Chapter 21. PostgreSQL
As discussed in Chapter 15, any relational database that is to be trusted with production data should be ACID-compliant. PostgreSQL is the most popular open-source relational database that is always ACID-complaint. You can achieve ACID compliance in a MySQL database if you use the InnoDB or the NDB storage engines. (As of this writing, the MySQL team is developing other ACID-compliant storage engines.) With PostgreSQL, all data is stored in an ACID-compliant fashion. PostgreSQL also offers sophisticated features such as point-in-time recovery, tablespaces, checkpoints, hot backups, and write ahead logging for fault tolerance. These are all very good things from a data-protection and data-integrity standpoint.
From a power-user standpoint, PostgreSQL is like any other database. The following terms mean essentially the same in PostgreSQL as they do in any other relational database:
A PostgreSQL cluster is analogous to an instance in other RDBMSs, and each cluster works with one or more databases. It is not typical to have more than one cluster per database server, but it is possible and is done in some cases. For example, consider a shared hosting environment with different sets of users that should not be given administrative access to each others’ data. Since user information is global within a cluster, you would need to create multiple instances to have multiple groups ...