title: How to Delete Record from Kafka global state store?
body: <p>Global state store during restoration will dump the data from the source topic(Which is consider as change-log topic for global-store).</p>
  
  <p>for delete a record i do something like below</p>
  
  <pre><code>kvStore.put("key-1",null)
  </code></pre>
  
  <p>how Kafka know's that the record is delete and during restoration it will dump record from source topic (consider source topic has a record with key-1)</p>
  
  <p>In my topology I have </p>
  
  <ul>
  <li>an input topic -> T1</li>
  <li>and a process is attached that read data from T1 and construct a key from the record and forward down to topic T2</li>
  <li>and topic T2 is a source topic for global state store.</li>
  </ul>
  
  <p>Example:</p>
  
  <ul>
  <li>T1 i got data: <code>{"id":'123', "name":"Mohit", "type":"insert"}</code></li>
  <li>construct a key for record and forward Down to topic with key and value as T2 -> key: <code>123</code> and value: <code>{"id":'123', "name":"Mohit"}</code></li>
  </ul>
  
  <p>After that same key record come as type delete in data.
  T1 got data: <code>{"id":'123', "name":"Mohit", "type":"insert"}</code></p>
  
  <p>so i am forward record as like this</p>
  
  <pre><code>this.context.forward(key, null)
  key: 123 value:null
  </code></pre>
  
  <p>Same is updated in state-store</p>
  
  <p>I just want to know that during restoration with this record will be delete means i get null if i go get on store with key <code>123</code>.</p>