PostgreSQL 14: advanced patterns with CTEs and Recursive Queries Leading to Infinite Loop
This might be a silly question, but I'm working with PostgreSQL 14 and trying to implement a recursive Common Table Expression (CTE) to traverse a hierarchical dataset. However, I'm experiencing unexpected behavior that seems to lead to an infinite loop. My CTE is meant to fetch employees and their direct reports from an `employees` table structured like this: ```sql CREATE TABLE employees ( id SERIAL PRIMARY KEY, name VARCHAR(100), manager_id INT REFERENCES employees(id) ); ``` I'm using the following query to get all employees under a specific manager recursively: ```sql WITH RECURSIVE employee_hierarchy AS ( SELECT id, name, manager_id FROM employees WHERE manager_id = 1 -- Starting from manager with ID 1 UNION ALL SELECT e.id, e.name, e.manager_id FROM employees e INNER JOIN employee_hierarchy eh ON e.manager_id = eh.id ) SELECT * FROM employee_hierarchy; ``` However, this query keeps running indefinitely and does not return any results. I've checked my data and there are no circular references in the `manager_id` column. I even tried limiting the depth of the recursion with an additional counter, but it didn't resolve the scenario. When I run this query without the recursion part, it correctly returns the direct reports for manager ID 1. It's only when I include the recursive section that it hangs. I also tried adding a `LIMIT` clause, but it still seems to get exploring. Has anyone encountered this scenario before, or does anyone have suggestions on how to troubleshoot this infinite loop with recursive CTEs in PostgreSQL? I'm working on a web app that needs to handle this. Has anyone dealt with something similar?