[jira] [Created] (HIVE-21544) Constant propagation corrupts coalesce/case/when expressions during folding

[Zoltan Haindrich (JIRA)]

Zoltan Haindrich created HIVE-21544:
---------------------------------------

             Summary: Constant propagation corrupts coalesce/case/when 
expressions during folding
                 Key: HIVE-21544
                 URL: https://issues.apache.org/jira/browse/HIVE-21544
             Project: Hive
          Issue Type: Bug
            Reporter: Zoltan Haindrich
            Assignee: Zoltan Haindrich


{code}
set hive.fetch.task.conversion=none;
set hive.optimize.ppd=false;

create table t (s1 string,s2 string);

insert into t values (null,null);

explain
select
        coalesce(s1, 'null_value' ), coalesce(s2, 'null_value' ),
        coalesce(s1, 'null_value' )=coalesce(s2, 'null_value' ),
        case when coalesce(s1, 'null_value' )=coalesce(s2, 'null_value' ) then 
'eq' else 'noteq' end
from t;

select
        coalesce(s1, 'null_value' ), coalesce(s2, 'null_value' ),
        coalesce(s1, 'null_value' )=coalesce(s2, 'null_value' ),
        case when coalesce(s1, 'null_value' )=coalesce(s2, 'null_value' ) then 
'eq' else 'noteq' end
from t;
{code}

incorrect result is:
{code}
null_value      null_value      NULL    noteq
{code}

expected result:
{code}
null_value     null_value      true    eq
{code}




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