[jira] [Created] (HIVE-18724) Improve error handling for subqueries referencing columns(correlated) of it's grand-parent query

["Vineet Garg (JIRA)" <ji...@apache.org>]

Vineet Garg created HIVE-18724:
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             Summary: Improve error handling for subqueries referencing columns(correlated) of it's grand-parent query
                 Key: HIVE-18724
                 URL: https://issues.apache.org/jira/browse/HIVE-18724
             Project: Hive
          Issue Type: Improvement
          Components: Query Planning
            Reporter: Vineet Garg


Currently Hive doesn't allow correlated subqueries which refer to columns of grand parent query e.g.

{code:sql}
select t1.a from t t1 where t1.b IN (select t2.c from t t2 where t2.a IN (select max(t3.b) from t t3, t t4 where t3.a=t2.a and t3.b=t1.b))
 {code}

In this example inner most query has column reference {{t3.b=t1.b}} where {{t1.b}} references outer most query.

The error which Hive compiler throw is 
{noformat}
FAILED: SemanticException Line 0:-1 Unsupported SubQuery Expression 'a': Nested SubQuery expressions are not supported.
{format}

This is very misleading since Hive does support Nested subqueries.



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