PostgreSQL: implementing Recursive CTE not Returning Expected Hierarchical Data
I just started working with Hey everyone, I'm running into an issue that's driving me crazy. I've been struggling with this for a few days now and could really use some help. I'm working with PostgreSQL 13.3 and trying to retrieve hierarchical data using a recursive Common Table Expression (CTE). My aim is to list all employees along with their direct and indirect subordinates in a company. However, the query doesn't seem to behave as expected. I'm getting results, but they don't include all levels of subordinates. Here's what I've tried: ```sql WITH RECURSIVE employee_hierarchy AS ( SELECT id, name, manager_id FROM employees WHERE manager_id IS NULL -- Start with top-level managers 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; ``` This should give me a complete list of employees starting from those with no manager (top-level) down to their subordinates. However, I notice that some employees who clearly have subordinates are missing from the result set. For instance, if Employee A manages Employees B and C, and C manages D, I expect to see a complete tree, but sometimes Employee A doesn't appear in the result, especially when certain attributes are NULL. I've checked for NULL values, and they seem to be correctly handled. Additionally, I've run the CTE with filtering only on certain departments, but the results still lack some expected entries. I've also tried rearranging the base query logic but without success. Can anyone point out what might be going wrong with my recursive CTE setup? Are there any known issues or particular nuances with using recursive CTEs in PostgreSQL that I might be overlooking? Any tips or insights would be greatly appreciated! I'm working on a API that needs to handle this. Any ideas what could be causing this? I'm working on a CLI tool that needs to handle this. I'd really appreciate any guidance on this. This is happening in both development and production on Ubuntu 20.04. Any ideas what could be causing this? For reference, this is a production web app.