Bug #28591: MySQL need not sort the records in case of

ORDER BY primary_key on InnoDB table

Queries that use an InnoDB secondary index to retrieve
data don't need to sort in case of ORDER BY primary key
if the secondary index is compared to constant(s).
They can also skip sorting if ORDER BY contains both the
the secondary key parts and the primary key parts (in
that order).
This is because InnoDB returns the rows in order of the
primary key for rows with the same values of the secondary
key columns.
Fixed by preventing temp table sort for the qualifying 
queries.


mysql-test/r/innodb_mysql.result:
  Bug #28591: test case
mysql-test/t/innodb_mysql.test:
  Bug #28591: test case
sql/sql_select.cc:
  Bug #28591: Use the primary key as suffix when testing
  if the key can be used for ORDER BY on supporting engines.
sql/table.cc:
  Bug #28591: can use the primary key
  as a suffix for the secondary keys

1 files changed, 33 insertions, 0 deletions

diff --git a/mysql-test/t/innodb_mysql.test b/mysql-test/t/innodb_mysql.test
index d4ce997ddb1..9a44c673548 100644
--- a/mysql-test/t/innodb_mysql.test
+++ b/mysql-test/t/innodb_mysql.test
@@ -741,4 +741,37 @@ set @@sort_buffer_size=default;
 
 DROP TABLE t1,t2;
 
+#
+# Bug #28591: MySQL need not sort the records in case of ORDER BY
+# primary_key on InnoDB table
+#
+
+CREATE TABLE t1 (a int, b int, PRIMARY KEY (a), KEY bkey (b)) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1,2),(3,2),(2,2),(4,2),(5,2),(6,2),(7,2),(8,2);
+INSERT INTO t1 SELECT a + 8, 2 FROM t1;
+INSERT INTO t1 SELECT a + 16, 1 FROM t1;
+query_vertical EXPLAIN SELECT * FROM t1 WHERE b=2 ORDER BY a;
+SELECT * FROM t1 WHERE b=2 ORDER BY a;
+query_vertical EXPLAIN SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY a;
+SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY a;
+query_vertical EXPLAIN SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY b,a;
+SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY b,a;
+
+CREATE TABLE t2 (a int, b int, c int, PRIMARY KEY (a), KEY bkey (b,c))
+  ENGINE=InnoDB;
+INSERT INTO t2 VALUES (1,1,1),(3,1,1),(2,1,1),(4,1,1);
+INSERT INTO t2 SELECT a + 4, 1, 1 FROM t2;
+INSERT INTO t2 SELECT a + 8, 1, 1 FROM t2;
+
+query_vertical EXPLAIN SELECT * FROM t2 WHERE b=1 ORDER BY a;
+SELECT * FROM t2 WHERE b=1 ORDER BY a;
+query_vertical EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY a;
+SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY a;
+query_vertical EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY b,c,a;
+SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY b,c,a;
+query_vertical EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY c,a;
+SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY c,a;
+
+DROP TABLE t1,t2;
+
 --echo End of 5.0 tests