November 14, 2024: PostgreSQL 17.1, 16.5, 15.9, 14.14, 13.17, and 12.21 Released!
Supported Versions: Current (17) / 16 / 15 / 14 / 13
Development Versions: devel
Unsupported versions: 12 / 11 / 10 / 9.6 / 9.5 / 9.4 / 9.3 / 9.2 / 9.1 / 9.0 / 8.4 / 8.3 / 8.2 / 8.1 / 8.0 / 7.4
This documentation is for an unsupported version of PostgreSQL.
You may want to view the same page for the current version, or one of the other supported versions listed above instead.
37.23. element_types
Prev  Up Chapter 37. The Information Schema Home  Next

37.23. 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 37.21. element_types Columns

Name Data Type Description
object_catalog sql_identifier Name of the database that contains the object that uses the array being described (always the current database)
object_schema sql_identifier Name of the schema that contains the object that uses the array being described
object_name sql_identifier Name of the object that uses the array being described
object_type character_data The type of the object that uses the array being described: one of TABLE (the array is used by a column of that table), USER-DEFINED TYPE (the array is used by an attribute of that composite type), DOMAIN (the array is used by that domain), ROUTINE (the array is used by a parameter or the return data type of that function).
collection_type_identifier sql_identifier The identifier of the data type descriptor of the array being described. Use this to join with the dtd_identifier columns of other information schema views.
data_type character_data Data type of the array elements, if it is a built-in type, else USER-DEFINED (in that case, the type is identified in udt_name and associated columns).
character_maximum_length cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL
character_octet_length cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL
character_set_catalog sql_identifier Applies to a feature not available in PostgreSQL
character_set_schema sql_identifier Applies to a feature not available in PostgreSQL
character_set_name sql_identifier Applies to a feature not available in PostgreSQL
collation_catalog sql_identifier 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
collation_schema sql_identifier Name of the schema containing the collation of the element type, null if default or the data type of the element is not collatable
collation_name sql_identifier Name of the collation of the element type, null if default or the data type of the element is not collatable
numeric_precision cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL
numeric_precision_radix cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL
numeric_scale cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL
datetime_precision cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL
interval_type character_data Always null, since this information is not applied to array element data types in PostgreSQL
interval_precision cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL
domain_default character_data Not yet implemented
udt_catalog sql_identifier Name of the database that the data type of the elements is defined in (always the current database)
udt_schema sql_identifier Name of the schema that the data type of the elements is defined in
udt_name sql_identifier Name of the data type of the elements
scope_catalog sql_identifier Applies to a feature not available in PostgreSQL
scope_schema sql_identifier Applies to a feature not available in PostgreSQL
scope_name sql_identifier Applies to a feature not available in PostgreSQL
maximum_cardinality cardinal_number Always null, because arrays always have unlimited maximum cardinality in PostgreSQL
dtd_identifier sql_identifier An identifier of the data type descriptor of the element. This is currently not useful.

Prev  Up  Next
37.22. domains  Home  37.24. enabled_roles