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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