6 files changed, 93 insertions, 2 deletions

diff --git a/mysql-test/r/select.result b/mysql-test/r/select.result
index 5a234c17409..3d1dc5ec170 100644
--- a/mysql-test/r/select.result
+++ b/mysql-test/r/select.result
@@ -5112,4 +5112,24 @@ INSERT INTO t2 VALUES (3),(4);
 SELECT * FROM t1, t2 WHERE a=3 AND a=b;
 a	b
 drop table t1,t2;
+#
+# Bug mdev-4250: wrong transformation of WHERE condition with OR
+#
+CREATE TABLE t1 (pk int PRIMARY KEY, a int);
+INSERT INTO t1 VALUES (3,0), (2,0), (4,1), (5,0), (1,0);
+SELECT * FROM t1 WHERE (1=2 OR t1.pk=2) AND t1.a <> 0;
+pk	a
+EXPLAIN EXTENDED 
+SELECT * FROM t1 WHERE (1=2 OR t1.pk=2) AND t1.a <> 0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
+Warnings:
+Note	1003	select 2 AS `pk`,0 AS `a` from `test`.`t1` where ((0 <> 0))
+DROP TABLE t1;
+SELECT * FROM mysql.time_zone 
+WHERE ( NOT (Use_leap_seconds <= Use_leap_seconds AND Time_zone_id != 1) 
+AND Time_zone_id = Time_zone_id 
+OR Time_zone_id <> Time_zone_id ) 
+AND Use_leap_seconds <> 'N';
+Time_zone_id	Use_leap_seconds
 End of 5.3 tests
diff --git a/mysql-test/r/select_jcl6.result b/mysql-test/r/select_jcl6.result
index b7f278a327f..e2e0db128b3 100644
--- a/mysql-test/r/select_jcl6.result
+++ b/mysql-test/r/select_jcl6.result
@@ -5123,6 +5123,26 @@ INSERT INTO t2 VALUES (3),(4);
 SELECT * FROM t1, t2 WHERE a=3 AND a=b;
 a	b
 drop table t1,t2;
+#
+# Bug mdev-4250: wrong transformation of WHERE condition with OR
+#
+CREATE TABLE t1 (pk int PRIMARY KEY, a int);
+INSERT INTO t1 VALUES (3,0), (2,0), (4,1), (5,0), (1,0);
+SELECT * FROM t1 WHERE (1=2 OR t1.pk=2) AND t1.a <> 0;
+pk	a
+EXPLAIN EXTENDED 
+SELECT * FROM t1 WHERE (1=2 OR t1.pk=2) AND t1.a <> 0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
+Warnings:
+Note	1003	select 2 AS `pk`,0 AS `a` from `test`.`t1` where ((0 <> 0))
+DROP TABLE t1;
+SELECT * FROM mysql.time_zone 
+WHERE ( NOT (Use_leap_seconds <= Use_leap_seconds AND Time_zone_id != 1) 
+AND Time_zone_id = Time_zone_id 
+OR Time_zone_id <> Time_zone_id ) 
+AND Use_leap_seconds <> 'N';
+Time_zone_id	Use_leap_seconds
 End of 5.3 tests
 set join_cache_level=default;
 show variables like 'join_cache_level';
diff --git a/mysql-test/r/select_pkeycache.result b/mysql-test/r/select_pkeycache.result
index 5a234c17409..3d1dc5ec170 100644
--- a/mysql-test/r/select_pkeycache.result
+++ b/mysql-test/r/select_pkeycache.result
@@ -5112,4 +5112,24 @@ INSERT INTO t2 VALUES (3),(4);
 SELECT * FROM t1, t2 WHERE a=3 AND a=b;
 a	b
 drop table t1,t2;
+#
+# Bug mdev-4250: wrong transformation of WHERE condition with OR
+#
+CREATE TABLE t1 (pk int PRIMARY KEY, a int);
+INSERT INTO t1 VALUES (3,0), (2,0), (4,1), (5,0), (1,0);
+SELECT * FROM t1 WHERE (1=2 OR t1.pk=2) AND t1.a <> 0;
+pk	a
+EXPLAIN EXTENDED 
+SELECT * FROM t1 WHERE (1=2 OR t1.pk=2) AND t1.a <> 0;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
+Warnings:
+Note	1003	select 2 AS `pk`,0 AS `a` from `test`.`t1` where ((0 <> 0))
+DROP TABLE t1;
+SELECT * FROM mysql.time_zone 
+WHERE ( NOT (Use_leap_seconds <= Use_leap_seconds AND Time_zone_id != 1) 
+AND Time_zone_id = Time_zone_id 
+OR Time_zone_id <> Time_zone_id ) 
+AND Use_leap_seconds <> 'N';
+Time_zone_id	Use_leap_seconds
 End of 5.3 tests
diff --git a/mysql-test/t/select.test b/mysql-test/t/select.test
index 890da70caad..e202e013377 100644
--- a/mysql-test/t/select.test
+++ b/mysql-test/t/select.test
@@ -4286,4 +4286,23 @@ INSERT INTO t2 VALUES (3),(4);
 SELECT * FROM t1, t2 WHERE a=3 AND a=b;
 drop table t1,t2;
 
+--echo #
+--echo # Bug mdev-4250: wrong transformation of WHERE condition with OR
+--echo #
+
+CREATE TABLE t1 (pk int PRIMARY KEY, a int);
+INSERT INTO t1 VALUES (3,0), (2,0), (4,1), (5,0), (1,0);
+
+SELECT * FROM t1 WHERE (1=2 OR t1.pk=2) AND t1.a <> 0;
+EXPLAIN EXTENDED 
+SELECT * FROM t1 WHERE (1=2 OR t1.pk=2) AND t1.a <> 0;
+
+DROP TABLE t1;
+
+SELECT * FROM mysql.time_zone 
+WHERE ( NOT (Use_leap_seconds <= Use_leap_seconds AND Time_zone_id != 1) 
+        AND Time_zone_id = Time_zone_id 
+     OR Time_zone_id <> Time_zone_id ) 
+  AND Use_leap_seconds <> 'N';
+
 --echo End of 5.3 tests
diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index 33f147b7b0f..1b8687cfcfc 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -1798,6 +1798,15 @@ public:
   { 
     upper_levels= 0;
   }
+  void copy(COND_EQUAL &cond_equal)
+  {
+    max_members= cond_equal.max_members;
+    upper_levels= cond_equal.upper_levels;
+    if (cond_equal.current_level.is_empty())
+      current_level.empty();
+    else
+      current_level= cond_equal.current_level;
+  }
 };
 
 
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 75f810598cd..24b0cb952a1 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -11383,7 +11383,9 @@ static COND *build_equal_items_for_cond(THD *thd, COND *cond,
                       item_equal->n_field_items());  
       }
 
-      ((Item_cond_and*)cond)->cond_equal= cond_equal;
+      ((Item_cond_and*)cond)->cond_equal.copy(cond_equal);
+      cond_equal.current_level=
+        ((Item_cond_and*)cond)->cond_equal.current_level;
       inherited= &(((Item_cond_and*)cond)->cond_equal);
     }
     /*
@@ -11461,7 +11463,8 @@ static COND *build_equal_items_for_cond(THD *thd, COND *cond,
           set_if_bigger(thd->lex->current_select->max_equal_elems,
                         item_equal->n_field_items());  
         }
-        and_cond->cond_equal= cond_equal;
+        and_cond->cond_equal.copy(cond_equal);
+        cond_equal.current_level= and_cond->cond_equal.current_level;
         args->concat((List<Item> *)&cond_equal.current_level);
         
         return and_cond;