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32.6. attributes

The view attributes contains information about the attributes of composite data types defined in the database. (Note that the view does not give information about table columns, which are sometimes called attributes in PostgreSQL contexts.)

Table 32-4. attributes Columns

Name Data Type Description
udt_catalog sql_identifier Name of the database containing the data type (always the current database)
udt_schema sql_identifier Name of the schema containing the data type
udt_name sql_identifier Name of the data type
attribute_name sql_identifier Name of the attribute
ordinal_position cardinal_number Ordinal position of the attribute within the data type (count starts at 1)
attribute_default character_data Default expression of the attribute
is_nullable character_data YES if the attribute is possibly nullable, NO if it is known not nullable.
data_type character_data Data type of the attribute, if it is a built-in type, or ARRAY if it is some array (in that case, see the view element_types), else USER-DEFINED (in that case, the type is identified in attribute_udt_name and associated columns).
character_maximum_length cardinal_number If data_type identifies a character or bit string type, the declared maximum length; null for all other data types or if no maximum length was declared.
character_octet_length cardinal_number If data_type identifies a character type, the maximum possible length in octets (bytes) of a datum (this should not be of concern to PostgreSQL users); null for all other data types.
numeric_precision cardinal_number If data_type identifies a numeric type, this column contains the (declared or implicit) precision of the type for this attribute. The precision indicates the number of significant digits. It may be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. For all other data types, this column is null.
numeric_precision_radix cardinal_number If data_type identifies a numeric type, this column indicates in which base the values in the columns numeric_precision and numeric_scale are expressed. The value is either 2 or 10. For all other data types, this column is null.
numeric_scale cardinal_number If data_type identifies an exact numeric type, this column contains the (declared or implicit) scale of the type for this attribute. The scale indicates the number of significant digits to the right of the decimal point. It may be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. For all other data types, this column is null.
datetime_precision cardinal_number If data_type identifies a date, time, or interval type, the declared precision; null for all other data types or if no precision was declared.
interval_type character_data Not yet implemented
interval_precision character_data Not yet implemented
attribute_udt_catalog sql_identifier Name of the database that the attribute data type is defined in (always the current database)
attribute_udt_schema sql_identifier Name of the schema that the attribute data type is defined in
attribute_udt_name sql_identifier Name of the attribute data type
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 column, unique among the data type descriptors pertaining to the table. This is mainly useful for joining with other instances of such identifiers. (The specific format of the identifier is not defined and not guaranteed to remain the same in future versions.)
is_derived_reference_attribute character_data Applies to a feature not available in PostgreSQL

See also under Section 32.12, a similarly structured view, for further information on some of the columns.

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