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<div id="class.mongodb-driver-readpreference" class="reference">

 <h1 class="title">A classe MongoDB\Driver\ReadPreference</h1>
 

 <div class="partintro"><p class="verinfo">(mongodb &gt;=1.0.0)</p>


  <div class="section" id="mongodb-driver-readpreference.intro">
   <h2 class="title">Introdução</h2>
   <p class="para">

   </p>
  </div>


  <div class="section" id="mongodb-driver-readpreference.synopsis">
   <h2 class="title">Resumo da classe</h2>


   <div class="classsynopsis">
    <span class="ooclass"><strong class="classname"></strong></span>


    <div class="classsynopsisinfo">
     <span class="modifier">final</span>
     <span class="ooclass">
      <span class="modifier">class</span> <strong class="classname">MongoDB\Driver\ReadPreference</strong>
     </span>

     <span class="oointerface"><span class="modifier">implements</span> 
       <a href="class.mongodb-bson-serializable.php" class="interfacename">MongoDB\BSON\Serializable</a></span><span class="oointerface">,  <a href="class.serializable.php" class="interfacename">Serializable</a></span> {</div>

    <div class="classsynopsisinfo classsynopsisinfo_comment">/* Constantes */</div>
    <div class="fieldsynopsis">
     <span class="modifier">const</span>
     <span class="type"><a href="language.types.string.php" class="type string">string</a></span>
      <var class="fieldsynopsis_varname"><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.primary"><var class="varname">PRIMARY</var></a></var><span class="initializer"> = primary</span>;</div>

    <div class="fieldsynopsis"><span class="modifier">const</span>
     <span class="type"><a href="language.types.string.php" class="type string">string</a></span>
      <var class="fieldsynopsis_varname"><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.primary-preferred"><var class="varname">PRIMARY_PREFERRED</var></a></var><span class="initializer"> = primaryPreferred</span>;</div>

    <div class="fieldsynopsis"><span class="modifier">const</span>
     <span class="type"><a href="language.types.string.php" class="type string">string</a></span>
      <var class="fieldsynopsis_varname"><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.secondary"><var class="varname">SECONDARY</var></a></var><span class="initializer"> = secondary</span>;</div>

    <div class="fieldsynopsis"><span class="modifier">const</span>
     <span class="type"><a href="language.types.string.php" class="type string">string</a></span>
      <var class="fieldsynopsis_varname"><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.secondary-preferred"><var class="varname">SECONDARY_PREFERRED</var></a></var><span class="initializer"> = secondaryPreferred</span>;</div>

    <div class="fieldsynopsis"><span class="modifier">const</span>
     <span class="type"><a href="language.types.string.php" class="type string">string</a></span>
      <var class="fieldsynopsis_varname"><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.nearest"><var class="varname">NEAREST</var></a></var><span class="initializer"> = nearest</span>;</div>

    <div class="fieldsynopsis"><span class="modifier">const</span>
     <span class="type"><a href="language.types.integer.php" class="type int">int</a></span>
      <var class="fieldsynopsis_varname"><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.no-max-staleness"><var class="varname">NO_MAX_STALENESS</var></a></var><span class="initializer"> = -1</span>;</div>

    <div class="fieldsynopsis"><span class="modifier">const</span>
     <span class="type"><a href="language.types.integer.php" class="type int">int</a></span>
      <var class="fieldsynopsis_varname"><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.smallest-max-staleness-seconds"><var class="varname">SMALLEST_MAX_STALENESS_SECONDS</var></a></var><span class="initializer"> = 90</span>;</div>


    <div class="classsynopsisinfo classsynopsisinfo_comment">/* Métodos */</div>
    <div class="methodsynopsis dc-description">
   <span class="modifier">final</span> <span class="modifier">public</span> <span class="methodname"><a href="mongodb-driver-readpreference.bsonserialize.php" class="methodname">bsonSerialize</a></span>(): <span class="type"><a href="class.stdclass.php" class="type stdClass">stdClass</a></span></div>
<div class="methodsynopsis dc-description"><span class="modifier">final</span> <span class="modifier">public</span> <span class="methodname"><a href="mongodb-driver-readpreference.construct.php" class="methodname">__construct</a></span>(<span class="methodparam"><span class="type"><a href="language.types.string.php" class="type string">string</a></span> <code class="parameter">$mode</code></span>, <span class="methodparam"><span class="type"><span class="type"><a href="language.types.null.php" class="type null">?</a></span><span class="type"><a href="language.types.array.php" class="type array">array</a></span></span> <code class="parameter">$tagSets</code><span class="initializer"> = <strong><code><a href="reserved.constants.php#constant.null">null</a></code></strong></span></span>, <span class="methodparam"><span class="type"><span class="type"><a href="language.types.null.php" class="type null">?</a></span><span class="type"><a href="language.types.array.php" class="type array">array</a></span></span> <code class="parameter">$options</code><span class="initializer"> = <strong><code><a href="reserved.constants.php#constant.null">null</a></code></strong></span></span>)</div>
<div class="methodsynopsis dc-description"><span class="modifier">final</span> <span class="modifier">public</span> <span class="methodname"><a href="mongodb-driver-readpreference.gethedge.php" class="methodname">getHedge</a></span>(): <span class="type"><span class="type"><a href="language.types.null.php" class="type null">?</a></span><span class="type"><a href="language.types.object.php" class="type object">object</a></span></span></div>
<div class="methodsynopsis dc-description"><span class="modifier">final</span> <span class="modifier">public</span> <span class="methodname"><a href="mongodb-driver-readpreference.getmaxstalenessseconds.php" class="methodname">getMaxStalenessSeconds</a></span>(): <span class="type"><a href="language.types.integer.php" class="type int">int</a></span></div>
<div class="methodsynopsis dc-description"><span class="modifier">final</span> <span class="modifier">public</span> <span class="methodname"><a href="mongodb-driver-readpreference.getmode.php" class="methodname">getMode</a></span>(): <span class="type"><a href="language.types.integer.php" class="type int">int</a></span></div>
<div class="methodsynopsis dc-description"><span class="modifier">final</span> <span class="modifier">public</span> <span class="methodname"><a href="mongodb-driver-readpreference.getmodestring.php" class="methodname">getModeString</a></span>(): <span class="type"><a href="language.types.string.php" class="type string">string</a></span></div>
<div class="methodsynopsis dc-description"><span class="modifier">final</span> <span class="modifier">public</span> <span class="methodname"><a href="mongodb-driver-readpreference.gettagsets.php" class="methodname">getTagSets</a></span>(): <span class="type"><a href="language.types.array.php" class="type array">array</a></span></div>

   }</div>


  </div>


  <div class="section" id="mongodb-driver-readpreference.constants">
   <h2 class="title">Constantes predefinidas</h2>
   <dl>

    
     <dt id="mongodb-driver-readpreference.constants.primary"><strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.primary">MongoDB\Driver\ReadPreference::PRIMARY</a></code></strong></dt>
     <dd>
      <p class="para">
       Todas as operações são lidas do conjunto de réplicas primário atual. Esta é a
       preferência de leitura padrão do MongoDB.
      </p>
     </dd>
    

    
     <dt id="mongodb-driver-readpreference.constants.primary-preferred"><strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.primary-preferred">MongoDB\Driver\ReadPreference::PRIMARY_PREFERRED</a></code></strong></dt>
     <dd>
      <p class="para">
       Na maioria das situações, as operações são lidas a partir dos membros primários, mas se não
       estiver disponível, as operações são lidas a partir dos membros secundários.
      </p>
     </dd>
    

    
     <dt id="mongodb-driver-readpreference.constants.secondary"><strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.secondary">MongoDB\Driver\ReadPreference::SECONDARY</a></code></strong></dt>
     <dd>
      <p class="para">
       Todas as operações são lidas nos membros secundários do conjunto de réplicas.
      </p>
     </dd>
    

    
     <dt id="mongodb-driver-readpreference.constants.secondary-preferred"><strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.secondary-preferred">MongoDB\Driver\ReadPreference::SECONDARY_PREFERRED</a></code></strong></dt>
     <dd>
      <p class="para">
       Na maioria das situações, as operações são lidas a partir de membros secundários, mas se nenhum
       membro secundário estiver disponível, as operações são lidas a partir do primário.
      </p>
     </dd>
    

    
     <dt id="mongodb-driver-readpreference.constants.nearest"><strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.nearest">MongoDB\Driver\ReadPreference::NEAREST</a></code></strong></dt>
     <dd>
      <p class="para">
       Operações lidas do membro do conjunto de réplicas com a menor latência
       de rede, independentemente do tipo do membro.
      </p>
     </dd>
    

    
     <dt id="mongodb-driver-readpreference.constants.no-max-staleness"><strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.no-max-staleness">MongoDB\Driver\ReadPreference::NO_MAX_STALENESS</a></code></strong></dt>
     <dd>
      <p class="para">
       O valor padrão para a opção <code class="literal">&quot;maxStalenessSeconds&quot;</code>
       é não especificar nenhum limite de inatividade máxima, o que significa que o
       driver não considerará o atraso de um secundário ao escolher para onde
       direcionar uma operação de leitura.
      </p>
     </dd>
    

    
     <dt id="mongodb-driver-readpreference.constants.smallest-max-staleness-seconds"><strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.smallest-max-staleness-seconds">MongoDB\Driver\ReadPreference::SMALLEST_MAX_STALENESS_SECONDS</a></code></strong></dt>
     <dd>
      <p class="para">
       O valor mínimo para a opção <code class="literal">&quot;maxStalenessSeconds&quot;</code>
       é 90 segundos. O driver estima a inatividade dos secundários
       verificando periodicamente a data de gravação mais recente de cada membro do conjunto de réplicas.
       Como essas verificações são pouco frequentes, a estimativa de inatividade é grosseira.
       Assim, o driver não pode impor um valor máximo de inatividade inferior a 90
       segundos.
      </p>
     </dd>
    

   </dl>
  </div>


  <div class="section">
   <h2 class="title">Registro de Alterações</h2>
   <p class="para">
    <table class="doctable informaltable">
     
      <thead>
       <tr>
        <th>Versão</th>
        <th>Descrição</th>
       </tr>

      </thead>

      <tbody class="tbody">
       <tr>
        <td>PECL mongodb 2.0.0</td>
        <td>
         <p class="para">
          Removidas as constantes
          <strong><code>MongoDB\Driver\ReadPreference::RP_PRIMARY</code></strong>,
          <strong><code>MongoDB\Driver\ReadPreference::RP_PRIMARY_PREFERRED</code></strong>,
          <strong><code>MongoDB\Driver\ReadPreference::RP_SECONDARY</code></strong>,
          <strong><code>MongoDB\Driver\ReadPreference::RP_SECONDARY_PREFERRED</code></strong>
          e <strong><code>MongoDB\Driver\ReadPreference::RP_NEAREST</code></strong>.
          O método <span class="methodname"><strong>getMode()</strong></span> também foi removido.
         </p>
        </td>
       </tr>

       <tr>
        <td>PECL mongodb 1.20.0</td>
        <td>
         <p class="para">
          As constantes
          <strong><code>MongoDB\Driver\ReadPreference::RP_PRIMARY</code></strong>,
          <strong><code>MongoDB\Driver\ReadPreference::RP_PRIMARY_PREFERRED</code></strong>,
          <strong><code>MongoDB\Driver\ReadPreference::RP_SECONDARY</code></strong>,
          <strong><code>MongoDB\Driver\ReadPreference::RP_SECONDARY_PREFERRED</code></strong>,
          e <strong><code>MongoDB\Driver\ReadPreference::RP_NEAREST</code></strong>
          foram descontinuadas.
         </p>
        </td>
       </tr>

       <tr>
        <td>PECL mongodb 1.7.0</td>
        <td>
         <p class="para">
          As constantes
          <strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.primary">MongoDB\Driver\ReadPreference::PRIMARY</a></code></strong>,
          <strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.primary-preferred">MongoDB\Driver\ReadPreference::PRIMARY_PREFERRED</a></code></strong>,
          <strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.secondary">MongoDB\Driver\ReadPreference::SECONDARY</a></code></strong>,
          <strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.secondary-preferred">MongoDB\Driver\ReadPreference::SECONDARY_PREFERRED</a></code></strong>,
          e <strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.nearest">MongoDB\Driver\ReadPreference::NEAREST</a></code></strong>
          foram adicionadas.
         </p>
         <p class="para">
          Implementa <span class="interfacename"><a href="class.serializable.php" class="interfacename">Serializable</a></span>.
         </p>
        </td>
       </tr>

       <tr>
        <td>PECL mongodb 1.2.0</td>
        <td>
         <p class="para">
          As constantes
          <strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.no-max-staleness">MongoDB\Driver\ReadPreference::NO_MAX_STALENESS</a></code></strong>
          e
          <strong><code><a href="class.mongodb-driver-readpreference.php#mongodb-driver-readpreference.constants.smallest-max-staleness-seconds">MongoDB\Driver\ReadPreference::SMALLEST_MAX_STALENESS_SECONDS</a></code></strong>
          foram adicionadas.
         </p>
         <p class="para">
          Implementa <span class="interfacename"><a href="class.mongodb-bson-serializable.php" class="interfacename">MongoDB\BSON\Serializable</a></span>.
         </p>
        </td>
       </tr>

      </tbody>
     
    </table>

   </p>
  </div>

 </div>

 

















































<h2>Índice</h2><ul class="chunklist chunklist_reference"><li><a href="mongodb-driver-readpreference.bsonserialize.php">MongoDB\Driver\ReadPreference::bsonSerialize</a> — Retorna um objeto para serializa&ccedil;&atilde;o BSON</li><li><a href="mongodb-driver-readpreference.construct.php">MongoDB\Driver\ReadPreference::__construct</a> — Cria uma nova prefer&ecirc;ncia de leitura</li><li><a href="mongodb-driver-readpreference.gethedge.php">MongoDB\Driver\ReadPreference::getHedge</a> — Retorna a op&ccedil;&atilde;o &quot;hedge&quot; do ReadPreference</li><li><a href="mongodb-driver-readpreference.getmaxstalenessseconds.php">MongoDB\Driver\ReadPreference::getMaxStalenessSeconds</a> — Retorna a op&ccedil;&atilde;o &quot;maxStalenessSeconds&quot; do ReadPreference</li><li><a href="mongodb-driver-readpreference.getmode.php">MongoDB\Driver\ReadPreference::getMode</a> — Retorna a op&ccedil;&atilde;o &quot;mode&quot; do ReadPreference</li><li><a href="mongodb-driver-readpreference.getmodestring.php">MongoDB\Driver\ReadPreference::getModeString</a> — Retorna a op&ccedil;&atilde;o &quot;mode&quot; do ReadPreference</li><li><a href="mongodb-driver-readpreference.gettagsets.php">MongoDB\Driver\ReadPreference::getTagSets</a> — Retorna a op&ccedil;&atilde;o &quot;tagSets&quot; do ReadPreference</li></ul>
</div>
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