In many places that I have worked we use databases, sometimes we have an official database administrator, sometimes it’s been the server admin who has learned how to manage the database on the job. Either way, in very few places has anyone really understood database indexes very well and even where someone understood, they rarely talked to the people who needed the information. I found a good online presentation which made things very clear for me about what indexes should be set up and how they should be set up.
The biggest revelation for me is that the indexes are really there to support the queries. Previously I thought that indexes are important and a few should be created based on single fields, but I now know that it’s not the right way to do it.