EXPLAIN Yourself! Finding Query Planner Stalls Across DBMSes

Geoffrey X. Yu, Ryan Marcus, Tim Kraska. 2026.

What this paper does with SQLancer

SQLancer's work is the related-work ground this paper stands on, and all seven of its oracle papers are cited: CERT, QPG and DQP as the performance-bug line, and NoREC, TLP, PQS and CODDTest as the correctness line whose query-pair approach it describes as similar in kind to performance bug finding. CERT is the one drawn on in detail -- the paper restates its principle, that making a query more restrictive should not raise the output cardinality estimate. Every mention is reached through a citation marker; the paper never writes the name SQLancer. This paper looks for query planner stalls -- cases where planning a query takes disproportionately long, before any of it is executed. Because planning cost is visible through EXPLAIN without running the query, the same probe works across DBMSes, which is what lets the study span several systems rather than instrumenting one. Written by claude-opus-5 from the 3 places this paper refers to SQLancer. The quotations below are the paper's own words, stored verbatim when the text was extracted.

How it was classified

uses infrastructure — no

Nothing describes reuse of SQLancer's code, generator or workload; planner stalls are measured through EXPLAIN.

extends technique — no

The paper measures planning cost rather than developing an oracle. M2 restates CERT's principle as background, not as something generalised.

compares with — no

The seven papers are cited as related work. No run of SQLancer or any of its oracles against this tool is reported.

describes as state of the art — no

The techniques are described by what they do; no standing is claimed for any of them.

SQLancer publications it cites (7)

Bibliography entries that resolved to a SQLancer publication, or to a paper by one of the project's authors. A sentence citing one of these numbers is a reference to SQLancer even when it never writes the name.

#	Entry	Matched as
3	Jinsheng Ba and Manuel Rigger. 2023. Testing Database Engines via Query Plan Guidance. In The 45th International Conference on Software Engineering (ICSE’23).	sqlancer publication · QPG
4	Jinsheng Ba and Manuel Rigger. 2024. CERT: Finding Performance Issues in Database Systems Through the Lens of Cardinality Estimation. In The 46th International Conference on Software Engineering (ICSE’24).	sqlancer publication · CERT
5	Jinsheng Ba and Manuel Rigger. 2024. Keep It Simple: Testing Databases via Differential Query Plans. Proceeding of ACM Management of Data (SIGMOD’24) (June 2024).	sqlancer publication · DQP
27	Manuel Rigger and Zhendong Su. 2020. Detecting Optimization Bugs in Database Engines via Non-Optimizing Reference Engine Construction. In Proceedings of the 2020 28th ACM Joint Meeting on European Software Engineering...	sqlancer publication · NOREC
28	Manuel Rigger and Zhendong Su. 2020. Finding Bugs in Database Systems via Query Partitioning. Proc. ACM Program. Lang. 4, OOPSLA, Article 211 (2020). doi:10.1145/3428279	sqlancer publication · TLP
29	Manuel Rigger and Zhendong Su. 2020. Testing Database Engines via Pivoted Query Synthesis. In 14th USENIX Symposium on Operating Systems Design and Implementation (OSDI ’20). USENIX Association, Banff, Alberta. https:...	sqlancer publication · PQS
40	Chi Zhang and Manuel Rigger. 2025. Constant Optimization Driven Database System Testing. 2025), 24 pages. doi:10.1145/3709674	sqlancer publication · CODDTEST

Every place it refers to SQLancer (3)

3 sentences, each stored verbatim from the extracted text with where it was found and how. “Citation marker” means the sentence names no tool at all and was reached through a reference number that resolved to a SQLancer publication.

Id	Sentence	Found by	Where
M1	Prior works propose techniques for finding query execution performance bugs in database systems [ 4,11,12,15,35,36].	citation marker background	4 Related Work page 6
M2	, making a query more restrictive should result in an output cardinality estimate no larger than the original query [ 4]).	citation marker definition	4 Related Work page 6
M3	A complementary set of papers propose techniques to find correctness bugs in database systems [ 3,5,16,27–29,40], applying a similar approach grounded in query pairs as in performance bug finding.	citation marker background	4 Related Work page 6

This page is rendered from _data/papers/paper_arxiv_2608_23402.json, extracted from arxiv. 7 pages, 41 references parsed.