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MDEV-15579 Crash in Item_field::used_tables() called by

Browse Source 
Item::derived_field_transformer_for_having

The crash occurred due to an inappropriate handling of multiple equalities
when pushing conditions into materialized views/derived tables. If equalities
extracted from a multiple equality can be pushed into a materialized
view/derived table they should be plainly conjuncted with other pushed
predicates rather than form a separate AND sub-formula.
This commit is contained in:
Galina Shalygina
2018-03-25 22:12:38 +02:00
parent 27c24808f7
commit 6223f1dd98
3 changed files with 211 additions and 0 deletions
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159
mysql-test/r/derived_cond_pushdown.result
View File

@ -8871,3 +8871,162 @@ EXPLAIN
}
DROP TABLE t1,t2;
SET sql_mode = DEFAULT;
#
# MDEV-15579: incorrect removal of sub-formulas to be pushed
# into WHERE of materialized derived with GROUP BY
#
CREATE TABLE t1 (a INT, b INT, c INT, d INT);
CREATE TABLE t2 (x INT, y INT, z INT);
INSERT INTO t1 VALUES (1,1,66,1), (1,1,56,2), (3,2,42,3);
INSERT INTO t2 VALUES (1,1,66), (1,12,32);
SELECT *
FROM t2,
(
SELECT a, b, max(c) AS max_c
FROM t1
GROUP BY a
HAVING max_c > 37
) AS v1
WHERE (v1.a=1) AND (v1.b=v1.a) AND
(v1.a=t2.x) AND (v1.max_c>30);
x y z a b max_c
1 1 66 1 1 66
1 12 32 1 1 66
EXPLAIN SELECT *
FROM t2,
(
SELECT a, b, max(c) AS max_c
FROM t1
GROUP BY a
HAVING max_c > 37
) AS v1
WHERE (v1.a=1) AND (v1.b=v1.a) AND
(v1.a=t2.x) AND (v1.max_c>30);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join)
2 DERIVED t1 ALL NULL NULL NULL NULL 3 Using where
EXPLAIN FORMAT=JSON SELECT *
FROM t2,
(
SELECT a, b, max(c) AS max_c
FROM t1
GROUP BY a
HAVING max_c > 37
) AS v1
WHERE (v1.a=1) AND (v1.b=v1.a) AND
(v1.a=t2.x) AND (v1.max_c>30);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 2,
"filtered": 100,
"attached_condition": "t2.x = 1"
},
"block-nl-join": {
"table": {
"table_name": "<derived2>",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "v1.a = 1 and v1.b = 1 and v1.max_c > 30"
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BNL",
"materialized": {
"query_block": {
"select_id": 2,
"having_condition": "max_c > 37 and max_c > 30 and t1.b = 1",
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "t1.a = 1"
}
}
}
}
}
}
SELECT *
FROM t2,
(
SELECT a, b, d, max(c) AS max_c
FROM t1
GROUP BY a,d
HAVING max_c > 37
) AS v1
WHERE (v1.a=1) AND (v1.b=v1.a) AND (v1.b=v1.d) AND
(v1.a=t2.x) AND (v1.max_c>30);
x y z a b d max_c
1 1 66 1 1 1 66
1 12 32 1 1 1 66
EXPLAIN SELECT *
FROM t2,
(
SELECT a, b, d, max(c) AS max_c
FROM t1
GROUP BY a,d
HAVING max_c > 37
) AS v1
WHERE (v1.a=1) AND (v1.b=v1.a) AND (v1.b=v1.d) AND
(v1.a=t2.x) AND (v1.max_c>30);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join)
2 DERIVED t1 ALL NULL NULL NULL NULL 3 Using where
EXPLAIN FORMAT=JSON SELECT *
FROM t2,
(
SELECT a, b, d, max(c) AS max_c
FROM t1
GROUP BY a,d
HAVING max_c > 37
) AS v1
WHERE (v1.a=1) AND (v1.b=v1.a) AND (v1.b=v1.d) AND
(v1.a=t2.x) AND (v1.max_c>30);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 2,
"filtered": 100,
"attached_condition": "t2.x = 1"
},
"block-nl-join": {
"table": {
"table_name": "<derived2>",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "v1.a = 1 and v1.b = 1 and v1.d = 1 and v1.max_c > 30"
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BNL",
"materialized": {
"query_block": {
"select_id": 2,
"having_condition": "max_c > 37 and max_c > 30 and t1.b = 1",
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "t1.a = 1 and t1.d = 1"
}
}
}
}
}
}
DROP TABLE t1,t2;

43
mysql-test/t/derived_cond_pushdown.test
View File

@ -1590,3 +1590,46 @@ eval EXPLAIN FORMAT=JSON $q;
DROP TABLE t1,t2;
SET sql_mode = DEFAULT;
--echo #
--echo # MDEV-15579: incorrect removal of sub-formulas to be pushed
--echo # into WHERE of materialized derived with GROUP BY
--echo #
CREATE TABLE t1 (a INT, b INT, c INT, d INT);
CREATE TABLE t2 (x INT, y INT, z INT);
INSERT INTO t1 VALUES (1,1,66,1), (1,1,56,2), (3,2,42,3);
INSERT INTO t2 VALUES (1,1,66), (1,12,32);
LET $query=
SELECT *
FROM t2,
(
SELECT a, b, max(c) AS max_c
FROM t1
GROUP BY a
HAVING max_c > 37
) AS v1
WHERE (v1.a=1) AND (v1.b=v1.a) AND
(v1.a=t2.x) AND (v1.max_c>30);
EVAL $query;
EVAL EXPLAIN $query;
EVAL EXPLAIN FORMAT=JSON $query;
LET $query=
SELECT *
FROM t2,
(
SELECT a, b, d, max(c) AS max_c
FROM t1
GROUP BY a,d
HAVING max_c > 37
) AS v1
WHERE (v1.a=1) AND (v1.b=v1.a) AND (v1.b=v1.d) AND
(v1.a=t2.x) AND (v1.max_c>30);
EVAL $query;
EVAL EXPLAIN $query;
EVAL EXPLAIN FORMAT=JSON $query;
DROP TABLE t1,t2;

9
sql/table.cc
View File

@ -8207,6 +8207,7 @@ Item* TABLE_LIST::build_pushable_cond_for_table(THD *thd, Item *cond)
return 0;
List_iterator<Item> li(*((Item_cond*) cond)->argument_list());
Item *item;
bool is_fix_needed= false;
while ((item=li++))
{
if (item->get_extraction_flag() == NO_EXTRACTION_FL)
@ -8220,8 +8221,16 @@ Item* TABLE_LIST::build_pushable_cond_for_table(THD *thd, Item *cond)
return 0;
if (!fix)
continue;
if (fix->type() == Item::COND_ITEM &&
((Item_cond*) fix)->functype() == Item_func::COND_AND_FUNC)
is_fix_needed= true;
new_cond->argument_list()->push_back(fix, thd->mem_root);
}
if (is_fix_needed)
new_cond->fix_fields(thd, 0);
switch (new_cond->argument_list()->elements)
{
case 0: