Another aspect of maintaining a highly available database is to know all of the important information about the contents of the database itself. In this case, we aim to focus on tables and indexes that receive the most activity. If any problems that might require maintenance or a restart arise, the most active portions are the likely origin.
What is activity? Inserts, updates, deletes, and selects are a good start. PostgreSQL collects statistics on all of this information, making it easy to collect and track. It also records how often indexes or tables are scanned and how many rows were affected by each. In addition to this, we can observe how much disk space any object consumes. Given the assistance of a couple of contributed tools, we can also calculate how much of this space is currently reusable.
Data like this identifies which tables and indexes...