Summary
The catalog pg_description stores optional descriptions (comments) 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.
(Description quoted from the official PostgreSQL documentation.)
Columns
The pg_description system catalog exposes the following columns (names, types and descriptions are taken verbatim from the PostgreSQL documentation):
objoidoidreferencesany OID column
The OID of the object this description pertains toclassoidoidreferencespg_class.oid
The OID of the system catalog this object appears inobjsubidint4
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.descriptiontext
Arbitrary text that serves as the description of this object
Related catalogs
This object references the following other system catalogs:
classoid→pg_class
Version applicability
Present in PostgreSQL 17, 18, 19 (verified against each release’s documentation). This is a long-standing system object that also exists in earlier PostgreSQL releases.
Related & references
Reference: PostgreSQL documentation — pg_description.