title: What is query_hash in instagram?
body: <p>I was working for the first time on graphql, and I saw that Instagram hash their queries.</p>
  
  <p>I searched something, but I don't know if it is correct. The hash is like a persistedquery stored in a cache memory?</p>
  
  <p>Or am I wrong?</p>
  
  <p>Example: this is my request payload</p>
  
  <pre><code>{
   "operationName":"user",
   "variables":{},
   "query":"query user {\n  users {\n    username\n    createdAt\n    _id\n  }\n}\n"
  }
  </code></pre>
  
  <p>this is instagram:</p>
  
  <pre><code> query_hash: 60b755363b5c230111347a7a4e242001
   variables: %7B%22only_stories%22%3Atrue%7D
  </code></pre>
  
  <p>(it is in urlencode mode). </p>
  
  <p>Now, how could I hash my query? I'm using NodeJS as backend and react js as frontend. 
  I would like to understand how it works x)! Thank you guys!</p>