# 52.6. pg_attrdef

The catalog pg_attrdef stores column default values. The main information about columns is stored in pg_attribute. Only columns for which a default value has been explicitly set will have an entry here.

Table 52.6. pg_attrdef Columns

Column Type

Description
oid oid

Row identifier
adrelid oid (references pg_class.oid)

The table this column belongs to
adnum int2 (references pg_attribute.attnum)

The number of the column
adbin pg_node_tree

The column default value, in nodeToString() representation. Use pg_get_expr(adbin, adrelid) to convert it to an SQL expression.