Skip to content

M
MariaDB
Commit b6a5d3e8 authored by Sergei Petrunia's avatar Sergei Petrunia
Browse files
Options

MDEV-9750: Quick memory exhaustion with 'extended_keys=on', Part #4 

Part #4:
- Fix comment
- Make tree pruning visible in the optimizer trace.
parent 00675d25
Show whitespace changes
Inline Side-by-side
Showing with 103 additions and 45 deletions
mysql-test/main/range.result
View file @ b6a5d3e8
......@@ -3193,8 +3193,8 @@ kp4 in (1,2,3,4,5,6,7,8,9,10)
;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index key1 key1 20 NULL 3 Using where; Using index
set @json= (select json_detailed(JSON_EXTRACT(trace, '$**.range_scan_alternatives'))
from information_schema.optimizer_trace);
set @trace= (select trace from information_schema.optimizer_trace);
set @json= json_detailed(json_extract(@trace, '$**.range_scan_alternatives'));
select left(@json, 500);
left(@json, 500)
[
......@@ -3216,6 +3216,41 @@ left(@json, 500)
"(9) <= (kp1) <= (9)",
"(10) <= (kp1) <= (10)"
set @json= json_detailed(json_extract(@trace, '$**.setup_range_conditions'));
select left(@json, 2500);
left(@json, 2500)
[
[
{
"enforce_sel_arg_weight_limit":
{
"index": "key1",
"old_weight": 110,
"new_weight": 10
}
},
{
"enforce_sel_arg_weight_limit":
{
"index": "key1",
"old_weight": 110,
"new_weight": 10
}
},
{
"enforce_sel_arg_weight_limit":
{
"index": "key1",
"old_weight": 110,
"new_weight": 10
}
}
]
]
## Repeat the above with a bit higher max_weight:
set @tmp9750_weight=@@optimizer_max_sel_arg_weight;
set optimizer_max_sel_arg_weight=120;
......
mysql-test/main/range.test
View file @ b6a5d3e8
......@@ -2161,10 +2161,13 @@ explain select * from t1 where
kp3 in (1,2,3,4,5,6,7,8,9,10) and
kp4 in (1,2,3,4,5,6,7,8,9,10)
;
set @json= (select json_detailed(JSON_EXTRACT(trace, '$**.range_scan_alternatives'))
from information_schema.optimizer_trace);
set @trace= (select trace from information_schema.optimizer_trace);
set @json= json_detailed(json_extract(@trace, '$**.range_scan_alternatives'));
select left(@json, 500);
set @json= json_detailed(json_extract(@trace, '$**.setup_range_conditions'));
select left(@json, 2500);
--echo ## Repeat the above with a bit higher max_weight:
set @tmp9750_weight=@@optimizer_max_sel_arg_weight;
set optimizer_max_sel_arg_weight=120;
......
sql/opt_range.cc
View file @ b6a5d3e8
......@@ -399,9 +399,9 @@ static SEL_ARG *key_or(RANGE_OPT_PARAM *param,
static SEL_ARG *key_and(RANGE_OPT_PARAM *param,
SEL_ARG *key1, SEL_ARG *key2,
uint clone_flag);
static SEL_ARG *key_or_with_limit(RANGE_OPT_PARAM *param,
static SEL_ARG *key_or_with_limit(RANGE_OPT_PARAM *param, uint keyno,
SEL_ARG *key1, SEL_ARG *key2);
static SEL_ARG *key_and_with_limit(RANGE_OPT_PARAM *param,
static SEL_ARG *key_and_with_limit(RANGE_OPT_PARAM *param, uint keyno,
SEL_ARG *key1, SEL_ARG *key2,
uint clone_flag);
static bool get_range(SEL_ARG **e1,SEL_ARG **e2,SEL_ARG *root1);
......@@ -415,7 +415,9 @@ static bool null_part_in_key(KEY_PART *key_part, const uchar *key,
uint length);
static bool is_key_scan_ror(PARAM *param, uint keynr, uint8 nparts);
static SEL_ARG *enforce_sel_arg_weight_limit(THD *thd, SEL_ARG *sel_arg);
static
SEL_ARG *enforce_sel_arg_weight_limit(RANGE_OPT_PARAM *param, uint keyno,
SEL_ARG *sel_arg);
#include "opt_range_mrr.cc"
......@@ -713,7 +715,8 @@ int SEL_IMERGE::or_sel_tree_with_checks(RANGE_OPT_PARAM *param,
SEL_ARG *key1= (*or_tree)->keys[key_no];
SEL_ARG *key2= tree->keys[key_no];
key2->incr_refs();
if ((result->keys[key_no]= key_or_with_limit(param, key1, key2)))
if ((result->keys[key_no]= key_or_with_limit(param, key_no, key1,
key2)))
{
result_keys.set_bit(key_no);
......@@ -5440,7 +5443,7 @@ TABLE_READ_PLAN *merge_same_index_scans(PARAM *param, SEL_IMERGE *imerge,
if ((*tree)->keys[key_idx])
(*tree)->keys[key_idx]->incr_refs();
if (((*changed_tree)->keys[key_idx]=
key_or_with_limit(param, key, (*tree)->keys[key_idx])))
key_or_with_limit(param, key_idx, key, (*tree)->keys[key_idx])))
(*changed_tree)->keys_map.set_bit(key_idx);
*tree= NULL;
removed_cnt++;
......@@ -9102,7 +9105,8 @@ int and_range_trees(RANGE_OPT_PARAM *param, SEL_TREE *tree1, SEL_TREE *tree2,
key2->incr_refs();
}
SEL_ARG *key;
if ((result->keys[key_no]= key =key_and_with_limit(param, key1, key2, flag)))
if ((result->keys[key_no]= key= key_and_with_limit(param, key_no,
key1, key2, flag)))
{
if (key && key->type == SEL_ARG::IMPOSSIBLE)
{
......@@ -9645,7 +9649,7 @@ tree_or(RANGE_OPT_PARAM *param,SEL_TREE *tree1,SEL_TREE *tree2)
key1->incr_refs();
key2->incr_refs();
}
if ((result->keys[key_no]= key_or_with_limit(param, key1, key2)))
if ((result->keys[key_no]= key_or_with_limit(param, key_no, key1, key2)))
result->keys_map.set_bit(key_no);
}
result->type= tree1->type;
......@@ -9968,11 +9972,12 @@ uint SEL_ARG::verify_weight()
}
#endif
static SEL_ARG *key_or_with_limit(RANGE_OPT_PARAM *param,
static
SEL_ARG *key_or_with_limit(RANGE_OPT_PARAM *param, uint keyno,
SEL_ARG *key1, SEL_ARG *key2)
{
SEL_ARG *res= enforce_sel_arg_weight_limit(param->thd, key_or(param,
key1, key2));
SEL_ARG *res= key_or(param, key1, key2);
res= enforce_sel_arg_weight_limit(param, keyno, res);
#ifndef DBUG_OFF
if (res)
res->verify_weight();
......@@ -9981,13 +9986,12 @@ static SEL_ARG *key_or_with_limit(RANGE_OPT_PARAM *param,
}
static SEL_ARG *key_and_with_limit(RANGE_OPT_PARAM *param,
SEL_ARG *key1, SEL_ARG *key2,
uint clone_flag)
static
SEL_ARG *key_and_with_limit(RANGE_OPT_PARAM *param, uint keyno,
SEL_ARG *key1, SEL_ARG *key2, uint clone_flag)
{
SEL_ARG *res= enforce_sel_arg_weight_limit(param->thd, key_and(param, key1,
key2,
clone_flag));
SEL_ARG *res= key_and(param, key1, key2, clone_flag);
res= enforce_sel_arg_weight_limit(param, keyno, res);
#ifndef DBUG_OFF
if (res)
res->verify_weight();
......@@ -10773,33 +10777,42 @@ void prune_sel_arg_graph(SEL_ARG *sel_arg, uint max_part)
limit.
*/
SEL_ARG *enforce_sel_arg_weight_limit(THD *thd, SEL_ARG *sel_arg)
SEL_ARG *enforce_sel_arg_weight_limit(RANGE_OPT_PARAM *param, uint keyno,
SEL_ARG *sel_arg)
{
if (!sel_arg || sel_arg->type != SEL_ARG::KEY_RANGE ||
!thd->variables.optimizer_max_sel_arg_weight)
!param->thd->variables.optimizer_max_sel_arg_weight)
return sel_arg;
uint weight1= sel_arg->weight;
while (1)
{
if (sel_arg->weight <= thd->variables.optimizer_max_sel_arg_weight)
return sel_arg;
if (sel_arg->weight <= param->thd->variables.optimizer_max_sel_arg_weight)
break;
uint max_part= sel_arg->get_max_key_part();
if (max_part == sel_arg->part)
return NULL;
#ifdef EXTRA_DEBUG
uint weight1= sel_arg->weight;
#endif
{
sel_arg= NULL;
break;
}
max_part--;
prune_sel_arg_graph(sel_arg, max_part);
}
#ifdef EXTRA_DEBUG
DBUG_PRINT("info", ("enforce_sel_arg_weight_limit: %d->%d", weight1,
sel_arg->weight));
#endif
uint weight2= sel_arg? sel_arg->weight : 0;
if (weight2 != weight1)
{
Json_writer_object wrapper(param->thd);
Json_writer_object obj(param->thd, "enforce_sel_arg_weight_limit");
obj.add("index", param->table->key_info[param->real_keynr[keyno]].name);
obj.add("old_weight", (longlong)weight1);
obj.add("new_weight", (longlong)weight2);
}
return sel_arg;
}
......
sql/opt_range.h
View file @ b6a5d3e8
......@@ -228,36 +228,43 @@ class RANGE_OPT_PARAM;
A SEL_ARG graph has a property we call weight, and we define it as follows:
<definition>
If the SEL_ARG graph does not have any node with multiple incoming
next_key_part edges, then its weight is the number of SEL_ARG objects used.
If there is a node with multiple next_key_part edges, clone the node (and
the nodes connected via prev/next links to it) and redirect one of the
incoming next_key_part to the clone. (If the node has "peer" nodes
connected to it via prev/next links, they will have to be cloned as well)
If there is a node with multiple incoming next_key_part edges, clone that
node, (and the nodes connected to it via prev/next links) and redirect one
of the incoming next_key_part edges to the clone.
Repeat this until we get a graph without multiple next_key_part edges
coming into the same node. Then, the number of SEL_ARG objects in the
graph is the weight.
Continue with cloning until we get a graph that has no nodes with multiple
incoming next_key_part edges. Then, the number of SEL_ARG objects in the
graph is the weight of the original graph.
</definition>
Example:
kp1 $ kp2 $ kp3
$ $
| +-------+ $ $
\->| kp1=2 |--$--------------$-+
+-------+ $ $ | +--------+
| $ $ ==>| kp3=11 |
+-------+ $ $ | +--------+
| kp1=3 |--$--------------$-+ |
| kp1>3 |--$--------------$-+ |
+-------+ $ $ +--------+
$ $ | kp3=14 |
$ $ +--------+
$ $ |
$ $ +--------+
$ $ | kp3=14 |
$ $ +--------+
Here, the weight is 2 + 2*2=6.
Here, the weight is 2 + 2*3=8.
The rationale behind the weight is:
The rationale behind using this definition of weight is:
- it has the same order-of-magnitude as the number of ranges that the
SEL_ARG graph is describing,
- it is a lot easier to compute,
- it is a lot easier to compute than computing the number of ranges,
- it can be updated incrementally when performing AND/OR operations on
parts of the graph.
*/
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7