title: hive extract keys from a dict like string by regexp_extract?
body: <p>I want to extract keys from a column from a hive table that likes this below</p>
  
  <pre><code>{"agya":3,"gentong":1,"tronton":0,"tasikmalaya":4,"tanja":2}
  {"afifah":3,"sctv":10,"samuel zylgwyn":2,"naysila mirdad":0,"shared":8}
  {"aferia":1,"jatimtimes":3,"apbdes":2,"siltap":4,"mudjito":0}
  {"aerox":0,"flasher":1,"lampu hazard":2,"aftermarket":4,"dcs":5}
  {"administratif":6,"fakta":7,"prabowo":5,"cek":4,"admistratif":0}
  {"adeg":2,"tiru":1,"film film":3,"romantis":0,"nggak":5}
  </code></pre>
  
  <p>for the first one I want to get <code>"agya", "gentong", "tronton"</code> etc. And later I can explode them to multiple rows.
  How to use regexp_extract to realize this ?</p>