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The view domains contains all domains defined in the current database.
Table 33-16. domains Columns
| Name | Data Type | Description |
|---|---|---|
| domain_catalog | sql_identifier | Name of the database that contains the domain (always the current database) |
| domain_schema | sql_identifier | Name of the schema that contains the domain |
| domain_name | sql_identifier | Name of the domain |
| data_type | character_data | Data type of the domain, 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 udt_name and associated columns). |
| character_maximum_length | cardinal_number | If the domain has 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 the domain has 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. |
| 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 | Applies to a feature not available in PostgreSQL |
| collation_schema | sql_identifier | Applies to a feature not available in PostgreSQL |
| collation_name | sql_identifier | Applies to a feature not available in PostgreSQL |
| numeric_precision | cardinal_number | If the domain has a numeric type, this column contains the (declared or implicit) precision of the type for this domain. 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 the domain has 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 the domain has an exact numeric type, this column contains the (declared or implicit) scale of the type for this domain. 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 domain, 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 | Not yet implemented |
| interval_precision | character_data | Not yet implemented |
| domain_default | character_data | Default expression of the domain |
| udt_catalog | sql_identifier | Name of the database that the domain data type is defined in (always the current database) |
| udt_schema | sql_identifier | Name of the schema that the domain data type is defined in |
| udt_name | sql_identifier | Name of the domain 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 domain, unique among the data type descriptors pertaining to the domain (which is trivial, because a domain only contains one data type descriptor). 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.) |