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itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="name">Leader Election</span><meta itemprop="position" content="2"></li></ul></nav><div class="tocCollapsible_ETCw theme-doc-toc-mobile tocMobile_ITEo"><button type="button" class="clean-btn tocCollapsibleButton_TO0P">On this page</button></div><div class="theme-doc-markdown markdown"><header><h1>Leader-Election</h1></header>
<p>RxDB comes with a leader-election which elects a leading instance between different instances in the same javascript runtime.
Before you read this, please check out on how many of your open browser-tabs you have opened the same website more than once. Count them, I will wait..</p>
<p>So if you would now inspect the traffic that these open tabs produce, you can see that many of them send exact the same data over wire for every tab. No matter if the data is sent with an open websocket or by polling.</p>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="use-case-example">Use-case-example<a href="#use-case-example" class="hash-link" aria-label="Direct link to Use-case-example" title="Direct link to Use-case-example"></a></h2>
<p>Imagine we have a website which displays the current temperature of the visitors location in various charts, numbers or heatmaps. To always display the live-data, the website opens a websocket to our API-Server which sends the current temperature every 10 seconds. Using the way most sites are currently build, we can now open it in 5 browser-tabs and it will open 5 websockets which send data 6*5=30 times per minute. This will not only waste the power of your clients device, but also wastes your api-servers resources by opening redundant connections.</p>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="solution">Solution<a href="#solution" class="hash-link" aria-label="Direct link to Solution" title="Direct link to Solution"></a></h2>
<p>The solution to this redundancy is the usage of a <a href="https://en.wikipedia.org/wiki/Leader_election" target="_blank" rel="noopener noreferrer">leader-election</a>-algorithm which makes sure that always exactly one tab is managing the remote-data-access. The managing tab is the elected leader and stays leader until it is closed. No matter how many tabs are opened or closed, there must be always exactly <strong>one</strong> leader.
You could now start implementing a messaging-system between your browser-tabs, hand out which one is leader, solve conflicts and reassign a new leader when the old one 'dies'.
Or just use RxDB which does all these things for you.</p>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="add-the-leader-election-plugin">Add the leader election plugin<a href="#add-the-leader-election-plugin" class="hash-link" aria-label="Direct link to Add the leader election plugin" title="Direct link to Add the leader election plugin"></a></h2>
<p>To enable the leader election, you have to add the <code>leader-election</code> plugin.</p>
<div class="language-javascript codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-javascript codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token keyword module" style="color:rgb(189, 147, 249);font-style:italic">import</span><span class="token plain"> </span><span class="token imports punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token imports"> addRxPlugin </span><span class="token imports punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"> </span><span class="token keyword module" style="color:rgb(189, 147, 249);font-style:italic">from</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'rxdb'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword module" style="color:rgb(189, 147, 249);font-style:italic">import</span><span class="token plain"> </span><span class="token imports punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token imports"> </span><span class="token imports maybe-class-name">RxDBLeaderElectionPlugin</span><span class="token imports"> </span><span class="token imports punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"> </span><span class="token keyword module" style="color:rgb(189, 147, 249);font-style:italic">from</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'rxdb/plugins/leader-election'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token function" style="color:rgb(80, 250, 123)">addRxPlugin</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token maybe-class-name">RxDBLeaderElectionPlugin</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="code-example">Code-example<a href="#code-example" class="hash-link" aria-label="Direct link to Code-example" title="Direct link to Code-example"></a></h2>
<p>To make it easy, here is an example where the temperature is pulled every ten seconds and saved to a collection. The pulling starts at the moment where the opened tab becomes the leader.</p>
<div class="language-javascript codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-javascript codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> db </span><span class="token operator">=</span><span class="token plain"> </span><span class="token keyword control-flow" style="color:rgb(189, 147, 249);font-style:italic">await</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">createRxDatabase</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">name</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'weatherDB'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">storage</span><span class="token operator">:</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">getRxStorageDexie</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">password</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'myPassword'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">multiInstance</span><span class="token operator">:</span><span class="token plain"> </span><span class="token boolean">true</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword control-flow" style="color:rgb(189, 147, 249);font-style:italic">await</span><span class="token plain"> db</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token method function property-access" style="color:rgb(80, 250, 123)">addCollections</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">temperature</span><span class="token operator">:</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">schema</span><span class="token operator">:</span><span class="token plain"> mySchema</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">db</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token method function property-access" style="color:rgb(80, 250, 123)">waitForLeadership</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token method function property-access" style="color:rgb(80, 250, 123)">then</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token arrow operator">=></span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token console class-name">console</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token method function property-access" style="color:rgb(80, 250, 123)">log</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">'Long lives the king!'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// <- runs when db becomes leader</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">setInterval</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">async</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token arrow operator">=></span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> temp </span><span class="token operator">=</span><span class="token plain"> </span><span class="token keyword control-flow" style="color:rgb(189, 147, 249);font-style:italic">await</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">fetch</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">'https://example.com/api/temp/'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> db</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token property-access">temperature</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token method function property-access" style="color:rgb(80, 250, 123)">insert</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">degrees</span><span class="token operator">:</span><span class="token plain"> temp</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">time</span><span class="token operator">:</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">new</span><span class="token plain"> </span><span class="token class-name">Date</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token method function property-access" style="color:rgb(80, 250, 123)">getTime</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> </span><span class="token number">1000</span><span class="token plain"> </span><span class="token operator">*</span><span class="token plain"> </span><span class="token number">10</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="handle-duplicate-leaders">Handle Duplicate Leaders<a href="#handle-duplicate-leaders" class="hash-link" aria-label="Direct link to Handle Duplicate Leaders" title="Direct link to Handle Duplicate Leaders"></a></h2>
<p>On rare occasions, it can happen that <a href="https://github.com/pubkey/broadcast-channel/blob/master/.github/README.md#handle-duplicate-leaders" target="_blank" rel="noopener noreferrer">more than one leader</a> is elected. This can happen when the CPU is on 100% or for any other reason the JavaScript process is fully blocked for a long time.
For most cases this is not really problem because on duplicate leaders, both browser tabs replicate with the same backend anyways.
To handle the duplicate leader event, you can access the leader elector and set a handler:</p>
<div class="language-ts codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-ts codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">import</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> getLeaderElectorByBroadcastChannel</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">from</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'rxdb/plugins/leader-election'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> leaderElector </span><span class="token operator">=</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">getLeaderElectorByBroadcastChannel</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">broadcastChannel</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">leaderElector</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function-variable function" style="color:rgb(80, 250, 123)">onduplicate</span><span class="token plain"> </span><span class="token operator">=</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">async</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token operator">=></span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// Duplicate leader detected -> reload the page.</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> location</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">reload</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="live-example">Live-Example<a href="#live-example" class="hash-link" aria-label="Direct link to Live-Example" title="Direct link to Live-Example"></a></h2>
<p>In this example the leader is marked with the crown ♛</p>
<p align="center"><img src="./files/leader-election.gif" alt="Leader Election" width="300"></p>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="try-it-out">Try it out<a href="#try-it-out" class="hash-link" aria-label="Direct link to Try it out" title="Direct link to Try it out"></a></h2>
<p>Run the <a href="https://github.com/pubkey/rxdb/tree/master/examples/angular" target="_blank" rel="noopener noreferrer">angular-example</a> where the leading tab is marked with a crown on the top-right-corner.</p>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="notice">Notice<a href="#notice" class="hash-link" aria-label="Direct link to Notice" title="Direct link to Notice"></a></h2>
<p>The leader election is implemented via the <a href="https://github.com/pubkey/broadcast-channel#using-the-leaderelection" target="_blank" rel="noopener noreferrer">broadcast-channel module</a>.
The leader is elected between different processes on the same javascript-runtime. Like multiple tabs in the same browser or multiple NodeJs-processes on the same machine. It will not run between different replicated instances.</p></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages"><a class="pagination-nav__link pagination-nav__link--prev" href="/backup.html"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">Backup</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/middleware.html"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">Middleware</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#use-case-example" class="table-of-contents__link toc-highlight">Use-case-example</a></li><li><a href="#solution" class="table-of-contents__link toc-highlight">Solution</a></li><li><a href="#add-the-leader-election-plugin" class="table-of-contents__link toc-highlight">Add the leader election plugin</a></li><li><a href="#code-example" class="table-of-contents__link toc-highlight">Code-example</a></li><li><a href="#handle-duplicate-leaders" class="table-of-contents__link toc-highlight">Handle Duplicate Leaders</a></li><li><a href="#live-example" class="table-of-contents__link toc-highlight">Live-Example</a></li><li><a href="#try-it-out" class="table-of-contents__link toc-highlight">Try it out</a></li><li><a href="#notice" class="table-of-contents__link toc-highlight">Notice</a></li></ul></div></div></div></div></main></div></div></div><div class="block footer"><div class="footer-block"><div class="footer-links"><span><a variant="text" href="/" class="footer-logo-button"><img src="/files/logo/logo.svg" alt="RxDB" loading="lazy"><div>RxDB</div></a><div class="footer-community-links"><a variant="text" href="/chat/" target="_blank"><img src="/img/community-links/discord-logo.svg" alt="RxDB Discord" loading="lazy"></a><a variant="text" href="/code/" target="_blank"><img src="/img/community-links/github-logo.svg" alt="RxDB Github" loading="lazy"></a><a variant="text" href="https://twitter.com/intent/user?screen_name=rxdbjs" target="_blank"><img src="/img/community-links/x-logo.svg" alt="RxDB Twitter" loading="lazy"></a><a variant="text" href="https://www.linkedin.com/company/rxdb" target="_blank"><img src="/img/community-links/linkedin-logo.svg" alt="RxDB LinkedIn" loading="lazy"></a><a variant="text" href="https://stackoverflow.com/questions/tagged/rxdb" target="_blank"><img src="/img/community-links/stack-overflow-logo.svg" alt="RxDB Stack Overflow" loading="lazy"></a></div></span><div class="footer-nav-links"><a variant="text" href="/premium/" target="">Premium</a><a variant="text" href="/consulting/" target="">Support</a><a variant="text" href="/overview.html" target="">Documentation</a><a variant="text" href="/chat/" target="_blank">Discord</a><a variant="text" href="/code/" target="_blank">Github</a><a variant="text" href="https://twitter.com/intent/user?screen_name=rxdbjs" target="_blank">Twitter</a><a variant="text" href="https://www.linkedin.com/company/rxdb" target="_blank">LinkedIn</a></div></div><div class="footer-policy"><div><a variant="text" href="/legal-notice/" target="_blank">Legal Notice</a></div><span class="footer-rights">© 2025 RxDB. All rights reserved.</span></div><img class="footer-img desktop-img" src="/img/footer-column.svg" alt="columns" loading="lazy"></div></div><div class="call-to-action-popup"><div class="close"><div class="text">✕</div></div></div></div>
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