Waiting for PostgreSQL 19 – Add pg_plan_advice contrib module.

This article discusses the new pg_plan_advice contrib module in PostgreSQL 19, committed by Robert Haas. It allows users to stabilize certain planner choices or force specific plan decisions, such as using a sequential scan over an index scan. The module works by analyzing a finished query plan to produce textual 'plan advice' that can be reused in future planning cycles. While powerful, it warns of potential misuse and harm if not carefully applied. The article covers the background, functionality, and controversy around constraining the planner's autonomy, focusing on technical details for database administrators and developers.