Fixed bug #29095.

INSERT into table from SELECT from the same table
with ORDER BY and LIMIT was inserting other data
than sole SELECT ... ORDER BY ... LIMIT returns.

One part of the patch for bug #9676 improperly pushed
LIMIT to temporary table in the presence of the ORDER BY
clause.
That part has been removed.

mysql-test/r/insert_select.result

@@ -688,7 +688,16 @@ ERROR 42S22: Unknown column 't2.x' in 'field list'
 drop table t1,t2;
 CREATE TABLE t1 (a int PRIMARY KEY);
 INSERT INTO t1 values (1), (2);
+flush status;
 INSERT INTO t1 SELECT a + 2 FROM t1 LIMIT 1;
+show status like 'Handler_read%';
+Variable_name	Value
+Handler_read_first	1
+Handler_read_key	0
+Handler_read_next	0
+Handler_read_prev	0
+Handler_read_rnd	0
+Handler_read_rnd_next	1
 DROP TABLE t1;
 CREATE TABLE t1 (x int, y int);
 CREATE TABLE t2 (z int, y int);
@@ -773,3 +782,25 @@ d
 20
 20
 DROP TABLE t1,t2;
+CREATE TABLE t1 (
+id INT AUTO_INCREMENT PRIMARY KEY,
+prev_id INT,
+join_id INT DEFAULT 0);
+INSERT INTO t1 (prev_id) VALUES (NULL), (1), (2);
+SELECT * FROM t1;
+id	prev_id	join_id
+1	NULL	0
+2	1	0
+3	2	0
+CREATE TABLE t2 (join_id INT);
+INSERT INTO t2 (join_id) VALUES (0);
+INSERT INTO t1 (prev_id) SELECT id
+FROM t2 LEFT JOIN t1 ON t1.join_id = t2.join_id
+ORDER BY id DESC LIMIT 1;
+SELECT * FROM t1;
+id	prev_id	join_id
+1	NULL	0
+2	1	0
+3	2	0
+4	3	0
+DROP TABLE t1,t2;

mysql-test/t/insert_select.test

@@ -233,7 +233,9 @@ drop table t1,t2;
 CREATE TABLE t1 (a int PRIMARY KEY);
 INSERT INTO t1 values (1), (2);
 
+flush status;
 INSERT INTO t1 SELECT a + 2 FROM t1 LIMIT 1;
+show status like 'Handler_read%';
 
 DROP TABLE t1;
 
@@ -332,3 +334,26 @@ INSERT INTO t2 (d)
 
 SELECT * FROM t2;
 DROP TABLE t1,t2;
+
+#
+# Bug #29095: incorrect pushing of LIMIT into the temporary
+# table ignoring ORDER BY clause
+#
+
+CREATE TABLE t1 (
+  id INT AUTO_INCREMENT PRIMARY KEY,
+  prev_id INT,
+  join_id INT DEFAULT 0);
+
+INSERT INTO t1 (prev_id) VALUES (NULL), (1), (2);
+SELECT * FROM t1;
+
+CREATE TABLE t2 (join_id INT);
+INSERT INTO t2 (join_id) VALUES (0);
+
+INSERT INTO t1 (prev_id) SELECT id
+  FROM t2 LEFT JOIN t1 ON t1.join_id = t2.join_id
+  ORDER BY id DESC LIMIT 1;
+SELECT * FROM t1;
+
+DROP TABLE t1,t2;

sql/sql_select.cc

@@ -1347,8 +1347,7 @@ JOIN::optimize()
       there are aggregate functions, because in all these cases we need
       all result rows.
     */
-    ha_rows tmp_rows_limit= ((order == 0 || skip_sort_order ||
-                              test(select_options & OPTION_BUFFER_RESULT)) &&
+    ha_rows tmp_rows_limit= ((order == 0 || skip_sort_order) &&
                              !tmp_group &&
                              !thd->lex->current_select->with_sum_func) ?
                             select_limit : HA_POS_ERROR;