<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Message deduplication · Apache Pulsar</title><meta name="viewport" content="width=device-width, initial-scale=1.0"/><meta name="generator" content="Docusaurus"/><meta name="description" content="When **Message deduplication** is enabled, it ensures that each message produced on Pulsar topics is persisted to disk *only once*, even if the message is produced more than once. Message deduplication is handled automatically on the server side. "/><meta name="docsearch:version" content="2.6.0"/><meta name="docsearch:language" content="en"/><meta property="og:title" content="Message deduplication · Apache Pulsar"/><meta property="og:type" content="website"/><meta property="og:url" content="https://pulsar.apache.org/"/><meta property="og:description" content="When **Message deduplication** is enabled, it ensures that each message produced on Pulsar topics is persisted to disk *only once*, even if the message is produced more than once. Message deduplication is handled automatically on the server side. "/><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>2.6.0</h3></a><div class="navigationWrapper navigationSlider"><nav class="slidingNav"><ul class="nav-site nav-site-internal"><li class="siteNavGroupActive"><a href="/docs/en/2.6.0/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/2.6.0/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/2.6.0/cookbooks-deduplication">日本語</a></li><li><a href="/docs/fr/2.6.0/cookbooks-deduplication">Français</a></li><li><a href="/docs/ko/2.6.0/cookbooks-deduplication">한국어</a></li><li><a href="/docs/zh-CN/2.6.0/cookbooks-deduplication">中文</a></li><li><a href="/docs/zh-TW/2.6.0/cookbooks-deduplication">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>To use message deduplication in Pulsar, you have to <a href="#configure-message-deduplication">configure</a> your Pulsar brokers and <a href="#pulsar-clients">clients</a>.</p>
<blockquote>
<p>For more details on message deduplication, refer to <a href="/docs/en/2.6.0/concepts-messaging#message-deduplication">Concepts and Architecture</a>.</p>
</blockquote>
<h2><a class="anchor" aria-hidden="true" id="how-it-works"></a><a href="#how-it-works" 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 it works</h2>
<p>You can enable or disable message deduplication on a per-namespace basis. By default, it is <em>disabled</em> on all namespaces. You can enable it in the following ways:</p>
<ul>
<li>Enable for all namespaces at the broker-level</li>
<li>Enable for specific namespaces with the <code>pulsar-admin namespaces</code> interface</li>
</ul>
<h2><a class="anchor" aria-hidden="true" id="configure-message-deduplication"></a><a href="#configure-message-deduplication" 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>Configure message deduplication</h2>
<p>You can configure message deduplication in Pulsar using the <a href="/docs/en/2.6.0/reference-configuration#broker"><code>broker.conf</code></a> configuration file. The following deduplication-related parameters are available.</p>
<table>
<thead>
<tr><th style="text-align:left">Parameter</th><th style="text-align:left">Description</th><th style="text-align:left">Default</th></tr>
</thead>
<tbody>
<tr><td style="text-align:left"><code>brokerDeduplicationEnabled</code></td><td style="text-align:left">Sets the default behavior for message deduplication in the Pulsar <a href="/docs/en/2.6.0/reference-terminology#broker">broker</a>. If it is set to <code>true</code>, message deduplication is enabled by default on all namespaces; if it is set to <code>false</code> (the default), you have to enable or disable deduplication on a per-namespace basis.</td><td style="text-align:left"><code>false</code></td></tr>
<tr><td style="text-align:left"><code>brokerDeduplicationMaxNumberOfProducers</code></td><td style="text-align:left">The maximum number of producers for which information is stored for deduplication purposes.</td><td style="text-align:left"><code>10000</code></td></tr>
<tr><td style="text-align:left"><code>brokerDeduplicationEntriesInterval</code></td><td style="text-align:left">The number of entries after which a deduplication informational snapshot is taken. A larger interval leads to fewer snapshots being taken, though this lengthens the topic recovery time (the time required for entries published after the snapshot to be replayed).</td><td style="text-align:left"><code>1000</code></td></tr>
<tr><td style="text-align:left"><code>brokerDeduplicationProducerInactivityTimeoutMinutes</code></td><td style="text-align:left">The time of inactivity (in minutes) after which the broker discards deduplication information related to a disconnected producer.</td><td style="text-align:left"><code>360</code> (6 hours)</td></tr>
</tbody>
</table>
<h3><a class="anchor" aria-hidden="true" id="set-default-value-at-the-broker-level"></a><a href="#set-default-value-at-the-broker-level" 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>Set default value at the broker-level</h3>
<p>By default, message deduplication is <em>disabled</em> on all Pulsar namespaces. To enable it by default on all namespaces, set the <code>brokerDeduplicationEnabled</code> parameter to <code>true</code> and re-start the broker.</p>
<p>Even if you set the value for <code>brokerDeduplicationEnabled</code>, enabling or disabling via Pulsar admin CLI will override the default settings at the broker-level.</p>
<h3><a class="anchor" aria-hidden="true" id="enable-message-deduplication"></a><a href="#enable-message-deduplication" 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>Enable message deduplication</h3>
<p>Though message deduplication is disabled by default at broker-level, you can enable message deduplication for specific namespaces using the <a href="/docs/en/2.6.0/reference-pulsar-admin#namespace-set-deduplication"><code>pulsar-admin namespace set-deduplication</code></a> command. You can use the <code>--enable</code>/<code>-e</code> flag and specify the namespace. The following is an example with <code>&lt;tenant&gt;/&lt;namespace&gt;</code>:</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin namespaces <span class="hljs-built_in">set</span>-deduplication \
  public/default \
  --<span class="hljs-built_in">enable</span> <span class="hljs-comment"># or just -e</span>
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="disable-message-deduplication"></a><a href="#disable-message-deduplication" 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>Disable message deduplication</h3>
<p>Even if you enable message deduplication at broker-level, you can disable message deduplication for a specific namespace using the <a href="/docs/en/2.6.0/reference-pulsar-admin#namespace-set-deduplication"><code>pulsar-admin namespace set-deduplication</code></a> command. Use the <code>--disable</code>/<code>-d</code> flag and specify the namespace. The following is an example with <code>&lt;tenant&gt;/&lt;namespace&gt;</code>:</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin namespaces <span class="hljs-built_in">set</span>-deduplication \
  public/default \
  --<span class="hljs-built_in">disable</span> <span class="hljs-comment"># or just -d</span>
</code></pre>
<h2><a class="anchor" aria-hidden="true" id="pulsar-clients"></a><a href="#pulsar-clients" 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>Pulsar clients</h2>
<p>If you enable message deduplication in Pulsar brokers, you need complete the following tasks for your client producers:</p>
<ol>
<li>Specify a name for the producer.</li>
<li>Set the message timeout to <code>0</code> (namely, no timeout).</li>
</ol>
<p>The instructions for Java, Python, and C++ clients are different.</p>
<div class="tabs"><div class="nav-tabs"><div id="tab-group-9800-tab-9801" class="nav-link active" data-group="group_9800" data-tab="tab-group-9800-content-9801">Java clients</div><div id="tab-group-9800-tab-9802" class="nav-link" data-group="group_9800" data-tab="tab-group-9800-content-9802">Python clients</div><div id="tab-group-9800-tab-9803" class="nav-link" data-group="group_9800" data-tab="tab-group-9800-content-9803">C++ clients</div></div><div class="tab-content"><div id="tab-group-9800-content-9801" class="tab-pane active" data-group="group_9800" tabindex="-1"><div><span><p>To enable message deduplication on a <a href="/docs/en/2.6.0/client-libraries-java#producers">Java producer</a>, set the producer name using the <code>producerName</code> setter, and set the timeout to <code>0</code> using the <code>sendTimeout</code> setter.</p>
<pre><code class="hljs css language-java"><span class="hljs-keyword">import</span> org.apache.pulsar.client.api.Producer;<br /><span class="hljs-keyword">import</span> org.apache.pulsar.client.api.PulsarClient;<br /><span class="hljs-keyword">import</span> java.util.concurrent.TimeUnit;<br /><br />PulsarClient pulsarClient = PulsarClient.builder()<br />        .serviceUrl(<span class="hljs-string">"pulsar://localhost:6650"</span>)<br />        .build();<br />Producer producer = pulsarClient.newProducer()<br />        .producerName(<span class="hljs-string">"producer-1"</span>)<br />        .topic(<span class="hljs-string">"persistent://public/default/topic-1"</span>)<br />        .sendTimeout(<span class="hljs-number">0</span>, TimeUnit.SECONDS)<br />        .create();<br /></code></pre>
</span></div></div><div id="tab-group-9800-content-9802" class="tab-pane" data-group="group_9800" tabindex="-1"><div><span><p>To enable message deduplication on a <a href="/docs/en/2.6.0/client-libraries-python#producers">Python producer</a>, set the producer name using <code>producer_name</code>, and set the timeout to <code>0</code> using <code>send_timeout_millis</code>.</p>
<pre><code class="hljs css language-python"><span class="hljs-keyword">import</span> pulsar<br /><br />client = pulsar.Client(<span class="hljs-string">"pulsar://localhost:6650"</span>)<br />producer = client.create_producer(<br />    <span class="hljs-string">"persistent://public/default/topic-1"</span>,<br />    producer_name=<span class="hljs-string">"producer-1"</span>,<br />    send_timeout_millis=<span class="hljs-number">0</span>)<br /></code></pre>
</span></div></div><div id="tab-group-9800-content-9803" class="tab-pane" data-group="group_9800" tabindex="-1"><div><span><p>To enable message deduplication on a <a href="/docs/en/2.6.0/client-libraries-cpp#producer">C++ producer</a>, set the producer name using <code>producer_name</code>, and set the timeout to <code>0</code> using <code>send_timeout_millis</code>.</p>
<pre><code class="hljs css language-cpp"><span class="hljs-meta">#<span class="hljs-meta-keyword">include</span> <span class="hljs-meta-string">&lt;pulsar/Client.h&gt;</span></span><br /><br /><span class="hljs-built_in">std</span>::<span class="hljs-built_in">string</span> serviceUrl = <span class="hljs-string">"pulsar://localhost:6650"</span>;<br /><span class="hljs-built_in">std</span>::<span class="hljs-built_in">string</span> topic = <span class="hljs-string">"persistent://some-tenant/ns1/topic-1"</span>;<br /><span class="hljs-built_in">std</span>::<span class="hljs-built_in">string</span> producerName = <span class="hljs-string">"producer-1"</span>;<br /><br /><span class="hljs-function">Client <span class="hljs-title">client</span><span class="hljs-params">(serviceUrl)</span></span>;<br /><br />ProducerConfiguration producerConfig;<br />producerConfig.setSendTimeout(<span class="hljs-number">0</span>);<br />producerConfig.setProducerName(producerName);<br /><br />Producer producer;<br /><br />Result result = client.createProducer(topic, producerConfig, producer);<br /></code></pre>
</span></div></div></div></div></span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/en/2.6.0/cookbooks-compaction"><span class="arrow-prev">← </span><span>Topic compaction</span></a><a class="docs-next button" href="/docs/en/2.6.0/cookbooks-non-persistent"><span>Non-persistent messaging</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#how-it-works">How it works</a></li><li><a href="#configure-message-deduplication">Configure message deduplication</a><ul class="toc-headings"><li><a href="#set-default-value-at-the-broker-level">Set default value at the broker-level</a></li><li><a href="#enable-message-deduplication">Enable message deduplication</a></li><li><a href="#disable-message-deduplication">Disable message deduplication</a></li></ul></li><li><a href="#pulsar-clients">Pulsar clients</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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