add VARIANCE function

mysql-test/r/func_group.result:
  add 'VARIANCE' tests
mysql-test/r/having.result:
  add 'VARIANCE' tests
mysql-test/r/select.result:
  add 'VARIANCE' tests
mysql-test/t/func_group.test:
  add 'VARIANCE' tests
mysql-test/t/having.test:
  add 'VARIANCE' tests
mysql-test/t/select.test:
  add 'VARIANCE' tests
sql/item.cc:
  add 'VARIANCE' sum function
sql/item.h:
  add 'VARIANCE' sum function
sql/item_sum.cc:
  add 'VARIANCE' sum function
sql/item_sum.h:
  add 'VARIANCE' sum function
BitKeeper/etc/logging_ok:
  Logging to logging@openlogging.org accepted

BitKeeper/etc/logging_ok

@@ -90,6 +90,7 @@ tonu@x153.internalnet
 tonu@x3.internalnet
 venu@myvenu.com
 venu@work.mysql.com
+vva@eagle.mysql.r18.ru
 vva@genie.(none)
 walrus@mysql.com
 wax@mysql.com

mysql-test/r/func_group.result

@@ -42,21 +42,21 @@ insert into t1 values (null,null,'');
 select count(distinct a),count(distinct grp) from t1;
 count(distinct a)	count(distinct grp)
 6	3
-select sum(a),count(a),avg(a),std(a),bit_or(a),bit_and(a),min(a),max(a),min(c),max(c) from t1;
-sum(a)	count(a)	avg(a)	std(a)	bit_or(a)	bit_and(a)	min(a)	max(a)	min(c)	max(c)
-21	6	3.5000	1.7078	7	0	1	6		E
-select grp, sum(a),count(a),avg(a),std(a),bit_or(a),bit_and(a),min(a),max(a),min(c),max(c) from t1 group by grp;
-grp	sum(a)	count(a)	avg(a)	std(a)	bit_or(a)	bit_and(a)	min(a)	max(a)	min(c)	max(c)
-NULL	0	0	NULL	NULL	0	0	NULL	NULL		
-1	1	1	1.0000	0.0000	1	1	1	1	a	a
-2	5	2	2.5000	0.5000	3	2	2	3	b	c
-3	15	3	5.0000	0.8165	7	4	4	6	C	E
-select grp, sum(a)+count(a)+avg(a)+std(a)+bit_or(a)+bit_and(a)+min(a)+max(a)+min(c)+max(c) as sum from t1 group by grp;
+select sum(a),count(a),avg(a),std(a),variance(a),bit_or(a),bit_and(a),min(a),max(a),min(c),max(c) from t1;
+sum(a)	count(a)	avg(a)	std(a)	variance(a)	bit_or(a)	bit_and(a)	min(a)	max(a)	min(c)	max(c)
+21	6	3.5000	1.7078	2.9167	7	0	1	6		E
+select grp, sum(a),count(a),avg(a),std(a),variance(a),bit_or(a),bit_and(a),min(a),max(a),min(c),max(c) from t1 group by grp;
+grp	sum(a)	count(a)	avg(a)	std(a)	variance(a)	bit_or(a)	bit_and(a)	min(a)	max(a)	min(c)	max(c)
+NULL	0	0	NULL	NULL	NULL	0	0	NULL	NULL		
+1	1	1	1.0000	0.0000	0.0000	1	1	1	1	a	a
+2	5	2	2.5000	0.5000	0.2500	3	2	2	3	b	c
+3	15	3	5.0000	0.8165	0.6667	7	4	4	6	C	E
+select grp, sum(a)+count(a)+avg(a)+std(a)+variance(a)+bit_or(a)+bit_and(a)+min(a)+max(a)+min(c)+max(c) as sum from t1 group by grp;
 grp	sum
 NULL	NULL
 1	7
-2	20
-3	44.816496580928
+2	20.25
+3	45.483163247594
 create table t2 (grp int, a bigint unsigned, c char(10));
 insert into t2 select grp,max(a)+max(grp),max(c) from t1 group by grp;
 replace into t2 select grp, a, c from t1 limit 2,1;
@@ -72,14 +72,14 @@ CREATE TABLE t1 (id int(11),value1 float(10,2));
 INSERT INTO t1 VALUES (1,0.00),(1,1.00), (1,2.00), (2,10.00), (2,11.00), (2,12.00);
 CREATE TABLE t2 (id int(11),name char(20));
 INSERT INTO t2 VALUES (1,'Set One'),(2,'Set Two');
-select id, avg(value1), std(value1) from t1 group by id;
-id	avg(value1)	std(value1)
-1	1.000000	0.816497
-2	11.000000	0.816497
-select name, avg(value1), std(value1) from t1, t2 where t1.id = t2.id group by t1.id;
-name	avg(value1)	std(value1)
-Set One	1.000000	0.816497
-Set Two	11.000000	0.816497
+select id, avg(value1), std(value1), variance(value1) from t1 group by id;
+id	avg(value1)	std(value1)	variance(value1)
+1	1.000000	0.816497	0.666667
+2	11.000000	0.816497	0.666667
+select name, avg(value1), std(value1), variance(value1) from t1, t2 where t1.id = t2.id group by t1.id;
+name	avg(value1)	std(value1)	variance(value1)
+Set One	1.000000	0.816497	0.666667
+Set Two	11.000000	0.816497	0.666667
 drop table t1,t2;
 create table t1 (id int not null);
 create table t2 (id int not null,rating int null);

mysql-test/r/having.result

@@ -62,4 +62,8 @@ select Fld1, max(Fld2) from t1 group by Fld1 having std(Fld2) is not null;
 Fld1	max(Fld2)
 1	20
 3	50
+select Fld1, max(Fld2) from t1 group by Fld1 having variance(Fld2) is not null;
+Fld1	max(Fld2)
+1	20
+3	50
 drop table t1;

mysql-test/r/select.result

@@ -2656,14 +2656,14 @@ companynr	count(*)
 58	23
 53	4
 50	11
-select count(*),min(fld4),max(fld4),sum(fld1),avg(fld1),std(fld1) from t2 where companynr = 34 and fld4<>"";
-count(*)	min(fld4)	max(fld4)	sum(fld1)	avg(fld1)	std(fld1)
-70	absentee	vest	17788966	254128.0857	3272.5940
-select companynr,count(*),min(fld4),max(fld4),sum(fld1),avg(fld1),std(fld1) from t2 group by companynr limit 3;
-companynr	count(*)	min(fld4)	max(fld4)	sum(fld1)	avg(fld1)	std(fld1)
-00	82	Anthony	windmills	10355753	126289.6707	115550.9757
-29	95	abut	wetness	14473298	152350.5053	8368.5480
-34	70	absentee	vest	17788966	254128.0857	3272.5940
+select count(*),min(fld4),max(fld4),sum(fld1),avg(fld1),std(fld1),variance(fld1) from t2 where companynr = 34 and fld4<>"";
+count(*)	min(fld4)	max(fld4)	sum(fld1)	avg(fld1)	std(fld1)	variance(fld1)
+70	absentee	vest	17788966	254128.0857	3272.5940	10709871.3069
+select companynr,count(*),min(fld4),max(fld4),sum(fld1),avg(fld1),std(fld1),variance(fld1) from t2 group by companynr limit 3;
+companynr	count(*)	min(fld4)	max(fld4)	sum(fld1)	avg(fld1)	std(fld1)	variance(fld1)
+00	82	Anthony	windmills	10355753	126289.6707	115550.9757	13352027981.7087
+29	95	abut	wetness	14473298	152350.5053	8368.5480	70032594.9026
+34	70	absentee	vest	17788966	254128.0857	3272.5940	10709871.3069
 select companynr,t2nr,count(price),sum(price),min(price),max(price),avg(price) from t3 where companynr = 37 group by companynr,t2nr limit 10;
 companynr	t2nr	count(price)	sum(price)	min(price)	max(price)	avg(price)
 37	1	1	5987435	5987435	5987435	5987435.0000

mysql-test/t/func_group.test

@@ -21,9 +21,9 @@ select count(distinct a),count(distinct grp) from t1;
 insert into t1 values (null,null,'');
 select count(distinct a),count(distinct grp) from t1;
 
-select sum(a),count(a),avg(a),std(a),bit_or(a),bit_and(a),min(a),max(a),min(c),max(c) from t1;
-select grp, sum(a),count(a),avg(a),std(a),bit_or(a),bit_and(a),min(a),max(a),min(c),max(c) from t1 group by grp;
-select grp, sum(a)+count(a)+avg(a)+std(a)+bit_or(a)+bit_and(a)+min(a)+max(a)+min(c)+max(c) as sum from t1 group by grp;
+select sum(a),count(a),avg(a),std(a),variance(a),bit_or(a),bit_and(a),min(a),max(a),min(c),max(c) from t1;
+select grp, sum(a),count(a),avg(a),std(a),variance(a),bit_or(a),bit_and(a),min(a),max(a),min(c),max(c) from t1 group by grp;
+select grp, sum(a)+count(a)+avg(a)+std(a)+variance(a)+bit_or(a)+bit_and(a)+min(a)+max(a)+min(c)+max(c) as sum from t1 group by grp;
 
 create table t2 (grp int, a bigint unsigned, c char(10));
 insert into t2 select grp,max(a)+max(grp),max(c) from t1 group by grp;
@@ -40,8 +40,8 @@ CREATE TABLE t1 (id int(11),value1 float(10,2));
 INSERT INTO t1 VALUES (1,0.00),(1,1.00), (1,2.00), (2,10.00), (2,11.00), (2,12.00); 
 CREATE TABLE t2 (id int(11),name char(20)); 
 INSERT INTO t2 VALUES (1,'Set One'),(2,'Set Two'); 
-select id, avg(value1), std(value1) from t1 group by id;
-select name, avg(value1), std(value1) from t1, t2 where t1.id = t2.id group by t1.id;
+select id, avg(value1), std(value1), variance(value1) from t1 group by id;
+select name, avg(value1), std(value1), variance(value1) from t1, t2 where t1.id = t2.id group by t1.id;
 drop table t1,t2;
 
 #

mysql-test/t/having.test

@@ -59,4 +59,5 @@ select Fld1, max(Fld2) as q from t1 group by Fld1 having q is not null;
 select Fld1, max(Fld2) from t1 group by Fld1 having max(Fld2) is not null;
 select Fld1, max(Fld2) from t1 group by Fld1 having avg(Fld2) is not null;
 select Fld1, max(Fld2) from t1 group by Fld1 having std(Fld2) is not null;
+select Fld1, max(Fld2) from t1 group by Fld1 having variance(Fld2) is not null;
 drop table t1;

mysql-test/t/select.test

@@ -1577,8 +1577,8 @@ select fld3 from t2 where (((fld3 like "_%L%" ) or (fld3 like "%ok%")) and ( fld
 select count(*) from t1;
 select companynr,count(*),sum(fld1) from t2 group by companynr;
 select companynr,count(*) from t2 group by companynr order by companynr desc limit 5;
-select count(*),min(fld4),max(fld4),sum(fld1),avg(fld1),std(fld1) from t2 where companynr = 34 and fld4<>"";
-select companynr,count(*),min(fld4),max(fld4),sum(fld1),avg(fld1),std(fld1) from t2 group by companynr limit 3;
+select count(*),min(fld4),max(fld4),sum(fld1),avg(fld1),std(fld1),variance(fld1) from t2 where companynr = 34 and fld4<>"";
+select companynr,count(*),min(fld4),max(fld4),sum(fld1),avg(fld1),std(fld1),variance(fld1) from t2 group by companynr limit 3;
 select companynr,t2nr,count(price),sum(price),min(price),max(price),avg(price) from t3 where companynr = 37 group by companynr,t2nr limit 10;
 select /*! SQL_SMALL_RESULT */ companynr,t2nr,count(price),sum(price),min(price),max(price),avg(price) from t3 where companynr = 37 group by companynr,t2nr limit 10;
 select companynr,count(price),sum(price),min(price),max(price),avg(price) from t3 group by companynr ;

sql/item.cc

@@ -686,7 +686,7 @@ void Item_avg_field::make_field(Send_field *tmp_field)
   init_make_field(tmp_field,FIELD_TYPE_DOUBLE);
 }
 
-void Item_std_field::make_field(Send_field *tmp_field)
+void Item_variance_field::make_field(Send_field *tmp_field)
 {
   init_make_field(tmp_field,FIELD_TYPE_DOUBLE);
 }

sql/item.h

@@ -33,7 +33,8 @@ class Item {
   enum Type {FIELD_ITEM,FUNC_ITEM,SUM_FUNC_ITEM,STRING_ITEM,
 	     INT_ITEM,REAL_ITEM,NULL_ITEM,VARBIN_ITEM,
 	     COPY_STR_ITEM,FIELD_AVG_ITEM, DEFAULT_ITEM,
-	     PROC_ITEM,COND_ITEM,REF_ITEM,FIELD_STD_ITEM, CONST_ITEM,
+	     PROC_ITEM,COND_ITEM,REF_ITEM,FIELD_STD_ITEM, 
+	     FIELD_VARIANCE_ITEM,CONST_ITEM,
              SUBSELECT_ITEM, ROW_ITEM};
   enum cond_result { COND_UNDEF,COND_OK,COND_TRUE,COND_FALSE };
 

sql/item_sum.cc

@@ -255,12 +255,24 @@ double Item_sum_avg::val()
 ** Standard deviation
 */
 
-void Item_sum_std::reset()
+double Item_sum_std::val()
 {
-  sum=sum_sqr=0.0; count=0; (void) Item_sum_std::add();
+  double tmp= Item_sum_variance::val();
+  return tmp <= 0.0 ? 0.0 : sqrt(tmp);
 }
 
-bool Item_sum_std::add()
+/*
+** variance
+*/
+
+void Item_sum_variance::reset()
+{
+  sum=sum_sqr=0.0; 
+  count=0; 
+  (void) Item_sum_variance::add();
+}
+
+bool Item_sum_variance::add()
 {
   double nr=args[0]->val();
   if (!args[0]->null_value)
@@ -272,7 +284,7 @@ bool Item_sum_std::add()
   return 0;
 }
 
-double Item_sum_std::val()
+double Item_sum_variance::val()
 {
   if (!count)
   {
@@ -283,11 +295,10 @@ double Item_sum_std::val()
   /* Avoid problems when the precision isn't good enough */
   double tmp=ulonglong2double(count);
   double tmp2=(sum_sqr - sum*sum/tmp)/tmp;
-  return tmp2 <= 0.0 ? 0.0 : sqrt(tmp2);
+  return tmp2 <= 0.0 ? 0.0 : tmp2;
 }
 
-
-void Item_sum_std::reset_field()
+void Item_sum_variance::reset_field()
 {
   double nr=args[0]->val();
   char *res=result_field->ptr;
@@ -304,7 +315,7 @@ void Item_sum_std::reset_field()
   }
 }
 
-void Item_sum_std::update_field(int offset)
+void Item_sum_variance::update_field(int offset)
 {
   double nr,old_nr,old_sqr;
   longlong field_count;
@@ -838,6 +849,17 @@ String *Item_avg_field::val_str(String *str)
 }
 
 Item_std_field::Item_std_field(Item_sum_std *item)
+  : Item_variance_field(item)
+{
+}
+
+double Item_std_field::val()
+{
+  double tmp= Item_variance_field::val();
+  return tmp <= 0.0 ? 0.0 : sqrt(tmp);
+}
+
+Item_variance_field::Item_variance_field(Item_sum_variance *item)
 {
   name=item->name;
   decimals=item->decimals;
@@ -846,7 +868,7 @@ Item_std_field::Item_std_field(Item_sum_std *item)
   maybe_null=1;
 }
 
-double Item_std_field::val()
+double Item_variance_field::val()
 {
   double sum,sum_sqr;
   longlong count;
@@ -862,10 +884,10 @@ double Item_std_field::val()
   null_value=0;
   double tmp= (double) count;
   double tmp2=(sum_sqr - sum*sum/tmp)/tmp;
-  return tmp2 <= 0.0 ? 0.0 : sqrt(tmp2);
+  return tmp2 <= 0.0 ? 0.0 : tmp2;
 }
 
-String *Item_std_field::val_str(String *str)
+String *Item_variance_field::val_str(String *str)
 {
   double nr=val();
   if (null_value)

sql/item_sum.h

@@ -27,7 +27,7 @@ class Item_sum :public Item_result_field
 {
 public:
   enum Sumfunctype {COUNT_FUNC,COUNT_DISTINCT_FUNC,SUM_FUNC,AVG_FUNC,MIN_FUNC,
-		    MAX_FUNC, UNIQUE_USERS_FUNC,STD_FUNC,SUM_BIT_FUNC,
+		    MAX_FUNC, UNIQUE_USERS_FUNC,STD_FUNC,VARIANCE_FUNC,SUM_BIT_FUNC,
 		    UDF_SUM_FUNC };
 
   Item **args,*tmp_args[2];
@@ -235,14 +235,14 @@ class Item_sum_avg :public Item_sum_num
   const char *func_name() const { return "avg"; }
 };
 
-class Item_sum_std;
+class Item_sum_variance;
 
-class Item_std_field :public Item_result_field
+class Item_variance_field :public Item_result_field
 {
 public:
   Field *field;
-  Item_std_field(Item_sum_std *item);
-  enum Type type() const { return FIELD_STD_ITEM; }
+  Item_variance_field(Item_sum_variance *item);
+  enum Type type() const {return FIELD_VARIANCE_ITEM; }
   double val();
   longlong val_int() { return (longlong) val(); }
   String *val_str(String*);
@@ -251,27 +251,60 @@ class Item_std_field :public Item_result_field
   void fix_length_and_dec() {}
 };
 
-class Item_sum_std :public Item_sum_num
+/*
+
+variance(a) =
+
+= sqrt ( sum (ai - avg(a))^2 / count(a) )
+= sqrt ( sum (ai^2 - 2*ai*avg(a) + avg(a)^2) / count(a) )
+= sqrt ( (sum(ai^2) - sum(2*ai*avg(a)) + sum(avg(a)^2))/count(a) ) = 
+= sqrt ( (sum(ai^2) - 2*avg(a)*sum(a) + count(a)*avg(a)^2)/count(a) ) = 
+= sqrt ( (sum(ai^2) - 2*sum(a)*sum(a)/count(a) + count(a)*sum(a)^2/count(a)^2 )/count(a) ) = 
+= sqrt ( (sum(ai^2) - 2*sum(a)^2/count(a) + sum(a)^2/count(a) )/count(a) ) = 
+= sqrt ( (sum(ai^2) - sum(a)^2/count(a))/count(a) )
+
+ */
+
+class Item_sum_variance : public Item_sum_num
 {
-  double sum;
-  double sum_sqr;
+  double sum, sum_sqr;
   ulonglong count;
   void fix_length_and_dec() { decimals+=4; maybe_null=1; }
 
   public:
-  Item_sum_std(Item *item_par) :Item_sum_num(item_par),count(0) {}
-  enum Sumfunctype sum_func () const { return STD_FUNC; }
+  Item_sum_variance(Item *item_par) :Item_sum_num(item_par),count(0) {}
+  enum Sumfunctype sum_func () const { return VARIANCE_FUNC; }
   void reset();
   bool add();
   double val();
   void reset_field();
   void update_field(int offset);
+  Item *result_item(Field *field)
+  { return new Item_variance_field(this); }
+  const char *func_name() const { return "variance"; }
+};
+
+class Item_sum_std;
+
+class Item_std_field :public Item_variance_field
+{
+public:
+  Item_std_field(Item_sum_std *item);
+  enum Type type() const { return FIELD_STD_ITEM; }
+  double val();
+};
+
+class Item_sum_std :public Item_sum_variance
+{
+  public:
+  Item_sum_std(Item *item_par) :Item_sum_variance(item_par){}
+  enum Sumfunctype sum_func () const { return STD_FUNC; }
+  double val();
   Item *result_item(Field *field)
     { return new Item_std_field(this); }
   const char *func_name() const { return "std"; }
 };
 
-
 // This class is a string or number function depending on num_func
 
 class Item_sum_hybrid :public Item_sum

sql/lex.h

@@ -584,6 +584,7 @@ static SYMBOL sql_functions[] = {
   { "UNIX_TIMESTAMP",	SYM(UNIX_TIMESTAMP),0,0},
   { "UPPER",		SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_ucase)},
   { "USER",		SYM(USER),0,0},
+  { "VARIANCE",		SYM(VARIANCE_SYM),0,0},
   { "VERSION",		SYM(FUNC_ARG0),0,CREATE_FUNC(create_func_version)},
   { "WEEK",		SYM(WEEK_SYM),0,0},
   { "WEEKDAY",		SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_weekday)},

sql/sql_select.cc

@@ -3773,7 +3773,8 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
       else
 	return new Field_double(item_sum->max_length,maybe_null,
 				item->name, table, item_sum->decimals);
-    case Item_sum::STD_FUNC:			/* Place for sum & count */
+    case Item_sum::VARIANCE_FUNC:			/* Place for sum & count */
+    case Item_sum::STD_FUNC:	
       if (group)
 	return	new Field_string(sizeof(double)*2+sizeof(longlong),
 				 maybe_null, item->name,table,my_charset_bin);

sql/sql_yacc.yy

@@ -158,6 +158,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 %token	SQL_THREAD
 %token	START_SYM
 %token	STD_SYM
+%token  VARIANCE_SYM
 %token	STOP_SYM
 %token	SUM_SYM
 %token	SUPER_SYM
@@ -2335,6 +2336,8 @@ sum_expr:
 	  { $$=new Item_sum_max($3); }
 	| STD_SYM '(' in_sum_expr ')'
 	  { $$=new Item_sum_std($3); }
+	| VARIANCE_SYM '(' in_sum_expr ')'
+	  { $$=new Item_sum_variance($3); }
 	| SUM_SYM '(' in_sum_expr ')'
 	  { $$=new Item_sum_sum($3); };