Anyone know of an in-depth guide for database indexing?

postgresql
rails

#1

I’ve been looking for an in-depth guide on database indexing that includes performance benchmarks and possibly anti-patterns.

Most guides stop short on comparing indexed vs non-indexes performance, but I’m looking for something more.

For example, I want to know the performance impact of multi-indexed columns vs single indexed. Or the performance impact of having 4 multi-indexed columns. Or the performance impact on writes from having too many indexes. Etc.

So far, I’ve been making the measurements myself, but I’d love to see if there’s something out there I can compare my results to.