<structfield>attgenerated</structfield> to
       determine whether this is a default or a generation expression.)
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>atthasmissing</structfield> <type>bool</type>
      </para>
      <para>
       This column has a value which is used where the column is entirely
       missing from the row, as happens when a column is added with a
       non-volatile <literal>DEFAULT</literal> value after the row is created.
       The actual value used is stored in the
       <structfield>attmissingval</structfield> column.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>attidentity</structfield> <type>char</type>
      </para>
      <para>
       If a zero byte (<literal>''</literal>), then not an identity column.
       Otherwise, <literal>a</literal> = generated
       always, <literal>d</literal> = generated by default.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>attgenerated</structfield> <type>char</type>
      </para>
      <para>
       If a zero byte (<literal>''</literal>), then not a generated column.
       Otherwise, <literal>s</literal> = stored, <literal>v</literal> =
       virtual.  A stored generated column is physically stored like a normal
       column.  A virtual generated column is physically stored as a null
       value, with the actual value being computed at run time.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>attisdropped</structfield> <type>bool</type>
      </para>
      <para>
       This column has been dropped and is no longer valid.  A dropped
       column is still physically present in the table, but is
       ignored by the parser and so cannot be accessed via SQL.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>attislocal</structfield> <type>bool</type>
      </para>
      <para>
       This column is defined locally in the relation.  Note that a column can
       be locally defined and inherited simultaneously.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>attinhcount</structfield> <type>int2</type>
      </para>
      <para>
       The number of direct ancestors this column has.  A column with a
       nonzero number of ancestors cannot be dropped nor renamed.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>attcollation</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-collation"><structname>pg_collation</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       The defined collation of the column, or zero if the column is
       not of a collatable data type
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>attstattarget</structfield> <type>int2</type>
      </para>
      <para>
       <structfield>attstattarget</structfield> controls the level of detail
       of statistics accumulated for this column by
       <link linkend="sql-analyze"><command>ANALYZE</command></link>.
       A zero value indicates that no statistics should be collected.
       A null value says to use the system default statistics target.
       The exact meaning of positive values is data type-dependent.
       For scalar data types, <structfield>attstattarget</structfield>
       is both the target number of <quote>most common values</quote>
       to collect, and the target number of histogram bins to create.