[IMPALA-5083] add ORDER BY clause to GROUP_CONCAT()

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Component/s: Backend, Frontend
• Labels: ramp-up sql-language
• Epic Color: ghx-label-9
• Assignee: Unassigned
• Reporter: Greg Rahn
• Created: 16/Mar/17 22:27
• Updated: 20/Jun/17 18:24
• Resolved: 20/Jun/17 18:24

Description

Currently GROUP_CONCAT() does not allow one to return an ordered result. The MySQL version does support this:

GROUP_CONCAT([DISTINCT] expr [,expr ...]
             [ORDER BY {unsigned_integer | col_name | expr}
                 [ASC | DESC] [,col_name ...]]
             [SEPARATOR str_val])

https://dev.mysql.com/doc/refman/8.0/en/group-by-functions.html#function_group-concat

For example:

mysql> SELECT student_name,
    ->     GROUP_CONCAT(DISTINCT test_score
    ->               ORDER BY test_score DESC SEPARATOR ' ')
    ->     FROM student
    ->     GROUP BY student_name;

Issue Links

• duplicates: IMPALA-4139 add support for ORDER BY to GROUP_CONCAT()
• is related to: IMPALA-5545 Add LISTAGG() fuction