neilconway commented on code in PR #21715: URL: https://github.com/apache/datafusion/pull/21715#discussion_r3124192712
########## datafusion/sqllogictest/test_files/group_by.slt: ########## @@ -5641,3 +5635,32 @@ set datafusion.execution.target_partitions = 4; statement count 0 drop table t; + +# Test that GROUP BY with a UNIQUE constraint does not incorrectly collapse +# NULL rows. UNIQUE allows multiple NULLs (NULLs are not equal in SQL), so +# a UNIQUE column cannot be used to eliminate other GROUP BY columns. +# Regression test for https://github.com/apache/datafusion/issues/21507 + +statement ok +CREATE TABLE t_unique_null(a INT, b INT, c INT, UNIQUE(a)); + +statement ok +INSERT INTO t_unique_null VALUES (1, 10, 100), (NULL, 20, 200), (NULL, 30, 300); + +# The two NULL rows must stay in separate groups (grouped by b as well). +query II rowsort +SELECT a, SUM(c) AS total FROM t_unique_null GROUP BY a, b; +---- +1 100 +NULL 200 +NULL 300 + +# GROUP BY on the UNIQUE column alone must still merge the NULL rows into one group. Review Comment: Can we add a test case for the `ORDER BY` case as well? #21362 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
