Merge macbook.local:/Users/kgeorge/mysql/work/mysql-5.0-opt

into  macbook.local:/Users/kgeorge/mysql/work/merge-5.1-opt


mysql-test/r/distinct.result:
  Auto merged
mysql-test/r/gis-rtree.result:
  Auto merged
mysql-test/r/ps.result:
  Auto merged
mysql-test/r/subselect.result:
  Auto merged
mysql-test/r/udf.result:
  Auto merged
mysql-test/t/gis-rtree.test:
  Auto merged
mysql-test/t/ps.test:
  Auto merged
mysql-test/t/subselect.test:
  Auto merged
mysql-test/t/udf.test:
  Auto merged
sql/item_subselect.cc:
  Auto merged
sql/item_subselect.h:
  Auto merged
sql/sql_lex.cc:
  Auto merged
sql/sql_select.cc:
  Auto merged
storage/myisam/mi_check.c:
  Auto merged
sql/sql_udf.cc:
  SCCS merged

5 files changed, 66 insertions, 7 deletions

diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index 0074e33cdea..f3f840bdaa9 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -391,6 +391,7 @@ Item_singlerow_subselect::select_transformer(JOIN *join)
       */
       !(select_lex->item_list.head()->type() == FIELD_ITEM ||
 	select_lex->item_list.head()->type() == REF_ITEM) &&
+      !join->conds && !join->having &&
       /*
         switch off this optimization for prepare statement,
         because we do not rollback this changes
@@ -415,8 +416,6 @@ Item_singlerow_subselect::select_transformer(JOIN *join)
     */
     substitution->walk(&Item::remove_dependence_processor, 0,
 		       (byte *) select_lex->outer_select());
-    /* SELECT without FROM clause can't have WHERE or HAVING clause */
-    DBUG_ASSERT(join->conds == 0 && join->having == 0);
     return RES_REDUCE;
   }
   return RES_OK;
@@ -2320,6 +2319,22 @@ bool subselect_single_select_engine::no_tables()
 
 
 /*
+  Check statically whether the subquery can return NULL
+
+  SINOPSYS
+    subselect_single_select_engine::may_be_null()
+
+  RETURN
+    FALSE  can guarantee that the subquery never return NULL
+    TRUE   otherwise
+*/
+bool subselect_single_select_engine::may_be_null()
+{
+  return ((no_tables() && !join->conds && !join->having) ? maybe_null : 1);
+}
+
+
+/*
   Report about presence of tables in subquery
 
   SYNOPSIS
diff --git a/sql/item_subselect.h b/sql/item_subselect.h
index a5068ff20e0..5a0b2788678 100644
--- a/sql/item_subselect.h
+++ b/sql/item_subselect.h
@@ -363,7 +363,7 @@ public:
   enum Item_result type() { return res_type; }
   enum_field_types field_type() { return res_field_type; }
   virtual void exclude()= 0;
-  bool may_be_null() { return maybe_null; };
+  virtual bool may_be_null() { return maybe_null; };
   virtual table_map upper_select_const_tables()= 0;
   static table_map calc_const_tables(TABLE_LIST *);
   virtual void print(String *str)= 0;
@@ -400,6 +400,7 @@ public:
   void print (String *str);
   bool change_result(Item_subselect *si, select_subselect *result);
   bool no_tables();
+  bool may_be_null();
   bool is_executed() const { return executed; }
   bool no_rows();
 };
diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index 18d30494701..ad098a55811 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -1934,7 +1934,6 @@ void st_select_lex_unit::set_limit(SELECT_LEX *sl)
 {
   ha_rows select_limit_val;
 
-  DBUG_ASSERT(! thd->stmt_arena->is_stmt_prepare());
   select_limit_val= (ha_rows)(sl->select_limit ? sl->select_limit->val_uint() :
                                                  HA_POS_ERROR);
   offset_limit_cnt= (ha_rows)(sl->offset_limit ? sl->offset_limit->val_uint() :
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 5da48c69e9e..3c1c2fe4778 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -8593,6 +8593,46 @@ remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
   return cond;					// Point at next and level
 }
 
+/* 
+  Check if equality can be used in removing components of GROUP BY/DISTINCT
+  
+  SYNOPSIS
+    test_if_equality_guarantees_uniqueness()
+      l          the left comparison argument (a field if any)
+      r          the right comparison argument (a const of any)
+  
+  DESCRIPTION    
+    Checks if an equality predicate can be used to take away 
+    DISTINCT/GROUP BY because it is known to be true for exactly one 
+    distinct value (e.g. <expr> == <const>).
+    Arguments must be of the same type because e.g. 
+    <string_field> = <int_const> may match more than 1 distinct value from 
+    the column. 
+    We must take into consideration and the optimization done for various 
+    string constants when compared to dates etc (see Item_int_with_ref) as
+    well as the collation of the arguments.
+  
+  RETURN VALUE  
+    TRUE    can be used
+    FALSE   cannot be used
+*/
+static bool
+test_if_equality_guarantees_uniqueness(Item *l, Item *r)
+{
+  return r->const_item() &&
+    /* elements must be of the same result type */
+    (r->result_type() == l->result_type() ||
+    /* or dates compared to longs */
+     (((l->type() == Item::FIELD_ITEM &&
+        ((Item_field *)l)->field->can_be_compared_as_longlong()) ||
+       (l->type() == Item::FUNC_ITEM &&
+        ((Item_func *)l)->result_as_longlong())) &&
+      r->result_type() == INT_RESULT))
+    /* and must have the same collation if compared as strings */
+    && (l->result_type() != STRING_RESULT ||
+        l->collation.collation == r->collation.collation);
+}
+
 /*
   Return 1 if the item is a const value in all the WHERE clause
 */
@@ -8629,7 +8669,7 @@ const_expression_in_where(COND *cond, Item *comp_item, Item **const_item)
     Item *right_item= ((Item_func*) cond)->arguments()[1];
     if (left_item->eq(comp_item,1))
     {
-      if (right_item->const_item())
+      if (test_if_equality_guarantees_uniqueness (left_item, right_item))
       {
 	if (*const_item)
 	  return right_item->eq(*const_item, 1);
@@ -8639,7 +8679,7 @@ const_expression_in_where(COND *cond, Item *comp_item, Item **const_item)
     }
     else if (right_item->eq(comp_item,1))
     {
-      if (left_item->const_item())
+      if (test_if_equality_guarantees_uniqueness (right_item, left_item))
       {
 	if (*const_item)
 	  return left_item->eq(*const_item, 1);
diff --git a/sql/sql_udf.cc b/sql/sql_udf.cc
index adda7316e3a..7dec58d9b6e 100644
--- a/sql/sql_udf.cc
+++ b/sql/sql_udf.cc
@@ -481,6 +481,8 @@ int mysql_drop_function(THD *thd,const LEX_STRING *udf_name)
   TABLE *table;
   TABLE_LIST tables;
   udf_func *udf;
+  char *exact_name_str;
+  uint exact_name_len;
   DBUG_ENTER("mysql_drop_function");
   if (!initialized)
   {
@@ -494,6 +496,8 @@ int mysql_drop_function(THD *thd,const LEX_STRING *udf_name)
     my_error(ER_FUNCTION_NOT_DEFINED, MYF(0), udf_name->str);
     goto err;
   }
+  exact_name_str= udf->name.str;
+  exact_name_len= udf->name.length;
   del_udf(udf);
   /*
     Close the handle if this was function that was found during boot or
@@ -508,7 +512,7 @@ int mysql_drop_function(THD *thd,const LEX_STRING *udf_name)
   if (!(table = open_ltable(thd,&tables,TL_WRITE)))
     goto err;
   table->use_all_columns();
-  table->field[0]->store(udf_name->str, udf_name->length, system_charset_info);
+  table->field[0]->store(exact_name_str, exact_name_len, &my_charset_bin);
   if (!table->file->index_read_idx(table->record[0], 0,
 				   (byte*) table->field[0]->ptr,
 				   table->key_info[0].key_length,