Aakar Sharma

You could have used explain format=json which would have given you more info something like this EXPLAIN: { "query_block": { "select_id": 1, "cost_info": { "query_cost": "16.72" }, "nested_loop": [ { "table": { "table_name": "departments", <skipped> }, { "table": { "table_name": "<subquery2>", "access_type": "eq_ref", "key": "<auto_key>", "key_length": "4", "ref": [ "employees.departments.dept_no" ], "rows_examined_per_scan": 1, "materialized_from_subquery": { "using_temporary_table": true, "query_block": { "table": { "table_name": "dept_manager", "access_type": "ALL", "possible_keys": [ "dept_no" ], "rows_examined_per_scan": 24, "rows_produced_per_join": 21, "filtered": "90.00", "cost_info": { "read_cost": "1.48", "eval_cost": "4.32", "prefix_cost": "5.80", "data_read_per_join": "345" }, "used_columns": [ "dept_no", "to_date" ], "attached_condition": "(`employees`.`dept_manager`.`to_date` is not null)" } } } } } ] } } This way few things could have been explain better.