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Commit 0de3c423 authored by Galina Shalygina's avatar Galina Shalygina
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MDEV-16765: Missing rows with pushdown condition defined with CASE using Item_cond 

The bug appears because of the wrong pushdown into the WHERE clause of the
materialized derived table/view work. For the excl_dep_on_grouping_fields()
method that checks if the condition can be pushed into the WHERE clause
the case when Item_cond is used is missing. For Item_cond elements this
method always returns positive result (that condition can be pushed).
So this condition is pushed even if is shouldn't be pushed.

To fix it new Item_cond::excl_dep_on_grouping_fields() method is added.
parent 862a9774
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mysql-test/r/derived_cond_pushdown.result
View file @ 0de3c423
......@@ -10017,3 +10017,206 @@ a
7
4
DROP TABLE t1,t2,t3;
#
# MDEV-16765: pushdown condition with the CASE structure
# defined with Item_cond item
#
CREATE TABLE t1(a INT, b INT);
INSERT INTO t1 VALUES (1,2), (3,4), (2,3);
SELECT *
FROM
(
SELECT CASE WHEN ((tab2.max_a=1) OR (tab2.max_a=2))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
max_a b
1 2
1 3
EXPLAIN FORMAT=JSON SELECT *
FROM
(
SELECT CASE WHEN ((tab2.max_a=1) OR (tab2.max_a=2))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "<derived3>",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "case when (tab2.max_a = 1 or tab2.max_a = 2) then 1 else 0 end = 1",
"materialized": {
"query_block": {
"select_id": 3,
"having_condition": "case when (max_a = 1 or max_a = 2) then 1 else 0 end = 1",
"filesort": {
"sort_key": "t1.b",
"temporary_table": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 3,
"filtered": 100
}
}
}
}
}
}
}
}
SELECT *
FROM
(
SELECT CASE WHEN ((tab2.max_a=1) OR ((tab2.max_a>2) AND (tab2.max_a<4)))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
max_a b
1 2
1 4
EXPLAIN FORMAT=JSON SELECT *
FROM
(
SELECT CASE WHEN ((tab2.max_a=1) OR ((tab2.max_a>2) AND (tab2.max_a<4)))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "<derived3>",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "case when (tab2.max_a = 1 or tab2.max_a > 2 and tab2.max_a < 4) then 1 else 0 end = 1",
"materialized": {
"query_block": {
"select_id": 3,
"having_condition": "case when (max_a = 1 or max_a > 2 and max_a < 4) then 1 else 0 end = 1",
"filesort": {
"sort_key": "t1.b",
"temporary_table": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 3,
"filtered": 100
}
}
}
}
}
}
}
}
SELECT *
FROM
(
SELECT CASE WHEN ((tab2.max_a>1) AND ((tab2.max_a=2) OR (tab2.max_a>2)))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
max_a b
1 3
1 4
EXPLAIN FORMAT=JSON SELECT *
FROM
(
SELECT CASE WHEN ((tab2.max_a>1) AND ((tab2.max_a=2) OR (tab2.max_a>2)))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "<derived3>",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "case when (tab2.max_a > 1 and (tab2.max_a = 2 or tab2.max_a > 2)) then 1 else 0 end = 1",
"materialized": {
"query_block": {
"select_id": 3,
"having_condition": "case when (max_a > 1 and (max_a = 2 or max_a > 2)) then 1 else 0 end = 1",
"filesort": {
"sort_key": "t1.b",
"temporary_table": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 3,
"filtered": 100
}
}
}
}
}
}
}
}
SELECT *
FROM
(
SELECT CASE WHEN ((tab2.b=2) OR (tab2.b=4))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
max_a b
1 2
1 4
EXPLAIN FORMAT=JSON SELECT *
FROM
(
SELECT CASE WHEN ((tab2.b=2) OR (tab2.b=4))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "<derived3>",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "case when (tab2.b = 2 or tab2.b = 4) then 1 else 0 end = 1",
"materialized": {
"query_block": {
"select_id": 3,
"filesort": {
"sort_key": "t1.b",
"temporary_table": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 3,
"filtered": 100,
"attached_condition": "case when (t1.b = 2 or t1.b = 4) then 1 else 0 end = 1"
}
}
}
}
}
}
}
}
DROP TABLE t1;
mysql-test/t/derived_cond_pushdown.test
View file @ 0de3c423
......@@ -1964,3 +1964,61 @@ eval $q3;
SELECT * FROM t2;
DROP TABLE t1,t2,t3;
--echo #
--echo # MDEV-16765: pushdown condition with the CASE structure
--echo # defined with Item_cond item
--echo #
CREATE TABLE t1(a INT, b INT);
INSERT INTO t1 VALUES (1,2), (3,4), (2,3);
LET $query=
SELECT *
FROM
(
SELECT CASE WHEN ((tab2.max_a=1) OR (tab2.max_a=2))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
EVAL $query;
EVAL EXPLAIN FORMAT=JSON $query;
LET $query=
SELECT *
FROM
(
SELECT CASE WHEN ((tab2.max_a=1) OR ((tab2.max_a>2) AND (tab2.max_a<4)))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
EVAL $query;
EVAL EXPLAIN FORMAT=JSON $query;
LET $query=
SELECT *
FROM
(
SELECT CASE WHEN ((tab2.max_a>1) AND ((tab2.max_a=2) OR (tab2.max_a>2)))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
EVAL $query;
EVAL EXPLAIN FORMAT=JSON $query;
LET $query=
SELECT *
FROM
(
SELECT CASE WHEN ((tab2.b=2) OR (tab2.b=4))
THEN 1 ELSE 0 END AS max_a,b
FROM (SELECT MAX(a) as max_a,b FROM t1 GROUP BY t1.b) AS tab2
) AS tab1
WHERE (tab1.max_a=1);
EVAL $query;
EVAL EXPLAIN FORMAT=JSON $query;
DROP TABLE t1;
sql/item_cmpfunc.cc
View file @ 0de3c423
......@@ -4970,6 +4970,19 @@ Item *Item_cond::build_clone(THD *thd, MEM_ROOT *mem_root)
}
bool Item_cond::excl_dep_on_grouping_fields(st_select_lex *sel)
{
List_iterator_fast<Item> li(list);
Item *item;
while ((item= li++))
{
if (!item->excl_dep_on_grouping_fields(sel))
return false;
}
return true;
}
void Item_cond_and::mark_as_condition_AND_part(TABLE_LIST *embedding)
{
List_iterator<Item> li(list);
......
sql/item_cmpfunc.h
View file @ 0de3c423
......@@ -2224,6 +2224,7 @@ class Item_cond :public Item_bool_func
Item_transformer transformer, uchar *arg_t);
bool eval_not_null_tables(void *opt_arg);
Item *build_clone(THD *thd, MEM_ROOT *mem_root);
bool excl_dep_on_grouping_fields(st_select_lex *sel);
};
template <template<class> class LI, class T> class Item_equal_iterator;
......
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