<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Partitioned topics · Apache Pulsar</title><meta name="viewport" content="width=device-width, initial-scale=1.0"/><meta name="generator" content="Docusaurus"/><meta name="description" content="By default, Pulsar topics are served by a single broker. Using only a single broker limits a topic&#x27;s maximum throughput. *Partitioned topics* are a special type of topic that can span multiple brokers and thus allow for much higher throughput. For an explanation of how partitioned topics work, see the [Partitioned Topics](/docs/en/2.5.1/concepts-messaging#partitioned-topics) concepts."/><meta name="docsearch:version" content="2.5.1"/><meta name="docsearch:language" content="en"/><meta property="og:title" content="Partitioned topics · Apache Pulsar"/><meta property="og:type" content="website"/><meta property="og:url" content="https://pulsar.apache.org/"/><meta property="og:description" content="By default, Pulsar topics are served by a single broker. Using only a single broker limits a topic&#x27;s maximum throughput. *Partitioned topics* are a special type of topic that can span multiple brokers and thus allow for much higher throughput. For an explanation of how partitioned topics work, see the [Partitioned Topics](/docs/en/2.5.1/concepts-messaging#partitioned-topics) concepts."/><meta name="twitter:card" content="summary"/><meta name="twitter:image" content="https://pulsar.apache.org/img/pulsar.svg"/><link rel="shortcut icon" href="/img/pulsar.ico"/><link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/atom-one-dark.min.css"/><link rel="alternate" type="application/atom+xml" href="https://pulsar.apache.org/blog/atom.xml" title="Apache Pulsar Blog ATOM Feed"/><link rel="alternate" type="application/rss+xml" href="https://pulsar.apache.org/blog/feed.xml" title="Apache Pulsar Blog RSS Feed"/><link rel="stylesheet" href="/css/code-blocks-buttons.css"/><script type="text/javascript" src="https://buttons.github.io/buttons.js"></script><script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/2.0.0/clipboard.min.js"></script><script type="text/javascript" src="/js/custom.js"></script><script src="/js/scrollSpy.js"></script><link rel="stylesheet" href="/css/main.css"/><script src="/js/codetabs.js"></script></head><body class="sideNavVisible separateOnPageNav"><div class="fixedHeaderContainer"><div class="headerWrapper wrapper"><header><a href="/en"><img class="logo" src="/img/pulsar.svg" alt="Apache Pulsar"/></a><a href="/en/versions"><h3>2.5.1</h3></a><div class="navigationWrapper navigationSlider"><nav class="slidingNav"><ul class="nav-site nav-site-internal"><li class="siteNavGroupActive"><a href="/docs/en/2.5.1/getting-started-standalone" target="_self">Docs</a></li><li class=""><a href="/en/download" target="_self">Download</a></li><li class="siteNavGroupActive"><a href="/docs/en/2.5.1/client-libraries" target="_self">Clients</a></li><li class=""><a href="#restapis" target="_self">REST APIs</a></li><li class=""><a href="#cli" target="_self">Cli</a></li><li class=""><a href="/blog/" target="_self">Blog</a></li><li class=""><a href="#community" target="_self">Community</a></li><li class=""><a href="#apache" target="_self">Apache</a></li><li class=""><a href="https://pulsar-next.staged.apache.org/" target="_self">New Website (Beta)</a></li><span><li><a id="languages-menu" href="#"><img class="languages-icon" src="/img/language.svg" alt="Languages icon"/>English</a><div id="languages-dropdown" class="hide"><ul id="languages-dropdown-items"><li><a href="/docs/ja/2.5.1/cookbooks-partitioned">日本語</a></li><li><a href="/docs/fr/2.5.1/cookbooks-partitioned">Français</a></li><li><a href="/docs/ko/2.5.1/cookbooks-partitioned">한국어</a></li><li><a href="/docs/zh-CN/2.5.1/cookbooks-partitioned">中文</a></li><li><a href="/docs/zh-TW/2.5.1/cookbooks-partitioned">繁體中文</a></li><li><a href="https://crowdin.com/project/apache-pulsar" target="_blank" rel="noreferrer noopener">Help Translate</a></li></ul></div></li><script>
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<p>You can publish to partitioned topics using Pulsar client libraries and you can <a href="#managing-partitioned-topics">create and manage</a> partitioned topics using Pulsar <a href="/docs/en/2.5.1/admin-api-overview">admin API</a>.</p>
<h2><a class="anchor" aria-hidden="true" id="publish-to-partitioned-topics"></a><a href="#publish-to-partitioned-topics" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Publish to partitioned topics</h2>
<p>When publishing to partitioned topics, you do not need to explicitly specify a <a href="/docs/en/2.5.1/concepts-messaging#routing-modes">routing mode</a> when you create a new producer. If you do not specify a routing mode, the round robin route mode is used. Take <a href="#java">Java</a> as an example.</p>
<p>Publishing messages to partitioned topics in the Java client works much like <a href="/docs/en/2.5.1/client-libraries-java#using-producers">publishing to normal topics</a>. The difference is that you need to specify either one of the currently available message routers or a custom router.</p>
<h3><a class="anchor" aria-hidden="true" id="routing-mode"></a><a href="#routing-mode" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Routing mode</h3>
<p>You can specify the routing mode in the ProducerConfiguration object that you use to configure your producer. Three options are available:</p>
<ul>
<li><code>SinglePartition</code></li>
<li><code>RoundRobinPartition</code></li>
<li><code>CustomPartition</code></li>
</ul>
<p>The following is an example:</p>
<pre><code class="hljs css language-java">String pulsarBrokerRootUrl = <span class="hljs-string">"pulsar://localhost:6650"</span>;
String topic = <span class="hljs-string">"persistent://my-tenant/my-namespace/my-topic"</span>;

PulsarClient pulsarClient = PulsarClient.builder().serviceUrl(pulsarBrokerRootUrl).build();
Producer&lt;<span class="hljs-keyword">byte</span>[]&gt; producer = pulsarClient.newProducer()
        .topic(topic)
        .messageRoutingMode(MessageRoutingMode.SinglePartition)
        .create();
producer.send(<span class="hljs-string">"Partitioned topic message"</span>.getBytes());
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="custom-message-router"></a><a href="#custom-message-router" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Custom message router</h3>
<p>To use a custom message router, you need to provide an implementation of the <a href="https://pulsar.apache.org/api/client/2.5.0-SNAPSHOT/org/apache/pulsar/client/api/MessageRouter">MessageRouter</a>
 interface, which has just one <code>choosePartition</code> method:</p>
<pre><code class="hljs css language-java"><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">interface</span> <span class="hljs-title">MessageRouter</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">Serializable</span> </span>{
    <span class="hljs-function"><span class="hljs-keyword">int</span> <span class="hljs-title">choosePartition</span><span class="hljs-params">(Message msg)</span></span>;
}
</code></pre>
<p>The following router routes every message to partition 10:</p>
<pre><code class="hljs css language-java"><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">AlwaysTenRouter</span> <span class="hljs-keyword">implements</span> <span class="hljs-title">MessageRouter</span> </span>{
    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">choosePartition</span><span class="hljs-params">(Message msg)</span> </span>{
        <span class="hljs-keyword">return</span> <span class="hljs-number">10</span>;
    }
}
</code></pre>
<p>With that implementation in hand, you can send</p>
<pre><code class="hljs css language-java">String pulsarBrokerRootUrl = <span class="hljs-string">"pulsar://localhost:6650"</span>;
String topic = <span class="hljs-string">"persistent://my-tenant/my-cluster-my-namespace/my-topic"</span>;

PulsarClient pulsarClient = PulsarClient.builder().serviceUrl(pulsarBrokerRootUrl).build();
Producer&lt;<span class="hljs-keyword">byte</span>[]&gt; producer = pulsarClient.newProducer()
        .topic(topic)
        .messageRouter(<span class="hljs-keyword">new</span> AlwaysTenRouter())
        .create();
producer.send(<span class="hljs-string">"Partitioned topic message"</span>.getBytes());
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="how-to-choose-partitions-when-using-a-key"></a><a href="#how-to-choose-partitions-when-using-a-key" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>How to choose partitions when using a key</h3>
<p>If a message has a key, it supersedes the round robin routing policy. The following example illustrates how to choose partition when you use a key.</p>
<pre><code class="hljs css language-java"><span class="hljs-comment">// If the message has a key, it supersedes the round robin routing policy</span>
        <span class="hljs-keyword">if</span> (msg.hasKey()) {
            <span class="hljs-keyword">return</span> signSafeMod(hash.makeHash(msg.getKey()), topicMetadata.numPartitions());
        }

        <span class="hljs-keyword">if</span> (isBatchingEnabled) { <span class="hljs-comment">// if batching is enabled, choose partition on `partitionSwitchMs` boundary.</span>
            <span class="hljs-keyword">long</span> currentMs = clock.millis();
            <span class="hljs-keyword">return</span> signSafeMod(currentMs / partitionSwitchMs + startPtnIdx, topicMetadata.numPartitions());
        } <span class="hljs-keyword">else</span> {
            <span class="hljs-keyword">return</span> signSafeMod(PARTITION_INDEX_UPDATER.getAndIncrement(<span class="hljs-keyword">this</span>), topicMetadata.numPartitions());
        }
</code></pre>
<h2><a class="anchor" aria-hidden="true" id="manage-partitioned-topics"></a><a href="#manage-partitioned-topics" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Manage partitioned topics</h2>
<p>You can use Pulsar <a href="/docs/en/2.5.1/admin-api-overview">admin API</a> to create and manage <a href="/docs/en/2.5.1/admin-api-partitioned-topics">partitioned topics</a>.</p>
</span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/en/2.5.1/cookbooks-non-persistent"><span class="arrow-prev">← </span><span>Non-persistent messaging</span></a><a class="docs-next button" href="/docs/en/2.5.1/cookbooks-retention-expiry"><span>Message retention and expiry</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#publish-to-partitioned-topics">Publish to partitioned topics</a><ul class="toc-headings"><li><a href="#routing-mode">Routing mode</a></li><li><a href="#custom-message-router">Custom message router</a></li><li><a href="#how-to-choose-partitions-when-using-a-key">How to choose partitions when using a key</a></li></ul></li><li><a href="#manage-partitioned-topics">Manage partitioned topics</a></li></ul></nav></div><footer class="nav-footer" id="footer"><section class="copyright">Copyright © 2022 The Apache Software Foundation. All Rights Reserved. Apache, Apache Pulsar and the Apache feather logo are trademarks of The Apache Software Foundation.</section><span><script>
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