Instruct: Classify Amazon reviews into positive or negative sentiment
Query: For everyday's PostgreSQL users

The book has done its job pretty well. It's for everyday's life of PostgreSQL users, and especially me that's just started to work on this DB. It covers almost everything about this exceptional open-source database. You'll never need another book. However, one thing I think I need more from it is "database performance tuning" issue. It touches on some of that stuff, but in the real world, if you're running a more or less stressful db, then this issue is critical.