PostgreSQL COMMENT attaches one replaceable note to almost any database object

The PostgreSQL COMMENT command defines or changes the comment on a database object. Only one comment string is stored per object; a new COMMENT replaces the prior text, and NULL or '' removes it. The synopsis covers ACCESS METHOD through VIEW, including COLUMN, TABLE, FUNCTION, SCHEMA, and many others.

Data and content teams often need human-readable meaning next to schema objects that agents and pipelines also consume. Comments live in the catalog beside the object they describe, so documentation can travel with the schema rather than only in external docs.

Shared meaning across systems starts with attaching intent to concrete objects. COMMENT is a native, governed place for that intent inside PostgreSQL—thin compared with full ontologies, but a durable hook for semantic layer and data contract work that must stay close to the tables and columns themselves.

Comments do not validate structure; they annotate it. Teams that treat catalog comments as part of the contract still need shapes, checks, or external models when meaning must be machine-enforced across systems.