Does anyone have information on Oracle SQL-tuning?

Question

Oracle

Hello everyone,
Maybe someone has a set of links on the subject, it is possible in English, I found a lot of things to structure a bit difficult for now. First of all, the materiel is of interest - indexes, trees, partitioning, how connections, groupings, sortings occur in different conditions.
Thank you!

Answer 1

quest software sql optimizer
shows real examples on real queries, otherwise the way to the official documentation is better not