I've linked this to MCOL-495. While predicates have been modified to use collation, many "where a=b" type statements are optimized to use a JOIN rather than a predicate, so we can't say MCOL-495 is complete until JOINs are complete.

Build tested: 5.5.1 (Drone 1251)

Issues found. If we want to fix these issues for 5.5.1, I will test again when the fix is available. If we defer additional fix for future release, then please create a MCOL to track them. Thx

Scenarios test for both case sensitive and insensitive tables
Case sensitive tables worked fine

For case insensitive tables
1. single table, column-to-string comparison, PASSED
2. single table, column-to-column comparison, FAILED
3. single table, self-join, FAILED
4. two tables, join, FAILED

The interesting thing is right after creating the tables, test #3 passed. But after #2 failed, #3 also would fail.

Case insensitive table

MariaDB [mytest]> create table t1 (c1 char(5), c2 char(5)) engine=columnstore collate=latin1_general_ci;
Query OK, 0 rows affected (0.147 sec)

MariaDB [mytest]> insert into t1 values ('hello','Hello');
Query OK, 1 row affected (0.154 sec)

MariaDB [mytest]> create table t4 (c1 char(5), c2 char(5)) engine=columnstore collate=latin1_general_ci;
Query OK, 0 rows affected (0.182 sec)

MariaDB [mytest]> insert into t4 values ('hello','Hello');
Query OK, 1 row affected (0.158 sec)

2.
MariaDB [mytest]> select * from t1 where c1=c2;
Empty set (0.012 sec)

3.
MariaDB [mytest]> select * from t1, t1 t2 where t1.c1=t2.c2;
Empty set (0.144 sec)

4.
MariaDB [mytest]> select * from t1, t4 where t1.c1=t4.c2;
Empty set (0.030 sec)

Build tested: 5.5.1 (Drone 1313)

The issue has been fixed