When comparing with ms-sql: Check how to get MySQL faster mysql ms-sql count_distinct (2000) | 89.00| 39.00| count_distinct_big (120) | 324.00| 121.00| count_distinct_group (1000) | 158.00| 107.00| count_distinct_group_on_key (1000) | 49.00| 17.00| count_distinct_group_on_key_parts (1| 157.00| 108.00| order_by_big (10) | 197.00| 89.00| order_by_big_key (10) | 170.00| 82.00| order_by_big_key2 (10) | 163.00| 73.00| order_by_big_key_desc (10) | 172.00| 84.00| order_by_big_key_diff (10) | 193.00| 89.00| order_by_big_key_prefix (10) | 165.00| 72.00| Why is the following slow on NT: NT Linux update_of_primary_key_many_keys (256| 560.00| 65.00|