Unexpectedly slow performance with complex SQL query using multiple JOINs in SQL Server 2019
I can't seem to get This might be a silly question, but I tried several approaches but none seem to work... I have a complex SQL query that involves multiple JOINs across four tables, and I've noticed that it runs extremely slowly in SQL Server 2019. The query retrieves user activity logs along with user details and product information, but the execution time sometimes exceeds 30 seconds, which is unacceptable for our application. I've already indexed the columns used in the WHERE clauses and the JOIN conditions, but I'm still facing performance issues. Here's the SQL query I'm using: ```sql SELECT u.id, u.username, p.product_name, COUNT(a.log_id) AS activity_count FROM users u JOIN activity_logs a ON u.id = a.user_id JOIN products p ON a.product_id = p.id WHERE a.activity_date BETWEEN '2023-01-01' AND '2023-12-31' GROUP BY u.id, u.username, p.product_name ORDER BY activity_count DESC; ``` When I run the query, I also get a warning stating: "Query is performing a full scan on table `activity_logs`. Consider using an index." I've tried adding indexes on `activity_date` and `user_id`, but it didn't seem to make a difference. I also checked the execution plan, and it shows that the query optimizer is choosing a suboptimal plan. The estimated number of rows for each join seems off, which might be contributing to the slowness. I've even tried using `OPTION (RECOMPILE)` to see if that helps, but the performance still isn't acceptable. Are there any best practices or specific optimizations I can apply to speed up this query? Should I consider breaking it down into smaller queries, or are there other indexing strategies I might be missing? I'm working on a API that needs to handle this. Any help would be greatly appreciated! Is there a better approach? I'm working on a service that needs to handle this. I'd really appreciate any guidance on this.