This book is divided into three parts. The first part of the book was designed as a guide to new PostgreSQL users. The middle section covered PostgreSQL programming. The third section is devoted to the topic of PostgreSQL administration. These three parts correspond to the real-world roles that we play when using PostgreSQL.
Users are concerned mostly with getting data into the database and getting it back out again. Programmers try to provide users with the functionality that they need. Administrators are responsible for ensuring that programmers and end-users can perform their jobs. Quite often, one person will fill two or three roles at the same time.
When you wear the hat of an administrator, you ensure that your users can store their data in a secure, reliable, high-availability, high-performance database.
Secure means that your data is safe from intruders. You must ensure that authorized users can do the things they need to do. You also need to ensure that users cannot gain access to data that they should not see.
Reliable means the data that goes into a database can be retrieved without corruption. Any data transformations should be expected, not accidental.
High-availability means that the database is available when needed. Your users should expect that the database is ready to use when they log in. Routine maintenance should follow a predictable schedule and should not interfere with normal use. High-availability may also affect your choice of operating system and hardware. You may want to choose a cluster configuration to prevent problems in the event of a single point of failure.
High-performance means that a user should be able to perform required tasks within an acceptable amount of time. A high-performance database should also feel responsive.
In this chapter, I'll introduce you to some of the tasks that a PostgreSQL administrator must perform. The remaining chapters cover each topic in greater detail.