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MDEV-3875 Wrong result (missing row) on a DISTINCT query with the same subquery in the SELECT list and GROUP BY

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fix remove_dup_with_hash_index() and remove_dup_with_compare() to take NULLs into account
This commit is contained in:
Sergei Golubchik 2013-01-26 22:33:18 +01:00
parent 298008dc4f
commit 0791692bdc
6 changed files with 120 additions and 72 deletions
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32
mysql-test/r/distinct.result
View File

@ -847,3 +847,35 @@ time(f1)
00:00:00.000200
00:00:00.000300
drop table t1;
create table t1(i int, g int);
insert into t1 values (null, 1), (0, 2);
select distinct i from t1 group by g;
i
NULL
0
drop table t1;
create table t1(i int, g blob);
insert into t1 values (null, 1), (0, 2);
select distinct i from t1 group by g;
i
NULL
0
drop table t1;
create table t1 (a int) engine=myisam;
insert into t1 values (0),(7);
create table t2 (b int) engine=myisam;
insert into t2 values (7),(0),(3);
create algorithm=temptable view v as
select distinct (select max(a) from t1 where alias.b = a) as field1 from t2 as alias group by field1;
select * from v;
field1
NULL
0
7
select distinct (select max(a) from t1 where alias.b = a) as field1 from t2 as alias group by field1;
field1
NULL
0
7
drop view v;
drop table t1, t2;

24
mysql-test/t/distinct.test
View File

@ -658,3 +658,27 @@ select time(f1) from t1 ;
select distinct time(f1) from t1 ;
drop table t1;
#
# MDEV-3875 Wrong result (missing row) on a DISTINCT query with the same subquery in the SELECT list and GROUP BY
# MySQL Bug#66896 Distinct not distinguishing 0 from NULL when GROUP BY is used
#
create table t1(i int, g int); # remove_dup_with_hash_index
insert into t1 values (null, 1), (0, 2);
select distinct i from t1 group by g;
drop table t1;
create table t1(i int, g blob); # remove_dup_with_compare
insert into t1 values (null, 1), (0, 2);
select distinct i from t1 group by g;
drop table t1;
create table t1 (a int) engine=myisam;
insert into t1 values (0),(7);
create table t2 (b int) engine=myisam;
insert into t2 values (7),(0),(3);
create algorithm=temptable view v as
select distinct (select max(a) from t1 where alias.b = a) as field1 from t2 as alias group by field1;
select * from v;
select distinct (select max(a) from t1 where alias.b = a) as field1 from t2 as alias group by field1;
drop view v;
drop table t1, t2;

15
sql/field.cc
View File

@ -1062,6 +1062,21 @@ bool Field::type_can_have_key_part(enum enum_field_types type)
}
void Field::make_sort_key(uchar *buff,uint length)
{
if (maybe_null())
{
if (is_null())
{
bzero(buff, length + 1);
return;
}
*buff++= 1;
}
sort_string(buff, length);
}
/**
Numeric fields base class constructor.
*/

1
sql/field.h
View File

@ -386,6 +386,7 @@ public:
return bytes;
}
void make_sort_key(uchar *buff, uint length);
virtual void make_field(Send_field *);
virtual void sort_string(uchar *buff,uint length)=0;
virtual bool optimize_range(uint idx, uint part);

25
sql/filesort.cc
View File

@ -783,21 +783,9 @@ static void make_sortkey(register SORTPARAM *param,
bool maybe_null=0;
if ((field=sort_field->field))
{ // Field
if (field->maybe_null())
{
if (field->is_null())
{
if (sort_field->reverse)
bfill(to,sort_field->length+1,(char) 255);
else
bzero((char*) to,sort_field->length+1);
to+= sort_field->length+1;
continue;
}
else
*to++=1;
}
field->sort_string(to, sort_field->length);
field->make_sort_key(to, sort_field->length);
if ((maybe_null = field->maybe_null()))
to++;
}
else
{ // Item
@ -949,8 +937,11 @@ static void make_sortkey(register SORTPARAM *param,
}
if (sort_field->reverse)
{ /* Revers key */
if (maybe_null)
to[-1]= ~to[-1];
if (maybe_null && (to[-1]= !to[-1]))
{
to+= sort_field->length; // don't waste the time reversing all 0's
continue;
}
length=sort_field->length;
while (length--)
{

95
sql/sql_select.cc
View File

@ -204,7 +204,7 @@ static int create_sort_index(THD *thd, JOIN *join, ORDER *order,
static int remove_duplicates(JOIN *join,TABLE *entry,List<Item> &fields,
Item *having);
static int remove_dup_with_compare(THD *thd, TABLE *entry, Field **field,
ulong offset,Item *having);
Item *having);
static int remove_dup_with_hash_index(THD *thd,TABLE *table,
uint field_count, Field **first_field,
ulong key_length,Item *having);
@ -18891,19 +18891,24 @@ static bool fix_having(JOIN *join, Item **having)
#endif
/*****************************************************************************
Remove duplicates from tmp table
This should be recoded to add a unique index to the table and remove
duplicates
Table is a locked single thread table
fields is the number of fields to check (from the end)
*****************************************************************************/
/**
Compare fields from table->record[0] and table->record[1],
possibly skipping few first fields.
@param table
@param ptr field to start the comparison from,
somewhere in the table->field[] array
@retval 1 different
@retval 0 identical
*/
static bool compare_record(TABLE *table, Field **ptr)
{
for (; *ptr ; ptr++)
{
if ((*ptr)->cmp_offset(table->s->rec_buff_length))
Field *f= *ptr;
if (f->is_null() != f->is_null(table->s->rec_buff_length) ||
(!f->is_null() && f->cmp_offset(table->s->rec_buff_length)))
return 1;
}
return 0;
@ -18931,15 +18936,15 @@ static void free_blobs(Field **ptr)
static int
remove_duplicates(JOIN *join, TABLE *entry,List<Item> &fields, Item *having)
remove_duplicates(JOIN *join, TABLE *table, List<Item> &fields, Item *having)
{
int error;
ulong reclength,offset;
ulong keylength= 0;
uint field_count;
THD *thd= join->thd;
DBUG_ENTER("remove_duplicates");
entry->reginfo.lock_type=TL_WRITE;
table->reginfo.lock_type=TL_WRITE;
/* Calculate how many saved fields there is in list */
field_count=0;
@ -18956,24 +18961,21 @@ remove_duplicates(JOIN *join, TABLE *entry,List<Item> &fields, Item *having)
join->unit->select_limit_cnt= 1; // Only send first row
DBUG_RETURN(0);
}
Field **first_field=entry->field+entry->s->fields - field_count;
offset= (field_count ?
entry->field[entry->s->fields - field_count]->
offset(entry->record[0]) : 0);
reclength=entry->s->reclength-offset;
free_io_cache(entry); // Safety
entry->file->info(HA_STATUS_VARIABLE);
if (entry->s->db_type() == heap_hton ||
(!entry->s->blob_fields &&
((ALIGN_SIZE(reclength) + HASH_OVERHEAD) * entry->file->stats.records <
Field **first_field=table->field+table->s->fields - field_count;
for (Field **ptr=first_field; *ptr; ptr++)
keylength+= (*ptr)->sort_length() + (*ptr)->maybe_null();
free_io_cache(table); // Safety
table->file->info(HA_STATUS_VARIABLE);
if (table->s->db_type() == heap_hton ||
(!table->s->blob_fields &&
((ALIGN_SIZE(keylength) + HASH_OVERHEAD) * table->file->stats.records <
thd->variables.sortbuff_size)))
error=remove_dup_with_hash_index(join->thd, entry,
field_count, first_field,
reclength, having);
error=remove_dup_with_hash_index(join->thd, table, field_count, first_field,
keylength, having);
else
error=remove_dup_with_compare(join->thd, entry, first_field, offset,
having);
error=remove_dup_with_compare(join->thd, table, first_field, having);
free_blobs(first_field);
DBUG_RETURN(error);
@ -18981,18 +18983,13 @@ remove_duplicates(JOIN *join, TABLE *entry,List<Item> &fields, Item *having)
static int remove_dup_with_compare(THD *thd, TABLE *table, Field **first_field,
ulong offset, Item *having)
Item *having)
{
handler *file=table->file;
char *org_record,*new_record;
uchar *record;
uchar *record=table->record[0];
int error;
ulong reclength= table->s->reclength-offset;
DBUG_ENTER("remove_dup_with_compare");
org_record=(char*) (record=table->record[0])+offset;
new_record=(char*) table->record[1]+offset;
if (file->ha_rnd_init_with_error(1))
DBUG_RETURN(1);
@ -19029,7 +19026,7 @@ static int remove_dup_with_compare(THD *thd, TABLE *table, Field **first_field,
error=0;
goto err;
}
memcpy(new_record,org_record,reclength);
store_record(table,record[1]);
/* Read through rest of file and mark duplicated rows deleted */
bool found=0;
@ -19088,8 +19085,9 @@ static int remove_dup_with_hash_index(THD *thd, TABLE *table,
int error;
handler *file= table->file;
ulong extra_length= ALIGN_SIZE(key_length)-key_length;
uint *field_lengths,*field_length;
uint *field_lengths, *field_length;
HASH hash;
Field **ptr;
DBUG_ENTER("remove_dup_with_hash_index");
if (!my_multi_malloc(MYF(MY_WME),
@ -19101,21 +19099,8 @@ static int remove_dup_with_hash_index(THD *thd, TABLE *table,
NullS))
DBUG_RETURN(1);
{
Field **ptr;
ulong total_length= 0;
for (ptr= first_field, field_length=field_lengths ; *ptr ; ptr++)
{
uint length= (*ptr)->sort_length();
(*field_length++)= length;
total_length+= length;
}
DBUG_PRINT("info",("field_count: %u key_length: %lu total_length: %lu",
field_count, key_length, total_length));
DBUG_ASSERT(total_length <= key_length);
key_length= total_length;
extra_length= ALIGN_SIZE(key_length)-key_length;
}
for (ptr= first_field, field_length=field_lengths ; *ptr ; ptr++)
(*field_length++)= (*ptr)->sort_length();
if (hash_init(&hash, &my_charset_bin, (uint) file->stats.records, 0,
key_length, (hash_get_key) 0, 0, 0))
@ -19155,13 +19140,13 @@ static int remove_dup_with_hash_index(THD *thd, TABLE *table,
/* copy fields to key buffer */
org_key_pos= key_pos;
field_length=field_lengths;
for (Field **ptr= first_field ; *ptr ; ptr++)
for (ptr= first_field ; *ptr ; ptr++)
{
(*ptr)->sort_string(key_pos,*field_length);
key_pos+= *field_length++;
(*ptr)->make_sort_key(key_pos, *field_length);
key_pos+= (*ptr)->maybe_null() + *field_length++;
}
/* Check if it exists before */
if (hash_search(&hash, org_key_pos, key_length))
if (my_hash_search(&hash, org_key_pos, key_length))
{
/* Duplicated found ; Remove the row */
if ((error= file->ha_delete_row(record)))