Fixed MDEV-5424: SELECT using ORDER BY DESC and LIMIT produces unexpected results (InnoDB/XtraDB)

This only happend when using an ORDER BY on a primary key part, where all other key parts where constant.
Remove of duplicated expressions in ORDER BY (as the old code did this in some strange cases)


mysql-test/r/group_by.result:
  Fixed results to take into account that duplicate order by parts are now deleted
mysql-test/r/group_by_innodb.result:
  Ensure extended keys are on
mysql-test/r/innodb_ext_key.result:
  More tests
mysql-test/r/order_by.result:
  More tests
mysql-test/t/group_by.test:
  Fixed results to take into account that duplicate order by parts are now deleted
mysql-test/t/group_by_innodb.test:
  Ensure extended keys are on
mysql-test/t/innodb_ext_key.test:
  More tests
mysql-test/t/order_by.test:
  More tests
sql/sql_select.cc:
  Fixed bug where we looked at extended key parts when we shouldn't
  Remove of duplicated expressions in ORDER BY
sql/table.cc:
  Indentation fixes

1 files changed, 3 insertions, 0 deletions

diff --git a/mysql-test/t/order_by.test b/mysql-test/t/order_by.test
index 3e20d22d726..35f1a7f744b 100644
--- a/mysql-test/t/order_by.test
+++ b/mysql-test/t/order_by.test
@@ -261,6 +261,9 @@ desc,b desc;
 explain select * from t1 where a = 2 and b > 0 order by a desc,b desc;
 explain select * from t1 where a = 2 and b < 2 order by a desc,b desc;
 explain select * from t1 where a = 1 order by b desc;
+explain select * from t1 where a = 2 and b > 0 order by a desc,b desc,b,a;
+explain select * from t1 where a = 2 and b < 2 order by a desc,a,b desc,a,b;
+
 select * from t1 where a = 1 order by b desc;
 #
 # Test things when we don't have NULL keys