[GitHub] [carbondata] dhatchayani opened a new pull request #3148: [CARBONDATA-3293] Prune datamaps improvement for count(*)

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dhatchayani opened a new pull request #3148: [CARBONDATA-3293] Prune datamaps improvement for count(*)
URL: https://github.com/apache/carbondata/pull/3148
 
 
   **Problem:**
   (1) Currently for count (*) , the prune is same as select * query. Blocklet and ExtendedBlocklet are formed from the DataMapRow and that is of no need and it is a time consuming process.
   (2) Checking the update/delete status all the time.
   
   **Solution:**
   (1) We have the blocklet row count in the DataMapRow itself, so it is just enough to read the count. With this count (*) query performance can be improved.
   (2) No need to check the update/delete status all the time unless the table is not updated/deleted.
   
    - [ ] Any interfaces changed?
    
    - [ ] Any backward compatibility impacted?
    
    - [ ] Document update required?
   
    - [x] Testing done
           Existing UT
          
    - [ ] For large changes, please consider breaking it into sub-tasks under an umbrella JIRA. 
   
   

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