From: Ole John Aske
Date: February 1 2012 9:59am
Subject: bzr push into mysql-trunk branch (ole.john.aske:3817 to 3818) Bug#13528826
List-Archive: http://lists.mysql.com/commits/142691
X-Bug: 13528826
Message-Id: <20120201095938.8B572235@fimafeng09.norway.sun.com>
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 3818 Ole John Aske	2012-02-01
      Fix for bug#13528826  TEST_IF_CHEAPER_ORDERING(): CALCULATES INCORRECT 'SELECT_LIMIT
      
      An incorrect 'adjusted select_limit' was returned from test_if_cheaper_ordering()
      if no excplicit limit-clause was specified in the query.
      
      This fix detect when a limit-clause was not specified, and returns the
      full 'table_records' when no limit-clause was used.
      
      Furthermore, this fix caused the testcase for bug #12838420 
      to change beyond what was required as a testcase for that bug.
            
      Fixed that by forcing correct query plan for testcase by
      introducing 'USE INDEX' and 'STRAIGHT_JOIN'.
     @ mysql-test/include/icp_tests.inc
        Slightly changed syntax of testcase in order to force required query plan
        for this testcase.
     @ mysql-test/include/order_by.inc
        New testcase for this bug
     @ mysql-test/r/innodb_icp.result
        Result should report the full number of records in table wo/ any limit clause.
        Also slightly changed syntax of testcase in order to force required query plan
        for this testcase.
     @ mysql-test/r/innodb_icp_all.result
        Result should report the full number of records in table wo/ any limit clause.
        Also slightly changed syntax of testcase in order to force required query plan
        for this testcase.
     @ mysql-test/r/innodb_icp_none.result
        Result should report the full number of records in table wo/ any limit clause.
        Also slightly changed syntax of testcase in order to force required query plan
        for this testcase.
     @ mysql-test/r/join_cache_nojb.result
        Result should report the full number of records in table wo/ any limit clause.
     @ mysql-test/r/myisam_icp.result
        Slightly changed syntax of testcase in order to force required query plan
        for this testcase.
     @ mysql-test/r/myisam_icp_all.result
        Slightly changed syntax of testcase in order to force required query plan
        for this testcase.
     @ mysql-test/r/myisam_icp_none.result
        Slightly changed syntax of testcase in order to force required query plan
        for this testcase.
     @ mysql-test/r/order_by_all.result
        Accept result for new testcase
     @ mysql-test/r/order_by_icp_mrr.result
        Accept result for new testcase
     @ mysql-test/r/order_by_none.result
        Accept result for new testcase

    modified:
      mysql-test/include/icp_tests.inc
      mysql-test/include/order_by.inc
      mysql-test/r/innodb_icp.result
      mysql-test/r/innodb_icp_all.result
      mysql-test/r/innodb_icp_none.result
      mysql-test/r/join_cache_nojb.result
      mysql-test/r/myisam_icp.result
      mysql-test/r/myisam_icp_all.result
      mysql-test/r/myisam_icp_none.result
      mysql-test/r/order_by_all.result
      mysql-test/r/order_by_icp_mrr.result
      mysql-test/r/order_by_none.result
      sql/sql_select.cc
 3817 Tor Didriksen	2012-02-01
      All the subquery_sj_xxx tests can get thread stack overrun on solaris

    modified:
      mysql-test/collections/default.experimental
=== modified file 'mysql-test/include/icp_tests.inc'
--- a/mysql-test/include/icp_tests.inc	2011-10-05 13:16:38 +0000
+++ b/mysql-test/include/icp_tests.inc	2012-02-01 09:59:13 +0000
@@ -1043,7 +1043,7 @@ INSERT INTO t2 VALUES (0,9),(3,10),(4,6)
 
 let $query=
 SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 

=== modified file 'mysql-test/include/order_by.inc'
--- a/mysql-test/include/order_by.inc	2012-01-25 14:52:00 +0000
+++ b/mysql-test/include/order_by.inc	2012-02-01 09:59:13 +0000
@@ -1781,3 +1781,33 @@ SELECT c FROM t1 WHERE a=2 AND (c=10 OR 
 SELECT c FROM t1 WHERE a=2 AND (c=10 OR c IS NULL) ORDER BY c DESC;
 
 DROP TABLE t1;
+
+--echo #
+--echo # Bug #13528826 
+--echo # TEST_IF_CHEAPER_ORDERING(): CALCULATES INCORRECT 'SELECT_LIMIT'
+--echo # 
+--echo #
+
+CREATE TABLE t1(a int PRIMARY KEY, b int) ENGINE=myisam;
+INSERT INTO t1 VALUES
+  (5, 10), (2, 70), (7, 80), (6, 20), (1, 50), (9, 40), (8, 30), (3, 60);
+CREATE TABLE t2 (p int, a int, INDEX i_a(a)) ENGINE=myisam;
+INSERT INTO t2 VALUES
+  (103, 7), (109, 3), (102, 3), (108, 1), (106, 3),
+  (107, 7), (105, 1), (101, 3), (100, 7), (110, 1);
+
+--echo # number of rows in t1 was incorrectly used as an 
+--echo # implicit limit-clause if not explicit specified
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a;
+
+--echo # Query above used to be explained identical to this:
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a LIMIT 8;
+
+-- echo # A really high limit was required to give the correct explain
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a LIMIT 1000;
+
+DROP TABLE t1, t2;
+

=== modified file 'mysql-test/r/innodb_icp.result'
--- a/mysql-test/r/innodb_icp.result	2012-01-25 12:45:56 +0000
+++ b/mysql-test/r/innodb_icp.result	2012-02-01 09:59:13 +0000
@@ -988,14 +988,14 @@ INSERT INTO t2 VALUES (0,9),(3,10),(4,6)
 set @old_opt_switch=@@optimizer_switch;
 SET optimizer_switch="block_nested_loop=off";
 EXPLAIN SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	range	PRIMARY,col_int_key	col_int_key	5	NULL	5	Using where; Using index
+1	SIMPLE	t2	range	col_int_key	col_int_key	5	NULL	5	Using where; Using index
 1	SIMPLE	t1	index	NULL	col_int_key	5	NULL	4	Using index
 SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 field1

=== modified file 'mysql-test/r/innodb_icp_all.result'
--- a/mysql-test/r/innodb_icp_all.result	2012-01-30 13:08:34 +0000
+++ b/mysql-test/r/innodb_icp_all.result	2012-02-01 09:59:13 +0000
@@ -988,14 +988,14 @@ INSERT INTO t2 VALUES (0,9),(3,10),(4,6)
 set @old_opt_switch=@@optimizer_switch;
 SET optimizer_switch="block_nested_loop=off";
 EXPLAIN SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	range	PRIMARY,col_int_key	col_int_key	5	NULL	5	Using where; Using index
+1	SIMPLE	t2	range	col_int_key	col_int_key	5	NULL	5	Using where; Using index
 1	SIMPLE	t1	index	NULL	col_int_key	5	NULL	4	Using index
 SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 field1

=== modified file 'mysql-test/r/innodb_icp_none.result'
--- a/mysql-test/r/innodb_icp_none.result	2012-01-25 12:45:56 +0000
+++ b/mysql-test/r/innodb_icp_none.result	2012-02-01 09:59:13 +0000
@@ -987,14 +987,14 @@ INSERT INTO t2 VALUES (0,9),(3,10),(4,6)
 set @old_opt_switch=@@optimizer_switch;
 SET optimizer_switch="block_nested_loop=off";
 EXPLAIN SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	range	PRIMARY,col_int_key	col_int_key	5	NULL	5	Using where; Using index
+1	SIMPLE	t2	range	col_int_key	col_int_key	5	NULL	5	Using where; Using index
 1	SIMPLE	t1	index	NULL	col_int_key	5	NULL	4	Using index
 SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 field1

=== modified file 'mysql-test/r/join_cache_nojb.result'
--- a/mysql-test/r/join_cache_nojb.result	2012-01-30 13:13:15 +0000
+++ b/mysql-test/r/join_cache_nojb.result	2012-02-01 09:59:13 +0000
@@ -1445,7 +1445,7 @@ explain
 select t1.a, count(t2.p) as count
 from t1 left join t2 on t1.a=t2.a and t2.p % 2 = 1 group by t1.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	8	Using index
 1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using where
 select t1.a, count(t2.p) as count
 from t1 left join t2 on t1.a=t2.a and t2.p % 2 = 1 group by t1.a;

=== modified file 'mysql-test/r/myisam_icp.result'
--- a/mysql-test/r/myisam_icp.result	2012-01-03 11:04:14 +0000
+++ b/mysql-test/r/myisam_icp.result	2012-02-01 09:59:13 +0000
@@ -983,14 +983,14 @@ INSERT INTO t2 VALUES (0,9),(3,10),(4,6)
 set @old_opt_switch=@@optimizer_switch;
 SET optimizer_switch="block_nested_loop=off";
 EXPLAIN SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index; Using temporary; Using filesort
-1	SIMPLE	t2	ALL	PRIMARY,col_int_key	NULL	NULL	NULL	6	Using where
+1	SIMPLE	t2	ALL	col_int_key	NULL	NULL	NULL	6	Using where; Using temporary; Using filesort
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index
 SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 field1

=== modified file 'mysql-test/r/myisam_icp_all.result'
--- a/mysql-test/r/myisam_icp_all.result	2012-01-03 11:04:14 +0000
+++ b/mysql-test/r/myisam_icp_all.result	2012-02-01 09:59:13 +0000
@@ -983,14 +983,14 @@ INSERT INTO t2 VALUES (0,9),(3,10),(4,6)
 set @old_opt_switch=@@optimizer_switch;
 SET optimizer_switch="block_nested_loop=off";
 EXPLAIN SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index; Using temporary; Using filesort
-1	SIMPLE	t2	ALL	PRIMARY,col_int_key	NULL	NULL	NULL	6	Using where
+1	SIMPLE	t2	ALL	col_int_key	NULL	NULL	NULL	6	Using where; Using temporary; Using filesort
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index
 SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 field1

=== modified file 'mysql-test/r/myisam_icp_none.result'
--- a/mysql-test/r/myisam_icp_none.result	2012-01-03 11:04:14 +0000
+++ b/mysql-test/r/myisam_icp_none.result	2012-02-01 09:59:13 +0000
@@ -982,14 +982,14 @@ INSERT INTO t2 VALUES (0,9),(3,10),(4,6)
 set @old_opt_switch=@@optimizer_switch;
 SET optimizer_switch="block_nested_loop=off";
 EXPLAIN SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index; Using temporary; Using filesort
-1	SIMPLE	t2	ALL	PRIMARY,col_int_key	NULL	NULL	NULL	6	Using where
+1	SIMPLE	t2	ALL	col_int_key	NULL	NULL	NULL	6	Using where; Using temporary; Using filesort
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index
 SELECT t2.col_int_key AS field1
-FROM t2 JOIN t1 ON t2.col_int_key
+FROM t2 USE INDEX(col_int_key) STRAIGHT_JOIN t1 ON t2.col_int_key
 WHERE t2.pk < 7 AND t2.col_int_key <> 7
 GROUP BY field1;
 field1

=== modified file 'mysql-test/r/order_by_all.result'
--- a/mysql-test/r/order_by_all.result	2012-01-30 13:08:34 +0000
+++ b/mysql-test/r/order_by_all.result	2012-02-01 09:59:13 +0000
@@ -2639,4 +2639,36 @@ c
 10
 NULL
 DROP TABLE t1;
+#
+# Bug #13528826 
+# TEST_IF_CHEAPER_ORDERING(): CALCULATES INCORRECT 'SELECT_LIMIT'
+# 
+#
+CREATE TABLE t1(a int PRIMARY KEY, b int) ENGINE=myisam;
+INSERT INTO t1 VALUES
+(5, 10), (2, 70), (7, 80), (6, 20), (1, 50), (9, 40), (8, 30), (3, 60);
+CREATE TABLE t2 (p int, a int, INDEX i_a(a)) ENGINE=myisam;
+INSERT INTO t2 VALUES
+(103, 7), (109, 3), (102, 3), (108, 1), (106, 3),
+(107, 7), (105, 1), (101, 3), (100, 7), (110, 1);
+# number of rows in t1 was incorrectly used as an 
+# implicit limit-clause if not explicit specified
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	8	Using index
+1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using index
+# Query above used to be explained identical to this:
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a LIMIT 8;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index
+1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using index
+# A really high limit was required to give the correct explain
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a LIMIT 1000;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	8	Using index
+1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using index
+DROP TABLE t1, t2;
 set optimizer_switch=default;

=== modified file 'mysql-test/r/order_by_icp_mrr.result'
--- a/mysql-test/r/order_by_icp_mrr.result	2012-01-25 14:52:00 +0000
+++ b/mysql-test/r/order_by_icp_mrr.result	2012-02-01 09:59:13 +0000
@@ -2639,4 +2639,36 @@ c
 10
 NULL
 DROP TABLE t1;
+#
+# Bug #13528826 
+# TEST_IF_CHEAPER_ORDERING(): CALCULATES INCORRECT 'SELECT_LIMIT'
+# 
+#
+CREATE TABLE t1(a int PRIMARY KEY, b int) ENGINE=myisam;
+INSERT INTO t1 VALUES
+(5, 10), (2, 70), (7, 80), (6, 20), (1, 50), (9, 40), (8, 30), (3, 60);
+CREATE TABLE t2 (p int, a int, INDEX i_a(a)) ENGINE=myisam;
+INSERT INTO t2 VALUES
+(103, 7), (109, 3), (102, 3), (108, 1), (106, 3),
+(107, 7), (105, 1), (101, 3), (100, 7), (110, 1);
+# number of rows in t1 was incorrectly used as an 
+# implicit limit-clause if not explicit specified
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	8	Using index
+1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using index
+# Query above used to be explained identical to this:
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a LIMIT 8;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index
+1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using index
+# A really high limit was required to give the correct explain
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a LIMIT 1000;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	8	Using index
+1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using index
+DROP TABLE t1, t2;
 set optimizer_switch=default;

=== modified file 'mysql-test/r/order_by_none.result'
--- a/mysql-test/r/order_by_none.result	2012-01-25 14:52:00 +0000
+++ b/mysql-test/r/order_by_none.result	2012-02-01 09:59:13 +0000
@@ -2638,4 +2638,36 @@ c
 10
 NULL
 DROP TABLE t1;
+#
+# Bug #13528826 
+# TEST_IF_CHEAPER_ORDERING(): CALCULATES INCORRECT 'SELECT_LIMIT'
+# 
+#
+CREATE TABLE t1(a int PRIMARY KEY, b int) ENGINE=myisam;
+INSERT INTO t1 VALUES
+(5, 10), (2, 70), (7, 80), (6, 20), (1, 50), (9, 40), (8, 30), (3, 60);
+CREATE TABLE t2 (p int, a int, INDEX i_a(a)) ENGINE=myisam;
+INSERT INTO t2 VALUES
+(103, 7), (109, 3), (102, 3), (108, 1), (106, 3),
+(107, 7), (105, 1), (101, 3), (100, 7), (110, 1);
+# number of rows in t1 was incorrectly used as an 
+# implicit limit-clause if not explicit specified
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	8	Using index
+1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using index
+# Query above used to be explained identical to this:
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a LIMIT 8;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	4	Using index
+1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using index
+# A really high limit was required to give the correct explain
+EXPLAIN
+SELECT t1.a FROM t1 LEFT JOIN t2 ON t1.a=t2.a ORDER BY t1.a LIMIT 1000;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	8	Using index
+1	SIMPLE	t2	ref	i_a	i_a	5	test.t1.a	2	Using index
+DROP TABLE t1, t2;
 set optimizer_switch=default;

=== modified file 'sql/sql_select.cc'
--- a/sql/sql_select.cc	2012-01-31 07:45:59 +0000
+++ b/sql/sql_select.cc	2012-02-01 09:59:13 +0000
@@ -4684,7 +4684,7 @@ bool JOIN::change_result(select_result *
   @param          ref_key             
                 * 0 <= key < MAX_KEY   - key number (hint) to start the search
                 * -1                   - no key number provided
-  @param          select_limit        LIMIT value
+  @param          select_limit        LIMIT value, or HA_POS_ERROR if no limit
   @param [out]    new_key             Key number if success, otherwise undefined
   @param [out]    new_key_direction   Return -1 (reverse) or +1 if success,
                                       otherwise undefined
@@ -4732,6 +4732,7 @@ test_if_cheaper_ordering(const JOIN_TAB 
   ha_rows table_records= table->file->stats.records;
   bool group= join && join->group && order == join->group_list;
   ha_rows ref_key_quick_rows= HA_POS_ERROR;
+  const bool has_limit= (select_limit != HA_POS_ERROR);
 
   /*
     If not used with LIMIT, only use keys if the whole query can be
@@ -4824,7 +4825,7 @@ test_if_cheaper_ordering(const JOIN_TAB 
             be included into the result set.
           */  
           if (select_limit > table_records/rec_per_key)
-              select_limit= table_records;
+            select_limit= table_records;
           else
             select_limit= (ha_rows) (select_limit*rec_per_key);
         }
@@ -4905,7 +4906,7 @@ test_if_cheaper_ordering(const JOIN_TAB 
   
   *new_key= best_key;
   *new_key_direction= best_key_direction;
-  *new_select_limit= best_select_limit;
+  *new_select_limit= has_limit ? best_select_limit : table_records;
   if (new_used_key_parts != NULL)
     *new_used_key_parts= best_key_parts;
 

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