The catalog pg_shdescription stores optional descriptions (comments) for shared database objects. Descriptions can be manipulated with the

The view pg_shadow exists for backwards compatibility: it emulates a catalog that existed in PostgreSQL before

The catalog pg_proc stores information about functions (or procedures). See

The catalog pg_cast stores data type conversion paths, both built-in and user-defined. It should be noted that

The view pg_user_mappings provides access to information about user mappings. This is essentially a publicly readable view of

The view pg_timezone_abbrevs provides a list of time zone abbreviations that are currently recognized by the datetime input routines. The contents

The view pg_roles provides access to information about database roles. This is simply a publicly readable view of

The view pg_policies provides access to useful information about each row-level security policy in the database.

The catalog pg_conversion describes encoding conversion procedures. See

The catalog pg_foreign_data_wrapper stores foreign-data wrapper definitions. A foreign-data wrapper is the mechanism by which external data