item_cmpfunc.h, opt_range.cc:

  Added inequality predicate to range optimization

sql/item_cmpfunc.h

@@ -238,7 +238,7 @@ public:
   longlong val_int();
   enum Functype functype() const { return NE_FUNC; }
   cond_result eq_cmp_result() const { return COND_FALSE; }
-  optimize_type select_optimize() const { return OPTIMIZE_NONE; }
+  optimize_type select_optimize() const { return OPTIMIZE_KEY; } 
   const char *func_name() const { return "<>"; }
 };
 

sql/opt_range.cc

@@ -880,10 +880,17 @@ static SEL_TREE *
 get_mm_parts(PARAM *param,Field *field, Item_func::Functype type,Item *value,
 	     Item_result cmp_type)
 {
+  bool ne_func= FALSE;
   DBUG_ENTER("get_mm_parts");
   if (field->table != param->table)
     DBUG_RETURN(0);
 
+  if (type == Item_func::NE_FUNC)
+  {
+    ne_func= TRUE;
+    type= Item_func::LT_FUNC;
+  }
+
   KEY_PART *key_part = param->key_parts,*end=param->key_parts_end;
   SEL_TREE *tree=0;
   if (value &&
@@ -913,6 +920,14 @@ get_mm_parts(PARAM *param,Field *field, Item_func::Functype type,Item *value,
       tree->keys[key_part->key]=sel_add(tree->keys[key_part->key],sel_arg);
     }
   }
+
+  if (ne_func)
+  {
+    SEL_TREE *tree2= get_mm_parts(param, field, Item_func::GT_FUNC,
+                                  value, cmp_type);
+    if (tree2)
+      tree= tree=tree_or(param,tree,tree2);
+  }
   DBUG_RETURN(tree);
 }