Managing Databases

21.1. Overview

A database is a named collection of SQL objects ("database objects"). Generally, every database object (tables, functions, etc.) belongs to one and only one database. (However there are a few system catalogs, for example pg_database, that belong to a whole cluster and are accessible from each database within the cluster.) More accurately, a database is a collection of schemas and the schemas contain the tables, functions, etc. So the full hierarchy is: server, database, schema, table (or some other kind of object, such as a function).

When connecting to the database server, a client must specify in its connection request the name of the database it wants to connect to. It is not possible to access more than one database per connection. However, an application is not restricted in the number of connections it opens to the same