# pg_attrdef

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


Table 1. `pg_catalog.pg_attrdef`

| column    | type     | references            | description                                                  |
| :-------- | :------- | :-------------------- | :----------------------------------------------------------- |
|`oid`|	oid|		|The object ID
|`adrelid`|	oid|	pg_class.oid	|The table this column belongs to
|`adnum`|	smallint|	pg_attribute.attnum|	The number of the column
|`adbin`|	pg_node_tree||		The internal representation of the column default value