[GitHub] [incubator-druid] quenlang opened a new issue #7297: thetaSketch aggrgator handle null or "" into unexpected value at ingesting

[GitBox <gi...@apache.org>]

quenlang opened a new issue #7297: thetaSketch aggrgator handle null or "" into unexpected value at ingesting 
URL: https://github.com/apache/incubator-druid/issues/7297
 
 
   @AlexanderSaydakov @gianm 
   I had found the thetaSketch aggrgator handle ```null``` or ```""``` into unexpected value at ingesting in our scene but i'm not sure why it happend.
   
   I defined a thetaSketch aggrgator in our metrics like this
   ```
    {
           "name": "prefix_success_business_no",
           "fieldName": "prefix_success_business_no",
           "type": "thetaSketch"
    }
   ```
   The value of prefix_success_business_no column in raw data before ingesting maybe `null`, `empty string` or `normal string` which like "quenlang@126.com". we found that even though the prefix_success_business_no's value is null or "" or combination of the two in raw data, then after ingesting, the distinct count of prefix_success_business_no was not null or zero when i performed a thetaSketch aggrgator query like this
   ```
   ...
   {
         "type": "thetaSketch",
         "name": "prefixSuccessBusinessNo",
         "fieldName": "prefix_success_business_no",
         "size": 16384,
         "shouldFinalize": true,
         "isInputThetaSketch": false,
         "errorBoundsStdDev": null
   }
   ...
   ```
   the result like this
   ```
   [ {
     "timestamp" : "2019-03-18T13:30:00.000Z",
     "result" : {
       "prefixSuccessBusiness_no" : 16.0
     }
   } ]
   ```
   All the orignal value of prefix_success_business_no is null in this query, but druid return the distinct count of prefix_success_business_no 16 for me.  I had no ideas about this situation, does the thetaSkect not handle null or "" fully? my druid version was  0.13.0.
   
   There was a new aggrgator in 0.13.0 which called HLLSkecth, can you tell me more about the difference between HLLSkecth and thetaSkect over space, speed and accuracy? which one i should use in my sense.
   
   
   Best wishes !
   
   
   
   
   
   

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