Adding the index may be physically hard because it takes a while and steals resources from your server. But cognitively, it is easy - find the query that is slo

Adding the index may be physically hard because it takes a while and steals resources from your server. But cognitively, it is easy - find the query that is slow and add the index to make it fast. It's usually very obvious from the query what index you need to add Deleting an index might be physically easy to do. But figuring out if it's safe to do is hard. You have to inspect every query you make and make sure none need that index. Once the index is there, in practice it's usually there forever.