Dongjoon Hyun created SPARK-21247:
-------------------------------------
Summary: Allow case-insensitive type comparisions in Set operation
Key: SPARK-21247
URL: https://issues.apache.org/jira/browse/SPARK-21247
Project: Spark
Issue Type: Improvement
Components: SQL
Affects Versions: 2.1.1
Reporter: Dongjoon Hyun
Spark supports case-sensitivity in columns. Especially, for Struct types, with
case sensitive option, the following is supported.
{code}
scala> sql("select named_struct('a', 1, 'A', 2).a").show
+--------------------------+
|named_struct(a, 1, A, 2).a|
+--------------------------+
| 1|
+--------------------------+
scala> sql("select named_struct('a', 1, 'A', 2).A").show
+--------------------------+
|named_struct(a, 1, A, 2).A|
+--------------------------+
| 2|
+--------------------------+
{code}
And vice versa, with case sensitive `false`, the following is supported.
{code}
scala> sql("select named_struct('a', 1).A, named_struct('A', 1).a").show
+--------------------+--------------------+
|named_struct(a, 1).A|named_struct(A, 1).a|
+--------------------+--------------------+
| 1| 1|
+--------------------+--------------------+
{code}
This issue aims to support case-insensitive type comparisions in Set operation.
Currently, SET operations fail due to case-sensitive type comparision failure .
{code}
scala> sql("SELECT struct(1 a) UNION ALL (SELECT struct(2 A))").show
org.apache.spark.sql.AnalysisException: Union can only be performed on tables
with the compatible column types. struct<A:int> <> struct<a:int> at the first
column of the second table;;
'Union
:- Project [named_struct(a, 1) AS named_struct(a, 1 AS `a`)#2]
: +- OneRowRelation$
+- Project [named_struct(A, 2) AS named_struct(A, 2 AS `A`)#3]
+- OneRowRelation$
{code}
Please note that this issue does not aim to change all type comparison
semantics.
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