In PostgreSQL, indexing is a large field and covers many aspects of database work. As I have outlined in this book already, indexing is the key to performance. There is no good performance without proper indexing. Therefore, it is worth inspecting these indexing- related features in more detail.
Understanding additional b-tree features
Combined indexes
In my job, as a professional PostgreSQL support vendor, I am often asked about the difference between combined and individual indexes. In this section, I will try to shed some light on this question.
The general rule is this if a single index can answer your question, it is usually the best choice. However, you cannot index all possible combinations of fields people are filtering...
