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

@@ -735,4 +735,249 @@ COUNT(*)
 3072
 set @@sort_buffer_size=default;
 DROP TABLE t1,t2;
+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;
+EXPLAIN SELECT * FROM t1 WHERE b=2 ORDER BY a;
+id	1
+select_type	SIMPLE
+table	t1
+type	ref
+possible_keys	bkey
+key	bkey
+key_len	5
+ref	const
+rows	16
+Extra	Using where; Using index
+SELECT * FROM t1 WHERE b=2 ORDER BY a;
+a	b
+1	2
+2	2
+3	2
+4	2
+5	2
+6	2
+7	2
+8	2
+9	2
+10	2
+11	2
+12	2
+13	2
+14	2
+15	2
+16	2
+EXPLAIN SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY a;
+id	1
+select_type	SIMPLE
+table	t1
+type	range
+possible_keys	bkey
+key	bkey
+key_len	5
+ref	NULL
+rows	16
+Extra	Using where; Using index; Using filesort
+SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY a;
+a	b
+1	2
+2	2
+3	2
+4	2
+5	2
+6	2
+7	2
+8	2
+9	2
+10	2
+11	2
+12	2
+13	2
+14	2
+15	2
+16	2
+17	1
+18	1
+19	1
+20	1
+21	1
+22	1
+23	1
+24	1
+25	1
+26	1
+27	1
+28	1
+29	1
+30	1
+31	1
+32	1
+EXPLAIN SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY b,a;
+id	1
+select_type	SIMPLE
+table	t1
+type	range
+possible_keys	bkey
+key	bkey
+key_len	5
+ref	NULL
+rows	16
+Extra	Using where; Using index
+SELECT * FROM t1 WHERE b BETWEEN 1 AND 2 ORDER BY b,a;
+a	b
+17	1
+18	1
+19	1
+20	1
+21	1
+22	1
+23	1
+24	1
+25	1
+26	1
+27	1
+28	1
+29	1
+30	1
+31	1
+32	1
+1	2
+2	2
+3	2
+4	2
+5	2
+6	2
+7	2
+8	2
+9	2
+10	2
+11	2
+12	2
+13	2
+14	2
+15	2
+16	2
+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;
+EXPLAIN SELECT * FROM t2 WHERE b=1 ORDER BY a;
+id	1
+select_type	SIMPLE
+table	t2
+type	ref
+possible_keys	bkey
+key	bkey
+key_len	5
+ref	const
+rows	8
+Extra	Using where; Using index; Using filesort
+SELECT * FROM t2 WHERE b=1 ORDER BY a;
+a	b	c
+1	1	1
+2	1	1
+3	1	1
+4	1	1
+5	1	1
+6	1	1
+7	1	1
+8	1	1
+9	1	1
+10	1	1
+11	1	1
+12	1	1
+13	1	1
+14	1	1
+15	1	1
+16	1	1
+EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY a;
+id	1
+select_type	SIMPLE
+table	t2
+type	ref
+possible_keys	bkey
+key	bkey
+key_len	10
+ref	const,const
+rows	8
+Extra	Using where; Using index
+SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY a;
+a	b	c
+1	1	1
+2	1	1
+3	1	1
+4	1	1
+5	1	1
+6	1	1
+7	1	1
+8	1	1
+9	1	1
+10	1	1
+11	1	1
+12	1	1
+13	1	1
+14	1	1
+15	1	1
+16	1	1
+EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY b,c,a;
+id	1
+select_type	SIMPLE
+table	t2
+type	ref
+possible_keys	bkey
+key	bkey
+key_len	10
+ref	const,const
+rows	8
+Extra	Using where; Using index
+SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY b,c,a;
+a	b	c
+1	1	1
+2	1	1
+3	1	1
+4	1	1
+5	1	1
+6	1	1
+7	1	1
+8	1	1
+9	1	1
+10	1	1
+11	1	1
+12	1	1
+13	1	1
+14	1	1
+15	1	1
+16	1	1
+EXPLAIN SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY c,a;
+id	1
+select_type	SIMPLE
+table	t2
+type	ref
+possible_keys	bkey
+key	bkey
+key_len	10
+ref	const,const
+rows	8
+Extra	Using where; Using index
+SELECT * FROM t2 WHERE b=1 AND c=1 ORDER BY c,a;
+a	b	c
+1	1	1
+2	1	1
+3	1	1
+4	1	1
+5	1	1
+6	1	1
+7	1	1
+8	1	1
+9	1	1
+10	1	1
+11	1	1
+12	1	1
+13	1	1
+14	1	1
+15	1	1
+16	1	1
+DROP TABLE t1,t2;
 End of 5.0 tests

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

sql/sql_select.cc

@@ -12009,6 +12009,7 @@ static int test_if_order_by_key(ORDER *order, TABLE *table, uint idx,
   key_part_end=key_part+table->key_info[idx].key_parts;
   key_part_map const_key_parts=table->const_key_parts[idx];
   int reverse=0;
+  my_bool on_primary_key= FALSE;
   DBUG_ENTER("test_if_order_by_key");
 
   for (; order ; order=order->next, const_key_parts>>=1)
@@ -12023,7 +12024,30 @@ static int test_if_order_by_key(ORDER *order, TABLE *table, uint idx,
     for (; const_key_parts & 1 ; const_key_parts>>= 1)
       key_part++; 
 
-    if (key_part == key_part_end || key_part->field != field)
+    if (key_part == key_part_end)
+    {
+      /* 
+        We are at the end of the key. Check if the engine has the primary
+        key as a suffix to the secondary keys. If it has continue to check
+        the primary key as a suffix.
+      */
+      if (!on_primary_key &&
+          (table->file->table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX) &&
+          table->s->primary_key != MAX_KEY)
+      {
+        on_primary_key= TRUE;
+        key_part= table->key_info[table->s->primary_key].key_part;
+        key_part_end=key_part+table->key_info[table->s->primary_key].key_parts;
+        const_key_parts=table->const_key_parts[table->s->primary_key];
+
+        for (; const_key_parts & 1 ; const_key_parts>>= 1)
+          key_part++; 
+      }
+      else
+        DBUG_RETURN(0);
+    }
+
+    if (key_part->field != field)
       DBUG_RETURN(0);
 
     /* set flag to 1 if we can use read-next on key, else to -1 */
@@ -12034,7 +12058,8 @@ static int test_if_order_by_key(ORDER *order, TABLE *table, uint idx,
     reverse=flag;				// Remember if reverse
     key_part++;
   }
-  *used_key_parts= (uint) (key_part - table->key_info[idx].key_part);
+  *used_key_parts= on_primary_key ? table->key_info[idx].key_parts :
+    (uint) (key_part - table->key_info[idx].key_part);
   if (reverse == -1 && !(table->file->index_flags(idx, *used_key_parts-1, 1) &
                          HA_READ_PREV))
     reverse= 0;                                 // Index can't be used

sql/table.cc

@@ -780,7 +780,11 @@ int openfrm(THD *thd, const char *name, const char *alias, uint db_stat,
 	      the primary key, then we can use any key to find this column
 	    */
 	    if (ha_option & HA_PRIMARY_KEY_IN_READ_INDEX)
+            {
 	      field->part_of_key= share->keys_in_use;
+              if (field->part_of_sortkey.is_set(key))
+                field->part_of_sortkey= share->keys_in_use;
+            }
 	  }
 	  if (field->key_length() != key_part->length)
 	  {