The postgresql_book.sql is a plain text SQL backup
that should be restored with psql.

It consists of data used in the book
[PostgreSQL: Up and Running, 4th Edition](https://www.oreilly.com/library/view/postgresql-up-and/9798341660885/ch01.html)

To restore:
```sql
CREATE DATABASE postgresql_book;
\connect postgresql_book
\i postgresql_book.sql
```

The chapter folders consist of code and data used in the relevant chapters.