Commit faad7355 authored by unknown's avatar unknown
Browse files

fix for bug #19690: ORDER BY eliminates rows from the result 

Depending on the queries we use different data processing methods
and can lose some data in case of double (and decimal in 4.1) fields.

The fix consists of two parts:
1. double comparison changed, now double a is equal to double b 
if (a-b) is less than 5*0.1^(1 + max(a->decimals, b->decimals)). 
For example, if a->decimals==1, b->decimals==2, a==b if (a-b)<0.005
2. if we use a temporary table, store double values there as is 
to avoid any data conversion (rounding).


mysql-test/r/type_float.result:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - test result
mysql-test/t/type_float.test:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - test case
sql/field.cc:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - use not_fixed flag instead of dec to check bounds.
sql/field.h:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - Field_Double::not_fixed flag introduced, which is set if dec == NOT_FIXED_DEC
      and is used in the ::store() to check bounds. 
    - new constructor introduced (with not_fixed_arg parameter).
sql/init.cc:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - fill log_01[] array with 0.1 powers.
sql/item_cmpfunc.cc:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - compare_real_fixed() and compare_e_real_fixed() introduced,
      they consider double a == double b if a-b is less than 'precision',
      'precision' is set to 5*0.1^(1 + max(a->decimals, b->decimals)), 
      for example, if a->decimals==1, b->decimals==2, 'precision' is 0.005
    - use the above functions if both arguments are fixed.
sql/item_cmpfunc.h:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - Arg_comparator::presision introduced.
    - Arg_comparator::compare_real_fixed(), Arg_comparator::compare_e_real_fixed() introduced.
sql/mysql_priv.h:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - log_01 array of 0.1 powers added.
sql/mysqld.cc:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - log_01 array of 0.1 powers added.
sql/sql_select.cc:
  fix for bug #19690: ORDER BY eliminates rows from the result
    - if we create double field in a temporary table, set not_fixed flag
      (use proper constructor) to avoid data conversion 
      in the Field_double::store(). Otherwise we can lose some data.
parent e167d79e

mysql-test/r/type_float.result

+71 −0
Original line number Diff line number Diff line
@@ -278,4 +278,75 @@ select 1e-308, 1.00000001e-300, 100000000e-300; 
select 10e307;

10e307

1e+308

create table t1(a int, b double(8, 2));

insert into t1 values

(1, 28.50), (1, 121.85), (1, 157.23), (1, 1351.00), (1, -1965.35), (1, 81.75), 

(1, 217.08), (1, 7.94), (4, 96.07), (4, 6404.65), (4, -6500.72), (2, 100.00),

(5, 5.00), (5, -2104.80), (5, 2033.80), (5, 0.07), (5, 65.93),

(3, -4986.24), (3, 5.00), (3, 4857.34), (3, 123.74), (3,  0.16),

(6, -1695.31), (6, 1003.77), (6, 499.72), (6, 191.82);

explain select sum(b) s from t1 group by a;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	26	Using temporary; Using filesort

select sum(b) s from t1 group by a;

s

0.00

100.00

0.00

-0.00

-0.00

0.00

select sum(b) s from t1 group by a having s <> 0;

s

100.00

select sum(b) s from t1 group by a having s <> 0 order by s;

s

100.00

select sum(b) s from t1 group by a having s <=> 0;

s

0.00

0.00

-0.00

-0.00

0.00

select sum(b) s from t1 group by a having s <=> 0 order by s;

s

-0.00

-0.00

0.00

0.00

0.00

alter table t1 add key (a, b);

explain select sum(b) s from t1 group by a;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t1	index	NULL	a	14	NULL	26	Using index

select sum(b) s from t1 group by a;

s

0.00

100.00

0.00

-0.00

0.00

0.00

select sum(b) s from t1 group by a having s <> 0;

s

100.00

select sum(b) s from t1 group by a having s <> 0 order by s;

s

100.00

select sum(b) s from t1 group by a having s <=> 0;

s

0.00

0.00

-0.00

0.00

0.00

select sum(b) s from t1 group by a having s <=> 0 order by s;

s

-0.00

0.00

0.00

0.00

0.00

drop table t1;

End of 4.1 tests

mysql-test/t/type_float.test

+25 −0
Original line number Diff line number Diff line
@@ -188,4 +188,29 @@ select 1e-308, 1.00000001e-300, 100000000e-300; 
# check if overflows are detected correctly

select 10e307;



#

# Bug #19690: ORDER BY eliminates rows from the result

#

create table t1(a int, b double(8, 2));

insert into t1 values

(1, 28.50), (1, 121.85), (1, 157.23), (1, 1351.00), (1, -1965.35), (1, 81.75), 

(1, 217.08), (1, 7.94), (4, 96.07), (4, 6404.65), (4, -6500.72), (2, 100.00),

(5, 5.00), (5, -2104.80), (5, 2033.80), (5, 0.07), (5, 65.93),

(3, -4986.24), (3, 5.00), (3, 4857.34), (3, 123.74), (3,  0.16),

(6, -1695.31), (6, 1003.77), (6, 499.72), (6, 191.82);

explain select sum(b) s from t1 group by a;

select sum(b) s from t1 group by a;

select sum(b) s from t1 group by a having s <> 0;

select sum(b) s from t1 group by a having s <> 0 order by s;

select sum(b) s from t1 group by a having s <=> 0;

select sum(b) s from t1 group by a having s <=> 0 order by s;

alter table t1 add key (a, b);

explain select sum(b) s from t1 group by a;

select sum(b) s from t1 group by a;

select sum(b) s from t1 group by a having s <> 0;

select sum(b) s from t1 group by a having s <> 0 order by s;

select sum(b) s from t1 group by a having s <=> 0;

select sum(b) s from t1 group by a having s <=> 0 order by s;

drop table t1;



--echo End of 4.1 tests

sql/field.cc

+1 −1
Original line number Diff line number Diff line
@@ -3318,7 +3318,7 @@ int Field_double::store(double nr) 
  else 

  {

    double max_value;

    if (dec >= NOT_FIXED_DEC)

    if (not_fixed)

    {

      max_value= DBL_MAX;

    }

sql/field.h

+12 −3
Original line number Diff line number Diff line
@@ -616,6 +616,7 @@ class Field_float :public Field_num { 


class Field_double :public Field_num {

public:

  my_bool not_fixed;

  Field_double(char *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,

	       uchar null_bit_arg,

	       enum utype unireg_check_arg, const char *field_name_arg,
@@ -623,12 +624,20 @@ class Field_double :public Field_num { 
	       uint8 dec_arg,bool zero_arg,bool unsigned_arg)

    :Field_num(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,

	       unireg_check_arg, field_name_arg, table_arg,

	       dec_arg, zero_arg,unsigned_arg)

	       dec_arg, zero_arg, unsigned_arg),

     not_fixed(dec_arg >= NOT_FIXED_DEC)

    {}

  Field_double(uint32 len_arg, bool maybe_null_arg, const char *field_name_arg,

	       struct st_table *table_arg, uint8 dec_arg)

    :Field_num((char *) 0, len_arg, maybe_null_arg ? (uchar *) "" : 0, (uint) 0,

	       NONE, field_name_arg, table_arg,dec_arg,0,0)

	       NONE, field_name_arg, table_arg,dec_arg, 0, 0),

     not_fixed(dec_arg >= NOT_FIXED_DEC)

    {}

  Field_double(uint32 len_arg, bool maybe_null_arg, const char *field_name_arg,

	       struct st_table *table_arg, uint8 dec_arg, my_bool not_fixed_srg)

    :Field_num((char *) 0, len_arg, maybe_null_arg ? (uchar *) "" : 0, (uint) 0,

	       NONE, field_name_arg, table_arg, dec_arg, 0, 0), 

    not_fixed(not_fixed_srg)

    {}

  enum_field_types type() const { return FIELD_TYPE_DOUBLE;}

  enum ha_base_keytype key_type() const { return HA_KEYTYPE_DOUBLE; }

sql/init.cc

+6 −0
Original line number Diff line number Diff line
@@ -45,6 +45,12 @@ void unireg_init(ulong options) 
  {					/* It's used by filesort... */

    log_10[i]= nr ; nr*= 10.0;

  }

  /* Make a tab of powers of 0.1 */

  for (i= 0, nr= 0.1; i < array_elements(log_01); i++)

  {

    log_01[i]= nr;

    nr*= 0.1;

  }

  specialflag|=options;			/* Set options from argv */

  DBUG_VOID_RETURN;

}