pg_attrdef

The pg_attrdef table stores column default values. The main information about columns is stored in pg_attribute. Only columns that explicitly specify a default value (when the table is created or the column is added) will have an entry here.

column	type	references	description
adrelid	oid	pg_class.oid	The table this column belongs to
adnum	int2	pg_attribute.attnum	The number of the column
adbin	text		The internal representation of the column default value
adsrc	text		A human-readable representation of the default value. This field is historical, and is best not used.

Parent topic: System Catalogs Definitions