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https://issues.apache.org/jira/browse/HIVE-3609?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13482087#comment-13482087
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Carl Steinbach commented on HIVE-3609:
--------------------------------------
This makes sense:
{noformat}
hive> SELECT * FROM src LIMIT 1;
OK
key value
238 val_238
Time taken: 0.061 seconds
hive> SELECT * FROM src a JOIN src b ON (a.key = b.key) LIMIT 1;
OK
key value key value
0 val_0 0 val_0
{noformat}
But this doesn't:
{noformat}
hive> SELECT * FROM (SELECT * FROM src a JOIN src b ON (a.key = b.key) LIMIT 1)
c;
OK
key value
0 val_0
{noformat}
Note that the third query produces the following SQL exception when run in
MySQL:
{noformat}
mysql> SELECT * FROM (SELECT * FROM src a JOIN src b ON (a.key=b.key) LIMIT 1)
as c;
ERROR 1060 (42S21): Duplicate column name 'key'
{noformat}
I think Hive should throw an exception in this situation too.
> Nested sub select queries with duplicate column aliases should throw an error
> instead of truncating columns
> -----------------------------------------------------------------------------------------------------------
>
> Key: HIVE-3609
> URL: https://issues.apache.org/jira/browse/HIVE-3609
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Carl Steinbach
>
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