# Chapter 51. Overview of PostgreSQL Internals

Table of Contents

51.1. The Path of a Query

51.2. How Connections Are Established

51.3. The Parser Stage

51.3.1. Parser

51.3.2. Transformation Process

51.4. The PostgreSQL Rule System

51.5. Planner/Optimizer

51.5.1. Generating Possible Plans

51.6. Executor

# Author

This chapter originated as part of [sim98] Stefan Simkovics' Master's Thesis prepared at Vienna University of Technology under the direction of O.Univ.Prof.Dr. Georg Gottlob and Univ.Ass. Mag. Katrin Seyr.

This chapter gives an overview of the internal structure of the backend of PostgreSQL. After having read the following sections you should have an idea of how a query is processed. This chapter is intended to help the reader understand the general sequence of operations that occur within the backend from the point at which a query is received, to the point at which the results are returned to the client.