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tocCollapsibleButton_TO0P">On this page</button></div><div class="theme-doc-markdown markdown"><header><h1>RxQuery</h1></header>
<p>To find documents inside of an <a href="/rx-collection.html">RxCollection</a>, RxDB uses the RxQuery interface that handles all query operations: it serves as the main interface for fetching documents, relies on a MongoDB-like <a href="https://github.com/cloudant/mango" target="_blank" rel="noopener noreferrer">Mango Query Syntax</a>, and provides three types of queries: <a href="#find">find()</a>, <a href="#findone">findOne()</a> and <a href="#count">count()</a>. By caching and de-duplicating results, RxQuery ensures efficient in-memory handling, and when queries are observed or re-run, the <a href="https://github.com/pubkey/event-reduce" target="_blank" rel="noopener noreferrer">EventReduce algorithm</a> speeds up updates for a fast real-time experience and queries that run more than once.</p>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="find">find()<a href="#find" class="hash-link" aria-label="Direct link to find()" title="Direct link to find()"></a></h2>
<p>To create a basic <code>RxQuery</code>, call <code>.find()</code> on a collection and insert selectors. The result-set of normal queries is an array with documents.</p>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">// find all that are older then 18</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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">find</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">selector</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">age</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">$gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">18</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 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 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="findone">findOne()<a href="#findone" class="hash-link" aria-label="Direct link to findOne()" title="Direct link to findOne()"></a></h2>
<p>A findOne-query has only a single <code>RxDocument</code> or <code>null</code> as result-set.</p>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">// find alice</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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">findOne</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">selector</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">name</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'alice'</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 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>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">// find the youngest one</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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">findOne</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">selector</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 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">sort</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 punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token literal-property property">age</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'asc'</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 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>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">// find one document by the primary key</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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">findOne</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">'foobar'</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="exec">exec()<a href="#exec" class="hash-link" aria-label="Direct link to exec()" title="Direct link to exec()"></a></h2>
<p>Returns a <code>Promise</code> that resolves with the result-set of the query.</p>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js 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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">find</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" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> results </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"> query</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)">exec</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 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)">dir</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">results</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)">// > [RxDocument,RxDocument,RxDocument..]</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>
<p>On <code>.findOne()</code> queries, you can call <code>.exec(true)</code> to ensure your document exists and to make TypeScript handling easier:</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 comment" style="color:rgb(98, 114, 164)">// docOrUndefined can be the type RxDocument or null which then has to be handled to be typesafe.</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"> docOrUndefined </span><span class="token operator">=</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">await</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">findOne</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 function" style="color:rgb(80, 250, 123)">exec</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"></span><span class="token comment" style="color:rgb(98, 114, 164)">// with .exec(true), it will throw if the document cannot be found and always have the type RxDocument</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"> doc </span><span class="token operator">=</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">await</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">findOne</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 function" style="color:rgb(80, 250, 123)">exec</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token boolean">true</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="observe-">Observe $<a href="#observe-" class="hash-link" aria-label="Direct link to Observe $" title="Direct link to Observe $"></a></h2>
<p>An <code>BehaviorSubject</code> <a href="https://medium.com/@luukgruijs/understanding-rxjs-behaviorsubject-replaysubject-and-asyncsubject-8cc061f1cfc0" target="_blank" rel="noopener noreferrer">see</a> that always has the current result-set as value.
This is extremely helpful when used together with UIs that should always show the same state as what is written in the database.</p>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token method function property-access" style="color:rgb(80, 250, 123)">find</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> querySub </span><span class="token operator">=</span><span class="token plain"> query</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token property-access">$</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)">subscribe</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token parameter">results</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)">'got results: '</span><span class="token plain"> </span><span class="token operator">+</span><span class="token plain"> results</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token property-access">length</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 comment" style="color:rgb(98, 114, 164)">// > 'got results: 5' // BehaviorSubjects emit on subscription</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 control-flow" style="color:rgb(189, 147, 249);font-style:italic">await</span><span class="token plain"> myCollection</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 comment" style="color:rgb(98, 114, 164)">/* ... */</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 comment" style="color:rgb(98, 114, 164)">// insert one</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)">// > 'got results: 6' // $.subscribe() was called again with the new results</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 comment" style="color:rgb(98, 114, 164)">// stop watching this query</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">querySub</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)">unsubscribe</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="update">update()<a href="#update" class="hash-link" aria-label="Direct link to update()" title="Direct link to update()"></a></h2>
<p>Runs an <a href="/rx-document.html#update">update</a> on every RxDocument of the query-result.</p>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><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 comment" style="color:rgb(98, 114, 164)">// to use the update() method, you need to add the update plugin.</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">RxDBUpdatePlugin</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/update'</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">RxDBUpdatePlugin</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"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">find</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">selector</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">age</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">$gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">18</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 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 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"> query</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)">update</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">$inc</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">age</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">1</span><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// increases age of every found document by 1</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 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="patch--incrementalpatch">patch() / incrementalPatch()<a href="#patch--incrementalpatch" class="hash-link" aria-label="Direct link to patch() / incrementalPatch()" title="Direct link to patch() / incrementalPatch()"></a></h2>
<p>Runs the <a href="/rx-document.html#patch">RxDocument.patch()</a> function on every RxDocument of the query result.</p>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js 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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">find</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">selector</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">age</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">$gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">18</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 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 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"> query</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)">patch</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">age</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">12</span><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// set the age of every found to 12</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="modify--incrementalmodify">modify() / incrementalModify()<a href="#modify--incrementalmodify" class="hash-link" aria-label="Direct link to modify() / incrementalModify()" title="Direct link to modify() / incrementalModify()"></a></h2>
<p>Runs the <a href="/rx-document.html#modify">RxDocument.modify()</a> function on every RxDocument of the query result.</p>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js 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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">find</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">selector</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">age</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">$gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">18</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 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 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"> query</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)">modify</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 parameter">docData</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"> docData</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token property-access">age</span><span class="token plain"> </span><span class="token operator">=</span><span class="token plain"> docData</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token property-access">age</span><span class="token plain"> </span><span class="token operator">+</span><span class="token plain"> </span><span class="token number">1</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)">// increases age of every found document by 1</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">return</span><span class="token plain"> docData</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="remove--incrementalremove">remove() / incrementalRemove()<a href="#remove--incrementalremove" class="hash-link" aria-label="Direct link to remove() / incrementalRemove()" title="Direct link to remove() / incrementalRemove()"></a></h2>
<p>Deletes all found documents. Returns a promise which resolves to the deleted documents.</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 comment" style="color:rgb(98, 114, 164)">// All documents where the age is less than 18</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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">find</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">selector</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">age</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">$lt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">18</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 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 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 comment" style="color:rgb(98, 114, 164)">// Remove the documents from the collection</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"> removedDocs </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"> query</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)">remove</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="doesdocumentdatamatch">doesDocumentDataMatch()<a href="#doesdocumentdatamatch" class="hash-link" aria-label="Direct link to doesDocumentDataMatch()" title="Direct link to doesDocumentDataMatch()"></a></h2>
<p>Returns <code>true</code> if the given document data matches the query.</p>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js 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"> documentData </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">id</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'foobar'</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">age</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">19</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><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">myCollection</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)">find</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">selector</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">age</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">$gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">18</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 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 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 method function property-access" style="color:rgb(80, 250, 123)">doesDocumentDataMatch</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">documentData</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)">// > true</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">myCollection</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)">find</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">selector</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">age</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">$gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">20</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 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 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 method function property-access" style="color:rgb(80, 250, 123)">doesDocumentDataMatch</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">documentData</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)">// > false</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="query-builder-plugin">Query Builder Plugin<a href="#query-builder-plugin" class="hash-link" aria-label="Direct link to Query Builder Plugin" title="Direct link to Query Builder Plugin"></a></h2>
<p>To use chained query methods, you can also use the <code>query-builder</code> plugin.</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 comment" style="color:rgb(98, 114, 164)">// add the query builder plugin</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">import</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"> addRxPlugin </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'</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">import</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"> RxDBQueryBuilderPlugin </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/query-builder'</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 plain">RxDBQueryBuilderPlugin</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"></span><span class="token comment" style="color:rgb(98, 114, 164)">// now you can use chained query methods</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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">find</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 function" style="color:rgb(80, 250, 123)">where</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">'age'</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 function" style="color:rgb(80, 250, 123)">gt</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token number">18</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" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> result </span><span class="token operator">=</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">await</span><span class="token plain"> query</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">exec</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="query-examples">Query Examples<a href="#query-examples" class="hash-link" aria-label="Direct link to Query Examples" title="Direct link to Query Examples"></a></h2>
<p>Here some examples to fast learn how to write queries without reading the docs.</p>
<ul>
<li><a href="https://github.com/pouchdb/pouchdb/blob/master/packages/node_modules/pouchdb-find/README.md" target="_blank" rel="noopener noreferrer">Pouch-find-docs</a> - learn how to use mango-queries</li>
<li><a href="https://github.com/aheckmann/mquery/blob/master/README.md" target="_blank" rel="noopener noreferrer">mquery-docs</a> - learn how to use chained-queries</li>
</ul>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js codeBlock_bY9V thin-scrollbar" style="color:#F8F8F2;background-color:#282A36"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)">// directly pass search-object</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">myCollection</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)">find</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">selector</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">name</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><span class="token literal-property property">$eq</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'foo'</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 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><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)">exec</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)">then</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token parameter">documents</span><span class="token plain"> </span><span class="token arrow operator">=></span><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)">dir</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">documents</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"></span><span class="token comment" style="color:rgb(98, 114, 164)">/*</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)"> * find by using sql equivalent '%like%' syntax</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)"> * This example will fe: match 'foo' but also 'fifoo' or 'foofa' or 'fifoofa'</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)"> * Notice that in RxDB queries, a regex is represented as a $regex string with the $options parameter for flags.</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)"> * Using a RegExp instance is not allowed because they are not JSON.stringify()-able and also</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)"> * RegExp instances are mutable which could cause undefined behavior when the RegExp is mutated</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)"> * after the query was parsed.</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token comment" style="color:rgb(98, 114, 164)"> */</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token method function property-access" style="color:rgb(80, 250, 123)">find</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">selector</span><span class="token operator">:</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">name</span><span class="token operator">:</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"> </span><span class="token literal-property property">$regex</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'.*foo.*'</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 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><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)">exec</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)">then</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token parameter">documents</span><span class="token plain"> </span><span class="token arrow operator">=></span><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)">dir</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">documents</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"></span><span class="token comment" style="color:rgb(98, 114, 164)">// find using a composite statement eg: $or</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token comment" style="color:rgb(98, 114, 164)">// This example checks where name is either foo or if name is not existent on the document</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token method function property-access" style="color:rgb(80, 250, 123)">find</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token literal-property property">selector</span><span class="token operator">:</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"> </span><span class="token literal-property property">$or</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><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><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 punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"> </span><span class="token literal-property property">$eq</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'foo'</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"> </span><span class="token literal-property property">name</span><span class="token operator">:</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"> </span><span class="token literal-property property">$exists</span><span class="token operator">:</span><span class="token plain"> </span><span class="token boolean">false</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</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 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><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)">exec</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)">then</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token parameter">documents</span><span class="token plain"> </span><span class="token arrow operator">=></span><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)">dir</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">documents</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"></span><span class="token comment" style="color:rgb(98, 114, 164)">// do a case insensitive search</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)">// This example will match 'foo' or 'FOO' or 'FoO' etc...</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">myCollection</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)">find</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">selector</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><span class="token literal-property property">name</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><span class="token literal-property property">$regex</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'^foo$'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> </span><span class="token literal-property property">$options</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'i'</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</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 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)">exec</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)">then</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token parameter">documents</span><span class="token plain"> </span><span class="token arrow operator">=></span><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)">dir</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">documents</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"></span><span class="token comment" style="color:rgb(98, 114, 164)">// chained queries</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">myCollection</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)">find</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)">where</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">'name'</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)">eq</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">'foo'</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)">exec</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)">then</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token parameter">documents</span><span class="token plain"> </span><span class="token arrow operator">=></span><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)">dir</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">documents</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>
<div class="theme-admonition theme-admonition-note admonition_xJq3 alert alert--secondary"><div class="admonitionHeading_Gvgb"><span class="admonitionIcon_Rf37"><svg viewBox="0 0 14 16"><path fill-rule="evenodd" d="M6.3 5.69a.942.942 0 0 1-.28-.7c0-.28.09-.52.28-.7.19-.18.42-.28.7-.28.28 0 .52.09.7.28.18.19.28.42.28.7 0 .28-.09.52-.28.7a1 1 0 0 1-.7.3c-.28 0-.52-.11-.7-.3zM8 7.99c-.02-.25-.11-.48-.31-.69-.2-.19-.42-.3-.69-.31H6c-.27.02-.48.13-.69.31-.2.2-.3.44-.31.69h1v3c.02.27.11.5.31.69.2.2.42.31.69.31h1c.27 0 .48-.11.69-.31.2-.19.3-.42.31-.69H8V7.98v.01zM7 2.3c-3.14 0-5.7 2.54-5.7 5.68 0 3.14 2.56 5.7 5.7 5.7s5.7-2.55 5.7-5.7c0-3.15-2.56-5.69-5.7-5.69v.01zM7 .98c3.86 0 7 3.14 7 7s-3.14 7-7 7-7-3.12-7-7 3.14-7 7-7z"></path></svg></span>RxDB will always append the primary key to the sort parameters</div><div class="admonitionContent_BuS1"><p>For several performance optimizations, like the <a href="https://github.com/pubkey/event-reduce" target="_blank" rel="noopener noreferrer">EventReduce algorithm</a>, RxDB expects all queries to return a deterministic sort order that does not depend on the insert order of the documents. To ensure a deterministic ordering, RxDB will always append the primary key as last sort parameter to all queries and to all indexes.
This works in contrast to most other databases where a query without sorting would return the documents in the order in which they had been inserted to the database.</p></div></div>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="setting-a-specific-index">Setting a specific index<a href="#setting-a-specific-index" class="hash-link" aria-label="Direct link to Setting a specific index" title="Direct link to Setting a specific index"></a></h2>
<p>By default, the query will be send to the RxStorage, where a query planner will determine which one of the available indexes must be used.
But the query planner cannot know everything and sometimes will not pick the most optimal index.
To improve query performance, you can specify which index must be used, when running the query.</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">const</span><span class="token plain"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</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 function" style="color:rgb(80, 250, 123)">findOne</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"> selector</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"> age</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"> $gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">18</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><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> gender</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"> $eq</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'m'</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 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><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token doc-comment comment" style="color:rgb(98, 114, 164)">/**</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * Because the developer knows that 50% of the documents are 'male',</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * but only 20% are below age 18,</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * it makes sense to enforce using the ['gender', 'age'] index to improve performance.</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * This could not be known by the query planer which might have chosen ['age', 'gender'] instead.</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> */</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> index</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 string" style="color:rgb(255, 121, 198)">'gender'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'age'</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="count">Count<a href="#count" class="hash-link" aria-label="Direct link to Count" title="Direct link to Count"></a></h2>
<p>When you only need the amount of documents that match a query, but you do not need the document data itself, you can use a count query for <strong>better performance</strong>.
The performance difference compared to a normal query differs depending on which <a href="/rx-storage.html">RxStorage</a> implementation is used.</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">const</span><span class="token plain"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">count</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"> selector</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"> age</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"> $gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">18</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 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 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)">// 'limit' and 'skip' MUST NOT be set for count queries.</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"></span><span class="token comment" style="color:rgb(98, 114, 164)">// get the count result once</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"> matchingAmount </span><span class="token operator">=</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">await</span><span class="token plain"> query</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">exec</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 comment" style="color:rgb(98, 114, 164)">// > number</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 comment" style="color:rgb(98, 114, 164)">// observe the result</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">query</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">$</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">subscribe</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">amount </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 builtin" style="color:rgb(189, 147, 249)">console</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" 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)">'Currently has '</span><span class="token plain"> </span><span class="token operator">+</span><span class="token plain"> amount </span><span class="token operator">+</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">' documents'</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>
<div class="theme-admonition theme-admonition-note admonition_xJq3 alert alert--secondary"><div class="admonitionHeading_Gvgb"><span class="admonitionIcon_Rf37"><svg viewBox="0 0 14 16"><path fill-rule="evenodd" d="M6.3 5.69a.942.942 0 0 1-.28-.7c0-.28.09-.52.28-.7.19-.18.42-.28.7-.28.28 0 .52.09.7.28.18.19.28.42.28.7 0 .28-.09.52-.28.7a1 1 0 0 1-.7.3c-.28 0-.52-.11-.7-.3zM8 7.99c-.02-.25-.11-.48-.31-.69-.2-.19-.42-.3-.69-.31H6c-.27.02-.48.13-.69.31-.2.2-.3.44-.31.69h1v3c.02.27.11.5.31.69.2.2.42.31.69.31h1c.27 0 .48-.11.69-.31.2-.19.3-.42.31-.69H8V7.98v.01zM7 2.3c-3.14 0-5.7 2.54-5.7 5.68 0 3.14 2.56 5.7 5.7 5.7s5.7-2.55 5.7-5.7c0-3.15-2.56-5.69-5.7-5.69v.01zM7 .98c3.86 0 7 3.14 7 7s-3.14 7-7 7-7-3.12-7-7 3.14-7 7-7z"></path></svg></span>note</div><div class="admonitionContent_BuS1"><p>Count queries have a better performance than normal queries because they do not have to fetch the full document data out of the storage. Therefore it is <strong>not</strong> possible to run a <code>count()</code> query with a selector that requires to fetch and compare the document data. So if your query selector <strong>does not</strong> fully match an index of the schema, it is not allowed to run it. These queries would have no performance benefit compared to normal queries but have the tradeoff of not using the fetched document data for caching.</p></div></div>
<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 doc-comment comment" style="color:rgb(98, 114, 164)">/**</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * The following will throw an error because</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * the count operation cannot run on any specific index range</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * because the $regex operator is used.</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> */</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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">count</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"> selector</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"> age</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"> $regex</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'foobar'</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 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 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"></span><span class="token doc-comment comment" style="color:rgb(98, 114, 164)">/**</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * The following will throw an error because</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * the count operation cannot run on any specific index range</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * because there is no ['age' ,'otherNumber'] index</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * defined in the schema.</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> */</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"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">count</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"> selector</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"> age</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"> $gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">20</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><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> otherNumber</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"> $gt</span><span class="token operator">:</span><span class="token plain"> </span><span class="token number">10</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 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 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" 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<p>If you want to count these kind of queries, you should do a normal query instead and use the length of the result set as counter. This has the same performance as running a non-fully-indexed count which has to fetch all document data from the database and run a query matcher.</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 comment" style="color:rgb(98, 114, 164)">// get count manually once</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"> resultSet </span><span class="token operator">=</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">await</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">find</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"> selector</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"> age</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"> $regex</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'foobar'</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 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 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 function" style="color:rgb(80, 250, 123)">exec</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" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> count </span><span class="token operator">=</span><span class="token plain"> resultSet</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">length</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 comment" style="color:rgb(98, 114, 164)">// observe count manually</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"> count$ </span><span class="token operator">=</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">find</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"> selector</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"> age</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"> $regex</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'foobar'</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">$</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">pipe</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)">map</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">result </span><span class="token operator">=></span><span class="token plain"> result</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token plain">length</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><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 doc-comment comment" style="color:rgb(98, 114, 164)">/**</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * To allow non-fully-indexed count queries,</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * you can also specify that by setting allowSlowCount=true</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> * when creating the database.</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token doc-comment comment" style="color:rgb(98, 114, 164)"> */</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"> database </span><span class="token operator">=</span><span class="token plain"> </span><span class="token keyword" 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"> name</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'mydatabase'</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"> allowSlowCount</span><span class="token operator">:</span><span class="token plain"> </span><span class="token boolean">true</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)">// set this to true [default=false]</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)">/* ... */</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" 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<h3 class="anchor anchorWithStickyNavbar_LWe7" id="allowslowcount"><code>allowSlowCount</code><a href="#allowslowcount" class="hash-link" aria-label="Direct link to allowslowcount" title="Direct link to allowslowcount"></a></h3>
<p>To allow non-fully-indexed count queries, you can also specify that by setting <code>allowSlowCount: true</code> when creating the database.
Doing this is mostly not wanted, because it would run the counting on the storage without having the document stored in the RxDB document cache.
This is only recommended if the RxStorage is running remotely like in a WebWorker and you not always want to send the document-data between the worker and the main thread. In this case you might only need the count-result instead to save performance.</p>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="rxquerys-are-immutable">RxQuery's are immutable<a href="#rxquerys-are-immutable" class="hash-link" aria-label="Direct link to RxQuery's are immutable" title="Direct link to RxQuery's are immutable"></a></h2>
<p>Because RxDB is a reactive database, we can do heavy performance-optimisation on query-results which change over time. To be able to do this, RxQuery's have to be immutable.
This means, when you have a <code>RxQuery</code> and run a <code>.where()</code> on it, the original RxQuery-Object is not changed. Instead the where-function returns a new <code>RxQuery</code>-Object with the changed where-field. Keep this in mind if you create RxQuery's and change them afterwards.</p>
<p>Example:</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"> queryObject </span><span class="token operator">=</span><span class="token plain"> myCollection</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)">find</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)">where</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">'age'</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)">gt</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token number">18</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 comment" style="color:rgb(98, 114, 164)">// Creates a new RxQuery object, does not modify previous one</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">queryObject</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)">sort</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">'name'</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" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> results </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"> queryObject</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)">exec</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 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)">dir</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">results</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)">// result-documents are not sorted by name</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"> queryObjectSort </span><span class="token operator">=</span><span class="token plain"> queryObject</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)">sort</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">'name'</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" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> results </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"> queryObjectSort</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)">exec</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 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)">dir</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">results</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)">// result-documents are now sorted</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>
<h3 class="anchor anchorWithStickyNavbar_LWe7" id="isrxquery">isRxQuery<a href="#isrxquery" class="hash-link" aria-label="Direct link to isRxQuery" title="Direct link to isRxQuery"></a></h3>
<p>Returns true if the given object is an instance of RxQuery. Returns false if not.</p>
<div class="language-js codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-js 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"> is </span><span class="token operator">=</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">isRxQuery</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">myObj</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="design-decisions">Design Decisions<a href="#design-decisions" class="hash-link" aria-label="Direct link to Design Decisions" title="Direct link to Design Decisions"></a></h2>
<p>Like most other noSQL-Databases, RxDB uses the <a href="https://github.com/cloudant/mango" target="_blank" rel="noopener noreferrer">mango-query-syntax</a> similar to MongoDB and others.</p>
<ul>
<li>We use the JSON based Mango Query Syntax because:<!-- -->
<ul>
<li>Mango Queries work better with TypeScript compared to SQL strings.</li>
<li>Mango Queries are composeable and easy to transform by code without joining SQL strings.</li>
<li>Queries can be run very fast and efficient with only a minimal query planer to plan the best indexes and operations.</li>
<li>NoSQL queries can be optimized with the <a href="https://github.com/pubkey/event-reduce" target="_blank" rel="noopener noreferrer">EventReduce</a> algorithm to improve performance of observed and cached queries.</li>
</ul>
</li>
</ul>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="faq">FAQ<a href="#faq" class="hash-link" aria-label="Direct link to FAQ" title="Direct link to FAQ"></a></h2>
<details class="details_lb9f alert alert--info details_b_Ee" data-collapsed="true"><summary>Can I specify which document fields are returned by an RxDB query?</summary><div><div class="collapsibleContent_i85q"><div><p>No, RxDB does not support partial document retrieval. Because RxDB is a client-side database with limited memory, it caches and de-duplicates entire documents across multiple queries. Even if you only need a few fields, most storages must still fetch the entire JSON data, so subselecting fields would not significantly improve performance. Therefore, RxDB always returns full documents. If you only need certain fields, you can filter them out in your application code or consider storing just the necessary data in a separate collection.</p></div></div></div></details>
<details class="details_lb9f alert alert--info details_b_Ee" data-collapsed="true"><summary>Why doesn't RxDB support aggregations on queries?</summary><div><div class="collapsibleContent_i85q"><div><p>RxDB runs entirely on the client side. Any "aggregation" or data processing you might do within RxDB would still happen in the same JavaScript environment as your application code. Therefore, there's no real performance advantage or difference between doing the aggregation in RxDB vs. doing it in your own code after fetching the data. As a result, RxDB doesn't provide built-in aggregation methods. Instead, just query the documents you need and perform any calculations directly in your app's code.</p></div></div></div></details>
<details class="details_lb9f alert alert--info details_b_Ee" data-collapsed="true"><summary>Why does RxDB not support cross-collection queries?</summary><div><div class="collapsibleContent_i85q"><div><p>RxDB is a client-side database and does not provide built-in cross-collection queries or transactions. Instead, you can execute multiple queries in your JavaScript code and combine their results as needed. Because everything runs in the same environment, this approach offers the same performance you would get if cross-collection queries were built in - without the added complexity.</p></div></div></div></details>
<details class="details_lb9f alert alert--info details_b_Ee" data-collapsed="true"><summary>Why Doesn't RxDB Support Case-Insensitive Search?</summary><div><div class="collapsibleContent_i85q"><div><p>RxDB relies on various storage engines as its backend, and these storage engines generally do not support case-insensitive search natively, like <a href="/rx-storage-indexeddb.html">IndexedDB</a> or <a href="/rx-storage-foundationdb.html">FoundationDB</a>. This limitation arises from the design of these engines, which prioritize efficiency and flexibility for specific types of queries rather than universal features like case-insensitivity. Although RxDB does not offer built-in support for case-insensitive search, there are two common workarounds:</p><ul>
<li><strong>Store Data in a Meta-Field for Lowercase Search</strong>: To enable case-insensitive search, you can store an additional field in your documents where the relevant text data is preprocessed and saved in lowercase.</li>
</ul><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">const</span><span class="token plain"> document </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"> name</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'John Doe'</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"> nameLowercase</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'john doe'</span><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// Meta-field</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><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">await</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">insert</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">document</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"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">find</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"> selector</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"> nameLowercase</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"> $eq</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'john doe'</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 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><ul>
<li><strong>Use a Regex Query</strong>: Regular expressions can perform case-insensitive searches. For example:</li>
</ul><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">const</span><span class="token plain"> query </span><span class="token operator">=</span><span class="token plain"> myCollection</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">find</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"> selector</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"> name</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"> $regex</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'^john doe$'</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> $options</span><span class="token operator">:</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">'i'</span><span class="token plain"> </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)">// Case-insensitive regex</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 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><p>However, this method has a significant downside: regex queries often cannot leverage indexes efficiently. As a result, they may be slower, especially for large datasets.</p></div></div></div></details></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages"><a class="pagination-nav__link pagination-nav__link--prev" href="/rx-document.html"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">RxDocument</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/rx-storage.html"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">RxStorage Overview</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="#find" class="table-of-contents__link toc-highlight">find()</a></li><li><a href="#findone" class="table-of-contents__link toc-highlight">findOne()</a></li><li><a href="#exec" class="table-of-contents__link toc-highlight">exec()</a></li><li><a href="#observe-" class="table-of-contents__link toc-highlight">Observe $</a></li><li><a href="#update" class="table-of-contents__link toc-highlight">update()</a></li><li><a href="#patch--incrementalpatch" class="table-of-contents__link toc-highlight">patch() / incrementalPatch()</a></li><li><a href="#modify--incrementalmodify" class="table-of-contents__link toc-highlight">modify() / incrementalModify()</a></li><li><a href="#remove--incrementalremove" class="table-of-contents__link toc-highlight">remove() / incrementalRemove()</a></li><li><a href="#doesdocumentdatamatch" class="table-of-contents__link toc-highlight">doesDocumentDataMatch()</a></li><li><a href="#query-builder-plugin" class="table-of-contents__link toc-highlight">Query Builder Plugin</a></li><li><a href="#query-examples" class="table-of-contents__link toc-highlight">Query Examples</a></li><li><a href="#setting-a-specific-index" class="table-of-contents__link toc-highlight">Setting a specific index</a></li><li><a href="#count" class="table-of-contents__link toc-highlight">Count</a><ul><li><a href="#allowslowcount" class="table-of-contents__link toc-highlight"><code>allowSlowCount</code></a></li></ul></li><li><a href="#rxquerys-are-immutable" class="table-of-contents__link toc-highlight">RxQuery's are immutable</a><ul><li><a href="#isrxquery" class="table-of-contents__link toc-highlight">isRxQuery</a></li></ul></li><li><a href="#design-decisions" class="table-of-contents__link toc-highlight">Design Decisions</a></li><li><a href="#faq" class="table-of-contents__link toc-highlight">FAQ</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. 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