In this paper, we discuss a novel technique for processing correlated subqueries in SQL. The core idea is to isolate the non-correlated part of the predicate and use it to reduce the number of evaluations of the correlated part. We target a specific class of queries for which we propose a potential rewrite and discuss the conditions under which it is advantageous. Next, we address the evaluation aspects of the proposed rewrites: 1) we describe our approach to adapting the block-based Volcano query processing model, and 2) we discuss the benefits of implementing that technique within a position-enabled column-store with late materialization support. Our evaluation has a quantitative part and a qualitative part. The former focuses on studying the impact of non-correlated predicate selectivity on our technique. The latter identifies the limitations of our approach by comparing it with alternative approaches available in existing systems. Overall, experiments conducted using PosDB (a position-enabled column-store) and PostgreSQL demonstrated that, under suitable conditions, our technique can achieve a 5× improvement.
Original languageEnglish
Title of host publicationModel and Data Engineering (MEDI 2025)
PublisherSpringer Nature
Pages160-167
Number of pages8
ISBN (Electronic)978-3-032-19865-5
ISBN (Print)978-3-032-19864-8
DOIs
StatePublished - 1 May 2026
Event14th International Conference on Model and Data Engineering (MEDI 2025) - ElSewedy University of Technology, Kilo 51, Cairo-Ismailia Road, Egypt, Каир, Egypt
Duration: 2 Nov 20254 Nov 2025
https://medi2025.sut.edu.eg/

Publication series

NameLecture Notes in Computer Science
Volume16427 LNCS

Conference

Conference14th International Conference on Model and Data Engineering (MEDI 2025)
Abbreviated titleMEDI 2025
Country/TerritoryEgypt
CityКаир
Period2/11/254/11/25
Internet address

    Scopus subject areas

  • Information Systems

    Research areas

  • Query Processing, Column-stores, Subquery Processing, Late Materialization, PosDB

ID: 154169087