[jira] [Created] (DRILL-2199) Wrong results while using case expression with decimal data type

["Mehant Baid (JIRA)" <ji...@apache.org>]

Mehant Baid created DRILL-2199:
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             Summary: Wrong results while using case expression with decimal data type
                 Key: DRILL-2199
                 URL: https://issues.apache.org/jira/browse/DRILL-2199
             Project: Apache Drill
          Issue Type: Bug
            Reporter: Mehant Baid
            Assignee: Mehant Baid


Consider the below SQL statement:

"select 
case when true then cast(employee_id as decimal(15, 5)) else cast('0.0' as decimal(5, 2)) end 
from cp.`employee.json` where employee_id = 1"

This should return 1.00000 instead Drill returns 100000. In the case statement the first expression (condition expression) is nullable and the else expression is non-nullable. For our codegen to work correctly we make the non-nullable expression also nullable using convertToNullableXHolder() functions. These functions however do not preserve the scale and precision of the input, hence the output we get is the unscaled value of the decimal.

Fix is to make the converToNullableDecimalHolder() functions preserve the scale and precision by returning the correct major type.



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