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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">  <html lang="en"> <head>  <title>ConsistencyLevel (apache-cassandra API)</title> <meta name="date" content="2014-09-07"> <link rel="stylesheet" type="text/css" href="../../../../stylesheet.css" title="Style"> </head> <body> <script type="text/javascript"> </script> <noscript> <div>JavaScript is disabled on your browser.</div> </noscript>  <div class="topNav"><a name="navbar_top">  </a><a href="#skip-navbar_top" title="Skip navigation links"></a><a name="navbar_top_firstrow">  </a> <ul class="navList" title="Navigation"> <li><a href="../../../../overview-summary.html">Overview</a></li> <li><a href="package-summary.html">Package</a></li> <li class="navBarCell1Rev">Class</li> <li><a href="class-use/ConsistencyLevel.html">Use</a></li> <li><a href="package-tree.html">Tree</a></li> <li><a href="../../../../deprecated-list.html">Deprecated</a></li> <li><a href="../../../../index-all.html">Index</a></li> <li><a href="../../../../help-doc.html">Help</a></li> </ul> </div> <div class="subNav"> <ul class="navList"> <li><a href="../../../../org/apache/cassandra/thrift/Compression.html" title="enum in org.apache.cassandra.thrift"><span class="strong">Prev Class</span></a></li> <li><a href="../../../../org/apache/cassandra/thrift/CounterColumn.html" title="class in org.apache.cassandra.thrift"><span class="strong">Next Class</span></a></li> </ul> <ul class="navList"> <li><a href="../../../../index.html?org/apache/cassandra/thrift/ConsistencyLevel.html" target="_top">Frames</a></li> <li><a href="ConsistencyLevel.html" target="_top">No Frames</a></li> </ul> <ul class="navList" id="allclasses_navbar_top"> <li><a href="../../../../allclasses-noframe.html">All Classes</a></li> </ul> <div> <script type="text/javascript"> </script> </div> <div> <ul class="subNavList"> <li>Summary: </li> <li>Nested | </li> <li><a href="#enum_constant_summary">Enum Constants</a> | </li> <li>Field | </li> <li><a href="#method_summary">Method</a></li> </ul> <ul class="subNavList"> <li>Detail: </li> <li><a href="#enum_constant_detail">Enum Constants</a> | </li> <li>Field | </li> <li><a href="#method_detail">Method</a></li> </ul> </div> <a name="skip-navbar_top">  </a></div>   <div class="header"> <div class="subTitle">org.apache.cassandra.thrift</div> <h2 title="Enum ConsistencyLevel" class="title">Enum ConsistencyLevel</h2> </div> <div class="contentContainer"> <ul class="inheritance"> <li>java.lang.Object</li> <li> <ul class="inheritance"> <li>java.lang.Enum<<a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a>></li> <li> <ul class="inheritance"> <li>org.apache.cassandra.thrift.ConsistencyLevel</li> </ul> </li> </ul> </li> </ul> <div class="description"> <ul class="blockList"> <li class="blockList"> <dl> <dt>All Implemented Interfaces:</dt> <dd>java.io.Serializable, java.lang.Comparable<<a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a>>, org.apache.thrift.TEnum</dd> </dl> <hr> <br> <pre>public enum <span class="strong">ConsistencyLevel</span> extends java.lang.Enum<<a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a>> implements org.apache.thrift.TEnum</pre> <div class="block">The ConsistencyLevel is an enum that controls both read and write behavior based on the ReplicationFactor of the keyspace. The different consistency levels have different meanings, depending on if you're doing a write or read operation. If W + R > ReplicationFactor, where W is the number of nodes to block for on write, and R the number to block for on reads, you will have strongly consistent behavior; that is, readers will always see the most recent write. Of these, the most interesting is to do QUORUM reads and writes, which gives you consistency while still allowing availability in the face of node failures up to half of <ReplicationFactor>. Of course if latency is more important than consistency then you can use lower values for either or both. Some ConsistencyLevels (ONE, TWO, THREE) refer to a specific number of replicas rather than a logical concept that adjusts automatically with the replication factor. Of these, only ONE is commonly used; TWO and (even more rarely) THREE are only useful when you care more about guaranteeing a certain level of durability, than consistency. Write consistency levels make the following guarantees before reporting success to the client: ANY Ensure that the write has been written once somewhere, including possibly being hinted in a non-target node. ONE Ensure that the write has been written to at least 1 node's commit log and memory table TWO Ensure that the write has been written to at least 2 node's commit log and memory table THREE Ensure that the write has been written to at least 3 node's commit log and memory table QUORUM Ensure that the write has been written to <ReplicationFactor> / 2 + 1 nodes LOCAL_ONE Ensure that the write has been written to 1 node within the local datacenter (requires NetworkTopologyStrategy) LOCAL_QUORUM Ensure that the write has been written to <ReplicationFactor> / 2 + 1 nodes, within the local datacenter (requires NetworkTopologyStrategy) EACH_QUORUM Ensure that the write has been written to <ReplicationFactor> / 2 + 1 nodes in each datacenter (requires NetworkTopologyStrategy) ALL Ensure that the write is written to <code><ReplicationFactor></code> nodes before responding to the client. Read consistency levels make the following guarantees before returning successful results to the client: ANY Not supported. You probably want ONE instead. ONE Returns the record obtained from a single replica. TWO Returns the record with the most recent timestamp once two replicas have replied. THREE Returns the record with the most recent timestamp once three replicas have replied. QUORUM Returns the record with the most recent timestamp once a majority of replicas have replied. LOCAL_ONE Returns the record with the most recent timestamp once a single replica within the local datacenter have replied. LOCAL_QUORUM Returns the record with the most recent timestamp once a majority of replicas within the local datacenter have replied. EACH_QUORUM Returns the record with the most recent timestamp once a majority of replicas within each datacenter have replied. ALL Returns the record with the most recent timestamp once all replicas have replied (implies no replica may be down)..</div> </li> </ul> </div> <div class="summary"> <ul class="blockList"> <li class="blockList">  <ul class="blockList"> <li class="blockList"><a name="enum_constant_summary">  </a> <h3>Enum Constant Summary</h3> <table class="overviewSummary" border="0" cellpadding="3" cellspacing="0" summary="Enum Constant Summary table, listing enum constants, and an explanation"> <caption><span>Enum Constants</span><span class="tabEnd"> </span></caption> <tr> <th class="colOne" scope="col">Enum Constant and Description</th> </tr> <tr class="altColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#ALL">ALL</a></strong></code> </td> </tr> <tr class="rowColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#ANY">ANY</a></strong></code> </td> </tr> <tr class="altColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#EACH_QUORUM">EACH_QUORUM</a></strong></code> </td> </tr> <tr class="rowColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#LOCAL_ONE">LOCAL_ONE</a></strong></code> </td> </tr> <tr class="altColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#LOCAL_QUORUM">LOCAL_QUORUM</a></strong></code> </td> </tr> <tr class="rowColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#LOCAL_SERIAL">LOCAL_SERIAL</a></strong></code> </td> </tr> <tr class="altColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#ONE">ONE</a></strong></code> </td> </tr> <tr class="rowColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#QUORUM">QUORUM</a></strong></code> </td> </tr> <tr class="altColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#SERIAL">SERIAL</a></strong></code> </td> </tr> <tr class="rowColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#THREE">THREE</a></strong></code> </td> </tr> <tr class="altColor"> <td class="colOne"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#TWO">TWO</a></strong></code> </td> </tr> </table> </li> </ul>  <ul class="blockList"> <li class="blockList"><a name="method_summary">  </a> <h3>Method Summary</h3> <table class="overviewSummary" border="0" cellpadding="3" cellspacing="0" summary="Method Summary table, listing methods, and an explanation"> <caption><span>Methods</span><span class="tabEnd"> </span></caption> <tr> <th class="colFirst" scope="col">Modifier and Type</th> <th class="colLast" scope="col">Method and Description</th> </tr> <tr class="altColor"> <td class="colFirst"><code>static <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a></code></td> <td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#findByValue(int)">findByValue</a></strong>(int value)</code> <div class="block">Find a the enum type by its integer value, as defined in the Thrift IDL.</div> </td> </tr> <tr class="rowColor"> <td class="colFirst"><code>int</code></td> <td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#getValue()">getValue</a></strong>()</code> <div class="block">Get the integer value of this enum value, as defined in the Thrift IDL.</div> </td> </tr> <tr class="altColor"> <td class="colFirst"><code>static <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a></code></td> <td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#valueOf(java.lang.String)">valueOf</a></strong>(java.lang.String name)</code> <div class="block">Returns the enum constant of this type with the specified name.</div> </td> </tr> <tr class="rowColor"> <td class="colFirst"><code>static <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a>[]</code></td> <td class="colLast"><code><strong><a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html#values()">values</a></strong>()</code> <div class="block">Returns an array containing the constants of this enum type, in the order they are declared.</div> </td> </tr> </table> <ul class="blockList"> <li class="blockList"><a name="methods_inherited_from_class_java.lang.Enum">  </a> <h3>Methods inherited from class java.lang.Enum</h3> <code>clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf</code></li> </ul> <ul class="blockList"> <li class="blockList"><a name="methods_inherited_from_class_java.lang.Object">  </a> <h3>Methods inherited from class java.lang.Object</h3> <code>getClass, notify, notifyAll, wait, wait, wait</code></li> </ul> </li> </ul> </li> </ul> </div> <div class="details"> <ul class="blockList"> <li class="blockList">  <ul class="blockList"> <li class="blockList"><a name="enum_constant_detail">  </a> <h3>Enum Constant Detail</h3> <a name="ONE">  </a> <ul class="blockList"> <li class="blockList"> <h4>ONE</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> ONE</pre> </li> </ul> <a name="QUORUM">  </a> <ul class="blockList"> <li class="blockList"> <h4>QUORUM</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> QUORUM</pre> </li> </ul> <a name="LOCAL_QUORUM">  </a> <ul class="blockList"> <li class="blockList"> <h4>LOCAL_QUORUM</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> LOCAL_QUORUM</pre> </li> </ul> <a name="EACH_QUORUM">  </a> <ul class="blockList"> <li class="blockList"> <h4>EACH_QUORUM</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> EACH_QUORUM</pre> </li> </ul> <a name="ALL">  </a> <ul class="blockList"> <li class="blockList"> <h4>ALL</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> ALL</pre> </li> </ul> <a name="ANY">  </a> <ul class="blockList"> <li class="blockList"> <h4>ANY</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> ANY</pre> </li> </ul> <a name="TWO">  </a> <ul class="blockList"> <li class="blockList"> <h4>TWO</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> TWO</pre> </li> </ul> <a name="THREE">  </a> <ul class="blockList"> <li class="blockList"> <h4>THREE</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> THREE</pre> </li> </ul> <a name="SERIAL">  </a> <ul class="blockList"> <li class="blockList"> <h4>SERIAL</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> SERIAL</pre> </li> </ul> <a name="LOCAL_SERIAL">  </a> <ul class="blockList"> <li class="blockList"> <h4>LOCAL_SERIAL</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> LOCAL_SERIAL</pre> </li> </ul> <a name="LOCAL_ONE">  </a> <ul class="blockListLast"> <li class="blockList"> <h4>LOCAL_ONE</h4> <pre>public static final <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> LOCAL_ONE</pre> </li> </ul> </li> </ul>  <ul class="blockList"> <li class="blockList"><a name="method_detail">  </a> <h3>Method Detail</h3> <a name="values()">  </a> <ul class="blockList"> <li class="blockList"> <h4>values</h4> <pre>public static <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a>[] values()</pre> <div class="block">Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows: <pre> for (ConsistencyLevel c : ConsistencyLevel.values())   System.out.println(c); </pre></div> <dl><dt><span class="strong">Returns:</span></dt><dd>an array containing the constants of this enum type, in the order they are declared</dd></dl> </li> </ul> <a name="valueOf(java.lang.String)">  </a> <ul class="blockList"> <li class="blockList"> <h4>valueOf</h4> <pre>public static <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> valueOf(java.lang.String name)</pre> <div class="block">Returns the enum constant of this type with the specified name. The string must match <i>exactly</i> an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)</div> <dl><dt><span class="strong">Parameters:</span></dt><dd><code>name</code> - the name of the enum constant to be returned.</dd> <dt><span class="strong">Returns:</span></dt><dd>the enum constant with the specified name</dd> <dt><span class="strong">Throws:</span></dt> <dd><code>java.lang.IllegalArgumentException</code> - if this enum type has no constant with the specified name</dd> <dd><code>java.lang.NullPointerException</code> - if the argument is null</dd></dl> </li> </ul> <a name="getValue()">  </a> <ul class="blockList"> <li class="blockList"> <h4>getValue</h4> <pre>public int getValue()</pre> <div class="block">Get the integer value of this enum value, as defined in the Thrift IDL.</div> <dl> <dt><strong>Specified by:</strong></dt> <dd><code>getValue</code> in interface <code>org.apache.thrift.TEnum</code></dd> </dl> </li> </ul> <a name="findByValue(int)">  </a> <ul class="blockListLast"> <li class="blockList"> <h4>findByValue</h4> <pre>public static <a href="../../../../org/apache/cassandra/thrift/ConsistencyLevel.html" title="enum in org.apache.cassandra.thrift">ConsistencyLevel</a> findByValue(int value)</pre> <div class="block">Find a the enum type by its integer value, as defined in the Thrift IDL.</div> <dl><dt><span class="strong">Returns:</span></dt><dd>null if the value is not found.</dd></dl> </li> </ul> </li> </ul> </li> </ul> </div> </div>   <div class="bottomNav"><a name="navbar_bottom">  </a><a href="#skip-navbar_bottom" title="Skip navigation links"></a><a name="navbar_bottom_firstrow">  </a> <ul class="navList" title="Navigation"> <li><a href="../../../../overview-summary.html">Overview</a></li> <li><a href="package-summary.html">Package</a></li> <li class="navBarCell1Rev">Class</li> <li><a href="class-use/ConsistencyLevel.html">Use</a></li> <li><a href="package-tree.html">Tree</a></li> <li><a href="../../../../deprecated-list.html">Deprecated</a></li> <li><a href="../../../../index-all.html">Index</a></li> <li><a href="../../../../help-doc.html">Help</a></li> </ul> </div> <div class="subNav"> <ul class="navList"> <li><a href="../../../../org/apache/cassandra/thrift/Compression.html" title="enum in org.apache.cassandra.thrift"><span class="strong">Prev Class</span></a></li> <li><a href="../../../../org/apache/cassandra/thrift/CounterColumn.html" title="class in org.apache.cassandra.thrift"><span class="strong">Next Class</span></a></li> </ul> <ul class="navList"> <li><a href="../../../../index.html?org/apache/cassandra/thrift/ConsistencyLevel.html" target="_top">Frames</a></li> <li><a href="ConsistencyLevel.html" target="_top">No Frames</a></li> </ul> <ul class="navList" id="allclasses_navbar_bottom"> <li><a href="../../../../allclasses-noframe.html">All Classes</a></li> </ul> <div> <script type="text/javascript"> </script> </div> <div> <ul class="subNavList"> <li>Summary: </li> <li>Nested | </li> <li><a href="#enum_constant_summary">Enum Constants</a> | </li> <li>Field | </li> <li><a href="#method_summary">Method</a></li> </ul> <ul class="subNavList"> <li>Detail: </li> <li><a href="#enum_constant_detail">Enum Constants</a> | </li> <li>Field | </li> <li><a href="#method_detail">Method</a></li> </ul> </div> <a name="skip-navbar_bottom">  </a></div>  <p class="legalCopy"><small>Copyright © 2014 The Apache Software Foundation</small></p> </body> </html>