50.6. 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 50.6. pg_attrdef Columns
| Column Type Description | 
|---|
| 
 Row identifier | 
| 
 The table this column belongs to | 
| 
 The number of the column | 
| 
  The column default value, in  |