[MCOL-2146] group_concat with distinct concatenates even non-distinct values - Jira

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If the group_concat contains distinct together with sorting over non-distinct column CS concatenates distinct values multiple times.

Here is the setting:

create table cs1 (i bigint, a bigint) engine=columnstore;

insert into cs1 values (1,2),(1,3),(2,5),(1,42);

MariaDB [tpch1]> select group_concat(distinct i order by a) s from cs1;

+---------+

| s       |

+---------+

| 1,1,2,1 |

+---------+

1 row in set (0.031 sec)

is duplicated by

MCOL-3805 CLONE - Fix group_concat

MCOL-2159 Fix group_concat

relates to

MCOL-1829 Output of 'select * (with order by limit) queries' returns unexpected result