>> The performance cost of an extra index for insert/update/delete queries is only a concern when you get to the point where you do need to manually manage inde

>> The performance cost of an extra index for insert/update/delete queries is only a concern when you get to the point where you do need to manually manage indexes - but for most database tables with less a few million rows there’s no reason for the server not to automatically add indexes on columns used in predicates. It won’t be perfect, but it’s better than allowing slow queries to always be slow. You'd be surprised. The thing that really drives index explosion is the number of distinct queries. IME, inspecting and reducing distinct queries is one of the easiest ways to optimize and it can typically be automated. I've migrated systems from millions of distinct queries down to hundreds or dozens. However the objective of the optimization is typically driven by requirements external to the database and may vary over time. Thus difficult to align with an optimizer.