considers interesting is unique. Using name of the extension or the
      output plugin itself is often a good choice.
     </para>
    </sect3>

    <sect3 id="logicaldecoding-output-plugin-filter-prepare">
     <title>Prepare Filter Callback</title>

     <para>
       The optional <function>filter_prepare_cb</function> callback
       is called to determine whether data that is part of the current
       two-phase commit transaction should be considered for decoding
       at this prepare stage or later as a regular one-phase transaction at
       <command>COMMIT PREPARED</command> time. To signal that
       decoding should be skipped, return <literal>true</literal>;
       <literal>false</literal> otherwise. When the callback is not
       defined, <literal>false</literal> is assumed (i.e. no filtering, all
       transactions using two-phase commit are decoded in two phases as well).
<programlisting>
typedef bool (*LogicalDecodeFilterPrepareCB) (struct LogicalDecodingContext *ctx,
                                              TransactionId xid,
                                              const char *gid);
</programlisting>
       The <parameter>ctx</parameter> parameter has the same contents as for
       the other callbacks. The parameters <parameter>xid</parameter>
       and <parameter>gid</parameter> provide two different ways to identify
       the transaction.  The later <command>COMMIT PREPARED</command> or
       <command>ROLLBACK PREPARED</command> carries both identifiers,
       providing an output plugin the choice of what to use.
     </para>
     <para>
       The callback may be invoked multiple times per transaction to decode
       and must provide the same static answer for a given pair of
       <parameter>xid</parameter> and <parameter>gid</parameter> every time
       it is called.
     </para>
     </sect3>

    <sect3 id="logicaldecoding-output-plugin-begin-prepare">
     <title>Transaction Begin Prepare Callback</title>

     <para>
      The required <function>begin_prepare_cb</function> callback is called
      whenever the start of a prepared transaction has been decoded. The
      <parameter>gid</parameter> field, which is part of the
      <parameter>txn</parameter> parameter, can be used in this callback to
      check if the plugin has already received this <command>PREPARE</command>
      in which case it can either error out or skip the remaining changes of
      the transaction.
<programlisting>
typedef void (*LogicalDecodeBeginPrepareCB) (struct LogicalDecodingContext *ctx,
                                             ReorderBufferTXN *txn);
</programlisting>
     </para>
    </sect3>

    <sect3 id="logicaldecoding-output-plugin-prepare">
     <title>Transaction Prepare Callback</title>

     <para>
      The required <function>prepare_cb</function> callback is called whenever
      a transaction which is prepared for two-phase commit has been
      decoded. The <function>change_cb</function> callback for all modified
      rows will have been called before this, if there have been any modified
      rows. The <parameter>gid</parameter> field, which is part of the
      <parameter>txn</parameter> parameter, can be used in this callback.
<programlisting>
typedef void (*LogicalDecodePrepareCB) (struct LogicalDecodingContext *ctx,
                                        ReorderBufferTXN *txn,
                                        XLogRecPtr prepare_lsn);
</programlisting>
     </para>
    </sect3>

    <sect3 id="logicaldecoding-output-plugin-commit-prepared">
     <title>Transaction Commit Prepared Callback</title>

     <para>
      The required <function>commit_prepared_cb</function> callback is called
      whenever a transaction <command>COMMIT PREPARED</command> has been decoded.
      The <parameter>gid</parameter> field, which is part of the
      <parameter>txn</parameter> parameter, can be used in this callback.
<programlisting>
typedef void (*LogicalDecodeCommitPreparedCB)