database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +03:00
Code Activity

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

Browse Source 
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).
This commit is contained in:
ramil/ram@mysql.com/ramil.myoffice.izhnet.ru
2007-01-31 09:51:05 +04:00
parent ba6e6d0754
commit eb415e4920
10 changed files with 177 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
sql/sql_select.cc
View File

@ -5006,6 +5006,8 @@ static Field* create_tmp_field_from_field(THD *thd, Field* org_field,
new_field->flags&= ~NOT_NULL_FLAG; // Because of outer join
if (org_field->type() == FIELD_TYPE_VAR_STRING)
table->db_create_options|= HA_OPTION_PACK_RECORD;
else if (org_field->type() == FIELD_TYPE_DOUBLE)
((Field_double *) new_field)->not_fixed= TRUE;
}
return new_field;
}
@ -5045,7 +5047,7 @@ static Field* create_tmp_field_from_item(THD *thd, Item *item, TABLE *table,
switch (item->result_type()) {
case REAL_RESULT:
new_field=new Field_double(item->max_length, maybe_null,
item->name, table, item->decimals);
item->name, table, item->decimals, TRUE);
break;
case INT_RESULT:
new_field=new Field_longlong(item->max_length, maybe_null,
@ -5136,8 +5138,8 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
return new Field_string(sizeof(double)+sizeof(longlong),
0, item->name,table,&my_charset_bin);
else
return new Field_double(item_sum->max_length,maybe_null,
item->name, table, item_sum->decimals);
return new Field_double(item_sum->max_length, maybe_null,
item->name, table, item_sum->decimals, TRUE);
case Item_sum::VARIANCE_FUNC: /* Place for sum & count */
case Item_sum::STD_FUNC:
if (group)
@ -5145,7 +5147,7 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
0, item->name,table,&my_charset_bin);
else
return new Field_double(item_sum->max_length, maybe_null,
item->name,table,item_sum->decimals);
item->name, table, item_sum->decimals, TRUE);
case Item_sum::UNIQUE_USERS_FUNC:
return new Field_long(9,maybe_null,item->name,table,1);
case Item_sum::MIN_FUNC:
@ -5160,8 +5162,8 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
default:
switch (item_sum->result_type()) {
case REAL_RESULT:
return new Field_double(item_sum->max_length,maybe_null,
item->name,table,item_sum->decimals);
return new Field_double(item_sum->max_length, maybe_null,
item->name, table, item_sum->decimals, TRUE);
case INT_RESULT:
return new Field_longlong(item_sum->max_length,maybe_null,
item->name,table,item->unsigned_flag);