DBUG_ASSERT(fixed == 0) added to fix_fields()

18 files changed, 292 insertions, 95 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 45cd85d1775..c0eff7e85c2 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -103,21 +103,33 @@ void Item::print_item_w_name(String *str)
 
 Item_ident::Item_ident(const char *db_name_par,const char *table_name_par,
 		       const char *field_name_par)
-  :db_name(db_name_par),table_name(table_name_par),field_name(field_name_par),
+  :changed_during_fix_field(0), db_name(db_name_par),
+   table_name(table_name_par), field_name(field_name_par),
    depended_from(0)
 {
   name = (char*) field_name_par;
 }
 
 // Constructor used by Item_field & Item_ref (see Item comment)
-Item_ident::Item_ident(THD *thd, Item_ident *item):
-  Item(thd, item),
-  db_name(item->db_name),
-  table_name(item->table_name),
-  field_name(item->field_name),
-  depended_from(item->depended_from)
+Item_ident::Item_ident(THD *thd, Item_ident *item)
+  :Item(thd, item),
+   changed_during_fix_field(0),
+   db_name(item->db_name),
+   table_name(item->table_name),
+   field_name(item->field_name),
+   depended_from(item->depended_from)
 {}
 
+void Item_ident::cleanup()
+{
+  Item::cleanup();
+  if (changed_during_fix_field)
+  {
+    *changed_during_fix_field= this;
+    changed_during_fix_field= 0;
+  }
+}
+
 bool Item_ident::remove_dependence_processor(byte * arg)
 {
   DBUG_ENTER("Item_ident::remove_dependence_processor");
@@ -289,11 +301,14 @@ bool DTCollation::aggregate(DTCollation &dt)
   return 0;
 }
 
-Item_field::Item_field(Field *f) :Item_ident(NullS,f->table_name,f->field_name)
+Item_field::Item_field(Field *f)
+  :Item_ident(NullS, f->table_name, f->field_name)
+#ifndef DBUG_OFF
+  ,double_fix(0)
+#endif
 {
   set_field(f);
   collation.set(DERIVATION_IMPLICIT);
-  fixed= 1; // This item is not needed in fix_fields
 }
 
 // Constructor need to process subselect with temporary tables (see Item)
@@ -301,6 +316,9 @@ Item_field::Item_field(THD *thd, Item_field *item)
   :Item_ident(thd, item),
    field(item->field),
    result_field(item->result_field)
+#ifndef DBUG_OFF
+  ,double_fix(0)
+#endif
 {
   collation.set(DERIVATION_IMPLICIT);
 }
@@ -786,6 +804,9 @@ bool Item::fix_fields(THD *thd,
 		      struct st_table_list *list,
 		      Item ** ref)
 {
+
+  // We do not check fields which are fixed during construction
+  DBUG_ASSERT(fixed == 0 || type() == INT_ITEM || type() == CACHE_ITEM);
   fixed= 1;
   return 0;
 }
@@ -847,6 +868,7 @@ static void mark_as_dependent(THD *thd, SELECT_LEX *last, SELECT_LEX *current,
 
 bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0 || double_fix == 0);
   if (!field)					// If field is not checked
   {
     TABLE_LIST *where= 0;
@@ -952,6 +974,7 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 			       ref,
 			       (char *)table_name,
 			       (char *)field_name);
+	register_item_tree_changing(ref);
 	if (!rf)
 	  return 1;
 	/*
@@ -1005,6 +1028,11 @@ void Item_field::cleanup()
 {
   DBUG_ENTER("Item_field::cleanup");
   Item_ident::cleanup();
+  /*
+    Even if this object was created by direct link to field in setup_wild()
+    it will be linked correctly next tyme by name of field and table alias.
+    I.e. we can drop 'field'.
+   */
   field= result_field= 0;
   DBUG_VOID_RETURN;
 }
@@ -1480,6 +1508,7 @@ bool Item_field::send(Protocol *protocol, String *buffer)
 
 bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 {
+  DBUG_ASSERT(fixed == 0);
   uint counter;
   if (!ref)
   {
@@ -1585,6 +1614,7 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 	Item_field* fld;
 	if (!((*reference)= fld= new Item_field(tmp)))
 	  return 1;
+	register_item_tree_changing(reference);
 	mark_as_dependent(thd, last, thd->lex->current_select, fld);
 	return 0;
       }
@@ -1696,6 +1726,7 @@ bool Item_default_value::fix_fields(THD *thd,
 				    struct st_table_list *table_list,
 				    Item **items)
 {
+  DBUG_ASSERT(fixed == 0);
   if (!arg)
     return 0;
   if (arg->fix_fields(thd, table_list, &arg))
@@ -1744,6 +1775,7 @@ bool Item_insert_value::fix_fields(THD *thd,
 				   struct st_table_list *table_list,
 				   Item **items)
 {
+  DBUG_ASSERT(fixed == 0);
   if (arg->fix_fields(thd, table_list, &arg))
     return 1;
 
diff --git a/sql/item.h b/sql/item.h
index 832fc775016..27f427c1ef4 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -233,7 +233,7 @@ public:
   Field *tmp_table_field_from_field_type(TABLE *table);
   
   /* Used in sql_select.cc:eliminate_not_funcs() */
-  virtual Item *neg_transformer() { return NULL; }
+  virtual Item *neg_transformer(THD *thd) { return NULL; }
   void delete_self()
   {
     cleanup();
@@ -245,6 +245,7 @@ public:
 class st_select_lex;
 class Item_ident :public Item
 {
+  Item **changed_during_fix_field;
 public:
   const char *db_name;
   const char *table_name;
@@ -254,7 +255,9 @@ public:
 	     const char *field_name_par);
   Item_ident(THD *thd, Item_ident *item);
   const char *full_name() const;
-
+  void cleanup();
+  void register_item_tree_changing(Item **ref)
+    { changed_during_fix_field= ref; }
   bool remove_dependence_processor(byte * arg);
 };
 
@@ -264,11 +267,17 @@ class Item_field :public Item_ident
   void set_field(Field *field);
 public:
   Field *field,*result_field;
-  // Item_field() {}
+#ifndef DBUG_OFF
+  bool double_fix;
+#endif
 
   Item_field(const char *db_par,const char *table_name_par,
 	     const char *field_name_par)
-    :Item_ident(db_par,table_name_par,field_name_par),field(0),result_field(0)
+    :Item_ident(db_par,table_name_par,field_name_par),
+     field(0), result_field(0)
+#ifndef DBUG_OFF
+    ,double_fix(0)
+#endif
   { collation.set(DERIVATION_IMPLICIT); }
   // Constructor need to process subselect with temporary tables (see Item)
   Item_field(THD *thd, Item_field *item);
@@ -324,6 +333,7 @@ public:
   enum_field_types field_type() const   { return MYSQL_TYPE_NULL; }
   bool fix_fields(THD *thd, struct st_table_list *list, Item **item)
   {
+    DBUG_ASSERT(fixed == 0);
     bool res= Item::fix_fields(thd, list, item);
     max_length=0;
     return res;
@@ -413,7 +423,8 @@ public:
   int save_in_field(Field *field, bool no_conversions);
   bool basic_const_item() const { return 1; }
   Item *new_item() { return new Item_int(name,value,max_length); }
-  void cleanup() { fixed= 1; } // to prevent drop fixed flag
+  // to prevent drop fixed flag (no need parent cleanup call)
+  void cleanup() { fixed= 1; }
   void print(String *str);
 };
 
@@ -422,14 +433,17 @@ class Item_uint :public Item_int
 {
 public:
   Item_uint(const char *str_arg, uint length) :
-    Item_int(str_arg, (longlong) strtoull(str_arg,(char**) 0,10), length) {}
-  Item_uint(uint32 i) :Item_int((longlong) i, 10) {}
+    Item_int(str_arg, (longlong) strtoull(str_arg,(char**) 0,10), length) 
+    { fixed= 0; }
+  Item_uint(uint32 i) :Item_int((longlong) i, 10) 
+    { fixed= 0; }
   double val() { return ulonglong2double((ulonglong)value); }
   String *val_str(String*);
   Item *new_item() { return new Item_uint(name,max_length); }
   int save_in_field(Field *field, bool no_conversions);
   bool fix_fields(THD *thd, struct st_table_list *list, Item **item)
   {
+    DBUG_ASSERT(fixed == 0);
     bool res= Item::fix_fields(thd, list, item);
     unsigned_flag= 1;
     return res;
@@ -903,7 +917,8 @@ public:
   static Item_cache* get_cache(Item_result type);
   table_map used_tables() const { return used_table_map; }
   virtual void keep_array() {}
-  void cleanup() { fixed= 1; } // to prevent drop fixed flag
+  // to prevent drop fixed flag (no need parent cleanup call)
+  void cleanup() { fixed= 1; }
   void print(String *str);
 };
 
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index ac1af32388f..23213c8009b 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -502,7 +502,6 @@ bool Item_in_optimizer::fix_left(THD *thd,
   not_null_tables_cache= args[0]->not_null_tables();
   with_sum_func= args[0]->with_sum_func;
   const_item_cache= args[0]->const_item();
-  fixed= 1;
   return 0;
 }
 
@@ -510,7 +509,8 @@ bool Item_in_optimizer::fix_left(THD *thd,
 bool Item_in_optimizer::fix_fields(THD *thd, struct st_table_list *tables,
 				   Item ** ref)
 {
-  if (fix_left(thd, tables, ref))
+  DBUG_ASSERT(fixed == 0);
+  if (!args[0]->fixed && fix_left(thd, tables, ref))
     return 1;
   if (args[0]->maybe_null)
     maybe_null=1;
@@ -529,6 +529,7 @@ bool Item_in_optimizer::fix_fields(THD *thd, struct st_table_list *tables,
   used_tables_cache|= args[1]->used_tables();
   not_null_tables_cache|= args[1]->not_null_tables();
   const_item_cache&= args[1]->const_item();
+  fixed= 1;
   return 0;
 }
 
@@ -1755,6 +1756,7 @@ void Item_cond::copy_andor_arguments(THD *thd, Item_cond *item)
 bool
 Item_cond::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   List_iterator<Item> li(list);
   Item *item;
 #ifndef EMBEDDED_LIBRARY
@@ -1878,14 +1880,27 @@ void Item_cond::print(String *str)
 }
 
 
-void Item_cond::neg_arguments()
+void Item_cond::neg_arguments(THD *thd)
 {
   List_iterator<Item> li(list);
   Item *item;
   while ((item= li++))		/* Apply not transformation to the arguments */
   {
-    Item *new_item= item->neg_transformer();
-    VOID(li.replace(new_item ? new_item : new Item_func_not(item)));
+    Item *new_item= item->neg_transformer(thd);
+    if (!new_item)
+    {
+      new_item= new Item_func_not(item);
+      /*
+	We can use 0 as tables list because Item_func_not do not use it
+	on fix_fields and its arguments are already fixed.
+
+	We do not check results of fix_fields, because there are not way
+	to return error in this functions interface, thd->net.report_error
+	will be checked on upper level call.
+      */
+      new_item->fix_fields(thd, 0, &new_item);
+    }
+    VOID(li.replace(new_item));
   }
 }
 
@@ -2097,6 +2112,7 @@ Item_func::optimize_type Item_func_like::select_optimize() const
 
 bool Item_func_like::fix_fields(THD *thd, TABLE_LIST *tlist, Item ** ref)
 {
+  DBUG_ASSERT(fixed == 0);
   if (Item_bool_func2::fix_fields(thd, tlist, ref))
     return 1;
 
@@ -2150,6 +2166,7 @@ bool Item_func_like::fix_fields(THD *thd, TABLE_LIST *tlist, Item ** ref)
 bool
 Item_func_regex::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   if (args[0]->fix_fields(thd, tables, args) || args[0]->check_cols(1) ||
       args[1]->fix_fields(thd,tables, args + 1) || args[1]->check_cols(1))
     return 1;					/* purecov: inspected */
@@ -2518,6 +2535,7 @@ longlong Item_cond_xor::val_int()
 
   SYNPOSIS
     neg_transformer()
+    thd		thread handler
 
   DESCRIPTION
     Transform the item using next rules:
@@ -2541,62 +2559,116 @@ longlong Item_cond_xor::val_int()
     NULL if we cannot apply NOT transformation (see Item::neg_transformer()).
 */
 
-Item *Item_func_not::neg_transformer()		/* NOT(x)  ->  x */
+Item *Item_func_not::neg_transformer(THD *thd)	/* NOT(x)  ->  x */
 {
-  /* We should apply negation elimination to the argument of the NOT function */
-  return eliminate_not_funcs(args[0]);
+  // We should apply negation elimination to the argument of the NOT function
+  return eliminate_not_funcs(thd, args[0]);
 }
 
-Item *Item_func_eq::neg_transformer()		/* a = b  ->  a != b */
+
+Item *Item_bool_rowready_func2::neg_transformer(THD *thd)
 {
-  return new Item_func_ne(args[0], args[1]);	
+  Item *item= negated_item();
+  if (item)
+  {
+    /*
+      We can use 0 as tables list because Item_func* family do not use it
+      on fix_fields and its arguments are already fixed.
+      
+      We do not check results of fix_fields, because there are not way
+      to return error in this functions interface, thd->net.report_error
+      will be checked on upper level call.
+    */
+    item->fix_fields(thd, 0, &item);
+  }
+  return item;
 }
 
-Item *Item_func_ne::neg_transformer()		/* a != b  ->  a = b */
+
+/* a IS NULL  ->  a IS NOT NULL */
+Item *Item_func_isnull::neg_transformer(THD *thd)
 {
-  return new Item_func_eq(args[0], args[1]);
+  Item *item= new Item_func_isnotnull(args[0]);
+  // see comment before fix_fields in Item_bool_rowready_func2::neg_transformer
+  if (item)
+    item->fix_fields(thd, 0, &item);
+  return item;
 }
 
-Item *Item_func_lt::neg_transformer()		/* a < b  ->  a >= b */
+
+/* a IS NOT NULL  ->  a IS NULL */
+Item *Item_func_isnotnull::neg_transformer(THD *thd)
 {
-  return new Item_func_ge(args[0], args[1]);
+  Item *item= new Item_func_isnull(args[0]);
+  // see comment before fix_fields in Item_bool_rowready_func2::neg_transformer
+  if (item)
+    item->fix_fields(thd, 0, &item);
+  return item;
 }
 
-Item *Item_func_ge::neg_transformer()		/* a >= b  ->  a < b */
+
+Item *Item_cond_and::neg_transformer(THD *thd)	/* NOT(a AND b AND ...)  -> */
+					/* NOT a OR NOT b OR ... */
 {
-  return new Item_func_lt(args[0], args[1]);
+  neg_arguments(thd);
+  Item *item= new Item_cond_or(list);
+  // see comment before fix_fields in Item_bool_rowready_func2::neg_transformer
+  if (item)
+    item->fix_fields(thd, 0, &item);
+  return item;
 }
 
-Item *Item_func_gt::neg_transformer()		/* a > b  ->  a <= b */
+
+Item *Item_cond_or::neg_transformer(THD *thd)	/* NOT(a OR b OR ...)  -> */
+					/* NOT a AND NOT b AND ... */
 {
-  return new Item_func_le(args[0], args[1]);
+  neg_arguments(thd);
+  Item *item= new Item_cond_and(list);
+  // see comment before fix_fields in Item_bool_rowready_func2::neg_transformer
+  if (item)
+    item->fix_fields(thd, 0, &item);
+  return item;
 }
 
-Item *Item_func_le::neg_transformer()		/* a <= b  ->  a > b */
+
+Item *Item_func_eq::negated_item()		/* a = b  ->  a != b */
 {
-  return new Item_func_gt(args[0], args[1]);
+  return new Item_func_ne(args[0], args[1]);
 }
 
-Item *Item_func_isnull::neg_transformer()	/* a IS NULL  ->  a IS NOT NULL */
+
+Item *Item_func_ne::negated_item()		/* a != b  ->  a = b */
 {
-  return new Item_func_isnotnull(args[0]);
+  return new Item_func_eq(args[0], args[1]);
 }
 
-Item *Item_func_isnotnull::neg_transformer()	/* a IS NOT NULL  ->  a IS NULL */
+
+Item *Item_func_lt::negated_item()		/* a < b  ->  a >= b */
 {
-  return new Item_func_isnull(args[0]);
+  return new Item_func_ge(args[0], args[1]);
 }
 
-Item *Item_cond_and::neg_transformer()		/* NOT(a AND b AND ...)  -> */
-					/* NOT a OR NOT b OR ... */
+
+Item *Item_func_ge::negated_item()		/* a >= b  ->  a < b */
 {
-  neg_arguments();
-  return new Item_cond_or(list);
+  return new Item_func_lt(args[0], args[1]);
 }
 
-Item *Item_cond_or::neg_transformer()		/* NOT(a OR b OR ...)  -> */
-					/* NOT a AND NOT b AND ... */
+
+Item *Item_func_gt::negated_item()		/* a > b  ->  a <= b */
 {
-  neg_arguments();
-  return new Item_cond_and(list);
+  return new Item_func_le(args[0], args[1]);
+}
+
+
+Item *Item_func_le::negated_item()		/* a <= b  ->  a > b */
+{
+  return new Item_func_gt(args[0], args[1]);
+}
+
+// just fake method, should never be called
+Item *Item_bool_rowready_func2::negated_item()
+{
+  DBUG_ASSERT(0);
+  return 0;
 }
diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index 9d39ddf4e76..463bb215da4 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -218,6 +218,8 @@ public:
     tmp_arg[1]= orig_b;
     DBUG_VOID_RETURN;
   }
+  Item *neg_transformer(THD *thd);
+  virtual Item *negated_item();
 };
 
 class Item_func_not :public Item_bool_func
@@ -227,7 +229,7 @@ public:
   longlong val_int();
   enum Functype functype() const { return NOT_FUNC; }
   const char *func_name() const { return "not"; }
-  Item *neg_transformer();
+  Item *neg_transformer(THD *thd);
 };
 
 class Item_func_not_all :public Item_func_not
@@ -254,7 +256,7 @@ public:
   enum Functype rev_functype() const { return EQ_FUNC; }
   cond_result eq_cmp_result() const { return COND_TRUE; }
   const char *func_name() const { return "="; }
-  Item *neg_transformer();
+  Item *negated_item();
 };
 
 class Item_func_equal :public Item_bool_rowready_func2
@@ -267,6 +269,7 @@ public:
   enum Functype rev_functype() const { return EQUAL_FUNC; }
   cond_result eq_cmp_result() const { return COND_TRUE; }
   const char *func_name() const { return "<=>"; }
+  Item* neg_transformer(THD *thd) { return 0; }
 };
 
 
@@ -279,7 +282,7 @@ public:
   enum Functype rev_functype() const { return LE_FUNC; }
   cond_result eq_cmp_result() const { return COND_TRUE; }
   const char *func_name() const { return ">="; }
-  Item *neg_transformer();
+  Item *negated_item();
 };
 
 
@@ -292,7 +295,7 @@ public:
   enum Functype rev_functype() const { return LT_FUNC; }
   cond_result eq_cmp_result() const { return COND_FALSE; }
   const char *func_name() const { return ">"; }
-  Item *neg_transformer();
+  Item *negated_item();
 };
 
 
@@ -305,7 +308,7 @@ public:
   enum Functype rev_functype() const { return GE_FUNC; }
   cond_result eq_cmp_result() const { return COND_TRUE; }
   const char *func_name() const { return "<="; }
-  Item *neg_transformer();
+  Item *negated_item();
 };
 
 
@@ -318,7 +321,7 @@ public:
   enum Functype rev_functype() const { return GT_FUNC; }
   cond_result eq_cmp_result() const { return COND_FALSE; }
   const char *func_name() const { return "<"; }
-  Item *neg_transformer();
+  Item *negated_item();
 };
 
 
@@ -331,7 +334,7 @@ public:
   cond_result eq_cmp_result() const { return COND_FALSE; }
   optimize_type select_optimize() const { return OPTIMIZE_KEY; } 
   const char *func_name() const { return "<>"; }
-  Item *neg_transformer();
+  Item *negated_item();
 };
 
 
@@ -409,6 +412,7 @@ public:
   enum Item_result result_type () const { return cached_result_type; }
   bool fix_fields(THD *thd,struct st_table_list *tlist, Item **ref)
   {
+    DBUG_ASSERT(fixed == 0);
     args[0]->top_level_item();
     return Item_func::fix_fields(thd, tlist, ref);
   }
@@ -726,6 +730,7 @@ class Item_func_in :public Item_int_func
   void cleanup()
   {
     DBUG_ENTER("Item_func_in::cleanup");
+    Item_int_func::cleanup();
     delete array;
     delete in_item;
     array= 0;
@@ -778,7 +783,7 @@ public:
   }
   table_map not_null_tables() const { return 0; }
   optimize_type select_optimize() const { return OPTIMIZE_NULL; }
-  Item *neg_transformer();
+  Item *neg_transformer(THD *thd);
   CHARSET_INFO *compare_collation() { return args[0]->collation.collation; }
 };
 
@@ -812,7 +817,7 @@ public:
   const char *func_name() const { return "isnotnull"; }
   optimize_type select_optimize() const { return OPTIMIZE_NULL; }
   table_map not_null_tables() const { return 0; }
-  Item *neg_transformer();
+  Item *neg_transformer(THD *thd);
   void print(String *str);
   CHARSET_INFO *compare_collation() { return args[0]->collation.collation; }
 };
@@ -920,7 +925,7 @@ public:
   void top_level_item() { abort_on_null=1; }
   void copy_andor_arguments(THD *thd, Item_cond *item);
   bool walk(Item_processor processor, byte *arg);
-  void neg_arguments();
+  void neg_arguments(THD *thd);
 };
 
 
@@ -941,7 +946,7 @@ public:
        item->copy_andor_arguments(thd, this);
     return item;
   }
-  Item *neg_transformer();
+  Item *neg_transformer(THD *thd);
 };
 
 class Item_cond_or :public Item_cond
@@ -962,7 +967,7 @@ public:
       item->copy_andor_arguments(thd, this);
     return item;
   }
-  Item *neg_transformer();
+  Item *neg_transformer(THD *thd);
 };
 
 
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 88c2bf824c6..c8d4178e739 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -199,6 +199,7 @@ Item_func::Item_func(THD *thd, Item_func *item)
 bool
 Item_func::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   Item **arg,**arg_end;
 #ifndef EMBEDDED_LIBRARY			// Avoid compiler warning
   char buff[STACK_BUFF_ALLOC];			// Max argument in function
@@ -215,7 +216,7 @@ Item_func::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
     {
       Item *item;
       /* We can't yet set item to *arg as fix_fields may change *arg */
-      if ((*arg)->fix_fields(thd, tables, arg) ||
+      if ((!(*arg)->fixed && (*arg)->fix_fields(thd, tables, arg)) ||
 	  (*arg)->check_cols(allowed_arg_cols))
 	return 1;				/* purecov: inspected */
       item= *arg;
@@ -2172,6 +2173,7 @@ static user_var_entry *get_variable(HASH *hash, LEX_STRING &name,
 bool Item_func_set_user_var::fix_fields(THD *thd, TABLE_LIST *tables,
 					Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   /* fix_fields will call Item_func_set_user_var::fix_length_and_dec */
   if (Item_func::fix_fields(thd, tables, ref) ||
       !(entry= get_variable(&thd->user_vars, name, 1)))
@@ -2741,6 +2743,7 @@ void Item_func_match::init_search(bool no_order)
 
 bool Item_func_match::fix_fields(THD *thd, TABLE_LIST *tlist, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   Item *item;
   LINT_INIT(item);				// Safe as arg_count is > 1
 
diff --git a/sql/item_func.h b/sql/item_func.h
index 8fbe5a124da..b463be1e0ca 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -765,6 +765,7 @@ public:
   const char *func_name() const { return udf.name(); }
   bool fix_fields(THD *thd, struct st_table_list *tables, Item **ref)
   {
+    DBUG_ASSERT(fixed == 0);
     bool res= udf.fix_fields(thd, tables, this, arg_count, args);
     used_tables_cache= udf.used_tables_cache;
     const_item_cache= udf.const_item_cache;
@@ -1000,6 +1001,7 @@ public:
   void cleanup()
   {
     DBUG_ENTER("Item_func_match");
+    Item_real_func::cleanup();
     if (!master && ft_handler)
     {
       ft_handler->please->close_search(ft_handler);
diff --git a/sql/item_row.cc b/sql/item_row.cc
index 2b0cd38e3c1..c7e4bc0acf4 100644
--- a/sql/item_row.cc
+++ b/sql/item_row.cc
@@ -55,6 +55,7 @@ void Item_row::illegal_method_call(const char *method)
 
 bool Item_row::fix_fields(THD *thd, TABLE_LIST *tabl, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   null_value= 0;
   maybe_null= 0;
   Item **arg, **arg_end;
@@ -78,6 +79,7 @@ bool Item_row::fix_fields(THD *thd, TABLE_LIST *tabl, Item **ref)
     maybe_null|= item->maybe_null;
     with_sum_func= with_sum_func || item->with_sum_func;
   }
+  fixed= 1;
   return 0;
 }
 
diff --git a/sql/item_strfunc.h b/sql/item_strfunc.h
index 5b9c442b5db..74b66d37491 100644
--- a/sql/item_strfunc.h
+++ b/sql/item_strfunc.h
@@ -100,6 +100,7 @@ public:
   void update_used_tables();
   bool fix_fields(THD *thd, TABLE_LIST *tlist, Item **ref)
   {
+    DBUG_ASSERT(fixed == 0);
     return (separator->fix_fields(thd, tlist, &separator) ||
 	    separator->check_cols(1) ||
 	    Item_func::fix_fields(thd, tlist, ref));
@@ -411,6 +412,7 @@ public:
   String *val_str(String *str);
   bool fix_fields(THD *thd, TABLE_LIST *tlist, Item **ref)
   {
+    DBUG_ASSERT(fixed == 0);
     return (item->fix_fields(thd, tlist, &item) ||
 	    item->check_cols(1) ||
 	    Item_func::fix_fields(thd, tlist, ref));
diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index deb1ebabef9..90070e21953 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -102,6 +102,7 @@ Item_subselect::select_transformer(JOIN *join)
 
 bool Item_subselect::fix_fields(THD *thd_param, TABLE_LIST *tables, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   engine->set_thd((thd= thd_param));
   stmt= thd->current_statement;
 
@@ -125,8 +126,10 @@ bool Item_subselect::fix_fields(THD *thd_param, TABLE_LIST *tables, Item **ref)
 	engine->exclude();
       substitution= 0;
       fixed= 1;
-      thd->where= "checking transformed subquery";
-      int ret= (*ref)->fix_fields(thd, tables, ref);
+      thd->where= "checking transformed subquery";      
+      int ret= 0;
+      if (!(*ref)->fixed)
+	ret= (*ref)->fix_fields(thd, tables, ref);
       // We can't substitute aggregate functions (like (SELECT (max(i)))
       if ((*ref)->with_sum_func)
       {
@@ -651,9 +654,7 @@ Item_in_subselect::single_value_transformer(JOIN *join,
       select_lex->item_list.empty();
       select_lex->item_list.push_back(item);
 
-      if (item->fix_fields(thd, join->tables_list,
-			   select_lex->item_list.head_ref()))
-	goto err;
+      // fix_fields call for 'item' will be made during new subquery fix_fields
 
       subs= new Item_singlerow_subselect(select_lex);
     }
diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index 77a910ae5d6..97fd8afb25e 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -162,6 +162,7 @@ Item_sum_int::val_str(String *str)
 bool
 Item_sum_num::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   if (!thd->allow_sum_func)
   {
     my_error(ER_INVALID_GROUP_FUNC_USE,MYF(0));
@@ -191,6 +192,7 @@ Item_sum_num::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 bool
 Item_sum_hybrid::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   Item *item= args[0];
   if (!thd->allow_sum_func)
   {
@@ -1116,6 +1118,7 @@ void Item_sum_count_distinct::cleanup()
 bool Item_sum_count_distinct::fix_fields(THD *thd, TABLE_LIST *tables,
 					 Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   if (Item_sum_num::fix_fields(thd, tables, ref))
     return 1;
   return 0;
@@ -1679,6 +1682,7 @@ Item_func_group_concat::Item_func_group_concat(bool is_distinct,
 void Item_func_group_concat::cleanup()
 {
   DBUG_ENTER("Item_func_group_concat::cleanup");
+  Item_sum::cleanup();
   /*
     Free table and tree if they belong to this item (if item have not pointer
     to original item from which was made copy => it own its objects )
@@ -1794,6 +1798,7 @@ void Item_func_group_concat::reset_field()
 bool
 Item_func_group_concat::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
+  DBUG_ASSERT(fixed == 0);
   uint i;			/* for loop variable */ 
 
   if (!thd->allow_sum_func)
diff --git a/sql/item_sum.h b/sql/item_sum.h
index 11c95100db5..41d700b0ff8 100644
--- a/sql/item_sum.h
+++ b/sql/item_sum.h
@@ -533,6 +533,7 @@ public:
   const char *func_name() const { return udf.name(); }
   bool fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
   {
+    DBUG_ASSERT(fixed == 0);
     fixed= 1;
     return udf.fix_fields(thd,tables,this,this->arg_count,this->args);
   }
diff --git a/sql/item_uniq.h b/sql/item_uniq.h
index 47f967b52c6..5de4b82a99d 100644
--- a/sql/item_uniq.h
+++ b/sql/item_uniq.h
@@ -48,6 +48,7 @@ public:
   void update_field() {}
   bool fix_fields(THD *thd, TABLE_LIST *tlist, Item **ref)
   {
+    DBUG_ASSERT(fixed == 0);
     fixed= 1;
     return 0;
   }
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index bdbb14f0819..a2f13c47694 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -2140,7 +2140,7 @@ int setup_fields(THD *thd, Item **ref_pointer_array, TABLE_LIST *tables,
   Item **ref= ref_pointer_array;
   while ((item= it++))
   {
-    if (item->fix_fields(thd, tables, it.ref()) ||
+    if (!item->fixed && item->fix_fields(thd, tables, it.ref()) ||
 	(item= *(it.ref()))->check_cols(1))
       DBUG_RETURN(-1); /* purecov: inspected */
     if (ref)
@@ -2322,7 +2322,8 @@ int setup_conds(THD *thd,TABLE_LIST *tables,COND **conds)
   if (*conds)
   {
     thd->where="where clause";
-    if ((*conds)->fix_fields(thd, tables, conds) || (*conds)->check_cols(1))
+    if (!(*conds)->fixed && (*conds)->fix_fields(thd, tables, conds) ||
+	(*conds)->check_cols(1))
       DBUG_RETURN(1);
     not_null_tables= (*conds)->not_null_tables();
   }
@@ -2334,7 +2335,9 @@ int setup_conds(THD *thd,TABLE_LIST *tables,COND **conds)
     {
       /* Make a join an a expression */
       thd->where="on clause";
-      if (table->on_expr->fix_fields(thd, tables, &table->on_expr) ||
+      
+      if (!table->on_expr->fixed &&
+	  table->on_expr->fix_fields(thd, tables, &table->on_expr) ||
 	  table->on_expr->check_cols(1))
 	DBUG_RETURN(1);
       thd->lex->current_select->cond_count++;
diff --git a/sql/sql_derived.cc b/sql/sql_derived.cc
index 0e04316a2e7..4bfb8cdfe3c 100644
--- a/sql/sql_derived.cc
+++ b/sql/sql_derived.cc
@@ -151,7 +151,11 @@ static int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit,
 
 
   if (is_union)
-    res= mysql_union(thd, lex, derived_result, unit);
+  {
+    // execute union without clean up
+    if (!(res= unit->prepare(thd, derived_result, SELECT_NO_UNLOCK)))
+      res= unit->exec();
+  }
   else
   {
     unit->offset_limit_cnt= first_select->offset_limit;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 00b573922fe..cc9f453e595 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -70,8 +70,10 @@ static int return_zero_rows(JOIN *join, select_result *res,TABLE_LIST *tables,
 			    uint select_options, const char *info,
 			    Item *having, Procedure *proc,
 			    SELECT_LEX_UNIT *unit);
-static COND *optimize_cond(COND *conds,Item::cond_result *cond_value);
-static COND *remove_eq_conds(COND *cond,Item::cond_result *cond_value);
+static COND *optimize_cond(THD *thd, COND *conds,
+			   Item::cond_result *cond_value);
+static COND *remove_eq_conds(THD *thd, COND *cond, 
+			     Item::cond_result *cond_value);
 static bool const_expression_in_where(COND *conds,Item *item, Item **comp_item);
 static bool open_tmp_table(TABLE *table);
 static bool create_myisam_tmp_table(TABLE *table,TMP_TABLE_PARAM *param,
@@ -286,6 +288,10 @@ JOIN::prepare(Item ***rref_pointer_array,
 {
   DBUG_ENTER("JOIN::prepare");
 
+  // to prevent double initialization on EXPLAIN
+  if (optimized)
+    DBUG_RETURN(0);
+
   conds= conds_init;
   order= order_init;
   group_list= group_init;
@@ -315,8 +321,9 @@ JOIN::prepare(Item ***rref_pointer_array,
     thd->where="having clause";
     thd->allow_sum_func=1;
     select_lex->having_fix_field= 1;
-    bool having_fix_rc= (having->fix_fields(thd, tables_list, &having) ||
-			 having->check_cols(1));
+    bool having_fix_rc= !having->fixed &&
+      (having->fix_fields(thd, tables_list, &having) ||
+       having->check_cols(1));
     select_lex->having_fix_field= 0;
     if (having_fix_rc || thd->net.report_error)
       DBUG_RETURN(-1);				/* purecov: inspected */
@@ -518,7 +525,7 @@ JOIN::optimize()
   }
 #endif
 
-  conds= optimize_cond(conds,&cond_value);
+  conds= optimize_cond(thd, conds,&cond_value);
   if (thd->net.report_error)
   {
     error= 1;
@@ -4333,6 +4340,7 @@ propagate_cond_constants(I_List<COND_CMP> *save_list,COND *and_father,
 
   SYNPOSIS
     eliminate_not_funcs()
+    thd		thread handler
     cond	condition tree
 
   DESCRIPTION
@@ -4349,7 +4357,7 @@ propagate_cond_constants(I_List<COND_CMP> *save_list,COND *and_father,
     New condition tree
 */
 
-COND *eliminate_not_funcs(COND *cond)
+COND *eliminate_not_funcs(THD *thd, COND *cond)
 {
   if (!cond)
     return cond;
@@ -4359,7 +4367,7 @@ COND *eliminate_not_funcs(COND *cond)
     Item *item;
     while ((item= li++))
     {
-      Item *new_item= eliminate_not_funcs(item);
+      Item *new_item= eliminate_not_funcs(thd, item);
       if (item != new_item)
 	VOID(li.replace(new_item));	/* replace item with a new condition */
     }
@@ -4367,14 +4375,13 @@ COND *eliminate_not_funcs(COND *cond)
   else if (cond->type() == Item::FUNC_ITEM &&	/* 'NOT' operation? */
 	   ((Item_func*) cond)->functype() == Item_func::NOT_FUNC)
   {
-    COND *new_cond= ((Item_func*) cond)->arguments()[0]->neg_transformer();
+    COND *new_cond= ((Item_func*) cond)->arguments()[0]->neg_transformer(thd);
     if (new_cond)
     {
       /*
         Here we can delete the NOT function. Something like: delete cond;
         But we don't need to do it. All items will be deleted later at once.
       */
-      new_cond->fix_fields(current_thd, 0, &new_cond);
       cond= new_cond;
     }
   }
@@ -4383,7 +4390,7 @@ COND *eliminate_not_funcs(COND *cond)
 
 
 static COND *
-optimize_cond(COND *conds,Item::cond_result *cond_value)
+optimize_cond(THD *thd, COND *conds, Item::cond_result *cond_value)
 {
   DBUG_ENTER("optimize_cond");
   if (!conds)
@@ -4393,7 +4400,7 @@ optimize_cond(COND *conds,Item::cond_result *cond_value)
   }
   DBUG_EXECUTE("where",print_where(conds,"original"););
   /* eliminate NOT operators */
-  conds= eliminate_not_funcs(conds);
+  conds= eliminate_not_funcs(thd, conds);
   DBUG_EXECUTE("where", print_where(conds, "after negation elimination"););
   /* change field = field to field = const for each found field = const */
   propagate_cond_constants((I_List<COND_CMP> *) 0,conds,conds);
@@ -4402,7 +4409,7 @@ optimize_cond(COND *conds,Item::cond_result *cond_value)
     Remove all and-levels where CONST item != CONST item
   */
   DBUG_EXECUTE("where",print_where(conds,"after const change"););
-  conds=remove_eq_conds(conds,cond_value) ;
+  conds= remove_eq_conds(thd, conds, cond_value) ;
   DBUG_EXECUTE("info",print_where(conds,"after remove"););
   DBUG_RETURN(conds);
 }
@@ -4417,7 +4424,7 @@ optimize_cond(COND *conds,Item::cond_result *cond_value)
 */
 
 static COND *
-remove_eq_conds(COND *cond,Item::cond_result *cond_value)
+remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
 {
   if (cond->type() == Item::COND_ITEM)
   {
@@ -4431,7 +4438,7 @@ remove_eq_conds(COND *cond,Item::cond_result *cond_value)
     Item *item;
     while ((item=li++))
     {
-      Item *new_item=remove_eq_conds(item,&tmp_cond_value);
+      Item *new_item=remove_eq_conds(thd, item, &tmp_cond_value);
       if (!new_item)
 	li.remove();
       else if (item != new_item)
@@ -4465,7 +4472,7 @@ remove_eq_conds(COND *cond,Item::cond_result *cond_value)
       }
     }
     if (should_fix_fields)
-      cond->fix_fields(current_thd,0, &cond);
+      cond->update_used_tables();
 
     if (!((Item_cond*) cond)->argument_list()->elements ||
 	*cond_value != Item::COND_OK)
@@ -4492,7 +4499,6 @@ remove_eq_conds(COND *cond,Item::cond_result *cond_value)
 
     Item_func_isnull *func=(Item_func_isnull*) cond;
     Item **args= func->arguments();
-    THD *thd=current_thd;
     if (args[0]->type() == Item::FIELD_ITEM)
     {
       Field *field=((Item_field*) args[0])->field;
@@ -7913,10 +7919,15 @@ find_order_in_list(THD *thd, Item **ref_pointer_array,
   }
   order->in_field_list=0;
   Item *it= *order->item;
-  if (it->fix_fields(thd, tables, order->item) ||
-      //'it' ressigned because fix_field can change it
-      (it= *order->item)->check_cols(1) ||
-      thd->is_fatal_error)
+  /*
+    we check it->fixed because Item_func_group_concat can put
+    arguments for which fix_fields already was called
+  */
+  if (!it->fixed &&
+      (it->fix_fields(thd, tables, order->item) ||
+       //'it' ressigned because fix_field can change it
+       (it= *order->item)->check_cols(1) ||
+       thd->is_fatal_error))
     return 1;					// Wrong field 
   uint el= all_fields.elements;
   all_fields.push_front(it);		        // Add new field to field list
diff --git a/sql/sql_select.h b/sql/sql_select.h
index 36526bee066..fea3f7c6b80 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -432,4 +432,4 @@ bool cp_buffer_from_ref(TABLE_REF *ref);
 bool error_if_full_join(JOIN *join);
 int report_error(TABLE *table, int error);
 int safe_index_read(JOIN_TAB *tab);
-COND *eliminate_not_funcs(COND *cond);
+COND *eliminate_not_funcs(THD *thd, COND *cond);
diff --git a/sql/sql_union.cc b/sql/sql_union.cc
index a05fa44cfc9..d45b867b197 100644
--- a/sql/sql_union.cc
+++ b/sql/sql_union.cc
@@ -203,6 +203,8 @@ int st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
     }
   }
 
+  item_list.empty();
+  // it is not single select
   if (first_select->next_select())
   {
     union_result->tmp_table_param.field_count= types.elements;
@@ -222,14 +224,17 @@ int st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
     result_table_list.table= table;
     union_result->set_table(table);
 
-    item_list.empty();
     thd_arg->lex->current_select= lex_select_save;
     {
       Field **field;
       for (field= table->field; *field; field++)
       {
-	if (item_list.push_back(new Item_field(*field)))
+	Item_field *item= new Item_field(*field);
+	if (item_list.push_back(item))
 	  DBUG_RETURN(-1);
+#ifndef DBUG_OFF
+	item->double_fix= 0;
+#endif
       }
     }
   }
diff --git a/tests/client_test.c b/tests/client_test.c
index fae8c3cd54d..31a53f6d81e 100644
--- a/tests/client_test.c
+++ b/tests/client_test.c
@@ -8206,7 +8206,6 @@ static void test_bug2247()
 }
 
 
-
 static void test_subqueries()
 {
   MYSQL_STMT *stmt;
@@ -8346,6 +8345,37 @@ static void test_bug2248()
   myquery(rc);
 }
 
+static void test_subqueries_ref()
+{
+  MYSQL_STMT *stmt;
+  int rc, i;
+  const char *query= "SELECT a as ccc from t1 where a+1=(SELECT 1+ccc from t1 where ccc+1=a+1 and a=1)";
+
+  myheader("test_subquery_ref");
+  
+  rc = mysql_query(mysql, "DROP TABLE IF EXISTS t1");
+  myquery(rc);
+  
+  rc= mysql_query(mysql,"CREATE TABLE t1 (a int);");
+  myquery(rc);
+
+  rc= mysql_query(mysql,
+		  "insert into t1 values (1), (2), (3), (4), (5);");
+  myquery(rc);
+
+  stmt= mysql_prepare(mysql, query, strlen(query));
+  mystmt_init(stmt);
+  for (i= 0; i < 3; i++)
+  {
+    rc= mysql_execute(stmt);
+    mystmt(stmt, rc);
+    assert(1 == my_process_stmt_result(stmt));
+  }
+  mysql_stmt_close(stmt);
+
+  rc= mysql_query(mysql, "DROP TABLE t1");
+  myquery(rc);
+}
 
 /*
   Read and parse arguments and MySQL options from my.cnf
@@ -8602,6 +8632,9 @@ int main(int argc, char **argv)
     test_subqueries();	    /* repeatable subqueries */
     test_bad_union();       /* correct setup of UNION */
     test_distinct();	    /* distinct aggregate functions */
+    test_subqueries_ref();  /* outer reference in subqueries converted
+			       Item_field -> Item_ref */
+
 
 
     end_time= time((time_t *)0);