https://tech.daniellbastos.com.br/tags/nested-queries/Recent content in Nested Queries on Daniel's Tech BlogHugoen-usSun, 19 Apr 2026 00:00:00 +0000https://tech.daniellbastos.com.br/posts/chapter-6-nested-queries/Sun, 19 Apr 2026 00:00:00 +0000https://tech.daniellbastos.com.br/posts/chapter-6-nested-queries/<blockquote> <p>This post closes the study of <a href="https://courses.cs.duke.edu/compsci516/cps216/spring03/papers/selinger-etal-1979.pdf">Access Path Selection in a Relational Database Management System (Selinger et al., 1979)</a>, covering chapters 6 and 7. I used available internet resources and tools to go deeper on the examples and make the concepts more concrete.</p> </blockquote> <h2 id="what-chapters-6-and-7-cover">What chapters 6 and 7 cover</h2> <p>Chapter 6 describes how the optimizer handles nested queries, which are queries that contain a subquery as a predicate operand. The chapter’s central distinction is whether the subquery references a column from the outer query. That single property determines how many times the subquery runs.</p>