Non-self Citations Over Time

Authors

Incoming Citations (Sorted by Pagerank)

Showing 22 of 122 citing papers.

Rank	Citing Paper	Year	Venue	Pagerank
8,956	T3: Accurate and Fast Performance Prediction for Relational Database Systems With Compiled Decision Trees	2025	SIGMOD	4.4214154e-05
9,187	POLAR: Adaptive and Non-invasive Join Order Selection via Plans of Least Resistance	2024	VLDB	4.3780059e-05
9,299	Engineering High-Performance Database Engines	2014	VLDB	4.3587894e-05
9,524	Detecting Attribute Dependencies from Query Feedback	2007	VLDB	4.3310217e-05
9,587	Low Rank Learning for Offline Query Optimization	2025	SIGMOD	4.3215645e-05
9,662	Efficient Query Re-optimization with Judicious Subquery Selections	2023	SIGMOD	4.3097631e-05
9,691	Selectivity Estimation for Queries Containing Predicates over Set-Valued Attributes	2023	SIGMOD	4.3035354e-05
9,693	ROME: Robust Query Optimization via Parallel Multi-Plan Execution	2024	SIGMOD	4.3027391e-05
9,747	Still Asking: How Good Are Query Optimizers, Really?	2025	VLDB	4.2897489e-05
9,812	A Practical Theory of Generalization in Selectivity Learning	2025	VLDB	4.2783272e-05
9,823	Thriving in the No Man’s Land between Compilers and Databases	2019	CIDR	4.2754485e-05
9,825	Athena: An Effective Learning-based Framework for Query Optimizer Performance Improvement	2025	SIGMOD	4.2751057e-05
9,869	Turbo-Charging SPJ Query Plans with Learned Physical Join Operator Selections	2022	VLDB	4.2675361e-05
9,878	PRICE: A Pretrained Model for Cross-Database Cardinality Estimation	2025	VLDB	4.2656547e-05
10,619	Data-Agnostic Cardinality Learning from Imperfect Workloads	2025	VLDB	4.1945683e-05
11,267	Anser: Adaptive Information Sharing Framework of AnalyticDB	2023	VLDB	4.1945683e-05
11,897	Capturing the Laws of (Data) Nature	2015	CIDR	4.1945683e-05
12,056	DBMS Metrology: Measuring Query Time	2013	SIGMOD	4.1945683e-05
12,291	Visualizing the robustness of query execution	2009	CIDR	4.1945683e-05
12,636	Adaptive Distributed Query Processing	2003	VLDB	4.1945683e-05
12,653	SMART: Making DB2 (More) Autonomic	2002	VLDB	4.1945683e-05
13,656	Automated Statistics Collection in Action	2005	SIGMOD	-

Outgoing Citations (Sorted by Pagerank)

Showing 11 of 11 cited papers.

Citations counted here include only citations to other VLDB/SIGMOD/CIDR/PODS papers in this database.

Rank	Cited Paper	Year	Venue	Pagerank
1	Access Path Selection in a Relational Database Management System	1979	SIGMOD	0.0040449103
64	Improved Histograms for Selectivity Estimation of Range Predicates	1996	SIGMOD	0.00063612837
99	On the Propagation of Errors in the Size of Join Results	1991	SIGMOD	0.00050022914
141	Selectivity Estimation Without the Attribute Value Independence Assumption	1997	VLDB	0.00041786333
220	Efficient Mid-Query Re-Optimization of Sub-Optimal Query Execution Plans	1998	SIGMOD	0.00033194808
252	Adaptive Selectivity Estimation Using Query Feedback	1994	SIGMOD	0.00030632263
269	Fast Incremental Maintenance of Approximate Histograms	1997	VLDB	0.00029656549
456	Cost-based Query Scrambling for Initial Delays	1998	SIGMOD	0.00022717134
529	Self-tuning Histograms: Building Histograms Without Looking at Data	1999	SIGMOD	0.00020828852
897	Selectivity Estimation and Query Optimization in Large Databases with Highly Skewed Distributions of Column Values	1988	VLDB	0.00015528028
3,053	Multiple Join Size Estimation by Virtual Domains (extended abstract)	1993	PODS	7.64969e-05

Semantically Similar Papers

Overall Rank	Paper	Year	Venue	Pagerank
1,272	Proactive Re-Optimization	2005	SIGMOD	0.00012920076
1,758	Sampling-Based Query Re-Optimization	2016	SIGMOD	0.00010655546
7,330	Lemo: A Cache-Enhanced Learned Optimizer for Concurrent Queries	2023	SIGMOD	4.7609373e-05
333	Neo: A Learned Query Optimizer	2019	VLDB	0.00027206884
7,221	Speeding Up End-to-end Query Execution via Learning-based Progressive Cardinality Estimation	2023	SIGMOD	4.797194e-05
11,350	DeepO: A Learned Query Optimizer	2022	SIGMOD	4.1945683e-05
5,334	LEON: A New Framework for ML-Aided Query Optimization	2023	VLDB	5.5649836e-05
10,225	LIO: A lightweight and interpretable query optimizer based on an evolutionary forest	2026	VLDB	4.1945683e-05
3,348	Lero: A Learning-to-Rank Query Optimizer	2023	VLDB	7.1904529e-05
8,113	Learning Table Access Cardinalities with LEO	2002	SIGMOD	4.5826944e-05