Github user maropu commented on the issue:
https://github.com/apache/spark/pull/18938
IMHO, other database(-like) systems prevent this name duplication in
temporary table/view, so it seems we might do so along with them.
```
// postgresql case
postgres=# create table s0 (a int, b int);
CREATE TABLE
postgres=# create table s1 (a int, b int);
CREATE TABLE
postgres=# select * from s0, s1 where s0.a = s1.a;
a | b | a | b
---+---+---+---
(0 rows)
postgres=# create view s2 as select * from s0, s1 where s0.a = s1.a;
ERROR: column "a" specified more than once
postgres=# create temporary view s2 as select * from s0, s1 where s0.a =
s1.a;
ERROR: column "a" specified more than once
// mysql case
mysql> create table s0 (a int, b int);
Query OK, 0 rows affected (0.02 sec)
mysql> create table s1 (a int, b int);
Query OK, 0 rows affected (0.02 sec)
mysql> select * from s0, s1 where s0.a = s1.a;
Empty set (0.00 sec)
mysql> create view s2 as select * from s0, s1 where s0.a = s1.a;
ERROR 1060 (42S21): Duplicate column name 'a'
mysql> create temporary table s2 as select * from s0, s1 where s0.a = s1.a;
ERROR 1060 (42S21): Duplicate column name 'a'
// hive case
hive> create table s0 (a int, b int);
OK
hive> create table s1 (a int, b int);
OK
hive> select * from s0, s1 where s0.a = s1.a;
OK
hive> create temporary view s2 as select * from s0, s1 where s0.a = s1.a;
FAILED: ParseException line 1:17 cannot recognize input near 'create'
'temporary' 'view' in ddl statement
hive> create view s2 as select * from s0, s1 where s0.a = s1.a;
FAILED: SemanticException
org.apache.hadoop.hive.ql.optimizer.calcite.CalciteViewSemanticException:
Duplicate column name: a
hive> create temporary table s2 as select * from s0, s1 where s0.a = s1.a;
FAILED: SemanticException [Error 10036]: Duplicate column name: a
```
But, I think this name duplication is an expected one in the 2.x releases
(for example, we already have some tests related to this:
https://github.com/apache/spark/blob/master/sql/hive/src/test/scala/org/apache/spark/sql/hive/ErrorPositionSuite.scala#L37).
So, this might be fixed for v3.x releases, maybe.
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