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MDEV-37510: crash when tracing with max_sel_arg_weight equal to 1 #4505

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MDEV-37510: crash when tracing with max_sel_arg_weight equal to 1 #4505

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78 changes: 75 additions & 3 deletions mysql-test/main/range_notembedded.result
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Original file line number Diff line number Diff line change
Expand Up @@ -124,7 +124,7 @@ left(@json, 2500)
"sel_arg_weight_heuristic":
{
"key1_field": "kp1",
"key2_field": "kp2",
"key2_type": 3,
"key1_weight": 10,
"key2_weight": 10
}
Expand All @@ -133,7 +133,7 @@ left(@json, 2500)
"sel_arg_weight_heuristic":
{
"key1_field": "kp1",
"key2_field": "kp3",
"key2_type": 3,
"key1_weight": 10,
"key2_weight": 10
}
Expand All @@ -142,7 +142,7 @@ left(@json, 2500)
"sel_arg_weight_heuristic":
{
"key1_field": "kp1",
"key2_field": "kp4",
"key2_type": 3,
"key1_weight": 10,
"key2_weight": 10
}
Expand Down Expand Up @@ -308,3 +308,75 @@ json_pretty(json_search(@trace, 'all', 'key1'))
"$[0].analyzing_range_alternatives.range_scan_alternatives[0].index"
]
drop table t1;
#
# MDEV-37510: Crash in sel_arg_and_weight_heuristic
#
SET @save_optimizer_trace=@@optimizer_trace;
SET @save_optimizer_max_sel_arg_weight=@@optimizer_max_sel_arg_weight;
SET optimizer_trace= 'enabled=on';
SET optimizer_max_sel_arg_weight=1;
CREATE TABLE t1 (c1 INT, c2 VARCHAR(10), c3 VARCHAR(10));
CREATE TABLE t2 (c1 INT, c2 VARCHAR(10), c3 VARCHAR(10));
INSERT INTO t1 values (2, 'two', 'prime'), (3, 'three', 'prime');
INSERT INTO t2 values (2, 'two', '2_table'), (4, 'four', '2_table');
EXPLAIN
SELECT t1.c1, v1.c2
FROM
(
t1
JOIN
(
SELECT c1, c2, c3 FROM t2
UNION SELECT c1, c2, c3 FROM t2
) v1
ON (
(t1.c1 = v1.c1 OR v1.c1 IS NULL) AND
(t1.c2 = v1.c2 OR v1.c3 IS NULL) AND
v1.c3 IN ('2_table', '3_table')
)
)
WHERE t1.c1 NOT IN (5, 6, 7);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where
1 PRIMARY <derived2> ALL distinct_key NULL NULL NULL 4 Using where; Using join buffer (flat, BNL join)
2 DERIVED t2 ALL NULL NULL NULL NULL 2 Using where
3 UNION t2 ALL NULL NULL NULL NULL 2 Using where
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
set @trace= (select trace from information_schema.optimizer_trace);
set @json= json_detailed(json_extract(@trace, '$**.setup_range_conditions'));
select left(@json, 2500);
left(@json, 2500)
[
[
{
"sel_arg_weight_heuristic":
{
"key1_type": 2,
"key2_type": 2,
"key1_weight": 1,
"key2_weight": 1
}
},
{
"sel_arg_weight_heuristic":
{
"key1_type": 2,
"key2_type": 3,
"key1_weight": 1,
"key2_weight": 1
}
},
{
"enforce_sel_arg_weight_limit":
{
"index": "distinct_key",
"old_weight": 2,
"new_weight": 0
}
}
]
]
DROP TABLE t1, t2;
SET optimizer_trace=@save_optimizer_trace;
SET optimizer_max_sel_arg_weight=@save_optimizer_max_sel_arg_weight;
# end of 11.4 tests
42 changes: 42 additions & 0 deletions mysql-test/main/range_notembedded.test
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Expand Up @@ -211,3 +211,45 @@ set @trace=json_extract((select trace from information_schema.optimizer_trace),
select json_pretty(json_search(@trace, 'all', 'key1'));
drop table t1;

--echo #
--echo # MDEV-37510: Crash in sel_arg_and_weight_heuristic
--echo #
SET @save_optimizer_trace=@@optimizer_trace;
SET @save_optimizer_max_sel_arg_weight=@@optimizer_max_sel_arg_weight;

SET optimizer_trace= 'enabled=on';
SET optimizer_max_sel_arg_weight=1;

CREATE TABLE t1 (c1 INT, c2 VARCHAR(10), c3 VARCHAR(10));
CREATE TABLE t2 (c1 INT, c2 VARCHAR(10), c3 VARCHAR(10));

INSERT INTO t1 values (2, 'two', 'prime'), (3, 'three', 'prime');
INSERT INTO t2 values (2, 'two', '2_table'), (4, 'four', '2_table');

EXPLAIN
SELECT t1.c1, v1.c2
FROM
(
t1
JOIN
(
SELECT c1, c2, c3 FROM t2
UNION SELECT c1, c2, c3 FROM t2
) v1
ON (
(t1.c1 = v1.c1 OR v1.c1 IS NULL) AND
(t1.c2 = v1.c2 OR v1.c3 IS NULL) AND
v1.c3 IN ('2_table', '3_table')
)
)
WHERE t1.c1 NOT IN (5, 6, 7);

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@spetrunia spetrunia Jan 7, 2026

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I don't believe this is the minimal testcase.

Please try to reduce it as much as possible.

Tables need to have two records to avoid the "1-row table is const table" code path.

when one sees

CREATE TABLE t2 (c1 INT, c2 VARCHAR(10), c3 VARCHAR(10) DEFAULT NULL);

one wonders what is DEFAULT NULL there for? It's not needed in any case, please remove it.

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@bsrikanth-mariadb bsrikanth-mariadb Jan 8, 2026

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sure

set @trace= (select trace from information_schema.optimizer_trace);
set @json= json_detailed(json_extract(@trace, '$**.setup_range_conditions'));
select left(@json, 2500);

DROP TABLE t1, t2;

SET optimizer_trace=@save_optimizer_trace;
SET optimizer_max_sel_arg_weight=@save_optimizer_max_sel_arg_weight;
--echo # end of 11.4 tests
14 changes: 9 additions & 5 deletions sql/opt_range.cc
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Expand Up @@ -11523,11 +11523,15 @@ bool sel_arg_and_weight_heuristic(RANGE_OPT_PARAM *param, SEL_ARG *key1,
{
Json_writer_object wrapper(param->thd);
Json_writer_object obj(param->thd, "sel_arg_weight_heuristic");
obj.
add("key1_field", key1->field->field_name).
add("key2_field", key2->field->field_name).
add("key1_weight", (longlong)key1->weight).
add("key2_weight", (longlong)key2->weight);

if (key1->type == SEL_ARG::KEY_RANGE)
obj.add("key1_field", key1->field->field_name);
else
obj.add("key1_type", (uint) key1->type);

obj.add("key2_type", (uint) key2->type);
obj.add("key1_weight", (longlong) key1->weight);
obj.add("key2_weight", (longlong) key2->weight);
}
return true; // Discard key2
}
Expand Down