Simple unions break sorting.

Here's a relatively simple query format that demonstrates this on a columnstore table:

SELECT
label,
count
FROM (
SELECT
label,
COUNT(my_table.id) as count
FROM my_table
GROUP BY label
UNION ALL
SELECT "NONE" as label, 0 as count
UNION ALL
SELECT "NONE" as label, -1 as count

) AS A ORDER BY count

This will yield a sort order where -1 is considered the largest value.

This is likely a signed/unsigned integer issue.

Of note:

• Does not break on a Sum, have not tested other grouping operations
• Have not tested other sort engines
• Did not break in our previous version of columnstore some ~4 years ago

Active Workaround:
replace literal for -1 with cast(-1 AS float) acts as workaround