pg_shdescription stores optional descriptions (comments) for shared database objects. Descriptions can be manipulated with the COMMENT command and viewed with psql's
pg_description, which performs a similar function for descriptions involving objects within a single database.
Unlike most system catalogs,
pg_shdescription is shared across all databases of a cluster: there is only one copy of
pg_shdescription per cluster, not one per database.
||any OID column||The OID of the object this description pertains to|
||The OID of the system catalog this object appears in|
||Arbitrary text that serves as the description of this object|