[GitHub] [incubator-hivemall] myui opened a new pull request #214: [HIVEMALL-281] Support max_by, min_by, majority_vote UDAFs

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

myui opened a new pull request #214: [HIVEMALL-281] Support max_by, min_by, majority_vote UDAFs
URL: https://github.com/apache/incubator-hivemall/pull/214
 
 
   ## What changes were proposed in this pull request?
   
   upport max_by, min_by, majority_vote UDAFs
   
   ## What type of PR is it?
   
   Feature
   
   ## What is the Jira issue?
   
   https://issues.apache.org/jira/browse/HIVEMALL-281
   
   ## How was this patch tested?
   
   manual tests on EMR
   
   ## How to use this feature?
   
   ```sql
   
   create table data1 as (
     select 'jake' as name, 18 as age
     union all
     select 'tom' as name, 64 as age
     union all
     select 'lisa' as name, 32 as age
   );
   
   select
     max_by(name, age) as max_name,
     min_by(name, age) as min_name
   from
     data1;
   > tom, jake
   
   create table data2 as
     select
       explode(array('1', '2', '2', '2', '5', '4', '1', '2')) as k;
   
   select
     majority_vote(k) as k
   from 
     data2;
   > 2
   ```
   
   ## Checklist
   
   (Please remove this section if not needed; check `x` for YES, blank for NO)
   
   - [x] Did you apply source code formatter, i.e., `./bin/format_code.sh`, for your commit?
   - [x] Did you run system tests on Hive (or Spark)?
   

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