element_types #
   The view element_types contains the data type
   descriptors of the elements of arrays.  When a table column, composite-type attribute,
   domain, function parameter, or function return value is defined to
   be of an array type, the respective information schema view only
   contains ARRAY in the column
   data_type.  To obtain information on the element
   type of the array, you can join the respective view with this view.
   For example, to show the columns of a table with data types and
   array element types, if applicable, you could do:
SELECT c.column_name, c.data_type, e.data_type AS element_type
FROM information_schema.columns c LEFT JOIN information_schema.element_types e
     ON ((c.table_catalog, c.table_schema, c.table_name, 'TABLE', c.dtd_identifier)
       = (e.object_catalog, e.object_schema, e.object_name, e.object_type, e.collection_type_identifier))
WHERE c.table_schema = '...' AND c.table_name = '...'
ORDER BY c.ordinal_position;
This view only includes objects that the current user has access to, by way of being the owner or having some privilege.
Table 35.22. element_types Columns
| Column Type Description | 
|---|
| 
        Name of the database that contains the object that uses the array being described (always the current database) | 
| 
        Name of the schema that contains the object that uses the array being described | 
| 
        Name of the object that uses the array being described | 
| 
        
       The type of the object that uses the array being described: one
       of  | 
| 
        
       The identifier of the data type descriptor of the array being
       described.  Use this to join with the
        | 
| 
        
       Data type of the array elements, if it is a built-in type, else
        | 
| 
        Always null, since this information is not applied to array element data types in PostgreSQL | 
| 
        Always null, since this information is not applied to array element data types in PostgreSQL | 
| 
        Applies to a feature not available in PostgreSQL | 
| 
        Applies to a feature not available in PostgreSQL | 
| 
        Applies to a feature not available in PostgreSQL | 
| 
        Name of the database containing the collation of the element type (always the current database), null if default or the data type of the element is not collatable | 
| 
        Name of the schema containing the collation of the element type, null if default or the data type of the element is not collatable | 
| 
        Name of the collation of the element type, null if default or the data type of the element is not collatable | 
| 
        Always null, since this information is not applied to array element data types in PostgreSQL | 
| 
        Always null, since this information is not applied to array element data types in PostgreSQL | 
| 
        Always null, since this information is not applied to array element data types in PostgreSQL | 
| 
        Always null, since this information is not applied to array element data types in PostgreSQL | 
| 
        Always null, since this information is not applied to array element data types in PostgreSQL | 
| 
        Always null, since this information is not applied to array element data types in PostgreSQL | 
| 
        Name of the database that the data type of the elements is defined in (always the current database) | 
| 
        Name of the schema that the data type of the elements is defined in | 
| 
        Name of the data type of the elements | 
| 
        Applies to a feature not available in PostgreSQL | 
| 
        Applies to a feature not available in PostgreSQL | 
| 
        Applies to a feature not available in PostgreSQL | 
| 
        Always null, because arrays always have unlimited maximum cardinality in PostgreSQL | 
| 
        An identifier of the data type descriptor of the element. This is currently not useful. |