information_schema.sgml

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

     <row>
      <entry><literal>domain_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the schema that contains the domain</entry>
     </row>

     <row>
      <entry><literal>domain_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the domain</entry>
     </row>
    </tbody>
   </tgroup>
  </table>
 </sect1>

 <sect1 id="infoschema-domains">
  <title><literal>domains</literal></title>

  <para>
   The view <literal>domains</literal> contains all domains defined in
   the current database.
  </para>

  <table>
   <title><literal>domains</literal> Columns</title>

   <tgroup cols="3">
    <thead>
     <row>
      <entry>Name</entry>
      <entry>Data Type</entry>
      <entry>Description</entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry><literal>domain_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the database that contains the domain (always the current database)</entry>
     </row>

     <row>
      <entry><literal>domain_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the schema that contains the domain</entry>
     </row>

     <row>
      <entry><literal>domain_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the domain</entry>
     </row>

     <row>
      <entry><literal>data_type</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>
       Data type of the domain, if it is a built-in type, or
       <literal>ARRAY</literal> if it is some array (in that case, see
       the view <literal>element_types</literal>), else
       <literal>USER-DEFINED</literal> (in that case, the type is
       identified in <literal>udt_name</literal> and associated
       columns).
      </entry>
     </row>

     <row>
      <entry><literal>character_maximum_length</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       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.
      </entry>
     </row>

     <row>
      <entry><literal>character_octet_length</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If the domain has a character type, the maximum possible length
       in octets (bytes) of a datum (this should not be of concern to
       <productname>PostgreSQL</productname> users); null for all
       other data types.
      </entry>
     </row>

     <row>
      <entry><literal>character_set_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>character_set_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>character_set_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>collation_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>collation_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>collation_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>numeric_precision</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If the domain has a numeric type, this column contains the
       (declared or implicit) precision of the type for this column.
       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
       <literal>numeric_precision_radix</literal>.  For all other data
       types, this column is null.
      </entry>
     </row>

     <row>
      <entry><literal>numeric_precision_radix</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If the domain has a numeric type, this column indicates in
       which base the values in the columns
       <literal>numeric_precision</literal> and
       <literal>numeric_scale</literal> are expressed.  The value is
       either 2 or 10.  For all other data types, this column is null.
      </entry>
     </row>

     <row>
      <entry><literal>numeric_scale</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If the domain has an exact numeric type, this column contains
       the (declared or implicit) scale of the type for this column.
       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
       <literal>numeric_precision_radix</literal>.  For all other data
       types, this column is null.
      </entry>
     </row>

     <row>
      <entry><literal>datetime_precision</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If the domain has a date, time, or interval type, the declared
       precision; null for all other data types or if no precision was
       declared.
      </entry>
     </row>

     <row>
      <entry><literal>interval_type</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>Not yet implemented</entry>
     </row>

     <row>
      <entry><literal>interval_precision</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>Not yet implemented</entry>
     </row>

     <row>
      <entry><literal>domain_default</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>Default expression of the domain</entry>
     </row>

     <row>
      <entry><literal>udt_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the database that the domain data type is defined in (always the current database)</entry>
     </row>

     <row>
      <entry><literal>udt_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the schema that the domain data type is defined in</entry>
     </row>

     <row>
      <entry><literal>udt_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the domain data type</entry>
     </row>

     <row>
      <entry><literal>scope_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>scope_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>scope_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>maximum_cardinality</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>Always null, because arrays always have unlimited maximum cardinality in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>dtd_identifier</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       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.)
      </entry>
     </row>
    </tbody>
   </tgroup>
  </table>
 </sect1>

 <sect1 id="infoschema-element-types">
  <title><literal>element_types</literal></title>

  <para>
   The view <literal>element_types</literal> contains the data type
   descriptors of the elements of arrays.  When a table column,
   domain, function parameter, or function return value is defined to
   be of an array type, the respective information schema view only
   contains <literal>ARRAY</literal> in the column
   <literal>data_type</literal>.  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
<programlisting>
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.array_type_identifier))
WHERE c.table_schema = '...' AND c.table_name = '...'
ORDER BY c.ordinal_position;
</programlisting>
   This view only includes objects that the current user has access
   to, by way of being the owner or having some privilege.
  </para>

  <table>
   <title><literal>element_types</literal> Columns</title>

   <tgroup cols="3">
    <thead>
     <row>
      <entry>Name</entry>
      <entry>Data Type</entry>
      <entry>Description</entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry><literal>object_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       Name of the database that contains the object that uses the
       array being described (always the current database)
      </entry>
     </row>

     <row>
      <entry><literal>object_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       Name of the schema that contains the object that uses the array
       being described
      </entry>
     </row>

     <row>
      <entry><literal>object_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       Name of the object that uses the array being described
      </entry>
     </row>

     <row>
      <entry><literal>object_type</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>
       The type of the object that uses the array being described: one
       of <literal>TABLE</literal> (the array is used by a column of
       that table), <literal>DOMAIN</literal> (the array is used by
       that domain), <literal>ROUTINE</literal> (the array is used by
       a parameter or the return data type of that function).
      </entry>
     </row>

     <row>
      <entry><literal>array_type_identifier</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       The identifier of the data type descriptor of the array being
       described.  Use this to join with the
       <literal>dtd_identifier</literal> columns of other information
       schema views.
      </entry>
     </row>

     <row>
      <entry><literal>data_type</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>
       Data type of the array elements, if it is a built-in type, else
       <literal>USER-DEFINED</literal> (in that case, the type is
       identified in <literal>udt_name</literal> and associated
       columns).
      </entry>
     </row>

     <row>
      <entry><literal>character_maximum_length</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>Always null, since this information is not applied to array element data types in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>character_octet_length</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>Always null, since this information is not applied to array element data types in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>character_set_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>character_set_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>character_set_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>collation_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>collation_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>collation_name</literal></entry>