After digging into some important optimizations implemented into PostgreSQL, I want to shift your attention a bit more to execution plans. You have already seen some plans in this book. However, in order to make full use of plans, it is important to develop a systematic approach to reading this information. Reading plans systematically is exactly within the scope of this section.
Understanding execution plans
Approaching plans systematically
The first thing you have to know is that an EXPLAIN clause can do quite a lot for you and, I would highly recommend making full use of those features.
As many readers might already know, an EXPLAIN ANALYZE clause will execute the query and return the plan, including real runtime information...
