[MDEV-22840] JSON_ARRAYAGG gives wrong results with NULL values and ORDER by clause - Jira

Here is an example

create table t1(a varchar(255));
insert into t1 values ('red'), ('blue'), (NULL);

MariaDB [test]> select json_arrayagg(a) from t1;

+---------------------+

| json_arrayagg(a)    |

+---------------------+

| ["red","blue",null] |

+---------------------+

1 row in set (0.002 sec)

So without ORDER BY clause inside JSON_ARRAYAGG we see null in the output

MariaDB [test]> select json_arrayagg(a order by a desc) from t1;

+----------------------------------+

| json_arrayagg(a order by a desc) |

+----------------------------------+

| ["red","blue",""]                |

+----------------------------------+

1 row in set (0.003 sec)

MariaDB [test]> select json_arrayagg(a order by a asc) from t1;

+---------------------------------+

| json_arrayagg(a order by a asc) |

+---------------------------------+

| ["","blue","red"]               |

+---------------------------------+

1 row in set (0.002 sec)

With ORDER BY clause there is no more null in the result

relates to

MDEV-22011 DISTINCT with JSON_ARRAYAGG gives wrong results

Varun Gupta (Inactive) added a comment - 2020-06-09 12:23 Patch https://github.com/MariaDB/server/commit/3fdc9d3380f8386c90ccbbb2f4e28b80eb2671d5

Ok to push

Sergei Petrunia added a comment - 2020-06-12 09:54 Ok to push

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