Furcy Pin created HIVE-13793:
--------------------------------
Summary: Columns in GROUP BY gaining an alias?
Key: HIVE-13793
URL: https://issues.apache.org/jira/browse/HIVE-13793
Project: Hive
Issue Type: Bug
Affects Versions: 2.0.0, 1.1.1
Reporter: Furcy Pin
Priority: Minor
I've found that Hive sometimes automatically gives an alias to
the columns that are in a group by.
I'm not sure if this is a bug or a feature but it seems to be inconsistent
with the way it usually resolves column names :
How to reproduce:
This query is ok :
{code}
SELECT
s.foo
FROM (SELECT NAMED_STRUCT("foo", 2) as s) T
;
+------+--+
| foo |
+------+--+
| 2 |
+------+--+
{code}
This query fails (and it's normal) because the column 'foo' does not exist (but
's.foo' does).
{code}
SELECT
foo
FROM (SELECT NAMED_STRUCT("foo", 2) as s) T
;
Error: Error while compiling statement: FAILED: SemanticException [Error
10004]: Line 2:0 Invalid table alias or column reference 'foo': (possible
column names are: s) (state=42000,code=10004)
{code}
But adding a GROUP BY seems to make Hive rename 's.foo' into 'foo',
and the following query works (which seems less normal to me) .
{code}
SELECT
foo
FROM (SELECT NAMED_STRUCT("foo", 2) as s) T
GROUP BY s.foo
;
+------+--+
| foo |
+------+--+
| 2 |
+------+--+
{code}
Is this a bug or a feature ?
In this example it is mostly harmless, but I though perhaps it might help
finding a flaw in the query processor.
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