PostgreSQL: Performance implementing Recursive CTEs in Large Data Sets
Hey everyone, I'm running into an issue that's driving me crazy... I'm reviewing some code and I'm updating my dependencies and I'm not sure how to approach This might be a silly question, but I'm experiencing important performance optimization when using a recursive Common Table Expression (CTE) in PostgreSQL 13... The CTE is intended to traverse a hierarchical structure, but as the data set grows (currently around 100,000 rows), the query execution time increases dramatically, sometimes taking minutes to complete. Here’s a simplified version of my CTE: ```sql WITH RECURSIVE my_hierarchy AS ( SELECT id, parent_id, name FROM my_table WHERE parent_id IS NULL UNION ALL SELECT t.id, t.parent_id, t.name FROM my_table t JOIN my_hierarchy mh ON t.parent_id = mh.id ) SELECT * FROM my_hierarchy; ``` I've already tried adding indexes on the `parent_id` and `id` columns, but it doesn't seem to make a important difference. I also considered using a different approach, such as materialized views, but that doesn't fit my use case as I need real-time data traversal. When I run the query, I often see the following execution plan: ``` Seq Scan on my_table (cost=0.00..123456.78 rows=100000 width=96) CTE my_hierarchy CTE Scan on my_hierarchy (cost=0.00..12.34 rows=1000 width=96) ``` I noticed that the execution plan shows a sequential scan, which I suspect is causing the inefficiency. Is there a more efficient way to handle large recursive queries in PostgreSQL? Could partitioning or other strategies help mitigate this performance scenario? Any advice or insights on optimizing recursive CTEs would be greatly appreciated! My development environment is Windows. I'm working in a macOS environment. Is there a simpler solution I'm overlooking? I recently upgraded to Sql latest. Hoping someone can shed some light on this. I'm using Sql 3.10 in this project. Is there a better approach?