36.6. 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.) Only those attributes are shown that the current user has access to (by way of being the owner of or having some privilege on the type).
Table 36.4. attributes
Columns
attributes
ColumnsColumn 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
yes_or_no
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; null for all other data types. The maximum octet length depends on the declared character maximum length (see above) and the server encoding.
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 attribute (always the current database), null if default or the data type of the attribute is not collatable
collation_schema
sql_identifier
Name of the schema containing the collation of the attribute, null if default or the data type of the attribute is not collatable
collation_name
sql_identifier
Name of the collation of the attribute, null if default or the data type of the attribute is not collatable
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 can 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 can 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, timestamp, or interval type, this column contains the (declared or implicit) fractional seconds precision of the type for this attribute, that is, the number of decimal digits maintained following the decimal point in the seconds value. For all other data types, this column is null.
interval_type
character_data
If data_type
identifies an interval type, this column contains the specification which fields the intervals include for this attribute, e.g., YEAR TO MONTH
, DAY TO SECOND
, etc. If no field restrictions were specified (that is, the interval accepts all fields), and for all other data types, this field is null.
interval_precision
cardinal_number
Applies to a feature not available in PostgreSQL (see datetime_precision
for the fractional seconds precision of interval type attributes)
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
yes_or_no
Applies to a feature not available in PostgreSQL
See also under Section 36.17, a similarly structured view, for further information on some of the columns.
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