37.6. 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 37.4.
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
|
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 37.16 , a similarly structured view, for further information on some of the columns.