Logical replication support for TRUNCATE

Update the built-in logical replication system to make use of the
previously added logical decoding for TRUNCATE support.  Add the
required truncate callback to pgoutput and a new logical replication
protocol message.

Publications get a new attribute to determine whether to replicate
truncate actions.  When updating a publication via pg_dump from an older
version, this is not set, thus preserving the previous behavior.

Author: Simon Riggs <simon@2ndquadrant.com>
Author: Marco Nenciarini <marco.nenciarini@2ndquadrant.it>
Author: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Reviewed-by: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>

doc/src/sgml/catalogs.sgml

@@ -5518,6 +5518,14 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
       <entry>If true, <command>DELETE</command> operations are replicated for
        tables in the publication.</entry>
      </row>
+
+     <row>
+      <entry><structfield>pubtruncate</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>If true, <command>TRUNCATE</command> operations are replicated for
+       tables in the publication.</entry>
+     </row>
     </tbody>
    </tgroup>
   </table>

doc/src/sgml/logical-replication.sgml

@@ -108,8 +108,8 @@
 
   <para>
    Publications can choose to limit the changes they produce to
-   any combination of <command>INSERT</command>, <command>UPDATE</command>, and
-   <command>DELETE</command>, similar to how triggers are fired by
+   any combination of <command>INSERT</command>, <command>UPDATE</command>,
+   <command>DELETE</command>, and <command>TRUNCATE</command>, similar to how triggers are fired by
    particular event types.  By default, all operation types are replicated.
   </para>
 
@@ -364,15 +364,6 @@
     </para>
    </listitem>
 
-   <listitem>
-    <para>
-     <command>TRUNCATE</command> commands are not replicated.  This can, of
-     course, be worked around by using <command>DELETE</command> instead.  To
-     avoid accidental <command>TRUNCATE</command> invocations, you can revoke
-     the <literal>TRUNCATE</literal> privilege from tables.
-    </para>
-   </listitem>
-
    <listitem>
     <para>
      Large objects (see <xref linkend="largeobjects"/>) are not replicated.

doc/src/sgml/protocol.sgml

@@ -6774,6 +6774,62 @@ Delete
 </listitem>
 </varlistentry>
 
+<varlistentry>
+<term>
+Truncate
+</term>
+<listitem>
+<para>
+
+<variablelist>
+<varlistentry>
+<term>
+        Byte1('T')
+</term>
+<listitem>
+<para>
+                Identifies the message as a truncate message.
+</para>
+</listitem>
+</varlistentry>
+<varlistentry>
+<term>
+        Int32
+</term>
+<listitem>
+<para>
+                Number of relations
+</para>
+</listitem>
+</varlistentry>
+<varlistentry>
+<term>
+        Int8
+</term>
+<listitem>
+<para>
+                Option bits for <command>TRUNCATE</command>:
+                1 for <literal>CASCADE</literal>, 2 for <literal>RESTART IDENTITY</literal>
+</para>
+</listitem>
+</varlistentry>
+<varlistentry>
+<term>
+        Int32
+</term>
+<listitem>
+<para>
+                ID of the relation corresponding to the ID in the relation
+                message.  This field is repeated for each relation.
+</para>
+</listitem>
+</varlistentry>
+
+</variablelist>
+</para>
+</listitem>
+</varlistentry>
+
 </variablelist>
 
 <para>

doc/src/sgml/ref/create_publication.sgml

@@ -106,10 +106,11 @@ CREATE PUBLICATION <replaceable class="parameter">name</replaceable>
           This parameter determines which DML operations will be published by
           the new publication to the subscribers.  The value is
           comma-separated list of operations.  The allowed operations are
-          <literal>insert</literal>, <literal>update</literal>, and
-          <literal>delete</literal>.  The default is to publish all actions,
+          <literal>insert</literal>, <literal>update</literal>,
+          <literal>delete</literal>, and <literal>truncate</literal>.
+          The default is to publish all actions,
           and so the default value for this option is
-          <literal>'insert, update, delete'</literal>.
+          <literal>'insert, update, delete, truncate'</literal>.
          </para>
         </listitem>
        </varlistentry>
@@ -168,8 +169,7 @@ CREATE PUBLICATION <replaceable class="parameter">name</replaceable>
   </para>
 
   <para>
-   <command>TRUNCATE</command> and <acronym>DDL</acronym> operations
-   are not published.
+   <acronym>DDL</acronym> operations are not published.
   </para>
  </refsect1>