MySQL 8.0: Performance implementing complex JOIN queries involving subqueries and large datasets
I'm performance testing and Hey everyone, I'm running into an issue that's driving me crazy..... I'm currently working with performance optimization with a series of complex JOIN queries in MySQL 8.0. My dataset consists of over 5 million records across multiple tables, and I'm trying to optimize my queries to reduce the execution time. For instance, I have a query that looks like this: ```sql SELECT a.*, b.column1, c.column2 FROM table_a AS a JOIN table_b AS b ON a.id = b.a_id JOIN (SELECT id, column2 FROM table_c WHERE column3 = 'value') AS c ON a.id = c.id WHERE b.column1 > 100; ``` This query takes about 15 seconds to execute, and I suspect that the subquery is causing a slowdown. I've tried adding indexes on `table_a.id`, `table_b.a_id`, and `table_c.id`, but the performance hasn't improved significantly. Additionally, I ran the query using the `EXPLAIN` command: ```sql EXPLAIN SELECT a.*, b.column1, c.column2 FROM table_a AS a JOIN table_b AS b ON a.id = b.a_id JOIN (SELECT id, column2 FROM table_c WHERE column3 = 'value') AS c ON a.id = c.id WHERE b.column1 > 100; ``` The output indicates that the `Using temporary; Using filesort` is in the Extra column, which I know is not ideal. I've also looked into query caching and tried enabling it, but it doesn't seem to help much with the execution time. Could anyone suggest effective strategies to optimize this query? Are there specific indexing strategies or query restructuring practices that might reduce the execution time? My development environment is Windows. Am I missing something obvious? I'm working on a CLI tool that needs to handle this. Is there a better approach? Is this even possible? Any ideas what could be causing this?