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Pengcheng Xiong commented on HIVE-14918: ---------------------------------------- [~wisgood] i just took a look at the link. it was not marked as a bug in MySQL {code} [19 Nov 2004 14:21] Sergei Golubchik Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.mysql.com/documentation/ and the instructions on how to report a bug at http://bugs.mysql.com/how-to-report.php Additional info: According to the manual, CONCAT_WS skips any `NULL' values after the separator argument. Thus CONCAT_WS(' ', NULL, NULL) has zero strings to concat, and the result, quite naturally, is empty string. It does not depend on the separator: mysql> select concat('>', concat_ws('=', NULL, NULL), '<'); +----------------------------------------------+ | concat('>', concat_ws('|', NULL, NULL), '<') | +----------------------------------------------+ | >< | +----------------------------------------------+ {code} > Function concat_ws get a wrong value > -------------------------------------- > > Key: HIVE-14918 > URL: https://issues.apache.org/jira/browse/HIVE-14918 > Project: Hive > Issue Type: Bug > Components: UDF > Affects Versions: 1.1.1, 2.0.0, 2.1.0, 2.0.1 > Reporter: Xiaowei Wang > Assignee: Xiaowei Wang > Priority: Critical > Fix For: 2.1.0 > > Attachments: HIVE-14918.0.patch > > > FROM src INSERT OVERWRITE TABLE dest1 SELECT 'abc', 'xyz', '8675309' WHERE > src.key = 86; > SELECT concat_ws('.',NULL) FROM dest1 ; > The result is a empty string "",but I think it should be return NULL . -- This message was sent by Atlassian JIRA (v6.3.4#6332)