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postgresql
19th chunk of `doc/src/sgml/dblink.sgml`
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 lower case.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>primary_key_attnums</parameter></term>
     <listitem>
      <para>
       Attribute numbers (1-based) of the primary key fields,
       for example <literal>1 2</literal>.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>num_primary_key_atts</parameter></term>
     <listitem>
      <para>
       The number of primary key fields.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>tgt_pk_att_vals_array</parameter></term>
     <listitem>
      <para>
       Values of the primary key fields to be used in the resulting
       <command>DELETE</command> command.  Each field is represented in text form.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </refsect1>

  <refsect1>
   <title>Return Value</title>

   <para>Returns the requested SQL statement as text.</para>
  </refsect1>

  <refsect1>
   <title>Notes</title>

   <para>
    As of <productname>PostgreSQL</productname> 9.0, the attribute numbers in
    <parameter>primary_key_attnums</parameter> are interpreted as logical
    column numbers, corresponding to the column's position in
    <literal>SELECT * FROM relname</literal>.  Previous versions interpreted the
    numbers as physical column positions.  There is a difference if any
    column(s) to the left of the indicated column have been dropped during
    the lifetime of the table.
   </para>
  </refsect1>

  <refsect1>
   <title>Examples</title>

<screen>
SELECT dblink_build_sql_delete('"MyFoo"', '1 2', 2, '{"1", "b"}');
           dblink_build_sql_delete
---------------------------------------------
 DELETE FROM "MyFoo" WHERE f1='1' AND f2='b'
(1 row)
</screen>
  </refsect1>
 </refentry>

 <refentry id="contrib-dblink-build-sql-update">
  <indexterm>
   <primary>dblink_build_sql_update</primary>
  </indexterm>

  <refmeta>
   <refentrytitle>dblink_build_sql_update</refentrytitle>
   <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
   <refname>dblink_build_sql_update</refname>
   <refpurpose>builds an UPDATE statement using a local tuple, replacing
    the primary key field values with alternative supplied values
   </refpurpose>
  </refnamediv>

  <refsynopsisdiv>
<synopsis>
dblink_build_sql_update(text relname,
                        int2vector primary_key_attnums,
                        integer num_primary_key_atts,
                        text[] src_pk_att_vals_array,
                        text[] tgt_pk_att_vals_array) returns text
</synopsis>
  </refsynopsisdiv>

  <refsect1>
   <title>Description</title>

   <para>
    <function>dblink_build_sql_update</function> can be useful in doing selective
    replication of a local table to a remote database.  It selects a row
    from the local table based on primary key, and then builds an SQL
    <command>UPDATE</command> command that will duplicate that row, but with
    the primary key values replaced by the values in the last argument.
    (To make an exact copy
Title: dblink_build_sql_delete Function Details and dblink_build_sql_update Introduction
Summary
This section provides further details on the `dblink_build_sql_delete` function, elaborating on its parameters and usage, including notes on how primary key attribute numbers are interpreted in different PostgreSQL versions. It also offers an example of using the function. Additionally, the section introduces the `dblink_build_sql_update` function, which is designed for selective replication. It updates a row in a remote database based on a local row's primary key, replacing the original primary key values with new ones.