Change of internal key_field=NULL handling to avoid error messages.

Optimized SELECT DISTINCT ... ORDER BY ... LIMIT
Fixed reference to uninitalized variable

25 files changed, 315 insertions, 119 deletions

diff --git a/mysql-test/r/distinct.result b/mysql-test/r/distinct.result
index 10a00995c9e..020d6c6534f 100644
--- a/mysql-test/r/distinct.result
+++ b/mysql-test/r/distinct.result
@@ -198,6 +198,30 @@ a
 select distinct 1 from t1,t3 where t1.a=t3.a;
 1
 1
+explain SELECT distinct t1.a from t1;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	index	NULL	PRIMARY	4	NULL	2	Using index
+explain SELECT distinct t1.a from t1 order by a desc;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	index	NULL	PRIMARY	4	NULL	2	Using index
+explain SELECT t1.a from t1 group by a order by a desc;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	index	NULL	PRIMARY	4	NULL	2	Using index
+explain SELECT distinct t1.a from t1 order by a desc limit 1;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	index	NULL	PRIMARY	4	NULL	2	Using index
+explain SELECT distinct a from t3 order by a desc limit 2;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t3	index	NULL	a	5	NULL	204	Using index
+explain SELECT distinct a,b from t3 order by a+1;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t3	ALL	NULL	NULL	NULL	NULL	204	Using temporary; Using filesort
+explain SELECT distinct a,b from t3 order by a limit 10;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t3	index	NULL	a	5	NULL	204	Using temporary
+explain SELECT a,b from t3 group by a,b order by a+1;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t3	ALL	NULL	NULL	NULL	NULL	204	Using temporary; Using filesort
 drop table t1,t2,t3,t4;
 CREATE TABLE t1 (name varchar(255));
 INSERT INTO t1 VALUES ('aa'),('ab'),('ac'),('ad'),('ae');
diff --git a/mysql-test/r/func_math.result b/mysql-test/r/func_math.result
index f1c0de2f88a..811a16fff6c 100644
--- a/mysql-test/r/func_math.result
+++ b/mysql-test/r/func_math.result
@@ -31,9 +31,10 @@ log10(100)	log10(18)	log10(-4)	log10(0)	log10(NULL)
 select pow(10,log10(10)),power(2,4);
 pow(10,log10(10))	power(2,4)
 10.000000	16.000000
+set @@rand_seed1=10000000,@@rand_seed2=1000000;
 select rand(999999),rand();
 rand(999999)	rand()
-0.014231365187309	0.8078568166195
+0.014231365187309	0.028870999839968
 select pi(),sin(pi()/2),cos(pi()/2),abs(tan(pi())),cot(1),asin(1),acos(0),atan(1);
 PI()	sin(pi()/2)	cos(pi()/2)	abs(tan(pi()))	cot(1)	asin(1)	acos(0)	atan(1)
 3.141593	1.000000	0.000000	0.000000	0.64209262	1.570796	1.570796	0.785398
diff --git a/mysql-test/r/innodb.result b/mysql-test/r/innodb.result
index 1e136acb21d..9d50a6a86e9 100644
--- a/mysql-test/r/innodb.result
+++ b/mysql-test/r/innodb.result
@@ -1036,3 +1036,25 @@ n	d
 1	30
 2	20
 drop table t1,t2;
+create table t1 (a int, b int) type=innodb;
+insert into t1 values(20,null);
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a;
+b	ifnull(t2.b,"this is null")
+NULL	this is null
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a order by 1;
+b	ifnull(t2.b,"this is null")
+NULL	this is null
+insert into t1 values(10,null);
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a order by 1;
+b	ifnull(t2.b,"this is null")
+NULL	this is null
+NULL	this is null
+drop table t1;
+create table t1 (a varchar(10) not null) type=myisam;
+create table t2 (b varchar(10) not null unique) type=innodb;
+select t1.a from t1,t2 where t1.a=t2.b;
+a
+drop table t1,t2;
diff --git a/mysql-test/r/null.result b/mysql-test/r/null.result
index 07724a56025..cdea66cbf58 100644
--- a/mysql-test/r/null.result
+++ b/mysql-test/r/null.result
@@ -6,7 +6,7 @@ select 1 | NULL,1 & NULL,1+NULL,1-NULL;
 NULL	NULL	NULL	NULL
 select NULL=NULL,NULL<>NULL,IFNULL(NULL,1.1)+0,IFNULL(NULL,1) | 0;
 NULL=NULL	NULL<>NULL	IFNULL(NULL,1.1)+0	IFNULL(NULL,1) | 0
-NULL	NULL	1.1	1
+NULL	NULL	1	1
 select strcmp("a",NULL),(1<NULL)+0.0,NULL regexp "a",null like "a%","a%" like null;
 strcmp("a",NULL)	(1<NULL)+0.0	NULL regexp "a"	null like "a%"	"a%" like null
 NULL	NULL	NULL	NULL	NULL
@@ -56,3 +56,20 @@ indexed_field
 NULL
 NULL
 DROP TABLE t1;
+create table t1 (a int, b int) type=myisam;
+insert into t1 values(20,null);
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a;
+b	ifnull(t2.b,"this is null")
+NULL	this is null
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a order by 1;
+b	ifnull(t2.b,"this is null")
+NULL	this is null
+insert into t1 values(10,null);
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a order by 1;
+b	ifnull(t2.b,"this is null")
+NULL	this is null
+NULL	this is null
+drop table t1;
diff --git a/mysql-test/t/distinct.test b/mysql-test/t/distinct.test
index aaffea3c5a5..7f75b6b1687 100644
--- a/mysql-test/t/distinct.test
+++ b/mysql-test/t/distinct.test
@@ -88,6 +88,16 @@ select distinct t1.a from t1,t3 where t1.a=t3.a;
 #flush status;
 select distinct 1 from t1,t3 where t1.a=t3.a;
 #show status like 'Handler%';
+
+explain SELECT distinct t1.a from t1;
+explain SELECT distinct t1.a from t1 order by a desc;
+explain SELECT t1.a from t1 group by a order by a desc;
+explain SELECT distinct t1.a from t1 order by a desc limit 1;
+explain SELECT distinct a from t3 order by a desc limit 2;
+explain SELECT distinct a,b from t3 order by a+1;
+explain SELECT distinct a,b from t3 order by a limit 10;
+explain SELECT a,b from t3 group by a,b order by a+1;
+
 drop table t1,t2,t3,t4;
 
 CREATE TABLE t1 (name varchar(255));
diff --git a/mysql-test/t/func_math.test b/mysql-test/t/func_math.test
index 74e8a5ce092..bd125dafd53 100644
--- a/mysql-test/t/func_math.test
+++ b/mysql-test/t/func_math.test
@@ -13,6 +13,7 @@ select ln(exp(10)),exp(ln(sqrt(10))*2),ln(-1),ln(0),ln(NULL);
 select log2(8),log2(15),log2(-2),log2(0),log2(NULL);
 select log10(100),log10(18),log10(-4),log10(0),log10(NULL);
 select pow(10,log10(10)),power(2,4);
+set @@rand_seed1=10000000,@@rand_seed2=1000000;
 select rand(999999),rand();
 select pi(),sin(pi()/2),cos(pi()/2),abs(tan(pi())),cot(1),asin(1),acos(0),atan(1);
 select degrees(pi()),radians(360);
diff --git a/mysql-test/t/innodb.test b/mysql-test/t/innodb.test
index 8edde83507a..eb5b0c9efd2 100644
--- a/mysql-test/t/innodb.test
+++ b/mysql-test/t/innodb.test
@@ -673,3 +673,26 @@ UPDATE t1,t2 SET t1.d=t2.d,t2.d=30 WHERE t1.n=t2.n;
 select * from t1;
 select * from t2;
 drop table t1,t2;
+
+#
+# Testing of IFNULL
+#
+create table t1 (a int, b int) type=innodb;
+insert into t1 values(20,null);
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a;
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a order by 1;
+insert into t1 values(10,null);
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a order by 1;
+drop table t1;
+
+#
+# Test of read_through not existing const_table
+#
+
+create table t1 (a varchar(10) not null) type=myisam;
+create table t2 (b varchar(10) not null unique) type=innodb;
+select t1.a from t1,t2 where t1.a=t2.b;
+drop table t1,t2;
diff --git a/mysql-test/t/null.test b/mysql-test/t/null.test
index 8bd9e806118..ad32e0be6ff 100644
--- a/mysql-test/t/null.test
+++ b/mysql-test/t/null.test
@@ -34,3 +34,17 @@ SELECT * FROM t1 WHERE indexed_field=NULL;
 SELECT * FROM t1 WHERE indexed_field IS NULL;
 SELECT * FROM t1 WHERE indexed_field<=>NULL;
 DROP TABLE t1;
+
+#
+# Testing of IFNULL
+#
+create table t1 (a int, b int) type=myisam;
+insert into t1 values(20,null);
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a;
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a order by 1;
+insert into t1 values(10,null);
+select t2.b, ifnull(t2.b,"this is null") from t1 as t2 left join t1 as t3 on
+t2.b=t3.a order by 1;
+drop table t1;
diff --git a/sql/field.h b/sql/field.h
index ba28a6a872e..f064724f6a2 100644
--- a/sql/field.h
+++ b/sql/field.h
@@ -1058,7 +1058,7 @@ Field *make_field(char *ptr, uint32 field_length,
 uint pack_length_to_packflag(uint type);
 uint32 calc_pack_length(enum_field_types type,uint32 length);
 bool set_field_to_null(Field *field);
-bool set_field_to_null_with_conversions(Field *field);
+bool set_field_to_null_with_conversions(Field *field, bool no_conversions);
 uint find_enum(TYPELIB *typelib,const char *x, uint length);
 ulonglong find_set(TYPELIB *typelib,const char *x, uint length);
 bool test_if_int(const char *str,int length);
diff --git a/sql/field_conv.cc b/sql/field_conv.cc
index 53b26920c14..ffc93f3e871 100644
--- a/sql/field_conv.cc
+++ b/sql/field_conv.cc
@@ -122,8 +122,26 @@ set_field_to_null(Field *field)
 }
 
 
+/*
+  Set field to NULL or TIMESTAMP or to next auto_increment number
+
+  SYNOPSIS
+    set_field_to_null_with_conversions()
+    field		Field to update
+    no_conversion	Set to 1 if we should return 1 if field can't
+			take null values.
+			If set to 0 we will do store the 'default value'
+			if the field is a special field. If not we will
+			give an error.
+
+  RETURN VALUES
+    0		Field could take 0 or an automatic conversion was used
+    1		Field could not take NULL and no conversion was used.
+		If no_conversion was not set, an error message is printed
+*/
+
 bool
-set_field_to_null_with_conversions(Field *field)
+set_field_to_null_with_conversions(Field *field, bool no_conversions)
 {
   if (field->real_maybe_null())
   {
@@ -131,6 +149,8 @@ set_field_to_null_with_conversions(Field *field)
     field->reset();
     return 0;
   }
+  if (no_conversions)
+    return 1;
 
   /*
     Check if this is a special type, which will get a special walue
@@ -156,8 +176,6 @@ set_field_to_null_with_conversions(Field *field)
 }
 
 
-
-
 static void do_skip(Copy_field *copy __attribute__((unused)))
 {
 }
diff --git a/sql/item.cc b/sql/item.cc
index b3b4e99e28a..ec9b07c443c 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -419,7 +419,7 @@ void Item_field::save_org_in_field(Field *to)
   if (field->is_null())
   {
     null_value=1;
-    set_field_to_null_with_conversions(to);
+    set_field_to_null_with_conversions(to, 1);
   }
   else
   {
@@ -429,12 +429,12 @@ void Item_field::save_org_in_field(Field *to)
   }
 }
 
-bool Item_field::save_in_field(Field *to)
+bool Item_field::save_in_field(Field *to, bool no_conversions)
 {
   if (result_field->is_null())
   {
     null_value=1;
-    return set_field_to_null_with_conversions(to);
+    return set_field_to_null_with_conversions(to, no_conversions);
   }
   else
   {
@@ -461,9 +461,9 @@ bool Item_field::save_in_field(Field *to)
     1	 Field doesn't support NULL values and can't handle 'field = NULL'
 */   
 
-bool Item_null::save_in_field(Field *field)
+bool Item_null::save_in_field(Field *field, bool no_conversions)
 {
-  return set_field_to_null_with_conversions(field);
+  return set_field_to_null_with_conversions(field, no_conversions);
 }
 
 
@@ -485,7 +485,7 @@ bool Item_null::save_safe_in_field(Field *field)
 }
 
 
-bool Item::save_in_field(Field *field)
+bool Item::save_in_field(Field *field, bool no_conversions)
 {
   if (result_type() == STRING_RESULT ||
       result_type() == REAL_RESULT &&
@@ -496,7 +496,7 @@ bool Item::save_in_field(Field *field)
     str_value.set_quick(buff,sizeof(buff));
     result=val_str(&str_value);
     if (null_value)
-      return set_field_to_null_with_conversions(field);
+      return set_field_to_null_with_conversions(field, no_conversions);
     field->set_notnull();
     field->store(result->ptr(),result->length());
     str_value.set_quick(0, 0);
@@ -513,7 +513,7 @@ bool Item::save_in_field(Field *field)
   {
     longlong nr=val_int();
     if (null_value)
-      return set_field_to_null_with_conversions(field);
+      return set_field_to_null_with_conversions(field, no_conversions);
     field->set_notnull();
     field->store(nr);
   }
@@ -521,7 +521,7 @@ bool Item::save_in_field(Field *field)
 }
 
 
-bool Item_string::save_in_field(Field *field)
+bool Item_string::save_in_field(Field *field, bool no_conversions)
 {
   String *result;
   result=val_str(&str_value);
@@ -532,7 +532,7 @@ bool Item_string::save_in_field(Field *field)
   return 0;
 }
 
-bool Item_int::save_in_field(Field *field)
+bool Item_int::save_in_field(Field *field, bool no_conversions)
 {
   longlong nr=val_int();
   if (null_value)
@@ -542,7 +542,7 @@ bool Item_int::save_in_field(Field *field)
   return 0;
 }
 
-bool Item_real::save_in_field(Field *field)
+bool Item_real::save_in_field(Field *field, bool no_conversions)
 {
   double nr=val();
   if (null_value)
@@ -597,7 +597,7 @@ longlong Item_varbinary::val_int()
 }
 
 
-bool Item_varbinary::save_in_field(Field *field)
+bool Item_varbinary::save_in_field(Field *field, bool no_conversions)
 {
   field->set_notnull();
   if (field->result_type() == STRING_RESULT)
@@ -658,9 +658,10 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables)
   return 0;
 }
 
+
 /*
-** If item is a const function, calculate it and return a const item
-** The original item is freed if not returned
+  If item is a const function, calculate it and return a const item
+  The original item is freed if not returned
 */
 
 Item_result item_cmp_type(Item_result a,Item_result b)
diff --git a/sql/item.h b/sql/item.h
index 563db2291fb..ad68287a92c 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -53,11 +53,11 @@ public:
   void set_name(char* str,uint length=0);
   void init_make_field(Send_field *tmp_field,enum enum_field_types type);
   virtual bool fix_fields(THD *,struct st_table_list *);
-  virtual bool save_in_field(Field *field);
+  virtual bool save_in_field(Field *field, bool no_conversions);
   virtual void save_org_in_field(Field *field)
-    { (void) save_in_field(field); }
+  { (void) save_in_field(field, 1); }
   virtual bool save_safe_in_field(Field *field)
-    { return save_in_field(field); }
+  { return save_in_field(field, 1); }
   virtual bool send(THD *thd, String *str);
   virtual bool eq(const Item *, bool binary_cmp) const;
   virtual Item_result result_type () const { return REAL_RESULT; }
@@ -130,7 +130,7 @@ public:
   }
   void make_field(Send_field *field);
   bool fix_fields(THD *,struct st_table_list *);
-  bool save_in_field(Field *field);
+  bool save_in_field(Field *field,bool no_conversions);
   void save_org_in_field(Field *field);
   table_map used_tables() const;
   enum Item_result result_type () const
@@ -156,7 +156,7 @@ public:
   longlong val_int();
   String *val_str(String *str);
   void make_field(Send_field *field);
-  bool save_in_field(Field *field);
+  bool save_in_field(Field *field, bool no_conversions);
   bool save_safe_in_field(Field *field);
   enum Item_result result_type () const
   { return STRING_RESULT; }
@@ -190,7 +190,7 @@ public:
   double val() { return (double) value; }
   String *val_str(String*);
   void make_field(Send_field *field);
-  bool save_in_field(Field *field);
+  bool 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 print(String *str);
@@ -232,7 +232,7 @@ public:
     max_length=length;
   }
   Item_real(double value_par) :value(value_par) {}
-  bool save_in_field(Field *field);
+  bool save_in_field(Field *field, bool no_conversions);
   enum Type type() const { return REAL_ITEM; }
   double val() { return value; }
   longlong val_int() { return (longlong) (value+(value > 0 ? 0.5 : -0.5));}
@@ -277,7 +277,7 @@ public:
   double val() { return atof(str_value.ptr()); }
   longlong val_int() { return strtoll(str_value.ptr(),(char**) 0,10); }
   String *val_str(String*) { return (String*) &str_value; }
-  bool save_in_field(Field *field);
+  bool save_in_field(Field *field, bool no_conversions);
   void make_field(Send_field *field);
   enum Item_result result_type () const { return STRING_RESULT; }
   bool basic_const_item() const { return 1; }
@@ -298,7 +298,7 @@ public:
   Item_default() { name= (char*) "DEFAULT"; }
   enum Type type() const { return DEFAULT_ITEM; }
   void make_field(Send_field *field) {}
-  bool save_in_field(Field *field)
+  bool save_in_field(Field *field, bool no_conversions)
   {
     field->set_default();
     return 0;
@@ -339,7 +339,7 @@ public:
   double val() { return (double) Item_varbinary::val_int(); }
   longlong val_int();
   String *val_str(String*) { return &str_value; }
-  bool save_in_field(Field *field);
+  bool save_in_field(Field *field, bool no_conversions);
   void make_field(Send_field *field);
   enum Item_result result_type () const { return INT_RESULT; }
   unsigned int size_of() { return sizeof(*this);}  
@@ -401,7 +401,8 @@ public:
   bool send(THD *thd, String *tmp)	{ return (*ref)->send(thd, tmp); }
   void make_field(Send_field *field)	{ (*ref)->make_field(field); }
   bool fix_fields(THD *,struct st_table_list *);
-  bool save_in_field(Field *field)	{ return (*ref)->save_in_field(field); }
+  bool save_in_field(Field *field, bool no_conversions)
+  { return (*ref)->save_in_field(field, no_conversions); }
   void save_org_in_field(Field *field)	{ (*ref)->save_org_in_field(field); }
   enum Item_result result_type () const { return (*ref)->result_type(); }
   table_map used_tables() const		{ return (*ref)->used_tables(); }
@@ -421,9 +422,9 @@ class Item_int_with_ref :public Item_int
 public:
   Item_int_with_ref(longlong i, Item *ref_arg) :Item_int(i), ref(ref_arg)
   {}
-  bool save_in_field(Field *field)
+  bool save_in_field(Field *field, bool no_conversions)
   {
-    return ref->save_in_field(field);
+    return ref->save_in_field(field, no_conversions);
   }
   unsigned int size_of() { return sizeof(*this);}  
 };
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index b5f21c8772e..0dc1e91d372 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -48,7 +48,7 @@ static bool convert_constant_item(Field *field, Item **item)
 {
   if ((*item)->const_item() && (*item)->type() != Item::INT_ITEM)
   {
-    if (!(*item)->save_in_field(field) &&
+    if (!(*item)->save_in_field(field, 1) &&
 	!((*item)->null_value))
     {
       Item *tmp=new Item_int_with_ref(field->val_int(), *item);
@@ -444,15 +444,29 @@ longlong Item_func_between::val_int()
   return 0;
 }
 
+static Item_result item_store_type(Item_result a,Item_result b)
+{
+  if (a == STRING_RESULT || b == STRING_RESULT)
+    return STRING_RESULT;
+  else if (a == REAL_RESULT || b == REAL_RESULT)
+    return REAL_RESULT;
+  else
+    return INT_RESULT;
+}
+
 void
 Item_func_ifnull::fix_length_and_dec()
 {
   maybe_null=args[1]->maybe_null;
   max_length=max(args[0]->max_length,args[1]->max_length);
   decimals=max(args[0]->decimals,args[1]->decimals);
-  cached_result_type=args[0]->result_type();
+  if ((cached_result_type=item_store_type(args[0]->result_type(),
+					  args[1]->result_type())) !=
+      REAL_RESULT)
+    decimals= 0;
 }
 
+
 double
 Item_func_ifnull::val()
 {
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 5721a2f5e8c..c3b1190a4b6 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -696,21 +696,20 @@ double Item_func_round::val()
 }
 
 
-double Item_func_rand::val()
+void Item_func_rand::fix_length_and_dec()
 {
-  THD* thd = current_thd;
+  decimals=NOT_FIXED_DEC; 
+  max_length=float_length(decimals);
   if (arg_count)
   {					// Only use argument once in query
     uint32 tmp= (uint32) (args[0]->val_int());
-    randominit(&thd->rand,(uint32) (tmp*0x10001L+55555555L),
-	       (uint32) (tmp*0x10000001L));
-#ifdef DELETE_ITEMS
-    delete args[0];
-#endif
-    arg_count=0;
+    if ((rand= (struct rand_struct*) sql_alloc(sizeof(*rand))))
+      randominit(rand,(uint32) (tmp*0x10001L+55555555L),
+		 (uint32) (tmp*0x10000001L));
   }
-  else if (!thd->rand_used)
+  else
   {
+    THD *thd= current_thd;
     /*
       No need to send a Rand log event if seed was given eg: RAND(seed),
       as it will be replicated in the query as such.
@@ -722,8 +721,14 @@ double Item_func_rand::val()
     thd->rand_used=1;
     thd->rand_saved_seed1=thd->rand.seed1;
     thd->rand_saved_seed2=thd->rand.seed2;
+    rand= &thd->rand;
   }
-  return rnd(&thd->rand);
+}
+
+
+double Item_func_rand::val()
+{
+  return rnd(rand);
 }
 
 longlong Item_func_sign::val_int()
diff --git a/sql/item_func.h b/sql/item_func.h
index b7e0cee540a..501dcdadc3f 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -459,20 +459,20 @@ public:
   const char *func_name() const { return truncate ? "truncate" : "round"; }
   double val();
   void fix_length_and_dec();
-  unsigned int size_of() { return sizeof(*this);}  
 };
 
 
 class Item_func_rand :public Item_real_func
 {
+  struct rand_struct *rand;
 public:
   Item_func_rand(Item *a) :Item_real_func(a) {}
   Item_func_rand()	  :Item_real_func()  {}
   double val();
   const char *func_name() const { return "rand"; }
-  void fix_length_and_dec() { decimals=NOT_FIXED_DEC; max_length=float_length(decimals); }
   bool const_item() const { return 0; }
   table_map used_tables() const { return RAND_TABLE_BIT; }
+  void fix_length_and_dec();
 };
 
 
diff --git a/sql/item_timefunc.cc b/sql/item_timefunc.cc
index ccbba3777c4..6a95c15a226 100644
--- a/sql/item_timefunc.cc
+++ b/sql/item_timefunc.cc
@@ -403,7 +403,7 @@ String *Item_date::val_str(String *str)
 }
 
 
-bool Item_date::save_in_field(Field *field)
+bool Item_date::save_in_field(Field *field, bool no_conversions)
 {
   TIME ltime;
   timestamp_type t_type=TIMESTAMP_FULL;
@@ -518,7 +518,7 @@ bool Item_func_now::get_date(TIME *res,
 }
 
 
-bool Item_func_now::save_in_field(Field *to)
+bool Item_func_now::save_in_field(Field *to, bool no_conversions)
 {
   to->set_notnull();
   to->store_time(&ltime,TIMESTAMP_FULL);
diff --git a/sql/item_timefunc.h b/sql/item_timefunc.h
index c0255e71d27..0ca2a36609d 100644
--- a/sql/item_timefunc.h
+++ b/sql/item_timefunc.h
@@ -231,7 +231,7 @@ public:
   double val() { return (double) val_int(); }
   const char *func_name() const { return "date"; }
   void fix_length_and_dec() { decimals=0; max_length=10; }
-  bool save_in_field(Field *to);
+  bool save_in_field(Field *to, bool no_conversions);
   void make_field(Send_field *tmp_field)
   {
     init_make_field(tmp_field,FIELD_TYPE_DATE);
@@ -316,7 +316,7 @@ public:
   enum Item_result result_type () const { return STRING_RESULT; }
   double val()	     { return (double) value; }
   longlong val_int() { return value; }
-  bool save_in_field(Field *to);
+  bool save_in_field(Field *to, bool no_conversions);
   String *val_str(String *str)
   { str_value.set(buff,buff_length); return &str_value; }
   const char *func_name() const { return "now"; }
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index d1f99604959..a18c0178b5d 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -1029,7 +1029,7 @@ get_mm_leaf(PARAM *param, Field *field, KEY_PART *key_part,
       field->cmp_type() != value->result_type())
     DBUG_RETURN(0);
 
-  if (value->save_in_field(field))
+  if (value->save_in_field(field, 1))
   {
     /* This happens when we try to insert a NULL field in a not null column */
     // TODO; Check if we can we remove the following block.
@@ -1038,9 +1038,9 @@ get_mm_leaf(PARAM *param, Field *field, KEY_PART *key_part,
       /* convert column_name <=> NULL -> column_name IS NULL */
       // Get local copy of key
       char *str= (char*) alloc_root(param->mem_root,1);
-      if (!*str)
+      if (!str)
 	DBUG_RETURN(0);
-      *str = 1;
+      *str= 1;
       DBUG_RETURN(new SEL_ARG(field,str,str));
     }
     DBUG_RETURN(&null_element);			// cmp with NULL is never true
diff --git a/sql/password.c b/sql/password.c
index 48181ea18e6..318c8e84db3 100644
--- a/sql/password.c
+++ b/sql/password.c
@@ -43,7 +43,7 @@
 void randominit(struct rand_struct *rand_st,ulong seed1, ulong seed2)
 {						/* For mysql 3.21.# */
 #ifdef HAVE_purify
-  bzero((char*) rand_st,sizeof(*rand_st));		/* Avoid UMC varnings */
+  bzero((char*) rand_st,sizeof(*rand_st));	/* Avoid UMC varnings */
 #endif
   rand_st->max_value= 0x3FFFFFFFL;
   rand_st->max_value_dbl=(double) rand_st->max_value;
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index 043ce44c140..7b7c8c01aab 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -2098,7 +2098,7 @@ fill_record(List<Item> &fields,List<Item> &values)
   while ((field=(Item_field*) f++))
   {
     value=v++;
-    if (value->save_in_field(field->field))
+    if (value->save_in_field(field->field, 0))
       DBUG_RETURN(1);
   }
   DBUG_RETURN(0);
@@ -2116,7 +2116,7 @@ fill_record(Field **ptr,List<Item> &values)
   while ((field = *ptr++))
   {
     value=v++;
-    if (value->save_in_field(field))
+    if (value->save_in_field(field, 0))
       DBUG_RETURN(1);
   }
   DBUG_RETURN(0);
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index a5f14a507f7..8b276cf0d9b 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -158,9 +158,8 @@ THD::THD():user_time(0),fatal_error(0),last_insert_id_used(0),
   {
     pthread_mutex_lock(&LOCK_thread_count);
     ulong tmp=(ulong) (rnd(&sql_rand) * 3000000);
-    randominit(&rand, tmp + (ulong) start_time,
-	       tmp + (ulong) thread_id);
     pthread_mutex_unlock(&LOCK_thread_count);
+    randominit(&rand, tmp + (ulong) start_time, tmp + (ulong) thread_id);
   }
 }
 
@@ -171,16 +170,16 @@ THD::THD():user_time(0),fatal_error(0),last_insert_id_used(0),
 
 void THD::init(void)
 {
+  pthread_mutex_lock(&LOCK_global_system_variables);
+  variables= global_system_variables;
+  pthread_mutex_unlock(&LOCK_global_system_variables);
   server_status= SERVER_STATUS_AUTOCOMMIT;
-  update_lock_default= (variables.low_priority_updates ?
-			TL_WRITE_LOW_PRIORITY :
-			TL_WRITE);
   options= thd_startup_options;
   sql_mode=(uint) opt_sql_mode;
   open_options=ha_open_options;
-  pthread_mutex_lock(&LOCK_global_system_variables);
-  variables= global_system_variables;
-  pthread_mutex_unlock(&LOCK_global_system_variables);
+  update_lock_default= (variables.low_priority_updates ?
+			TL_WRITE_LOW_PRIORITY :
+			TL_WRITE);
   session_tx_isolation= (enum_tx_isolation) variables.tx_isolation;
 }
 
diff --git a/sql/sql_handler.cc b/sql/sql_handler.cc
index ea02c46c0f4..289d2434225 100644
--- a/sql/sql_handler.cc
+++ b/sql/sql_handler.cc
@@ -180,10 +180,10 @@ int mysql_ha_read(THD *thd, TABLE_LIST *tables,
       Item *item;
       for (key_len=0 ; (item=it_ke++) ; key_part++)
       {
-	item->save_in_field(key_part->field);
+	item->save_in_field(key_part->field, 1);
 	key_len+=key_part->store_length;
       }
-      if (!(key= (byte*) sql_calloc(ALIGN_SIZE(key_len))))
+      if (!(key= (byte*) thd->calloc(ALIGN_SIZE(key_len))))
       {
 	send_error(&thd->net,ER_OUTOFMEMORY);
 	goto err;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 89f0ac1885a..eaa291f4d90 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -130,7 +130,9 @@ static int setup_group(THD *thd,TABLE_LIST *tables,List<Item> &fields,
 		       List<Item> &all_fields, ORDER *order, bool *hidden);
 static bool setup_new_fields(THD *thd,TABLE_LIST *tables,List<Item> &fields,
 			     List<Item> &all_fields,ORDER *new_order);
-static ORDER *create_distinct_group(ORDER *order, List<Item> &fields);
+static ORDER *create_distinct_group(THD *thd, ORDER *order,
+				    List<Item> &fields,
+				    bool *all_order_by_fields_used);
 static bool test_if_subpart(ORDER *a,ORDER *b);
 static TABLE *get_sort_by_table(ORDER *a,ORDER *b,TABLE_LIST *tables);
 static void calc_group_buffer(JOIN *join,ORDER *group);
@@ -228,6 +230,10 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
   bzero((char*) &keyuse,sizeof(keyuse));
   thd->proc_info="init";
   thd->used_tables=0;				// Updated by setup_fields
+  /* select_limit is used to decide if we are likely to scan the whole table */
+  select_limit= thd->select_limit;
+  if (having || (select_options & OPTION_FOUND_ROWS))
+    select_limit= HA_POS_ERROR;
 
   if (setup_tables(tables) ||
       setup_fields(thd,tables,fields,1,&all_fields,1) ||
@@ -436,6 +442,7 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
   thd->proc_info="statistics";
   if (make_join_statistics(&join,tables,conds,&keyuse) || thd->fatal_error)
     goto err;
+
   thd->proc_info="preparing";
   if (result->initialize_tables(&join))
     goto err;
@@ -444,7 +451,8 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
   {
     error=return_zero_rows(&join,result,tables,fields,
 			   join.tmp_table_param.sum_func_count != 0 &&
-			   !group,0,"",having,procedure);
+			   !group,0,"no matching row in const table",having,
+			   procedure);
     goto err;
   }
   if (!(thd->options & OPTION_BIG_SELECTS) &&
@@ -504,21 +512,47 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
     if (! hidden_group_fields)
       select_distinct=0;
   }
-  else if (select_distinct && join.tables - join.const_tables == 1 &&
-	   (thd->select_limit == HA_POS_ERROR ||
-	    (join.select_options & OPTION_FOUND_ROWS) ||
-	    order &&
-	    !(skip_sort_order=
-	      test_if_skip_sort_order(&join.join_tab[join.const_tables],
-				      order, thd->select_limit,1))))
+  else if (select_distinct && join.tables - join.const_tables == 1)
   {
-    if ((group=create_distinct_group(order,fields)))
-    {
-      select_distinct=0;
-      no_order= !order;
-      join.group=1;				// For end_write_group
-    }
-    else if (thd->fatal_error)			// End of memory
+    /*
+      We are only using one table. In this case we change DISTINCT to a
+      GROUP BY query if:
+      - The GROUP BY can be done through indexes (no sort) and the ORDER
+        BY only uses selected fields.
+	(In this case we can later optimize away GROUP BY and ORDER BY)
+      - We are scanning the whole table without LIMIT
+        This can happen if:
+        - We are using CALC_FOUND_ROWS
+        - We are using an ORDER BY that can't be optimized away.
+
+      We don't want to use this optimization when we are using LIMIT
+      because in this case we can just create a temporary table that
+      holds LIMIT rows and stop when this table is full.
+    */
+    JOIN_TAB *tab= &join.join_tab[join.const_tables];
+    bool all_order_fields_used;
+    if (order)
+      skip_sort_order= test_if_skip_sort_order(tab, order, select_limit, 1);
+    if ((group=create_distinct_group(thd, order, fields,
+				     &all_order_fields_used)))
+    {
+      bool skip_group= (skip_sort_order &&
+			test_if_skip_sort_order(tab, group, select_limit,
+						1) != 0);
+      if ((skip_group && all_order_fields_used) ||
+	  select_limit == HA_POS_ERROR ||
+	  (order && !skip_sort_order))
+      {
+	/*  Change DISTINCT to GROUP BY */
+	select_distinct= 0;
+	no_order= !order;
+	if (all_order_fields_used)
+	  order=0;
+	join.group=1;				// For end_write_group
+      }
+      else
+	group= 0;
+    } else if (thd->fatal_error)			// End of memory
       goto err;
   }
   group=remove_const(&join,group,conds,&simple_group);
@@ -622,10 +656,9 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
       order=group;
     if (order &&
 	(join.const_tables == join.tables ||
-	 (simple_order &&
+	 ((simple_order || skip_sort_order) &&
 	  test_if_skip_sort_order(&join.join_tab[join.const_tables], order,
-				  (join.select_options & OPTION_FOUND_ROWS) ?
-				  HA_POS_ERROR : thd->select_limit,0))))
+				  select_limit, 0))))
       order=0;
     select_describe(&join,need_tmp,
 		    order != 0 && !skip_sort_order,
@@ -653,7 +686,7 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
 			   group ? 0 : select_distinct,
 			   group && simple_group,
 			   (order == 0 || skip_sort_order) &&
-			   !(join.select_options & OPTION_FOUND_ROWS),
+			   select_limit != HA_POS_ERROR,
 			   join.select_options)))
       goto err;					/* purecov: inspected */
 
@@ -706,9 +739,10 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
       /* Optimize "select distinct b from t1 order by key_part_1 limit #" */
       if (order && skip_sort_order)
       {
-	(void) test_if_skip_sort_order(&join.join_tab[join.const_tables],
-				       order, thd->select_limit,0);
-	order=0;
+	/* Should always succeed */
+	if (test_if_skip_sort_order(&join.join_tab[join.const_tables],
+				    order, thd->select_limit,0))
+	  order=0;
       }
     }
 
@@ -877,8 +911,7 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
 	DBUG_EXECUTE("where",print_where(conds,"having after sort"););
       }
     }
-    select_limit= thd->select_limit;
-    if (having || group || (join.select_options & OPTION_FOUND_ROWS))
+    if (group)
       select_limit= HA_POS_ERROR;
     else
     {
@@ -953,13 +986,21 @@ static ha_rows get_quick_record_count(SQL_SELECT *select,TABLE *table,
 }
 
 
+/*
+  Calculate the best possible join and initialize the join structure
+
+  RETURN VALUES
+  0	ok
+  1	Fatal error
+*/
+  
 static bool
 make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
 		     DYNAMIC_ARRAY *keyuse_array)
 {
   int error;
   uint i,table_count,const_count,found_ref,refs,key,const_ref,eq_part;
-  table_map const_table_map,found_const_table_map,all_table_map;
+  table_map found_const_table_map,all_table_map;
   TABLE **table_vector;
   JOIN_TAB *stat,*stat_end,*s,**stat_ref;
   SQL_SELECT *select;
@@ -979,7 +1020,7 @@ make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
   join->best_ref=stat_vector;
 
   stat_end=stat+table_count;
-  const_table_map=found_const_table_map=all_table_map=0;
+  found_const_table_map=all_table_map=0;
   const_count=0;
 
   for (s=stat,i=0 ; tables ; s++,tables=tables->next,i++)
@@ -1070,7 +1111,7 @@ make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
       DBUG_RETURN(1);
 
   /* Read tables with 0 or 1 rows (system tables) */
-  join->const_table_map=const_table_map;
+  join->const_table_map= 0;
 
   for (POSITION *p_pos=join->positions, *p_end=p_pos+const_count;
        p_pos < p_end ;
@@ -1107,16 +1148,16 @@ make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
       if (s->dependent)				// If dependent on some table
       {
 	// All dep. must be constants
-	if (s->dependent & ~(join->const_table_map))
+	if (s->dependent & ~(found_const_table_map))
 	  continue;
 	if (table->file->records <= 1L &&
 	    !(table->file->table_flags() & HA_NOT_EXACT_COUNT))
 	{					// system table
-	  int tmp;
+	  int tmp= 0;
 	  s->type=JT_SYSTEM;
 	  join->const_table_map|=table->map;
 	  set_position(join,const_count++,s,(KEYUSE*) 0);
-	  if ((tmp=join_read_const_table(s,join->positions+const_count-1)))
+	  if ((tmp= join_read_const_table(s,join->positions+const_count-1)))
 	  {
 	    if (tmp > 0)
 	      DBUG_RETURN(1);			// Fatal error
@@ -1141,7 +1182,7 @@ make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
 	  {
 	    if (keyuse->val->type() != Item::NULL_ITEM)
 	    {
-	      if (!((~join->const_table_map) & keyuse->used_tables))
+	      if (!((~found_const_table_map) & keyuse->used_tables))
 		const_ref|= (key_map) 1 << keyuse->keypart;
 	      else
 		refs|=keyuse->used_tables;
@@ -1162,7 +1203,7 @@ make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
 	      join->const_table_map|=table->map;
 	      set_position(join,const_count++,s,start_keyuse);
 	      if (create_ref_for_key(join, s, start_keyuse,
-				     join->const_table_map))
+				     found_const_table_map))
 		DBUG_RETURN(1);
 	      if ((tmp=join_read_const_table(s,
 					     join->positions+const_count-1)))
@@ -1210,8 +1251,8 @@ make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
     {
       ha_rows records;
       if (!select)
-	select=make_select(s->table, join->const_table_map,
-			   join->const_table_map,
+	select=make_select(s->table, found_const_table_map,
+			   found_const_table_map,
 			   and_conds(conds,s->on_expr),&error);
       records=get_quick_record_count(select,s->table, s->const_keys,
 				     join->row_limit);
@@ -2373,12 +2414,13 @@ get_store_key(THD *thd, KEYUSE *keyuse, table_map used_tables,
 bool
 store_val_in_field(Field *field,Item *item)
 {
+  bool error;
   THD *thd=current_thd;
   ha_rows cuted_fields=thd->cuted_fields;
   thd->count_cuted_fields=1;
-  item->save_in_field(field);
+  error= item->save_in_field(field, 1);
   thd->count_cuted_fields=0;
-  return cuted_fields != thd->cuted_fields;
+  return error || cuted_fields != thd->cuted_fields;
 }
 
 
@@ -6577,12 +6619,14 @@ setup_new_fields(THD *thd,TABLE_LIST *tables,List<Item> &fields,
 */
 
 static ORDER *
-create_distinct_group(ORDER *order_list,List<Item> &fields)
+create_distinct_group(THD *thd, ORDER *order_list, List<Item> &fields, 
+		      bool *all_order_by_fields_used)
 {
   List_iterator<Item> li(fields);
   Item *item;
   ORDER *order,*group,**prev;
 
+  *all_order_by_fields_used= 1;
   while ((item=li++))
     item->marker=0;			/* Marker that field is not used */
 
@@ -6591,13 +6635,15 @@ create_distinct_group(ORDER *order_list,List<Item> &fields)
   {
     if (order->in_field_list)
     {
-      ORDER *ord=(ORDER*) sql_memdup(order,sizeof(ORDER));
+      ORDER *ord=(ORDER*) thd->memdup((char*) order,sizeof(ORDER));
       if (!ord)
 	return 0;
       *prev=ord;
       prev= &ord->next;
       (*ord->item)->marker=1;
     }
+    else
+      *all_order_by_fields_used= 0;
   }
 
   li.rewind();
@@ -6607,7 +6653,7 @@ create_distinct_group(ORDER *order_list,List<Item> &fields)
       continue;
     if (!item->marker)
     {
-      ORDER *ord=(ORDER*) sql_calloc(sizeof(ORDER));
+      ORDER *ord=(ORDER*) thd->calloc(sizeof(ORDER));
       if (!ord)
 	return 0;
       ord->item=li.ref();
@@ -7059,7 +7105,7 @@ copy_sum_funcs(Item_sum **func_ptr)
 {
   Item_sum *func;
   for (; (func = *func_ptr) ; func_ptr++)
-    (void) func->save_in_field(func->result_field);
+    (void) func->save_in_field(func->result_field, 1);
   return;
 }
 
@@ -7090,7 +7136,7 @@ copy_funcs(Item_result_field **func_ptr)
 {
   Item_result_field *func;
   for (; (func = *func_ptr) ; func_ptr++)
-    (void) func->save_in_field(func->result_field);
+    (void) func->save_in_field(func->result_field, 1);
   return;
 }
 
diff --git a/sql/sql_select.h b/sql/sql_select.h
index a90b2fe3582..d0e10f75727 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -247,12 +247,12 @@ class store_key_field: public store_key
       copy_field.set(to_field,from_field,0);
     }
   }
- bool copy()
- {
-   copy_field.do_copy(&copy_field);
-   return err != 0;
- }
- const char *name() const { return field_name; }
+  bool copy()
+  {
+    copy_field.do_copy(&copy_field);
+    return err != 0;
+  }
+  const char *name() const { return field_name; }
 };
 
 
@@ -269,8 +269,7 @@ public:
   {}
   bool copy()
   {
-    item->save_in_field(to_field);
-    return err != 0;
+    return item->save_in_field(to_field, 1) || err != 0;
   }
   const char *name() const { return "func"; }
 };
@@ -293,7 +292,8 @@ public:
     if (!inited)
     {
       inited=1;
-      item->save_in_field(to_field);
+      if (item->save_in_field(to_field, 1))
+	err= 1;
     }
     return err != 0;
   }
diff --git a/sql/unireg.cc b/sql/unireg.cc
index cc8440da1e4..5183f471fa2 100644
--- a/sql/unireg.cc
+++ b/sql/unireg.cc
@@ -574,7 +574,7 @@ static bool make_empty_rec(File file,enum db_type table_type,
     if (field->def &&
 	(regfield->real_type() != FIELD_TYPE_YEAR ||
 	 field->def->val_int() != 0))
-      field->def->save_in_field(regfield);
+      field->def->save_in_field(regfield, 1);
     else if (regfield->real_type() == FIELD_TYPE_ENUM &&
 	     (field->flags & NOT_NULL_FLAG))
     {