The catalog pg_description can store an optional description or comment for each database object. Descriptions can be manipulated with the COMMENT command and viewed with psql's \d commands. Descriptions of many built-in system objects are provided in the initial contents of pg_description.
Table 43-14. pg_description Columns
|objoid||oid||any OID column||The OID of the object this description pertains to|
|classoid||oid||pg_class.oid||The OID of the system catalog this object appears in|
|objsubid||int4||For a comment on a table column, this is the column number (the objoid and classoid refer to the table itself). For all other object types, this column is zero.|
|description||text||Arbitrary text that serves as the description of this object.|