The catalog pg_namespace stores namespaces. A namespace is the structure underlying SQL schemas: each namespace can have a separate collection

The catalog pg_operator stores information about operators. See CREATE

The view pg_tables provides access to useful information about each table in the database.

The catalog pg_transform stores information about transforms, which are a mechanism to adapt data types to procedural languages. See

The catalog pg_largeobject holds the data making up "large objects". A large object is identified by an OID assigned

The catalog pg_aggregate stores information about aggregate functions. An aggregate function is a function that operates on a set of values

The catalog pg_shseclabel stores security labels on shared database objects. Security labels can be manipulated with the

The catalog pg_auth_members shows the membership relations between roles. Any non-circular set of relationships is allowed.

The catalog pg_collation describes the available collations, which are essentially mappings from an SQL name to operating system locale categories

The view pg_config describes the compile-time configuration parameters of the currently installed version of PostgreSQL