In the previous chapter we have covered the basics of using
    SQL to store and access your data in
    PostgreSQL.  We will now discuss some
    more advanced features of SQL that simplify
    management and prevent loss or corruption of your data.  Finally,
    we will look at some PostgreSQL
    extensions.
   
    This chapter will on occasion refer to examples found in Chapter 2 to change or improve them, so it will be
    of advantage if you have read that chapter.  Some examples from
    this chapter can also be found in
    advanced.sql in the tutorial directory.  This
    file also contains some example data to load, which is not
    repeated here.  (Refer to Section 2.1 for
    how to use the file.)