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MDEV-8779: mysqld got signal 11 in sql/opt_range_mrr.cc:100(step_down…
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…_to)

The crash was caused by range optimizer using RANGE_OPT_PARAM::min_key
(and max_key) to store keys. Buffer size was a good upper bound for
range analysis and partition pruning, but not for EITS selectivity
calculations.

Fixed by making these buffers variable-size. The sizes are calculated
from [pseudo]indexes used for range analysis.
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@spetrunia
spetrunia committed Sep 21, 2015
1 parent 139ce6c commit 9b9e36e
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Showing 4 changed files with 73 additions and 4 deletions.
17 changes: 17 additions & 0 deletions mysql-test/r/selectivity_no_engine.result
View file
Expand Up @@ -276,6 +276,23 @@ id select_type table type possible_keys key key_len ref rows filtered Extra
Warnings:
Note 1003 select `test`.`ta`.`a` AS `a`,`test`.`tb`.`a` AS `a` from `test`.`t1` `ta` join `test`.`t2` `tb` where ((`test`.`tb`.`a` = `test`.`ta`.`a`) and (`test`.`ta`.`a` < 40) and (`test`.`ta`.`a` < 100))
drop table t0,t1,t2;
#
# MDEV-8779: mysqld got signal 11 in sql/opt_range_mrr.cc:100(step_down_to)
#
set @tmp_mdev8779=@@optimizer_use_condition_selectivity;
set optimizer_use_condition_selectivity=5;
CREATE TABLE t1 (
i int(10) unsigned NOT NULL AUTO_INCREMENT,
n varchar(2048) NOT NULL,
d tinyint(1) unsigned NOT NULL,
p int(10) unsigned NOT NULL,
PRIMARY KEY (i)
) DEFAULT CHARSET=utf8;
insert into t1 values (1,'aaa',1,1), (2,'bbb',2,2);
SELECT * FROM t1 WHERE t1.d = 0 AND t1.p = '1' AND t1.i != '-1' AND t1.n = 'some text';
i n d p
set optimizer_use_condition_selectivity= @tmp_mdev8779;
DROP TABLE t1;
#
# End of the test file
#
Expand Down
17 changes: 17 additions & 0 deletions mysql-test/t/selectivity_no_engine.test
View file
Expand Up @@ -210,6 +210,23 @@ explain extended select * from t1 ta, t2 tb where ta.a < 40 and tb.a < 100 and t

drop table t0,t1,t2;

--echo #
--echo # MDEV-8779: mysqld got signal 11 in sql/opt_range_mrr.cc:100(step_down_to)
--echo #
set @tmp_mdev8779=@@optimizer_use_condition_selectivity;
set optimizer_use_condition_selectivity=5;
CREATE TABLE t1 (
i int(10) unsigned NOT NULL AUTO_INCREMENT,
n varchar(2048) NOT NULL,
d tinyint(1) unsigned NOT NULL,
p int(10) unsigned NOT NULL,
PRIMARY KEY (i)
) DEFAULT CHARSET=utf8;
insert into t1 values (1,'aaa',1,1), (2,'bbb',2,2);
SELECT * FROM t1 WHERE t1.d = 0 AND t1.p = '1' AND t1.i != '-1' AND t1.n = 'some text';
set optimizer_use_condition_selectivity= @tmp_mdev8779;
DROP TABLE t1;

--echo #
--echo # End of the test file
--echo #
Expand Down
39 changes: 37 additions & 2 deletions sql/opt_range.cc
View file
Expand Up @@ -2469,13 +2469,13 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
DBUG_RETURN(0); // Can't use range
}
key_parts= param.key_parts;
thd->mem_root= &alloc;

/*
Make an array with description of all key parts of all table keys.
This is used in get_mm_parts function.
*/
key_info= head->key_info;
uint max_key_len= 0;
for (idx=0 ; idx < head->s->keys ; idx++, key_info++)
{
KEY_PART_INFO *key_part_info;
Expand All @@ -2488,13 +2488,15 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,

param.key[param.keys]=key_parts;
key_part_info= key_info->key_part;
uint cur_key_len= 0;
for (uint part= 0 ; part < n_key_parts ;
part++, key_parts++, key_part_info++)
{
key_parts->key= param.keys;
key_parts->part= part;
key_parts->length= key_part_info->length;
key_parts->store_length= key_part_info->store_length;
cur_key_len += key_part_info->store_length;
key_parts->field= key_part_info->field;
key_parts->null_bit= key_part_info->null_bit;
key_parts->image_type =
Expand All @@ -2503,10 +2505,21 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
key_parts->flag= (uint8) key_part_info->key_part_flag;
}
param.real_keynr[param.keys++]=idx;
if (cur_key_len > max_key_len)
max_key_len= cur_key_len;
}
param.key_parts_end=key_parts;
param.alloced_sel_args= 0;

if (!(param.min_key= (uchar*)alloc_root(&alloc,max_key_len)) ||
!(param.max_key= (uchar*)alloc_root(&alloc,max_key_len)))
{
thd->no_errors=0;
free_root(&alloc,MYF(0)); // Return memory & allocator
DBUG_RETURN(0); // Can't use range
}

thd->mem_root= &alloc;
/* Calculate cost of full index read for the shortest covering index */
if (!force_quick_range && !head->covering_keys.is_clear_all())
{
Expand Down Expand Up @@ -2730,7 +2743,7 @@ bool create_key_parts_for_pseudo_indexes(RANGE_OPT_PARAM *param,
return TRUE;

param->key_parts= key_part;

uint max_key_len= 0;
for (field_ptr= table->field; *field_ptr; field_ptr++)
{
if (bitmap_is_set(used_fields, (*field_ptr)->field_index))
Expand All @@ -2745,6 +2758,8 @@ bool create_key_parts_for_pseudo_indexes(RANGE_OPT_PARAM *param,
store_length+= HA_KEY_NULL_LENGTH;
if (field->real_type() == MYSQL_TYPE_VARCHAR)
store_length+= HA_KEY_BLOB_LENGTH;
if (max_key_len < store_length)
max_key_len= store_length;
key_part->store_length= store_length;
key_part->field= field;
key_part->image_type= Field::itRAW;
Expand All @@ -2754,6 +2769,12 @@ bool create_key_parts_for_pseudo_indexes(RANGE_OPT_PARAM *param,
key_part++;
}
}

if (!(param->min_key= (uchar*)alloc_root(param->mem_root, max_key_len)) ||
!(param->max_key= (uchar*)alloc_root(param->mem_root, max_key_len)))
{
return true;
}
param->keys= keys;
param->key_parts_end= key_part;

Expand Down Expand Up @@ -4306,12 +4327,15 @@ static bool create_partition_index_description(PART_PRUNE_PARAM *ppar)
Field **field= (ppar->part_fields)? part_info->part_field_array :
part_info->subpart_field_array;
bool in_subpart_fields= FALSE;
uint max_key_len= 0;
uint cur_key_len;
for (uint part= 0; part < total_parts; part++, key_part++)
{
key_part->key= 0;
key_part->part= part;
key_part->length= (uint16)(*field)->key_length();
key_part->store_length= (uint16)get_partition_field_store_length(*field);
cur_key_len += key_part->store_length;

DBUG_PRINT("info", ("part %u length %u store_length %u", part,
key_part->length, key_part->store_length));
Expand All @@ -4337,10 +4361,21 @@ static bool create_partition_index_description(PART_PRUNE_PARAM *ppar)
{
field= part_info->subpart_field_array;
in_subpart_fields= TRUE;
max_key_len= cur_key_len;
cur_key_len= 0;
}
}
range_par->key_parts_end= key_part;

if (cur_key_len > max_key_len)
max_key_len= cur_key_len;

if (!(range_par->min_key= (uchar*)alloc_root(alloc,max_key_len)) ||
!(range_par->max_key= (uchar*)alloc_root(alloc,max_key_len)))
{
return true;
}

DBUG_EXECUTE("info", print_partitioning_index(range_par->key_parts,
range_par->key_parts_end););
return FALSE;
Expand Down
4 changes: 2 additions & 2 deletions sql/opt_range.h
View file
Expand Up @@ -643,8 +643,8 @@ class RANGE_OPT_PARAM
Used to store 'current key tuples', in both range analysis and
partitioning (list) analysis
*/
uchar min_key[MAX_KEY_LENGTH+MAX_FIELD_WIDTH],
max_key[MAX_KEY_LENGTH+MAX_FIELD_WIDTH];
uchar *min_key;
uchar *max_key;

/* Number of SEL_ARG objects allocated by SEL_ARG::clone_tree operations */
uint alloced_sel_args;
Expand Down

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