<div id="docs-body">
 <div class="section">
  <div class="titlepage">
   <div>
    <div>
     <h4 class="title">
      <a name="mysql-cluster-api-definition">
      </a>
      25.4.3.7 Defining SQL and Other API Nodes in an NDB Cluster
     </h4>
    </div>
   </div>
  </div>
  <a class="indexterm" name="idm46045114596848">
  </a>
  <a class="indexterm" name="idm46045114595360">
  </a>
  <a class="indexterm" name="idm46045114593872">
  </a>
  <p>
   The
   <code class="literal">
    [mysqld]
   </code>
   and
   <code class="literal">
    [api]
   </code>
   sections in the
   <code class="filename">
    config.ini
   </code>
   file define the
        behavior of the MySQL servers (SQL nodes) and other applications
        (API nodes) used to access cluster data. None of the parameters
        shown is required. If no computer or host name is provided, any
        host can use this SQL or API node.
  </p>
  <p>
   Generally speaking, a
   <code class="literal">
    [mysqld]
   </code>
   section is
        used to indicate a MySQL server providing an SQL interface to
        the cluster, and an
   <code class="literal">
    [api]
   </code>
   section is used for
        applications other than
   <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
    <span class="command">
     <strong>
      mysqld
     </strong>
    </span>
   </a>
   processes
        accessing cluster data, but the two designations are actually
        synonymous; you can, for instance, list parameters for a MySQL
        server acting as an SQL node in an
   <code class="literal">
    [api]
   </code>
   section.
  </p>
  <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
   <div class="admon-title">
    Note
   </div>
   <p>
    For a discussion of MySQL server options for NDB Cluster, see
    <a class="xref" href="mysql-cluster-options-variables.html#mysql-cluster-program-options-mysqld" title="25.4.3.9.1 MySQL Server Options for NDB Cluster">
     Section 25.4.3.9.1, “MySQL Server Options for NDB Cluster”
    </a>
    . For
          information about MySQL server system variables relating to
          NDB Cluster, see
    <a class="xref" href="mysql-cluster-options-variables.html#mysql-cluster-system-variables" title="25.4.3.9.2 NDB Cluster System Variables">
     Section 25.4.3.9.2, “NDB Cluster System Variables”
    </a>
    .
   </p>
  </div>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <a name="ndbparam-api-id">
      </a>
      <code class="literal">
       Id
      </code>
     </p>
     <a class="indexterm" name="idm46045114581088">
     </a>
     <div class="informaltable">
      <a name="id-api-table">
      </a>
      <table frame="box" rules="all" summary="Id API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          unsigned
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          [...]
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          1 - 255
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Initial System Restart:
            </strong>
           </span>
           Requires a complete shutdown of the
                    cluster, wiping and restoring the cluster file
                    system from a
           <a class="link" href="mysql-cluster-backup.html" title="25.6.8 Online Backup of NDB Cluster">
            backup
           </a>
           ,
                    and then restarting the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      The
      <code class="literal">
       Id
      </code>
      is an integer value used to
            identify the node in all cluster internal messages. The
            permitted range of values is 1 to 255 inclusive. This value
            must be unique for each node in the cluster, regardless of
            the type of node.
     </p>
     <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
      <div class="admon-title">
       Note
      </div>
      <p>
       Data node IDs must be less than 145. If you plan to deploy
              a large number of data nodes, it is a good idea to limit
              the node IDs for API nodes (and management nodes) to
              values greater than 144.
      </p>
     </div>
     <p>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-nodeid">
       <code class="literal">
        NodeId
       </code>
      </a>
      is the
            preferred parameter name to use when identifying API nodes.
            (
      <code class="literal">
       Id
      </code>
      continues to be supported for
            backward compatibility, but is now deprecated and generates
            a warning when used. It is also subject to future removal.)
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-connectionmap">
      </a>
      <code class="literal">
       ConnectionMap
      </code>
     </p>
     <a class="indexterm" name="idm46045114556688">
     </a>
     <div class="informaltable">
      <a name="connectionmap-api-table">
      </a>
      <table frame="box" rules="all" summary="ConnectionMap API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          string
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          [...]
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          ...
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      Specifies which data nodes to connect.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-nodeid">
      </a>
      <code class="literal">
       NodeId
      </code>
     </p>
     <a class="indexterm" name="idm46045114536928">
     </a>
     <div class="informaltable">
      <a name="nodeid-api-table">
      </a>
      <table frame="box" rules="all" summary="NodeId API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          unsigned
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          [...]
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          1 - 255
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Initial System Restart:
            </strong>
           </span>
           Requires a complete shutdown of the
                    cluster, wiping and restoring the cluster file
                    system from a
           <a class="link" href="mysql-cluster-backup.html" title="25.6.8 Online Backup of NDB Cluster">
            backup
           </a>
           ,
                    and then restarting the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      The
      <code class="literal">
       NodeId
      </code>
      is an integer value used to
            identify the node in all cluster internal messages. The
            permitted range of values is 1 to 255 inclusive. This value
            must be unique for each node in the cluster, regardless of
            the type of node.
     </p>
     <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
      <div class="admon-title">
       Note
      </div>
      <p>
       Data node IDs must be less than 145. If you plan to deploy
              a large number of data nodes, it is a good idea to limit
              the node IDs for API nodes (and management nodes) to
              values greater than 144.
      </p>
     </div>
     <p>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-nodeid">
       <code class="literal">
        NodeId
       </code>
      </a>
      is the
            preferred parameter name to use when identifying management
            nodes. An alias,
      <code class="literal">
       Id
      </code>
      , was used for this
            purpose in very old versions of NDB Cluster, and continues
            to be supported for backward compatibility; it is now
            deprecated and generates a warning when used, and is subject
            to removal in a future release of NDB Cluster.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-executeoncomputer">
      </a>
      <code class="literal">
       ExecuteOnComputer
      </code>
     </p>
     <a class="indexterm" name="idm46045114512288">
     </a>
     <div class="informaltable">
      <a name="executeoncomputer-api-table">
      </a>
      <table frame="box" rules="all" summary="ExecuteOnComputer API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          name
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          [...]
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          ...
         </td>
        </tr>
        <tr>
         <th>
          Deprecated
         </th>
         <td>
          Yes (in NDB 7.5)
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             System Restart:
            </strong>
           </span>
           Requires a complete shutdown and restart
                    of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      This refers to the
      <code class="literal">
       Id
      </code>
      set for one of the
            computers (hosts) defined in a
      <code class="literal">
       [computer]
      </code>
      section of the configuration file.
     </p>
     <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
      <div class="admon-title">
       Important
      </div>
      <p>
       This parameter is deprecated, and is subject to removal in
              a future release. Use the
       <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-hostname">
        <code class="literal">
         HostName
        </code>
       </a>
       parameter
              instead.
      </p>
     </div>
    </li>
    <li class="listitem">
     <a name="ndbparam-api-dedicated">
     </a>
     <a class="indexterm" name="idm46045114488496">
     </a>
     <p>
     </p>
     <p>
      The node ID for this node can be given out only to
            connections that explicitly request it. A management server
            that requests
      <span class="quote">
       “
       <span class="quote">
        any
       </span>
       ”
      </span>
      node ID cannot use this
            one. This parameter can be used when running multiple
            management servers on the same host, and
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-hostname">
       <code class="literal">
        HostName
       </code>
      </a>
      is not
            sufficient for distinguishing among processes.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-hostname">
      </a>
      <code class="literal">
       HostName
      </code>
     </p>
     <a class="indexterm" name="idm46045114482272">
     </a>
     <div class="informaltable">
      <a name="hostname-api-table">
      </a>
      <table frame="box" rules="all" summary="HostName API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          name or IP address
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          [...]
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          ...
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      Specifying this parameter defines the hostname of the
            computer on which the SQL node (API node) is to reside. Use
      <code class="literal">
       HostName
      </code>
      to specify a host name other
            than
      <code class="literal">
       localhost
      </code>
      .
     </p>
     <p>
      If no
      <code class="literal">
       HostName
      </code>
      is specified in a given
      <code class="literal">
       [mysql]
      </code>
      or
      <code class="literal">
       [api]
      </code>
      section of the
      <code class="filename">
       config.ini
      </code>
      file, then an
            SQL or API node may connect using the corresponding
      <span class="quote">
       “
       <span class="quote">
        slot
       </span>
       ”
      </span>
      from any host which can establish a
            network connection to the management server host machine.
      <span class="emphasis">
       <em>
        This differs from the default behavior for data
            nodes, where
        <code class="literal">
         localhost
        </code>
        is assumed for
        <code class="literal">
         HostName
        </code>
        unless otherwise
            specified
       </em>
      </span>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-locationdomainid">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-locationdomainid">
       <code class="literal">
        LocationDomainId
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114454368">
     </a>
     <div class="informaltable">
      <a name="locationdomainid-api-table">
      </a>
      <table frame="box" rules="all" summary="LocationDomainId API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          integer
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          0
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          0 - 16
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             System Restart:
            </strong>
           </span>
           Requires a complete shutdown and restart
                    of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      Assigns an SQL or other API node to a specific
      <a class="ulink" href="https://docs.us-phoenix-1.oraclecloud.com/Content/General/Concepts/regions.htm" target="_blank">
       availability
            domain
      </a>
      (also known as an availability zone) within a
            cloud. By informing
      <code class="literal">
       NDB
      </code>
      which nodes are
            in which availability domains, performance can be improved
            in a cloud environment in the following ways:
     </p>
     <div class="itemizedlist">
      <ul class="itemizedlist" style="list-style-type: circle; ">
       <li class="listitem">
        <p>
         If requested data is not found on the same node, reads
                can be directed to another node in the same availability
                domain.
        </p>
       </li>
       <li class="listitem">
        <p>
         Communication between nodes in different availability
                domains are guaranteed to use
         <code class="literal">
          NDB
         </code>
         transporters' WAN support without any further
                manual intervention.
        </p>
       </li>
       <li class="listitem">
        <p>
         The transporter's group number can be based on
                which availability domain is used, such that also SQL
                and other API nodes communicate with local data nodes in
                the same availability domain whenever possible.
        </p>
       </li>
       <li class="listitem">
        <p>
         The arbitrator can be selected from an availability
                domain in which no data nodes are present, or, if no
                such availability domain can be found, from a third
                availability domain.
        </p>
       </li>
      </ul>
     </div>
     <p>
      <code class="literal">
       LocationDomainId
      </code>
      takes an integer value
            between 0 and 16 inclusive, with 0 being the default; using
            0 is the same as leaving the parameter unset.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-arbitrationrank">
      </a>
      <code class="literal">
       ArbitrationRank
      </code>
     </p>
     <a class="indexterm" name="idm46045114427280">
     </a>
     <div class="informaltable">
      <a name="arbitrationrank-api-table">
      </a>
      <table frame="box" rules="all" summary="ArbitrationRank API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          0-2
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          0
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          0 - 2
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      This parameter defines which nodes can act as arbitrators.
            Both management nodes and SQL nodes can be arbitrators. A
            value of 0 means that the given node is never used as an
            arbitrator, a value of 1 gives the node high priority as an
            arbitrator, and a value of 2 gives it low priority. A normal
            configuration uses the management server as arbitrator,
            setting its
      <code class="literal">
       ArbitrationRank
      </code>
      to 1 (the
            default for management nodes) and those for all SQL nodes to
            0 (the default for SQL nodes).
     </p>
     <p>
      By setting
      <code class="literal">
       ArbitrationRank
      </code>
      to 0 on all
            management and SQL nodes, you can disable arbitration
            completely. You can also control arbitration by overriding
            this parameter; to do so, set the
      <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-arbitration">
       <code class="literal">
        Arbitration
       </code>
      </a>
      parameter in the
      <code class="literal">
       [ndbd default]
      </code>
      section
            of the
      <code class="filename">
       config.ini
      </code>
      global configuration
            file.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-arbitrationdelay">
      </a>
      <code class="literal">
       ArbitrationDelay
      </code>
     </p>
     <a class="indexterm" name="idm46045114402208">
     </a>
     <div class="informaltable">
      <a name="arbitrationdelay-api-table">
      </a>
      <table frame="box" rules="all" summary="ArbitrationDelay API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          milliseconds
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          0
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          0 - 4294967039 (0xFFFFFEFF)
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      Setting this parameter to any other value than 0 (the
            default) means that responses by the arbitrator to
            arbitration requests are delayed by the stated number of
            milliseconds. It is usually not necessary to change this
            value.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-batchbytesize">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-batchbytesize">
       <code class="literal">
        BatchByteSize
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114381472">
     </a>
     <div class="informaltable">
      <a name="batchbytesize-api-table">
      </a>
      <table frame="box" rules="all" summary="BatchByteSize API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          bytes
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          16K
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          1K - 1M
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      For queries that are translated into full table scans or
            range scans on indexes, it is important for best performance
            to fetch records in properly sized batches. It is possible
            to set the proper size both in terms of number of records
            (
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-batchsize">
       <code class="literal">
        BatchSize
       </code>
      </a>
      ) and in
            terms of bytes (
      <code class="literal">
       BatchByteSize
      </code>
      ). The
            actual batch size is limited by both parameters.
     </p>
     <p>
      The speed at which queries are performed can vary by more
            than 40% depending upon how this parameter is set.
     </p>
     <p>
      This parameter is measured in bytes. The default value is
            16K.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-batchsize">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-batchsize">
       <code class="literal">
        BatchSize
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114357888">
     </a>
     <div class="informaltable">
      <a name="batchsize-api-table">
      </a>
      <table frame="box" rules="all" summary="BatchSize API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          records
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          256
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          1 - 992
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      This parameter is measured in number of records and is by
            default set to 256. The maximum size is 992.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-extrasendbuffermemory">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-extrasendbuffermemory">
       <code class="literal">
        ExtraSendBufferMemory
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114337392">
     </a>
     <div class="informaltable">
      <a name="extrasendbuffermemory-api-table">
      </a>
      <table frame="box" rules="all" summary="ExtraSendBufferMemory API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          bytes
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          0
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          0 - 4294967039 (0xFFFFFEFF)
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      This parameter specifies the amount of transporter send
            buffer memory to allocate in addition to any that has been
            set using
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-totalsendbuffermemory">
       <code class="literal">
        TotalSendBufferMemory
       </code>
      </a>
      ,
      <a class="link" href="mysql-cluster-tcp-definition.html#ndbparam-tcp-sendbuffermemory">
       <code class="literal">
        SendBufferMemory
       </code>
      </a>
      , or
            both.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-heartbeatthreadpriority">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-heartbeatthreadpriority">
       <code class="literal">
        HeartbeatThreadPriority
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114313888">
     </a>
     <div class="informaltable">
      <a name="heartbeatthreadpriority-api-table">
      </a>
      <table frame="box" rules="all" summary="HeartbeatThreadPriority API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          string
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          [...]
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          ...
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      Use this parameter to set the scheduling policy and priority
            of heartbeat threads for management and API nodes. The
            syntax for setting this parameter is shown here:
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa94625309"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">HeartbeatThreadPriority <span class="token operator">=</span> <em class="replaceable">policy</em><span class="token punctuation">[</span><span class="token punctuation">,</span> <em class="replaceable">priority</em><span class="token punctuation">]</span>

<em class="replaceable">policy</em><span class="token operator">:</span>
  <span class="token punctuation">{</span>FIFO <span class="token operator">|</span> RR<span class="token punctuation">}</span></code></pre>
     </div>
     <p>
      When setting this parameter, you must specify a policy. This
            is one of
      <code class="literal">
       FIFO
      </code>
      (first in, first in) or
      <code class="literal">
       RR
      </code>
      (round robin). This followed
            optionally by the priority (an integer).
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-maxscanbatchsize">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-maxscanbatchsize">
       <code class="literal">
        MaxScanBatchSize
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114289072">
     </a>
     <div class="informaltable">
      <a name="maxscanbatchsize-api-table">
      </a>
      <table frame="box" rules="all" summary="MaxScanBatchSize API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          bytes
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          256K
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          32K - 16M
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      The batch size is the size of each batch sent from each data
            node. Most scans are performed in parallel to protect the
            MySQL Server from receiving too much data from many nodes in
            parallel; this parameter sets a limit to the total batch
            size over all nodes.
     </p>
     <p>
      The default value of this parameter is set to 256KB. Its
            maximum size is 16MB.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-totalsendbuffermemory">
      </a>
      <code class="literal">
       TotalSendBufferMemory
      </code>
     </p>
     <a class="indexterm" name="idm46045114268448">
     </a>
     <div class="informaltable">
      <a name="totalsendbuffermemory-api-table">
      </a>
      <table frame="box" rules="all" summary="TotalSendBufferMemory API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          bytes
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          0
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          256K - 4294967039 (0xFFFFFEFF)
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      This parameter is used to determine the total amount of
            memory to allocate on this node for shared send buffer
            memory among all configured transporters.
     </p>
     <p>
      If this parameter is set, its minimum permitted value is
            256KB; 0 indicates that the parameter has not been set. For
            more detailed information, see
      <a class="xref" href="mysql-cluster-config-send-buffers.html" title="25.4.3.14 Configuring NDB Cluster Send Buffer Parameters">
       Section 25.4.3.14, “Configuring NDB Cluster Send Buffer Parameters”
      </a>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-autoreconnect">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-autoreconnect">
       <code class="literal">
        AutoReconnect
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114246224">
     </a>
     <div class="informaltable">
      <a name="autoreconnect-api-table">
      </a>
      <table frame="box" rules="all" summary="AutoReconnect API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          boolean
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          false
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          true, false
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      This parameter is
      <code class="literal">
       false
      </code>
      by default. This
            forces disconnected API nodes (including MySQL Servers
            acting as SQL nodes) to use a new connection to the cluster
            rather than attempting to re-use an existing one, as re-use
            of connections can cause problems when using
            dynamically-allocated node IDs. (Bug #45921)
     </p>
     <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
      <div class="admon-title">
       Note
      </div>
      <p>
       This parameter can be overridden using the NDB API. For
              more information, see
       <a class="ulink" href="/doc/ndbapi/en/ndb-ndb-cluster-connection.html#ndb-ndb-cluster-connection-set-auto-reconnect" target="_top">
        Ndb_cluster_connection::set_auto_reconnect()
       </a>
       ,
              and
       <a class="ulink" href="/doc/ndbapi/en/ndb-ndb-cluster-connection.html#ndb-ndb-cluster-connection-get-auto-reconnect" target="_top">
        Ndb_cluster_connection::get_auto_reconnect()
       </a>
       .
      </p>
     </div>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-defaultoperationredoproblemaction">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-defaultoperationredoproblemaction">
       <code class="literal">
        DefaultOperationRedoProblemAction
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114221648">
     </a>
     <div class="informaltable">
      <a name="defaultoperationredoproblemaction-api-table">
      </a>
      <table frame="box" rules="all" summary="DefaultOperationRedoProblemAction API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          enumeration
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          QUEUE
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          ABORT, QUEUE
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      This parameter (along with
      <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redoovercommitlimit">
       <code class="literal">
        RedoOverCommitLimit
       </code>
      </a>
      and
      <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redoovercommitcounter">
       <code class="literal">
        RedoOverCommitCounter
       </code>
      </a>
      )
            controls the data node's handling of operations when
            too much time is taken flushing redo logs to disk. This
            occurs when a given redo log flush takes longer than
      <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redoovercommitlimit">
       <code class="literal">
        RedoOverCommitLimit
       </code>
      </a>
      seconds, more than
      <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redoovercommitcounter">
       <code class="literal">
        RedoOverCommitCounter
       </code>
      </a>
      times, causing any pending transactions to be aborted.
     </p>
     <p>
      When this happens, the node can respond in either of two
            ways, according to the value of
      <code class="literal">
       DefaultOperationRedoProblemAction
      </code>
      , listed
            here:
     </p>
     <div class="itemizedlist">
      <ul class="itemizedlist" style="list-style-type: circle; ">
       <li class="listitem">
        <p>
         <code class="literal">
          ABORT
         </code>
         : Any pending operations from
                aborted transactions are also aborted.
        </p>
       </li>
       <li class="listitem">
        <p>
         <code class="literal">
          QUEUE
         </code>
         : Pending operations from
                transactions that were aborted are queued up to be
                re-tried. This the default. Pending operations are still
                aborted when the redo log runs out of space—that
                is, when
         <span class="errorname">
          P_TAIL_PROBLEM
         </span>
         errors
                occur.
        </p>
       </li>
      </ul>
     </div>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-defaulthashmapsize">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-defaulthashmapsize">
       <code class="literal">
        DefaultHashMapSize
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114189696">
     </a>
     <div class="informaltable">
      <a name="defaulthashmapsize-api-table">
      </a>
      <table frame="box" rules="all" summary="DefaultHashMapSize API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          buckets
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          3840
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          0 - 3840
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      The size of the table hash maps used by
      <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
       <code class="literal">
        NDB
       </code>
      </a>
      is configurable using this
            parameter.
      <code class="literal">
       DefaultHashMapSize
      </code>
      can take
            any of three possible values (0, 240, 3840). These values
            and their effects are described in the following table.
     </p>
     <div class="table">
      <a name="idm46045114169664">
      </a>
      <p class="title">
       <b>
        Table 25.16 DefaultHashMapSize parameter values
       </b>
      </p>
      <div class="table-contents">
       <table>
        <colgroup>
         <col style="width: 20%"/>
         <col style="width: 80%"/>
        </colgroup>
        <thead>
         <tr>
          <th>
           Value
          </th>
          <th>
           Description / Effect
          </th>
         </tr>
        </thead>
        <tbody>
         <tr>
          <td>
           <code class="literal">
            0
           </code>
          </td>
          <td>
           Use the lowest value set, if any, for this parameter among all data
                  nodes and API nodes in the cluster; if it is not set
                  on any data or API node, use the default value.
          </td>
         </tr>
         <tr>
          <td>
           <code class="literal">
            240
           </code>
          </td>
          <td>
           Old default hash map size
          </td>
         </tr>
         <tr>
          <td>
           <code class="literal">
            3840
           </code>
          </td>
          <td>
           Hash map size used by default in NDB 8.4
          </td>
         </tr>
        </tbody>
       </table>
      </div>
     </div>
     <br class="table-break"/>
     <p>
      The original intended use for this parameter was to
            facilitate upgrades and downgrades to and from older NDB
            Cluster versions, in which the hash map size differed, due
            to the fact that this change was not otherwise backward
            compatible.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-wan">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-wan">
       <code class="literal">
        Wan
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114153456">
     </a>
     <div class="informaltable">
      <a name="wan-api-table">
      </a>
      <table frame="box" rules="all" summary="wan API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          boolean
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          false
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          true, false
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      Use WAN TCP setting as default.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-connectbackoffmaxtime">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-connectbackoffmaxtime">
       <code class="literal">
        ConnectBackoffMaxTime
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114133056">
     </a>
     <div class="informaltable">
      <a name="connectbackoffmaxtime-api-table">
      </a>
      <table frame="box" rules="all" summary="ConnectBackoffMaxTime API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          integer
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          0
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          0 - 4294967039 (0xFFFFFEFF)
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      In an NDB Cluster with many unstarted data nodes, the value
            of this parameter can be raised to circumvent connection
            attempts to data nodes which have not yet begun to function
            in the cluster, as well as moderate high traffic to
            management nodes. As long as the API node is not connected
            to any new data nodes, the value of the
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-startconnectbackoffmaxtime">
       <code class="literal">
        StartConnectBackoffMaxTime
       </code>
      </a>
      parameter is applied; otherwise,
      <code class="literal">
       ConnectBackoffMaxTime
      </code>
      is used to
            determine the length of time in milliseconds to wait between
            connection attempts.
     </p>
     <p>
      Time elapsed
      <span class="emphasis">
       <em>
        during
       </em>
      </span>
      node connection
            attempts is not taken into account when calculating elapsed
            time for this parameter. The timeout is applied with
            approximately 100 ms resolution, starting with a 100 ms
            delay; for each subsequent attempt, the length of this
            period is doubled until it reaches
      <code class="literal">
       ConnectBackoffMaxTime
      </code>
      milliseconds, up to
            a maximum of 100000 ms (100s).
     </p>
     <p>
      Once the API node is connected to a data node and that node
            reports (in a heartbeat message) that it has connected to
            other data nodes, connection attempts to those data nodes
            are no longer affected by this parameter, and are made every
            100 ms thereafter until connected. Once a data node has
            started, it can take up
      <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-heartbeatintervaldbapi">
       <code class="literal">
        HeartbeatIntervalDbApi
       </code>
      </a>
      for the API node to be notified that this has occurred.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a name="ndbparam-api-startconnectbackoffmaxtime">
      </a>
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-startconnectbackoffmaxtime">
       <code class="literal">
        StartConnectBackoffMaxTime
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045114105728">
     </a>
     <div class="informaltable">
      <a name="startconnectbackoffmaxtime-api-table">
      </a>
      <table frame="box" rules="all" summary="StartConnectBackoffMaxTime API node configuration parameter type and value information" width="35%">
       <colgroup>
        <col style="width: 50%"/>
        <col style="width: 50%"/>
       </colgroup>
       <tbody>
        <tr>
         <th>
          Version (or later)
         </th>
         <td>
          NDB 8.4.0
         </td>
        </tr>
        <tr>
         <th>
          Type or units
         </th>
         <td>
          integer
         </td>
        </tr>
        <tr>
         <th>
          Default
         </th>
         <td>
          0
         </td>
        </tr>
        <tr>
         <th>
          Range
         </th>
         <td>
          0 - 4294967039 (0xFFFFFEFF)
         </td>
        </tr>
        <tr>
         <th>
          Restart Type
         </th>
         <td>
          <p>
           <span class="bold">
            <strong>
             Node Restart:
            </strong>
           </span>
           Requires a
           <a class="link" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
            rolling
                    restart
           </a>
           of the cluster. (NDB 8.4.0)
          </p>
         </td>
        </tr>
       </tbody>
      </table>
     </div>
     <p>
      In an NDB Cluster with many unstarted data nodes, the value
            of this parameter can be raised to circumvent connection
            attempts to data nodes which have not yet begun to function
            in the cluster, as well as moderate high traffic to
            management nodes. As long as the API node is not connected
            to any new data nodes, the value of the
      <code class="literal">
       StartConnectBackoffMaxTime
      </code>
      parameter is
            applied; otherwise,
      <a class="link" href="mysql-cluster-api-definition.html#ndbparam-api-connectbackoffmaxtime">
       <code class="literal">
        ConnectBackoffMaxTime
       </code>
      </a>
      is used to determine the length of time in milliseconds to
            wait between connection attempts.
     </p>
     <p>
      Time elapsed
      <span class="emphasis">
       <em>
        during
       </em>
      </span>
      node connection
            attempts is not taken into account when calculating elapsed
            time for this parameter. The timeout is applied with
            approximately 100 ms resolution, starting with a 100 ms
            delay; for each subsequent attempt, the length of this
            period is doubled until it reaches
      <code class="literal">
       StartConnectBackoffMaxTime
      </code>
      milliseconds,
            up to a maximum of 100000 ms (100s).
     </p>
     <p>
      Once the API node is connected to a data node and that node
            reports (in a heartbeat message) that it has connected to
            other data nodes, connection attempts to those data nodes
            are no longer affected by this parameter, and are made every
            100 ms thereafter until connected. Once a data node has
            started, it can take up
      <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-heartbeatintervaldbapi">
       <code class="literal">
        HeartbeatIntervalDbApi
       </code>
      </a>
      for the API node to be notified that this has occurred.
     </p>
    </li>
   </ul>
  </div>
  <p>
   <a name="ndbparam-api-apiverbose">
   </a>
   <b>
    API Node Debugging Parameters.
   </b>
   You can use the
   <code class="literal">
    ApiVerbose
   </code>
   configuration
          parameter to enable debugging output from a given API node.
          This parameter takes an integer value. 0 is the default, and
          disables such debugging; 1 enables debugging output to the
          cluster log; 2 adds
   <a class="ulink" href="/doc/ndb-internals/en/ndb-internals-kernel-blocks-dbdict.html" target="_top">
    <code class="literal">
     DBDICT
    </code>
   </a>
   debugging output as well. (Bug #20638450) See also
   <a class="ulink" href="/doc/ndb-internals/en/dump-command-1229.html" target="_top">
    DUMP 1229
   </a>
   .
  </p>
  <p>
   You can also obtain information from a MySQL server running as
        an NDB Cluster SQL node using
   <a class="link" href="show-status.html" title="15.7.7.37 SHOW STATUS Statement">
    <code class="literal">
     SHOW
        STATUS
    </code>
   </a>
   in the
   <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
    <span class="command">
     <strong>
      mysql
     </strong>
    </span>
   </a>
   client, as
        shown here:
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa96556202"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SHOW</span> <span class="token keyword">STATUS</span> <span class="token operator">LIKE</span> <span class="token string">'ndb%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Variable_name               <span class="token punctuation">|</span> Value          <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Ndb_cluster_node_id         <span class="token punctuation">|</span> 5              <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Ndb_config_from_host        <span class="token punctuation">|</span> 198.51.100.112 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Ndb_config_from_port        <span class="token punctuation">|</span> 1186           <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Ndb_number_of_storage_nodes <span class="token punctuation">|</span> 4              <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">4 rows in set (0.02 sec)</span></code></pre>
  </div>
  <p>
   For information about the status variables appearing in the
        output from this statement, see
   <a class="xref" href="mysql-cluster-options-variables.html#mysql-cluster-status-variables" title="25.4.3.9.3 NDB Cluster Status Variables">
    Section 25.4.3.9.3, “NDB Cluster Status Variables”
   </a>
   .
  </p>
  <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
   <div class="admon-title">
    Note
   </div>
   <p>
    To add new SQL or API nodes to the configuration of a running
          NDB Cluster, it is necessary to perform a rolling restart of
          all cluster nodes after adding new
    <code class="literal">
     [mysqld]
    </code>
    or
    <code class="literal">
     [api]
    </code>
    sections to the
    <code class="filename">
     config.ini
    </code>
    file (or files, if you are
          using more than one management server). This must be done
          before the new SQL or API nodes can connect to the cluster.
   </p>
   <p>
    It is
    <span class="emphasis">
     <em>
      not
     </em>
    </span>
    necessary to perform any
          restart of the cluster if new SQL or API nodes can employ
          previously unused API slots in the cluster configuration to
          connect to the cluster.
   </p>
  </div>
  <p>
   <a name="mysql-cluster-api-definition-restart-types">
   </a>
   <b>
    Restart types.
   </b>
   Information about the restart types used by the parameter
          descriptions in this section is shown in the following table:
  </p>
  <div class="table">
   <a name="idm46045114063744">
   </a>
   <p class="title">
    <b>
     Table 25.17 NDB Cluster restart types
    </b>
   </p>
   <div class="table-contents">
    <table>
     <colgroup>
      <col style="width: 10%"/>
      <col style="width: 30%"/>
      <col style="width: 60%"/>
     </colgroup>
     <thead>
      <tr>
       <th scope="col">
        Symbol
       </th>
       <th scope="col">
        Restart Type
       </th>
       <th scope="col">
        Description
       </th>
      </tr>
     </thead>
     <tbody>
      <tr>
       <th scope="row">
        N
       </th>
       <td>
        Node
       </td>
       <td>
        The parameter can be updated using a rolling restart (see
        <a class="xref" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster">
         Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster”
        </a>
        )
       </td>
      </tr>
      <tr>
       <th scope="row">
        S
       </th>
       <td>
        System
       </td>
       <td>
        All cluster nodes must be shut down completely, then restarted, to
              effect a change in this parameter
       </td>
      </tr>
      <tr>
       <th scope="row">
        I
       </th>
       <td>
        Initial
       </td>
       <td>
        Data nodes must be restarted using the
        <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial">
         <code class="option">
          --initial
         </code>
        </a>
        option
       </td>
      </tr>
     </tbody>
    </table>
   </div>
  </div>
  <br class="table-break"/>
 </div>
 <br/>
</div>
