Comments - Should GROUP BY require ORDER BY in columnstore?

Hi,

That behaviour does not sound correct. Can you please file a bug, preferably with a test case, at:

https://jira.mariadb.org/projects/MCOL/

Thanks Andrew,

I have created MCOL-1180.

Also, seems like this may be related to MCOL-643. If you wrap the SUM or AVG function with a FORMAT function in the test case you get the error message:

 Error Code: 1815
Internal error: IDB-2015: Sorting length exceeded. Session variable max_length_for_sort_data needs to be set higher.

I found this to be the case even if I put the main query in a derived table. The query will execute if max_length_for_sort_data is set to 3M but will fail with the default of 1024.

SELECT `Day`,FORMAT(Total,4), FORMAT(Average,4) 
    FROM (
            SELECT DAY(timestamp_) AS 'Day',SUM(numeric_val) AS Total, AVG(numeric_val) AS Average 
                FROM cs1
                WHERE timestamp_ >= '2017-09-01 00:00:00' AND timestamp_ < '2017-10-01 00:00:00'
                  AND id IN (228091,228231,228233,227867,228216,228241)
                  GROUP BY DAY(timestamp_) ASC                
           ) dt 
      ORDER BY `Day`
;

Thanks Andrew, I had originally tested this as one query. I should have pasted in this query,

SELECT DAY(timestamp_),FORMAT(SUM(numeric_val),4), FORMAT(AVG(numeric_val),4) 
    FROM cs1
    WHERE timestamp_ >= '2017-09-01 00:00:00' AND timestamp_ < '2017-10-01 00:00:00'
       AND id IN (228091,228231,228233,227867,228216,228241)
      GROUP BY DAY(timestamp_) ASC;

I separated it hoping to get past the max_length_for_sort_data problem. This query executes if the columns 'Total' and 'Average' are not formatted.