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https://issues.apache.org/jira/browse/HIVE-12566?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15036062#comment-15036062
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Chaoyu Tang commented on HIVE-12566:
------------------------------------
I verified the query in MySQL and Oracle, they all return following results
{code}
2 NULL CD5415192225530 00071 NULL NULL NULL
{code}
The issue exists since Hive 0.13. I wonder if it is related to
HIVE-5555/HIVE-5557 because the where clause
COALESCE(l.la,'EMPTY')=COALESCE(r.ra,'EMPTY') is pushed down to the join
condition, and no row in rtable match those in ltable when using the new join
condition
l.lk1 = r.rk1 AND l.lk2 = r.rk2 and
COALESCE(l.la,'EMPTY')=COALESCE(r.ra,'EMPTY'),
therefore the extra row (1 NULL CD5415192314304 00071 NULL NULL
NULL) returns.
[~rhbutani] & [~ashutoshc] Do you have any insight to this issue? Thanks
> Incorrect result returns when using COALESCE in WHERE condition with LEFT JOIN
> ------------------------------------------------------------------------------
>
> Key: HIVE-12566
> URL: https://issues.apache.org/jira/browse/HIVE-12566
> Project: Hive
> Issue Type: Bug
> Components: Query Planning
> Affects Versions: 0.13.0
> Reporter: Chaoyu Tang
> Priority: Critical
>
> The left join query with on/where clause returns incorrect result (more rows
> are returned). See the reproducible sample below.
> Left table with data:
> {code}
> CREATE TABLE ltable (i int, la int, lk1 string, lk2 string) ROW FORMAT
> DELIMITED FIELDS TERMINATED BY ',';
> ---
> 1,\N,CD5415192314304,00071
> 2,\N,CD5415192225530,00071
> {code}
> Right table with data:
> {code}
> CREATE TABLE rtable (ra int, rk1 string, rk2 string) ROW FORMAT DELIMITED
> FIELDS TERMINATED BY ',';
> ---
> 1,CD5415192314304,00071
> 45,CD5415192314304,00072
> {code}
> Query:
> {code}
> SELECT * FROM ltable l LEFT OUTER JOIN rtable r on (l.lk1 = r.rk1 AND l.lk2 =
> r.rk2) WHERE COALESCE(l.la,'EMPTY')=COALESCE(r.ra,'EMPTY');
> {code}
> Result returns:
> {code}
> 1 NULL CD5415192314304 00071 NULL NULL NULL
> 2 NULL CD5415192225530 00071 NULL NULL NULL
> {code}
> The correct result should be
> {code}
> 2 NULL CD5415192225530 00071 NULL NULL NULL
> {code}
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