[GitHub] [iotdb] 5Reasons commented on pull request #1890: Finish DIFF encoding algorithm which is reserved in enum before

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

5Reasons commented on pull request #1890:
URL: https://github.com/apache/iotdb/pull/1890#issuecomment-720967886


   > 1. there are too many duplications between `DIFFEncoder` and `DeltaBinaryEncoder`. Better to inherit `DeltaBinaryEncoder`, rather than copy codes.
   > 2. What is the benefit to add such a method? Trying to give some experimental results to show when should we use it...
   
   I have made some experiment abouot it(https://cwiki.apache.org/confluence/display/IOTDB/DIFF+encoding%27s+perfomance).
   As I said in email-list, this method's performance is not better than TS_2DIFF (included in 'DeltaBinaryEncoder'), only when the data set is in best circumstances, the new method can save very little room (about 4 bytes, in head)
   
   I add it beacuse DIFF is a reserved method, it's one of the recommending method when user want to choose a encoding method in IoTDB, but it's not finished before. It's in the system prompt, but user can't chooose it
   ![system_prompt](https://user-images.githubusercontent.com/61086064/97960647-d05a5380-1dec-11eb-8bba-b75eb9f0198f.png)


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