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MDEV-32012 hash unique corrupts index on virtual blobs

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as always when copying record[0] aside one needs to detach
Field_blob::value's from it, and restore them when record[0]
is restored from a backup.
This commit is contained in:
Sergei Golubchik 2023-08-25 14:01:43 +02:00
parent 4d96dba767
commit 382c543f53
3 changed files with 59 additions and 0 deletions
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24
mysql-test/main/long_unique_bugs.result
View file

@ -454,5 +454,29 @@ create table t1 (f text not null, unique (f));
insert into t1 (f) select 'f';
drop table t1;
#
# MDEV-32012 hash unique corrupts index on virtual blobs
#
create table t1 (
f1 varchar(25),
v1 mediumtext generated always as (concat('f1:', f1)) virtual,
unique key (f1) using hash,
key (v1(1000))
);
flush status;
insert ignore t1 (f1) values (9599),(94410);
show status like 'handler_read_next';
Variable_name Value
Handler_read_next 1
# the above MUST BE =1
check table t1 extended;
Table Op Msg_type Msg_text
test.t1 check status OK
update t1 set f1=100 where f1=9599;
update t1 set f1=9599 where f1=100;
check table t1 extended;
Table Op Msg_type Msg_text
test.t1 check status OK
drop table t1;
#
# End of 10.4 tests
#

24
mysql-test/main/long_unique_bugs.test
View file

@ -455,6 +455,30 @@ create table t1 (f text not null, unique (f));
insert into t1 (f) select 'f';
drop table t1;
--echo #
--echo # MDEV-32012 hash unique corrupts index on virtual blobs
--echo #
create table t1 (
f1 varchar(25),
v1 mediumtext generated always as (concat('f1:', f1)) virtual,
unique key (f1) using hash,
key (v1(1000))
);
flush status;
insert ignore t1 (f1) values (9599),(94410);
# handler_read_next must be 1 below, meaning there was a hash collision above.
# if a change in the hash function causes these values not to collide anymore,
# the test must be adjusted to use some other values that collide.
# to find a collision add an assert into check_duplicate_long_entry_key()
# and run, like, insert...select * seq_from_1_to_1000000000
show status like 'handler_read_next';
--echo # the above MUST BE =1
check table t1 extended;
update t1 set f1=100 where f1=9599;
update t1 set f1=9599 where f1=100;
check table t1 extended;
drop table t1;
--echo #
--echo # End of 10.4 tests
--echo #

11
sql/handler.cc
View file

@ -6658,6 +6658,7 @@ static int check_duplicate_long_entry_key(TABLE *table, handler *h,
KEY *key_info= table->key_info + key_no;
hash_field= key_info->key_part->field;
uchar ptr[HA_HASH_KEY_LENGTH_WITH_NULL];
String *blob_storage;
DBUG_ASSERT((key_info->flags & HA_NULL_PART_KEY &&
key_info->key_length == HA_HASH_KEY_LENGTH_WITH_NULL)
@ -6675,6 +6676,8 @@ static int check_duplicate_long_entry_key(TABLE *table, handler *h,
result= h->ha_index_init(key_no, 0);
if (result)
return result;
blob_storage= (String*)alloca(sizeof(String)*table->s->virtual_not_stored_blob_fields);
table->remember_blob_values(blob_storage);
store_record(table, check_unique_buf);
result= h->ha_index_read_map(table->record[0],
ptr, HA_WHOLE_KEY, HA_READ_KEY_EXACT);
@ -6685,6 +6688,13 @@ static int check_duplicate_long_entry_key(TABLE *table, handler *h,
Item_func_hash * temp= (Item_func_hash *)hash_field->vcol_info->expr;
Item ** arguments= temp->arguments();
uint arg_count= temp->argument_count();
// restore pointers after swap_values in TABLE::update_virtual_fields()
for (Field **vf= table->vfield; *vf; vf++)
{
if (!(*vf)->stored_in_db() && (*vf)->flags & BLOB_FLAG &&
bitmap_is_set(table->read_set, (*vf)->field_index))
((Field_blob*)*vf)->swap_value_and_read_value();
}
do
{
my_ptrdiff_t diff= table->check_unique_buf - new_rec;
@ -6731,6 +6741,7 @@ exit:
}
}
restore_record(table, check_unique_buf);
table->restore_blob_values(blob_storage);
h->ha_index_end();
return error;
}