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MDEV-29954 Unique hash key on column prefix is computed incorrectly

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use the original, not the truncated, field in the long unique prefix,
that is, in the hash(left(field, length)) expression.

because MyISAM CHECK/REPAIR in compute_vcols() moves table->field
but not prefix fields from keyparts.

Also, implement Field_string::cmp_prefix() for prefix comparison
of CHAR columns to work.
This commit is contained in:
Sergei Golubchik 2024-01-22 18:02:11 +01:00
parent 14d00fdb15
commit a7ee3bc58b
6 changed files with 35 additions and 4 deletions
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9
mysql-test/main/long_unique_bugs.result
View File

@ -651,5 +651,14 @@ f1 f2 f3 f4 f5 f6 f7
4 00004 0001009089999 netstes psit e
drop table t1;
#
# MDEV-29954 Unique hash key on column prefix is computed incorrectly
#
create table t1 (c char(10),unique key a using hash (c(1)));
insert into t1 values (0);
check table t1 extended;
Table Op Msg_type Msg_text
test.t1 check status OK
drop table t1;
#
# End of 10.5 tests
#

8
mysql-test/main/long_unique_bugs.test
View File

@ -634,6 +634,14 @@ replace t1 (f2, f3, f4, f5, f6, f7) values ('00004', '0001009089999', '', 'netst
select * from t1;
drop table t1;
--echo #
--echo # MDEV-29954 Unique hash key on column prefix is computed incorrectly
--echo #
create table t1 (c char(10),unique key a using hash (c(1)));
insert into t1 values (0);
check table t1 extended;
drop table t1;
--echo #
--echo # End of 10.5 tests
--echo #

13
sql/field.cc
View File

@ -7566,6 +7566,19 @@ int Field_string::cmp(const uchar *a_ptr, const uchar *b_ptr) const
}
int Field_string::cmp_prefix(const uchar *a_ptr, const uchar *b_ptr,
size_t prefix_char_len) const
{
size_t field_len= table->field[field_index]->field_length;
return field_charset()->coll->strnncollsp_nchars(field_charset(),
a_ptr, field_len,
b_ptr, field_len,
prefix_char_len,
0);
}
void Field_string::sort_string(uchar *to,uint length)
{
#ifdef DBUG_ASSERT_EXISTS

2
sql/field.h
View File

@ -4038,6 +4038,8 @@ public:
String *val_str(String *, String *) override;
my_decimal *val_decimal(my_decimal *) override;
int cmp(const uchar *,const uchar *) const override;
int cmp_prefix(const uchar *a, const uchar *b, size_t prefix_char_len) const
override;
void sort_string(uchar *buff,uint length) override;
void update_data_type_statistics(Data_type_statistics *st) const override
{

2
sql/key.cc
View File

@ -605,7 +605,7 @@ int key_rec_cmp(void *key_p, uchar *first_rec, uchar *second_rec)
}
/*
No null values in the fields
We use the virtual method cmp_max with a max length parameter.
We use the virtual method cmp_prefix with a max length parameter.
For most field types this translates into a cmp without
max length. The exceptions are the BLOB and VARCHAR field types
that take the max length into account.

5
sql/table.cc
View File

@ -1272,12 +1272,11 @@ bool parse_vcol_defs(THD *thd, MEM_ROOT *mem_root, TABLE *table,
if (keypart->key_part_flag & HA_PART_KEY_SEG)
{
int length= keypart->length/keypart->field->charset()->mbmaxlen;
Field *kpf= table->field[keypart->field->field_index];
list_item= new (mem_root) Item_func_left(thd,
new (mem_root) Item_field(thd, keypart->field),
new (mem_root) Item_field(thd, kpf),
new (mem_root) Item_int(thd, length));
list_item->fix_fields(thd, NULL);
keypart->field->vcol_info=
table->field[keypart->field->field_index]->vcol_info;
}
else
list_item= new (mem_root) Item_field(thd, keypart->field);