Merge 5.3->5.5.

In particular:
Merged the patch for bug mdev-4418 from 5.3 into 5.5.
Fixed a bug in the patch that should be backported to 5.3.

6 files changed, 387 insertions, 170 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 206c059813f..0b4789a4f35 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -5738,10 +5738,12 @@ void Item_equal::merge(Item_equal *item)
   @brief
   Merge members of another Item_equal object into this one
   
-  @param item    multiple equality whose members are to be merged
+  @param item         multiple equality whose members are to be merged
+  @param save_merged  keep the list of equalities in 'item' intact
+                      (e.g. for other merges)
 
   @details
-  If the Item_equal 'item' happened to have some elements of the list
+  If the Item_equal 'item' happens to have some elements of the list
   of equal items belonging to 'this' object then the function merges
   the equal items from 'item' into this list.
   If both lists contains constants and they are different then
@@ -5756,24 +5758,45 @@ void Item_equal::merge(Item_equal *item)
   The method 'merge' just joins the list of equal items belonging to 'item'
   to the list of equal items belonging to this object assuming that the lists
   are disjoint. It would be more correct to call the method 'join'.
-  The method 'merge_with_check' really merges two lists of equal items if they
-  have common members.  
+  The method 'merge_into_with_check' really merges two lists of equal items if
+  they have common members.  
 */
   
-bool Item_equal::merge_with_check(Item_equal *item)
+bool Item_equal::merge_with_check(Item_equal *item, bool save_merged)
 {
   bool intersected= FALSE;
-  Item_equal_fields_iterator_slow fi(*this);
+  Item_equal_fields_iterator_slow fi(*item);
+  
   while (fi++)
   {
-    if (item->contains(fi.get_curr_field()))
+    if (contains(fi.get_curr_field()))
     {
-      fi.remove();
       intersected= TRUE;
+      if (!save_merged)
+        fi.remove();
     }
   }
   if (intersected)
-    item->merge(this);
+  {
+    if (!save_merged)
+      merge(item);
+    else
+    {
+      Item *c= item->get_const();
+      if (c)
+        add_const(c);
+      if (!cond_false)
+      {
+        Item *item;
+        fi.rewind();
+        while ((item= fi++))
+	{
+          if (!contains(fi.get_curr_field()))
+            add(item);
+        }
+      }
+    }         
+  }
   return intersected;
 }
 
@@ -5782,17 +5805,25 @@ bool Item_equal::merge_with_check(Item_equal *item)
   @brief
   Merge this object into a list of Item_equal objects 
   
-  @param list   the list of Item_equal objects to merge into
+  @param list                 the list of Item_equal objects to merge into
+  @param save_merged          keep the list of equalities in 'this' intact
+                              (e.g. for other merges)
+  @param only_intersected     do not merge if there are no common members
+                              in any of Item_equal objects from the list
+                              and this Item_equal
 
   @details
   If the list of equal items from 'this' object contains common members
   with the lists of equal items belonging to Item_equal objects from 'list'
   then all involved Item_equal objects e1,...,ek are merged into one 
-  Item equal that replaces e1,...,ek in the 'list'. Otherwise this
+  Item equal that replaces e1,...,ek in the 'list'. Otherwise, in the case
+  when the value of the parameter only_if_intersected is false, this
   Item_equal is joined to the 'list'.
 */
 
-void Item_equal::merge_into_list(List<Item_equal> *list)
+void Item_equal::merge_into_list(List<Item_equal> *list,
+                                 bool save_merged,
+                                 bool only_intersected)
 {
   Item_equal *item;
   List_iterator<Item_equal> it(*list);
@@ -5801,16 +5832,16 @@ void Item_equal::merge_into_list(List<Item_equal> *list)
   {
     if (!merge_into)
     {
-      if (merge_with_check(item))
+      if (item->merge_with_check(this, save_merged))
         merge_into= item;
     }
     else
     {
-      if (item->merge_with_check(merge_into))
+      if (merge_into->merge_with_check(item, false))
         it.remove();
     }
   }
-  if (!merge_into)
+  if (!only_intersected && !merge_into)
     list->push_back(this);
 }
 
diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index 0be9730c63e..251d06499bf 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -1754,8 +1754,9 @@ public:
   /** Get number of field items / references to field items in this object */   
   uint n_field_items() { return equal_items.elements-test(with_const); }
   void merge(Item_equal *item);
-  bool merge_with_check(Item_equal *equal_item);
-  void merge_into_list(List<Item_equal> *list);
+  bool merge_with_check(Item_equal *equal_item, bool save_merged);
+  void merge_into_list(List<Item_equal> *list, bool save_merged,
+                      bool only_intersected);
   void update_const();
   enum Functype functype() const { return MULT_EQUAL_FUNC; }
   longlong val_int(); 
diff --git a/sql/spatial.cc b/sql/spatial.cc
index a01d2c59a49..32a2012a49d 100644
--- a/sql/spatial.cc
+++ b/sql/spatial.cc
@@ -447,19 +447,18 @@ const char *Geometry::append_points(String *txt, uint32 n_points,
 const char *Geometry::get_mbr_for_points(MBR *mbr, const char *data,
 					 uint offset) const
 {
-  uint32 n_points;
+  uint32 points;
   /* read number of points */
   if (no_data(data, 4))
     return 0;
-  n_points= uint4korr(data);
+  points= uint4korr(data);
   data+= 4;
 
-  if (n_points > max_n_points ||
-      no_data(data, (POINT_DATA_SIZE + offset) * n_points))
+  if (not_enough_points(data, points, offset))
     return 0;
 
   /* Calculate MBR for points */
-  while (n_points--)
+  while (points--)
   {
     data+= offset;
     mbr->add_xy(data, data + SIZEOF_STORED_DOUBLE);
@@ -563,12 +562,16 @@ const Geometry::Class_info *Gis_point::get_class_info() const
 
 uint32 Gis_line_string::get_data_size() const 
 {
-  uint32 n_points, size;
-  if (no_data(m_data, 4) ||
-      (n_points= uint4korr(m_data)) > max_n_points ||
-      no_data(m_data, (size= 4 + n_points * POINT_DATA_SIZE)))
+  uint32 n_points;
+  if (no_data(m_data, 4))
     return GET_SIZE_ERROR;
-  return size;
+
+  n_points= uint4korr(m_data);
+
+  if (not_enough_points(m_data + 4, n_points))
+    return GET_SIZE_ERROR;
+
+  return 4 + n_points * POINT_DATA_SIZE;
 }
 
 
@@ -607,9 +610,8 @@ uint Gis_line_string::init_from_wkb(const char *wkb, uint len,
   const char *wkb_end;
   Gis_point p;
 
-  if (len < 4 ||
-      (n_points= wkb_get_uint(wkb, bo)) < 1 ||
-      n_points > max_n_points)
+  if (len < 4 || (n_points= wkb_get_uint(wkb, bo)) < 1 ||
+      ((len - 4) / POINT_DATA_SIZE) < n_points)
     return 0;
   proper_length= 4 + n_points * POINT_DATA_SIZE;
 
@@ -638,8 +640,8 @@ bool Gis_line_string::get_data_as_wkt(String *txt, const char **end) const
   n_points= uint4korr(data);
   data += 4;
 
-  if (n_points < 1 || n_points > max_n_points ||
-      no_data(data, POINT_DATA_SIZE * n_points) ||
+  if (n_points < 1 ||
+      not_enough_points(data, n_points) ||
       txt->reserve(((MAX_DIGITS_IN_DOUBLE + 1)*2 + 1) * n_points))
     return 1;
 
@@ -676,8 +678,7 @@ int Gis_line_string::geom_length(double *len, const char **end) const
     return 1;
   n_points= uint4korr(data);
   data+= 4;
-  if (n_points < 1 || n_points > max_n_points ||
-      no_data(data, POINT_DATA_SIZE * n_points))
+  if (n_points < 1 || not_enough_points(data, n_points))
     return 1;
 
   get_point(&prev_x, &prev_y, data);
@@ -725,8 +726,7 @@ int Gis_line_string::is_closed(int *closed) const
     return 0;
   }
   data+= 4;
-  if (n_points == 0 || n_points > max_n_points ||
-      no_data(data, POINT_DATA_SIZE * n_points))
+  if (n_points == 0 || not_enough_points(data, n_points))
     return 1;
 
   /* Get first point */
@@ -761,8 +761,7 @@ int Gis_line_string::end_point(String *result) const
   if (no_data(m_data, 4))
     return 1;
   n_points= uint4korr(m_data);
-  if (n_points == 0 || n_points > max_n_points ||
-      no_data(m_data, POINT_DATA_SIZE * n_points))
+  if (n_points == 0 || not_enough_points(m_data+4, n_points))
     return 1;
   return create_point(result, m_data + 4 + (n_points - 1) * POINT_DATA_SIZE);
 }
@@ -775,9 +774,7 @@ int Gis_line_string::point_n(uint32 num, String *result) const
     return 1;
   num--;
   n_points= uint4korr(m_data);
-  if (num >= n_points ||
-      num > max_n_points || // means (num > n_points || num < 1)
-      no_data(m_data, num * POINT_DATA_SIZE))
+  if (num >= n_points || not_enough_points(m_data+4, n_points))
     return 1;
 
   return create_point(result, m_data + 4 + num*POINT_DATA_SIZE);
@@ -796,8 +793,7 @@ int Gis_line_string::store_shapes(Gcalc_shape_transporter *trn) const
     return 1;
   n_points= uint4korr(data);
   data+= 4;
-  if (n_points < 1 ||  n_points > max_n_points ||
-      no_data(data, POINT_DATA_SIZE * n_points))
+  if (n_points < 1 || no_data(data, POINT_DATA_SIZE * n_points))
     return 1;
 
   trn->start_line();
@@ -840,7 +836,7 @@ uint32 Gis_polygon::get_data_size() const
   while (n_linear_rings--)
   {
     if (no_data(data, 4) ||
-        (n_points= uint4korr(data)) > max_n_points)
+        not_enough_points(data+4, n_points= uint4korr(data)))
       return GET_SIZE_ERROR;
     data+= 4 + n_points*POINT_DATA_SIZE;
   }
@@ -986,7 +982,7 @@ bool Gis_polygon::get_data_as_wkt(String *txt, const char **end) const
       return 1;
     n_points= uint4korr(data);
     data+= 4;
-    if (n_points > max_n_points || no_data(data, POINT_DATA_SIZE * n_points) ||
+    if (not_enough_points(data, n_points) ||
 	txt->reserve(2 + ((MAX_DIGITS_IN_DOUBLE + 1) * 2 + 1) * n_points))
       return 1;
     txt->qs_append('(');
@@ -1040,8 +1036,8 @@ int Gis_polygon::area(double *ar, const char **end_of_data) const
     if (no_data(data, 4))
       return 1;
     n_points= uint4korr(data);
-    if (n_points == 0 || n_points > max_n_points ||
-        no_data(data, POINT_DATA_SIZE * n_points))
+    if (n_points == 0 ||
+        not_enough_points(data, n_points))
       return 1;
     get_point(&prev_x, &prev_y, data+4);
     data+= (4+POINT_DATA_SIZE);
@@ -1077,8 +1073,7 @@ int Gis_polygon::exterior_ring(String *result) const
   n_points= uint4korr(data);
   data+= 4;
   length= n_points * POINT_DATA_SIZE;
-  if (n_points > max_n_points ||
-      no_data(data, length) || result->reserve(1 + 4 + 4 + length))
+  if (not_enough_points(data, n_points) || result->reserve(1+4+4+ length))
     return 1;
 
   result->q_append((char) wkb_ndr);
@@ -1124,8 +1119,7 @@ int Gis_polygon::interior_ring_n(uint32 num, String *result) const
   n_points= uint4korr(data);
   points_size= n_points * POINT_DATA_SIZE;
   data+= 4;
-  if (n_points > max_n_points ||
-      no_data(data, points_size) || result->reserve(1 + 4 + 4 + points_size))
+  if (not_enough_points(data, n_points) || result->reserve(1+4+4+ points_size))
     return 1;
 
   result->q_append((char) wkb_ndr);
@@ -1162,8 +1156,7 @@ int Gis_polygon::centroid_xy(double *x, double *y) const
       return 1;
     org_n_points= n_points= uint4korr(data);
     data+= 4;
-    if (n_points == 0 || n_points > max_n_points ||
-        no_data(data, POINT_DATA_SIZE * n_points))
+    if (n_points == 0 || not_enough_points(data, n_points))
       return 1;
     get_point(&prev_x, &prev_y, data);
     data+= POINT_DATA_SIZE;
@@ -1237,8 +1230,7 @@ int Gis_polygon::store_shapes(Gcalc_shape_transporter *trn) const
       return 1;
     n_points= uint4korr(data);
     data+= 4;
-    if (!n_points || n_points > max_n_points ||
-        no_data(data, POINT_DATA_SIZE * n_points))
+    if (!n_points || no_data(data, POINT_DATA_SIZE * n_points))
       return 1;
 
     trn->start_ring();
@@ -1292,13 +1284,12 @@ const Geometry::Class_info *Gis_polygon::get_class_info() const
 uint32 Gis_multi_point::get_data_size() const 
 {
   uint32 n_points;
-  uint32 size;
 
   if (no_data(m_data, 4) ||
-      (n_points= uint4korr(m_data)) > max_n_points ||
-      no_data(m_data, (size= 4 + n_points*(POINT_DATA_SIZE + WKB_HEADER_SIZE))))
+      not_enough_points(m_data+4, (n_points= uint4korr(m_data)),
+        WKB_HEADER_SIZE))
      return GET_SIZE_ERROR;
-  return size;
+  return  4 + n_points * (POINT_DATA_SIZE + WKB_HEADER_SIZE);
 }
 
 
@@ -1393,7 +1384,7 @@ bool Gis_multi_point::get_data_as_wkt(String *txt, const char **end) const
 
   n_points= uint4korr(m_data);
   if (n_points > max_n_points ||
-      no_data(m_data+4, n_points * (POINT_DATA_SIZE + WKB_HEADER_SIZE)) ||
+      not_enough_points(m_data+4, n_points, WKB_HEADER_SIZE) ||
       txt->reserve(((MAX_DIGITS_IN_DOUBLE + 1) * 2 + 1) * n_points))
     return 1;
   *end= append_points(txt, n_points, m_data+4, WKB_HEADER_SIZE);
@@ -1485,7 +1476,8 @@ uint32 Gis_multi_line_string::get_data_size() const
   while (n_line_strings--)
   {
     if (no_data(data, WKB_HEADER_SIZE + 4) ||
-        (n_points= uint4korr(data + WKB_HEADER_SIZE)) > max_n_points)
+        not_enough_points(data + WKB_HEADER_SIZE+4,
+                          (n_points= uint4korr(data + WKB_HEADER_SIZE))))
       return GET_SIZE_ERROR;
     data+= (WKB_HEADER_SIZE + 4 + n_points*POINT_DATA_SIZE);
   }
@@ -1614,7 +1606,7 @@ bool Gis_multi_line_string::get_data_as_wkt(String *txt,
       return 1;
     n_points= uint4korr(data + WKB_HEADER_SIZE);
     data+= WKB_HEADER_SIZE + 4;
-    if (n_points > max_n_points || no_data(data, n_points * POINT_DATA_SIZE) ||
+    if (not_enough_points(data, n_points) ||
 	txt->reserve(2 + ((MAX_DIGITS_IN_DOUBLE + 1) * 2 + 1) * n_points))
       return 1;
     txt->qs_append('(');
@@ -1675,7 +1667,7 @@ int Gis_multi_line_string::geometry_n(uint32 num, String *result) const
       return 1;
     n_points= uint4korr(data + WKB_HEADER_SIZE);
     length= WKB_HEADER_SIZE + 4+ POINT_DATA_SIZE * n_points;
-    if (n_points > max_n_points || no_data(data, length))
+    if (not_enough_points(data+WKB_HEADER_SIZE+4, n_points))
       return 1;
     if (!--num)
       break;
@@ -1806,7 +1798,7 @@ uint32 Gis_multi_polygon::get_data_size() const
     while (n_linear_rings--)
     {
       if (no_data(data, 4) ||
-          (n_points= uint4korr(data)) > max_n_points)
+          not_enough_points(data+4, (n_points= uint4korr(data))))
 	return GET_SIZE_ERROR;
       data+= 4 + n_points * POINT_DATA_SIZE;
     }
@@ -1940,8 +1932,7 @@ bool Gis_multi_polygon::get_data_as_wkt(String *txt, const char **end) const
         return 1;
       uint32 n_points= uint4korr(data);
       data+= 4;
-      if (n_points > max_n_points ||
-          no_data(data, POINT_DATA_SIZE * n_points) ||
+      if (not_enough_points(data, n_points) ||
 	  txt->reserve(2 + ((MAX_DIGITS_IN_DOUBLE + 1) * 2 + 1) * n_points,
 		       512))
 	return 1;
@@ -2024,7 +2015,7 @@ int Gis_multi_polygon::geometry_n(uint32 num, String *result) const
       if (no_data(data, 4))
 	return 1;
       n_points= uint4korr(data);
-      if (n_points > max_n_points)
+      if (not_enough_points(data + 4, n_points))
         return 1;
       data+= 4 + POINT_DATA_SIZE * n_points;
     }
diff --git a/sql/spatial.h b/sql/spatial.h
index 6df6e37e9b8..ee2d6d5ec8d 100644
--- a/sql/spatial.h
+++ b/sql/spatial.h
@@ -214,11 +214,6 @@ struct Geometry_buffer;
 class Geometry
 {
 public:
-  // Maximum number of points in feature that can fit into String
-  static const uint32 max_n_points=
-    (uint32) (INT_MAX32 - WKB_HEADER_SIZE - 4 /* n_points */) /
-    POINT_DATA_SIZE;
-
   Geometry() {}                               /* Remove gcc warning */
   virtual ~Geometry() {}                        /* Remove gcc warning */
   static void *operator new(size_t size, void *buffer)
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index f90874ff62c..b6b56bc49f2 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -1261,6 +1261,20 @@ JOIN::optimize()
     /* Handle the case where we have an OUTER JOIN without a WHERE */
     conds=new Item_int((longlong) 1,1);	// Always true
   }
+
+  if (const_tables && conds)
+  {
+    conds= remove_eq_conds(thd, conds, &cond_value);
+    if (cond_value == Item::COND_FALSE)
+    {
+      zero_result_cause=
+        "Impossible WHERE noticed after reading const tables";
+      select_lex->mark_const_derived(zero_result_cause);
+      conds=new Item_int((longlong) 0,1);
+      goto setup_subq_exit;
+    }
+  }
+
   select= make_select(*table, const_table_map,
                       const_table_map, conds, 1, &error);
   if (error)
@@ -8827,19 +8841,18 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
 	  else
 	  {
 	    sel->needed_reg=tab->needed_reg;
-	    sel->quick_keys.clear_all();
 	  }
+	  sel->quick_keys= tab->table->quick_keys;
 	  if (!sel->quick_keys.is_subset(tab->checked_keys) ||
               !sel->needed_reg.is_subset(tab->checked_keys))
 	  {
-	    tab->keys=sel->quick_keys;
-            tab->keys.merge(sel->needed_reg);
 	    tab->use_quick= (!sel->needed_reg.is_clear_all() &&
-			     (select->quick_keys.is_clear_all() ||
-			      (select->quick &&
-			       (select->quick->records >= 100L)))) ?
+			     (sel->quick_keys.is_clear_all() ||
+			      (sel->quick &&
+			       (sel->quick->records >= 100L)))) ?
 	      2 : 1;
 	    sel->read_tables= used_tables & ~current_map;
+            sel->quick_keys.clear_all();
 	  }
 	  if (i != join->const_tables && tab->use_quick != 2 &&
               !tab->first_inner)
@@ -13422,22 +13435,175 @@ optimize_cond(JOIN *join, COND *conds,
 
 
 /**
-  Handles the recursive job  remove_eq_conds()
+  @brief
+  Propagate multiple equalities to the sub-expressions of a condition
+
+  @param thd             thread handle
+  @param cond            the condition where equalities are to be propagated
+  @param *new_equalities the multiple equalities to be propagated
+  @param inherited        path to all inherited multiple equality items
+  @param[out] is_simplifiable_cond   'cond' may be simplified after the
+                                      propagation of the equalities
+ 
+  @details
+  The function recursively traverses the tree of the condition 'cond' and
+  for each its AND sub-level of any depth the function merges the multiple
+  equalities from the list 'new_equalities' into the multiple equalities
+  attached to the AND item created for this sub-level.
+  The function also [re]sets references to the equalities formed by the
+  merges of multiple equalities in all field items occurred in 'cond'
+  that are encountered in the equalities.
+  If the result of any merge of multiple equalities is an impossible
+  condition the function returns TRUE in the parameter is_simplifiable_cond.   
+*/
 
-  Remove const and eq items. Return new item, or NULL if no condition
-  cond_value is set to according:
-  COND_OK    query is possible (field = constant)
-  COND_TRUE  always true	( 1 = 1 )
-  COND_FALSE always false	( 1 = 2 )
+void propagate_new_equalities(THD *thd, Item *cond,
+                              List<Item_equal> *new_equalities,
+                              COND_EQUAL *inherited,
+                              bool *is_simplifiable_cond)
+{
+  if (cond->type() == Item::COND_ITEM)
+  {
+    bool and_level= ((Item_cond*) cond)->functype() == Item_func::COND_AND_FUNC;
+    if (and_level)
+    {
+      Item_cond_and *cond_and= (Item_cond_and *) cond; 
+      List<Item_equal> *cond_equalities= &cond_and->cond_equal.current_level;
+      inherited= cond_and->cond_equal.upper_levels;
+      if (!cond_equalities->is_empty() && cond_equalities != new_equalities)
+      {
+        Item_equal *equal_item;
+        List_iterator<Item_equal> it(*new_equalities);
+	while ((equal_item= it++))
+	{
+          equal_item->merge_into_list(cond_equalities, true, true);
+        }
+        List_iterator<Item_equal> ei(*cond_equalities);
+        while ((equal_item= ei++))
+	{
+          if (equal_item->const_item() && !equal_item->val_int())
+	  {
+            *is_simplifiable_cond= true;
+            return;
+          }
+        }
+      }
+    }
 
-  SYNOPSIS
-    internal_remove_eq_conds()
-    thd 			THD environment
-    cond                        the condition to handle
-    cond_value                  the resulting value of the condition
+    Item *item;
+    List_iterator<Item> li(*((Item_cond*) cond)->argument_list());
+    while ((item= li++))
+    {
+      propagate_new_equalities(thd, item, new_equalities, inherited,
+                               is_simplifiable_cond);
+    }
+  }
+  else if (cond->type() == Item::FUNC_ITEM && 
+           ((Item_cond*) cond)->functype() == Item_func::MULT_EQUAL_FUNC)
+  {
+    Item_equal *equal_item;
+    List_iterator<Item_equal> it(*new_equalities);
+    Item_equal *equality= (Item_equal *) cond;
+    while ((equal_item= it++))
+    {
+      equality->merge_with_check(equal_item, true);
+    }
+    if (equality->const_item() && !equality->val_int())
+      *is_simplifiable_cond= true;
+  }
+  else
+  {
+    uchar* is_subst_valid= (uchar *) Item::ANY_SUBST;
+    cond= cond->compile(&Item::subst_argument_checker,
+                        &is_subst_valid, 
+                        &Item::equal_fields_propagator,
+                        (uchar *) inherited);
+    cond->update_used_tables();
+  }          
+} 
 
-  RETURN
-    *COND with the simplified condition
+
+
+/**
+  @brief
+  Evaluate all constant boolean sub-expressions in a condition
+ 
+  @param thd        thread handle
+  @param cond       condition where where to evaluate constant sub-expressions
+  @param[out] cond_value : the returned value of the condition 
+                           (TRUE/FALSE/UNKNOWN:
+                           Item::COND_TRUE/Item::COND_FALSE/Item::COND_OK)
+  @return
+   the item that is the result of the substitution of all inexpensive constant
+   boolean sub-expressions into cond, or,
+   NULL if the condition is constant and is evaluated to FALSE.
+
+  @details
+  This function looks for all inexpensive constant boolean sub-expressions in
+  the given condition 'cond' and substitutes them for their values.
+  For example, the condition 2 > (5 + 1) or a < (10 / 2)
+  will be transformed to the condition a < (10 / 2).
+  Note that a constant sub-expression is evaluated only if it is constant and
+  inexpensive. A sub-expression with an uncorrelated subquery may be evaluated
+  only if the subquery is considered as inexpensive.
+  The function does not evaluate a constant sub-expression if it is not on one
+  of AND/OR levels of the condition 'cond'. For example, the subquery in the
+  condition a > (select max(b) from t1 where b > 5) will never be evaluated
+  by this function. 
+  If a constant boolean sub-expression is evaluated to TRUE then:
+    - when the sub-expression is a conjunct of an AND formula it is simply
+      removed from this formula
+    - when the sub-expression is a disjunct of an OR formula the whole OR
+      formula is converted to TRUE 
+  If a constant boolean sub-expression is evaluated to FALSE then:
+    - when the sub-expression is a disjunct of an OR formula it is simply
+      removed from this formula
+    - when the sub-expression is a conjuct of an AND formula the whole AND
+      formula is converted to FALSE
+  When a disjunct/conjunct is removed from an OR/AND formula it might happen
+  that there is only one conjunct/disjunct remaining. In this case this
+  remaining disjunct/conjunct must be merged into underlying AND/OR formula,
+  because AND/OR levels must alternate in the same way as they alternate
+  after fix_fields() is called for the original condition.
+  The specifics of merging a formula f into an AND formula A appears
+  when A contains multiple equalities and f contains multiple equalities.
+  In this case the multiple equalities from f and A have to be merged.
+  After this the resulting multiple equalities have to be propagated into
+  the all AND/OR levels of the formula A (see propagate_new_equalities()).
+  The propagation of multiple equalities might result in forming multiple
+  equalities that are always FALSE. This, in its turn, might trigger further
+  simplification of the condition.
+
+  @note
+  EXAMPLE 1:
+  SELECT * FROM t1 WHERE (b = 1 OR a = 1) AND (b = 5 AND a = 5 OR 1 != 1);
+  First 1 != 1 will be removed from the second conjunct:
+  => SELECT * FROM t1 WHERE (b = 1 OR a = 1) AND (b = 5 AND a = 5);
+  Then (b = 5 AND a = 5) will be merged into the top level condition:
+  => SELECT * FROM t1 WHERE (b = 1 OR a = 1) AND (b = 5) AND (a = 5);
+  Then (b = 5), (a = 5)  will be propagated into the disjuncs of 
+  (b = 1 OR a = 1):
+  => SELECT * FROM t1 WHERE ((b = 1) AND (b = 5) AND (a = 5) OR
+                             (a = 1) AND (b = 5) AND (a = 5)) AND
+                            (b = 5) AND (a = 5)
+  => SELECT * FROM t1 WHERE ((FALSE AND (a = 5)) OR
+                             (FALSE AND (b = 5))) AND
+                             (b = 5) AND (a = 5)
+  After this an additional call of remove_eq_conds() converts it
+  to FALSE
+
+  EXAMPLE 2:  
+  SELECT * FROM t1 WHERE (b = 1 OR a = 5) AND (b = 5 AND a = 5 OR 1 != 1);
+  => SELECT * FROM t1 WHERE (b = 1 OR a = 5) AND (b = 5 AND a = 5);
+  => SELECT * FROM t1 WHERE (b = 1 OR a = 5) AND (b = 5) AND (a = 5);
+  => SELECT * FROM t1 WHERE ((b = 1) AND (b = 5) AND (a = 5) OR
+                             (a = 5) AND (b = 5) AND (a = 5)) AND
+                            (b = 5) AND (a = 5)
+  => SELECT * FROM t1 WHERE ((FALSE AND (a = 5)) OR
+                             ((b = 5) AND (a = 5))) AND
+                             (b = 5) AND (a = 5)
+  After this an additional call of  remove_eq_conds() converts it to
+ =>  SELECT * FROM t1 WHERE (b = 5) AND (a = 5)                            
 */
 
 static COND *
@@ -13445,9 +13611,11 @@ internal_remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
 {
   if (cond->type() == Item::COND_ITEM)
   {
+    List<Item_equal> new_equalities;
     bool and_level= ((Item_cond*) cond)->functype()
       == Item_func::COND_AND_FUNC;
-    List_iterator<Item> li(*((Item_cond*) cond)->argument_list());
+    List<Item> *cond_arg_list= ((Item_cond*) cond)->argument_list();
+    List_iterator<Item> li(*cond_arg_list);
     Item::cond_result tmp_cond_value;
     bool should_fix_fields=0;
 
@@ -13457,92 +13625,72 @@ internal_remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
     {
       Item *new_item=internal_remove_eq_conds(thd, item, &tmp_cond_value);
       if (!new_item)
+      {
+        /* This can happen only when item is converted to TRUE or FALSE */
 	li.remove();
+      }
       else if (item != new_item)
       {
-        if (and_level)
-	{
-          /*
-            Take a special care of multiple equality predicates
-            that may be part of 'cond' and 'new_item'.
-            Those multiple equalities that have common members
-            must be merged.
-	  */  
-          Item_cond_and *cond_and= (Item_cond_and *) cond;
-          List<Item_equal> *cond_equal_items=
-            &cond_and->cond_equal.current_level;
-          List<Item> *cond_and_list= cond_and->argument_list();
-
-          if (new_item->type() == Item::COND_ITEM && 
-              ((Item_cond*) new_item)->functype() == Item_func::COND_AND_FUNC)
-          {
-            Item_cond_and *new_item_and= (Item_cond_and *) new_item;
-            List<Item_equal> *new_item_equal_items=
-              &new_item_and->cond_equal.current_level;
-            List<Item> *new_item_and_list= new_item_and->argument_list();
-            cond_and_list->disjoin((List<Item>*) cond_equal_items);
-            new_item_and_list->disjoin((List<Item>*) new_item_equal_items);
-            Item_equal *equal_item;
-            List_iterator<Item_equal> it(*new_item_equal_items);
-	    while ((equal_item= it++))
-	    {
-              equal_item->merge_into_list(cond_equal_items);
-            }
-            if (new_item_and_list->is_empty())
-              li.remove();
-            else
+        /* 
+          This can happen when:
+          - item was an OR formula converted to one disjunct
+          - item was an AND formula converted to one conjunct
+          In these cases the disjunct/conjunct must be merged into the
+          argument list of cond.
+	*/
+        if (new_item->type() == Item::COND_ITEM)
+        {
+          DBUG_ASSERT(((Item_cond *) cond)->functype() == 
+                      ((Item_cond *) new_item)->functype());          
+	  List<Item> *new_item_arg_list=
+            ((Item_cond *) new_item)->argument_list();
+          if (and_level)
+	  {
+            /*
+              If new_item is an AND formula then multiple equalities
+              of new_item_arg_list must merged into multiple equalities
+              of cond_arg_list. 
+	    */
+            List<Item_equal> *new_item_equalities=
+              &((Item_cond_and *) new_item)->cond_equal.current_level;
+            if (!new_item_equalities->is_empty())
 	    {
-              Item *list_item;
-              Item *new_list_item; 
-              uint cnt= new_item_and_list->elements;     
-              List_iterator<Item> it(*new_item_and_list);
-              while ((list_item= it++))
-	      {
-                uchar* is_subst_valid= (uchar *) Item::ANY_SUBST;
-                new_list_item= 
-                  list_item->compile(&Item::subst_argument_checker,
-                                         &is_subst_valid, 
-                                         &Item::equal_fields_propagator,
-                                         (uchar *) &cond_and->cond_equal);
-                if (new_list_item != list_item)
-                  it.replace(new_list_item);
-                new_list_item->update_used_tables();
-              }              
-              li.replace(*new_item_and_list);
-              for (cnt--; cnt; cnt--)
-                item= li++;  
+              /*
+                Cut the multiple equalities from the new_item_arg_list and
+                append them on the list new_equalities. Later the equalities
+                from this list will be merged into the multiple equalities
+                of cond_arg_list all together.
+	      */
+              new_item_arg_list->disjoin((List<Item> *) new_item_equalities);
+              new_equalities.concat(new_item_equalities);
             }
-            cond_and_list->concat((List<Item>*) cond_equal_items); 
           }
-          else if (new_item->type() == Item::FUNC_ITEM && 
-                   ((Item_cond*) new_item)->functype() ==
-                   Item_func::MULT_EQUAL_FUNC)
+          if (new_item_arg_list->is_empty())
+	    li.remove();
+	  else
 	  {
-            cond_and_list->disjoin((List<Item>*) cond_equal_items);
-            ((Item_equal *) new_item)->merge_into_list(cond_equal_items);
-            li.remove();
-            cond_and_list->concat((List<Item>*) cond_equal_items); 
+            uint cnt= new_item_arg_list->elements;
+            li.replace(*new_item_arg_list);
+            /* Make iterator li ignore new items */
+            for (cnt--; cnt; cnt--)
+              li++;
+            should_fix_fields= 1;
           }
-          else
-            li.replace(new_item);
+        }
+        else if (and_level && 
+                 new_item->type() == Item::FUNC_ITEM && 
+                 ((Item_cond*) new_item)->functype() ==
+                  Item_func::MULT_EQUAL_FUNC)
+	{
+          li.remove();
+          new_equalities.push_back((Item_equal *) new_item);
         }
         else
-	{ 
-          if (new_item->type() == Item::COND_ITEM &&
-              ((Item_cond*) new_item)->functype() == 
-              ((Item_cond*) cond)->functype())
-	  {
-            List<Item> *arg_list= ((Item_cond*) new_item)->argument_list();
-            uint cnt= arg_list->elements;
-            li.replace(*arg_list);
-            for ( cnt--; cnt; cnt--)
-              item= li++;
-          }
-	  else
-            li.replace(new_item);
+	{
+          li.replace(new_item);
+          should_fix_fields= 1;
         } 
-	should_fix_fields=1;
-      }
+      }   
       if (*cond_value == Item::COND_UNDEF)
 	*cond_value=tmp_cond_value;
       switch (tmp_cond_value) {
@@ -13568,6 +13716,53 @@ internal_remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
 	break; /* purecov: deadcode */
       }
     }
+    if (!new_equalities.is_empty())
+    {
+      DBUG_ASSERT(and_level);
+      /* 
+        Merge multiple equalities that were cut from the results of 
+        simplification of OR formulas converted into AND formulas.
+        These multiple equalities are to be merged into the
+        multiple equalities of  cond_arg_list.
+      */
+      COND_EQUAL *cond_equal= &((Item_cond_and *) cond)->cond_equal;
+      List<Item_equal> *cond_equalities= &cond_equal->current_level;
+      cond_arg_list->disjoin((List<Item> *) cond_equalities);
+      Item_equal *equality;
+      List_iterator_fast<Item_equal> it(new_equalities);
+      while ((equality= it++))
+      {
+        equality->merge_into_list(cond_equalities, false, false);
+        List_iterator_fast<Item_equal> ei(*cond_equalities);
+        while ((equality= ei++))
+	{
+          if (equality->const_item() && !equality->val_int())
+	  {
+            *cond_value= Item::COND_FALSE;
+            return (COND*) 0;
+          }
+        }
+      }
+      cond_arg_list->concat((List<Item> *) cond_equalities);
+      /* 
+        Propagate the newly formed multiple equalities to
+        the all AND/OR levels of cond 
+      */
+      bool is_simplifiable_cond= true;
+      propagate_new_equalities(thd, cond, cond_equalities,
+                               cond_equal->upper_levels,
+                               &is_simplifiable_cond);
+      /*
+        If the above propagation of multiple equalities brings us
+        to multiple equalities that are always FALSE then try to
+        simplify the condition with remove_eq_cond() again.
+      */ 
+      if (is_simplifiable_cond)
+      {
+        if (!(cond= remove_eq_conds(thd, cond, cond_value)))
+          return cond;
+      }          
+    }
     if (should_fix_fields)
       cond->update_used_tables();
 
@@ -13732,7 +13927,7 @@ remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
 }
 
 
-/* 
+/**
   Check if equality can be used in removing components of GROUP BY/DISTINCT
   
   @param    l          the left comparison argument (a field if any)
diff --git a/sql/table.cc b/sql/table.cc
index 7635e03ad6b..5bc63fb02c3 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -2070,7 +2070,7 @@ bool fix_vcol_expr(THD *thd,
   Item* func_expr= vcol_info->expr_item;
   bool result= TRUE;
   TABLE_LIST tables;
-  int error;
+  int error= 0;
   const char *save_where;
   Field **ptr, *field;
   enum_mark_columns save_mark_used_columns= thd->mark_used_columns;
@@ -2083,7 +2083,11 @@ bool fix_vcol_expr(THD *thd,
   thd->where= "virtual column function";
 
   /* Fix fields referenced to by the virtual column function */
-  error= func_expr->fix_fields(thd, (Item**)0);
+  if (!func_expr->fixed)
+    error= func_expr->fix_fields(thd, &vcol_info->expr_item);
+  /* fix_fields could change the expression */
+  func_expr= vcol_info->expr_item;
+  /* Number of columns will be checked later */
 
   if (unlikely(error))
   {