Sep 26, 2023 · Databases

Why PostgreSQL Shows InitPlan and One‑Time Filter in Self‑Join Queries

This article walks through a puzzling PostgreSQL self‑join query, shows how different alias placements change the execution plan, explains the meaning of InitPlan and One‑Time Filter nodes, and demonstrates their impact with concrete examples and EXPLAIN output.

InitPlanOne-Time FilterPostgreSQL

0 likes · 11 min read

Why PostgreSQL Shows InitPlan and One‑Time Filter in Self‑Join Queries

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Aug 13, 2023 · Databases

Why Does This PostgreSQL Self‑Join Behave Unexpectedly? InitPlan & One‑Time Filter

The article examines a puzzling PostgreSQL self‑join query that yields surprising true/false results, walks through step‑by‑step rewrites, analyzes the resulting execution plans—including the appearance of InitPlan and One‑Time Filter nodes—and explains how correlated versus uncorrelated subqueries affect query evaluation.

InitPlanPostgreSQLSQL

0 likes · 11 min read

Why Does This PostgreSQL Self‑Join Behave Unexpectedly? InitPlan & One‑Time Filter