PG_ATTRDEF

PG_ATTRDEF records default values of columns.

Table 1 PG_ATTRDEF columns

Name	Type	Description
oid	oid	Row identifier (hidden attribute, which must be specified)
adrelid	oid	Table to which a column belongs
adnum	smallint	Number of columns
adbin	pg_node_tree	Internal representation of the default value of a column or of a generated expression
adsrc	text	Internal representation of a readable default value or of a generated expression
adgencol	"char"	Specifies whether a column is a generated column. The value s indicates that the column is a generated column, and the value '\0 indicates that the column is a common column. The default value is '\0.
adbin_on_update	pg_node_tree	Converts a storage expression into a character string.
adsrc_on_update	text	Specifies the name of a storage expression.