This chapter covers a range of general recipes for your tables and working with the data they contain. Many of the recipes contain general advice, though with specific PostgreSQL examples.
Some system administrators I've met work only on the external aspects of the database server. What's actually in the database is someone else's problem.
Look after your data, and your database will look after you. Keep your data clean, and your queries will run faster and cause less application errors. You'll also gain many friends in the business. Getting called in the middle of the night to fix data problems just isn't cool.