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     <h4 class="title">
      <a name="mysql-cluster-limitations-exclusive-to-cluster">
      </a>
      25.2.7.8 Issues Exclusive to NDB Cluster
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  <p>
   The following are limitations specific to the
   <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
    <code class="literal">
     NDB
    </code>
   </a>
   storage engine:
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    <li class="listitem">
     <p>
      <b>
       Machine architecture.
      </b>
      All machines used in the cluster must have the same
              architecture. That is, all machines hosting nodes must be
              either big-endian or little-endian, and you cannot use a
              mixture of both. For example, you cannot have a management
              node running on a PowerPC which directs a data node that
              is running on an x86 machine. This restriction does not
              apply to machines simply running
      <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
       <span class="command">
        <strong>
         mysql
        </strong>
       </span>
      </a>
      or other clients that may be accessing the cluster's
              SQL nodes.
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    </li>
    <li class="listitem">
     <p>
      <b>
       Binary logging.
      </b>
      <a class="indexterm" name="idm46045123213216">
      </a>
      <a class="indexterm" name="idm46045123211728">
      </a>
      NDB Cluster has the following limitations or restrictions
              with regard to binary logging:
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        <p>
         NDB Cluster cannot produce a binary log for tables
                having
         <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types">
          <code class="literal">
           BLOB
          </code>
         </a>
         columns but
                no primary key.
        </p>
       </li>
       <li class="listitem">
        <p>
         Only the following schema operations are logged in a
                cluster binary log which is
         <span class="emphasis">
          <em>
           not
          </em>
         </span>
         on
                the
         <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
          <span class="command">
           <strong>
            mysqld
           </strong>
          </span>
         </a>
         executing the statement:
        </p>
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           <p>
            <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
             <code class="literal">
              CREATE TABLE
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
             <code class="literal">
              ALTER TABLE
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement">
             <code class="literal">
              DROP TABLE
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="create-database.html" title="15.1.12 CREATE DATABASE Statement">
             <code class="literal">
              CREATE DATABASE
             </code>
            </a>
            /
            <a class="link" href="create-database.html" title="15.1.12 CREATE DATABASE Statement">
             <code class="literal">
              CREATE
                    SCHEMA
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="drop-database.html" title="15.1.24 DROP DATABASE Statement">
             <code class="literal">
              DROP DATABASE
             </code>
            </a>
            /
            <a class="link" href="drop-database.html" title="15.1.24 DROP DATABASE Statement">
             <code class="literal">
              DROP
                    SCHEMA
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement">
             <code class="literal">
              CREATE TABLESPACE
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement">
             <code class="literal">
              ALTER TABLESPACE
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="drop-tablespace.html" title="15.1.33 DROP TABLESPACE Statement">
             <code class="literal">
              DROP TABLESPACE
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="create-logfile-group.html" title="15.1.16 CREATE LOGFILE GROUP Statement">
             <code class="literal">
              CREATE LOGFILE GROUP
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="alter-logfile-group.html" title="15.1.6 ALTER LOGFILE GROUP Statement">
             <code class="literal">
              ALTER LOGFILE GROUP
             </code>
            </a>
           </p>
          </li>
          <li class="listitem">
           <p>
            <a class="link" href="drop-logfile-group.html" title="15.1.28 DROP LOGFILE GROUP Statement">
             <code class="literal">
              DROP LOGFILE GROUP
             </code>
            </a>
           </p>
          </li>
         </ul>
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       </li>
      </ul>
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    </li>
    <li class="listitem">
     <p>
      <b>
       Schema operations.
      </b>
      Schema operations (DDL statements) are rejected while any
              data node restarts. Schema operations are also not
              supported while performing an online upgrade or downgrade.
     </p>
    </li>
    <li class="listitem">
     <p>
      <b>
       Number of fragment replicas.
      </b>
      The number of fragment replicas, as determined by the
      <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-noofreplicas">
       <code class="literal">
        NoOfReplicas
       </code>
      </a>
      data
              node configuration parameter, is the number of copies of
              all data stored by NDB Cluster. Setting this parameter to
              1 means there is only a single copy; in this case, no
              redundancy is provided, and the loss of a data node
              entails loss of data. To guarantee redundancy, and thus
              preservation of data even if a data node fails, set this
              parameter to 2, which is the default and recommended value
              in production.
     </p>
     <p>
      Setting
      <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-noofreplicas">
       <code class="literal">
        NoOfReplicas
       </code>
      </a>
      to a value greater than 2 is supported (to a maximum of 4)
            but unnecessary to guard against loss of data.
     </p>
    </li>
   </ul>
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  <p>
   See also
   <a class="xref" href="mysql-cluster-limitations-multiple-nodes.html" title="25.2.7.10 Limitations Relating to Multiple NDB Cluster Nodes">
    Section 25.2.7.10, “Limitations Relating to Multiple NDB Cluster Nodes”
   </a>
   .
  </p>
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