[jira] [Created] (HIVE-26722) HiveFilterSetOpTransposeRule incorrectly prune UNION ALL operands

["Alessandro Solimando (Jira)" <ji...@apache.org>]

Alessandro Solimando created HIVE-26722:
-------------------------------------------

             Summary: HiveFilterSetOpTransposeRule incorrectly prune UNION ALL operands
                 Key: HIVE-26722
                 URL: https://issues.apache.org/jira/browse/HIVE-26722
             Project: Hive
          Issue Type: Bug
          Components: CBO
    Affects Versions: 4.0.0-alpha-1
            Reporter: Alessandro Solimando
            Assignee: Alessandro Solimando


Consider the following query:

 
{code:java}
set hive.cbo.rule.exclusion.regex=ReduceExpressionsRule\(Project\);

CREATE EXTERNAL TABLE t (a string, b string);
INSERT INTO t VALUES ('1000', 'b1');
INSERT INTO t VALUES ('2000', 'b2');

SELECT * FROM (
  SELECT
   a,
   b
  FROM t
   UNION ALL
  SELECT
   a,
   CAST(NULL AS string)
   FROM t) AS t2
WHERE a = 1000;EXPLAIN CBO
SELECT * FROM (
  SELECT
   a,
   b
  FROM t
   UNION ALL
  SELECT
   a,
   CAST(NULL AS string)
   FROM t) AS t2
WHERE a = 1000; {code}
 

 

The expected result is:

 
{code:java}
1000    b1
1000    NULL{code}
 

An example of correct plan is as follows:

 
{noformat}
CBO PLAN:
HiveUnion(all=[true])
  HiveProject(a=[$0], b=[$1])
    HiveFilter(condition=[=(CAST($0):DOUBLE, 1000)])
      HiveTableScan(table=[[default, t]], table:alias=[t])
  HiveProject(a=[$0], _o__c1=[null:VARCHAR(2147483647) CHARACTER SET "UTF-16LE"])
    HiveFilter(condition=[=(CAST($0):DOUBLE, 1000)])
      HiveTableScan(table=[[default, t]], table:alias=[t]){noformat}
 

 

Consider now a scenario where expression reduction in projections is disabled by setting the following property{_}:{_}
{noformat}
set hive.cbo.rule.exclusion.regex=ReduceExpressionsRule\(Project\);
{noformat}
In this case, the simplification of _CAST(NULL)_ into _NULL_ does not happen, and we get the following (invalid) result:
1000    b1






 



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