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  <div class="titlepage">
   <div>
    <div>
     <h4 class="title">
      <a name="channels-with-prev-replication">
      </a>
      19.2.2.2 Compatibility with Previous Replication Statements
     </h4>
    </div>
   </div>
  </div>
  <a class="indexterm" name="idm46045138141424">
  </a>
  <p>
   When a replica has multiple channels and a
   <code class="literal">
    FOR CHANNEL
    <em class="replaceable">
     <code>
      channel
     </code>
    </em>
   </code>
   option is not
      specified, a valid statement generally acts on all available
      channels, with some specific exceptions.
  </p>
  <p>
   For example, the following statements behave as expected for all
      except certain Group Replication channels:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <a class="link" href="start-replica.html" title="15.4.2.4 START REPLICA Statement">
       <code class="literal">
        START REPLICA
       </code>
      </a>
      starts
          replication threads for all channels, except the
      <code class="literal">
       group_replication_recovery
      </code>
      and
      <code class="literal">
       group_replication_applier
      </code>
      channels.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="link" href="stop-replica.html" title="15.4.2.5 STOP REPLICA Statement">
       <code class="literal">
        STOP REPLICA
       </code>
      </a>
      stops replication
          threads for all channels, except the
      <code class="literal">
       group_replication_recovery
      </code>
      and
      <code class="literal">
       group_replication_applier
      </code>
      channels.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="link" href="show-replica-status.html" title="15.7.7.35 SHOW REPLICA STATUS Statement">
       <code class="literal">
        SHOW REPLICA STATUS
       </code>
      </a>
      reports the
          status for all channels, except the
      <code class="literal">
       group_replication_applier
      </code>
      channel.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="link" href="reset-replica.html" title="15.4.2.3 RESET REPLICA Statement">
       <code class="literal">
        RESET REPLICA
       </code>
      </a>
      resets all
          channels.
     </p>
    </li>
   </ul>
  </div>
  <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
   <div class="admon-title">
    Warning
   </div>
   <p>
    Use
    <a class="link" href="reset-replica.html" title="15.4.2.3 RESET REPLICA Statement">
     <code class="literal">
      RESET REPLICA
     </code>
    </a>
    with caution as
        this statement deletes all existing channels, purges their relay
        log files, and recreates only the default channel.
   </p>
  </div>
  <p>
   Some replication statements cannot operate on all channels. In
      this case, error 1964
   <span class="errortext">
    Multiple channels exist on the
      replica. Please provide channel name as an argument.
   </span>
   is generated. The following statements and functions generate this
      error when used in a multi-source replication topology and a
   <code class="literal">
    FOR CHANNEL
    <em class="replaceable">
     <code>
      channel
     </code>
    </em>
   </code>
   option is not used to specify which channel to act on:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <a class="link" href="show-relaylog-events.html" title="15.7.7.34 SHOW RELAYLOG EVENTS Statement">
       <code class="literal">
        SHOW RELAYLOG EVENTS
       </code>
      </a>
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement">
       <code class="literal">
        CHANGE REPLICATION SOURCE TO
       </code>
      </a>
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="link" href="replication-functions-synchronization.html#function_source-pos-wait">
       <code class="literal">
        SOURCE_POS_WAIT()
       </code>
      </a>
     </p>
    </li>
   </ul>
  </div>
  <p>
   Note that a default channel always exists in a single source
      replication topology, where statements and functions behave as in
      previous versions of MySQL.
  </p>
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