3122 Jorgen Loland 2011-05-26
Bug#11765699 (58690) !TABLE ||
(!TABLE->READ_SET ||
BITMAP_IS_SET(TABLE->READ_SET, FIELD_INDEX
JOIN::conds points to the same expression tree as
SELECT_LEX::where, so modifying the expression tree of
JOIN::conds effectively does the same modifications to
SELECT_LEX::where.
JOIN::conds is optimized in JOIN::optimize()
conds= optimize_cond(conds);
optimize_cond() makes modifications to the conds input
parameter. One of these modifications removes an item from
the input conds parameter. This was not a problem for
JOIN::conds because removed items are included in the
condition returned from the function and therefore assigned
to conds as can be seen above. However, the removed parts of
the condition were lost from SELECT_LEX::where.
This bug was about a query with three levels of subselects:
SELECT 1 FROM t1 WHERE a =
(SELECT 1 FROM t2 WHERE b =
(SELECT 1 FROM t1 t11 WHERE c = 1 OR t1.a = 1 AND 1 = 2)
GROUP BY b
);
Prior to optimization, select#3 has
join->conds = select_lex->where = "c = 1 OR t1.a = 1 AND 1 = 2"
As part of optimize_cond(), remove_eq_conds() sees that
"t1.a = 1 AND 1 = 2" is FALSE and correctly removes this
condition. This leaves the OR item with only one argument:
"c = 1". With only one argument left in this OR,
internal_remove_eq_conds() empties the argument list of the OR
and returns "c = 1". The effect is that after optimize_cond(),
select#3 has:
join->conds = "c = 1"
select_lex->where = "" // <- !!
Fixed by not emptying the argument list of an Item_cond even
when there is only one argument. The effect is that after
optimize_cond(), select_lex->where is an OR-item with only
one argument: "c = 1". This is slightly inefficient (evaluation
would have to go through the OR), but it works correctly. Note
that condition evaluation is performed using the correctly
optimized JOIN::conds.
@ mysql-test/include/subquery.inc
Added test for BUG#11765699
@ mysql-test/r/subquery_nomat_nosj.result
Added test for BUG#11765699
@ mysql-test/r/subquery_none.result
Added test for BUG#11765699
@ sql/sql_select.cc
In internal_remove_eq_conds(): Do not empty argument_list() of
an Item_cond with only one argument. This will result in lost
condition parts in SELECT_LEX::where/having
modified:
mysql-test/include/subquery.inc
mysql-test/r/subquery_nomat_nosj.result
mysql-test/r/subquery_none.result
sql/sql_select.cc
3121 Sergey Glukhov 2011-05-26 [merge]
5.5 -> trunk merge
@ mysql-test/r/func_math.result
5.5 -> trunk merge
@ mysql-test/t/func_math.test
5.5 -> trunk merge
@ sql/item_func.cc
5.5 -> trunk merge
modified:
mysql-test/r/func_math.result
mysql-test/t/func_math.test
sql/item_func.cc
=== modified file 'mysql-test/include/subquery.inc'
--- a/mysql-test/include/subquery.inc 2011-05-05 07:41:53 +0000
+++ b/mysql-test/include/subquery.inc 2011-05-26 11:09:57 +0000
@@ -5354,3 +5354,32 @@ CREATE TABLE t(a VARCHAR(245) DEFAULT
INSERT INTO t VALUES (''),(''),(''),(''),(''),(''),(''),(''),(''),(''),('');
SELECT * FROM (SELECT default(a) FROM t GROUP BY a) d;
DROP TABLE t;
+
+--echo #
+--echo # Bug 11765699 - 58690: !TABLE || (!TABLE->READ_SET ||
+--echo # BITMAP_IS_SET(TABLE->READ_SET, FIELD_INDEX
+--echo #
+
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES (0), (1);
+
+CREATE TABLE t2(
+ b TEXT,
+ c INT,
+ PRIMARY KEY (b(1))
+);
+INSERT INTO t2 VALUES ('a', 2), ('b', 3);
+
+SELECT 1 FROM t1 WHERE a =
+ (SELECT 1 FROM t2 WHERE b =
+ (SELECT 1 FROM t1 t11 WHERE c = 1 OR t1.a = 1 AND 1 = 2)
+ ORDER BY b
+ );
+
+SELECT 1 FROM t1 WHERE a =
+ (SELECT 1 FROM t2 WHERE b =
+ (SELECT 1 FROM t1 t11 WHERE c = 1 OR t1.a = 1 AND 1 = 2)
+ GROUP BY b
+ );
+
+DROP TABLE t1, t2;
=== modified file 'mysql-test/r/subquery_nomat_nosj.result'
--- a/mysql-test/r/subquery_nomat_nosj.result 2011-05-05 07:41:53 +0000
+++ b/mysql-test/r/subquery_nomat_nosj.result 2011-05-26 11:09:57 +0000
@@ -6507,4 +6507,29 @@ SELECT * FROM (SELECT default(a) FROM t
default(a)
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
DROP TABLE t;
+#
+# Bug 11765699 - 58690: !TABLE || (!TABLE->READ_SET ||
+# BITMAP_IS_SET(TABLE->READ_SET, FIELD_INDEX
+#
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES (0), (1);
+CREATE TABLE t2(
+b TEXT,
+c INT,
+PRIMARY KEY (b(1))
+);
+INSERT INTO t2 VALUES ('a', 2), ('b', 3);
+SELECT 1 FROM t1 WHERE a =
+(SELECT 1 FROM t2 WHERE b =
+(SELECT 1 FROM t1 t11 WHERE c = 1 OR t1.a = 1 AND 1 = 2)
+ORDER BY b
+);
+1
+SELECT 1 FROM t1 WHERE a =
+(SELECT 1 FROM t2 WHERE b =
+(SELECT 1 FROM t1 t11 WHERE c = 1 OR t1.a = 1 AND 1 = 2)
+GROUP BY b
+);
+1
+DROP TABLE t1, t2;
set optimizer_switch=default;
=== modified file 'mysql-test/r/subquery_none.result'
--- a/mysql-test/r/subquery_none.result 2011-05-05 07:41:53 +0000
+++ b/mysql-test/r/subquery_none.result 2011-05-26 11:09:57 +0000
@@ -6506,4 +6506,29 @@ SELECT * FROM (SELECT default(a) FROM t
default(a)
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
DROP TABLE t;
+#
+# Bug 11765699 - 58690: !TABLE || (!TABLE->READ_SET ||
+# BITMAP_IS_SET(TABLE->READ_SET, FIELD_INDEX
+#
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES (0), (1);
+CREATE TABLE t2(
+b TEXT,
+c INT,
+PRIMARY KEY (b(1))
+);
+INSERT INTO t2 VALUES ('a', 2), ('b', 3);
+SELECT 1 FROM t1 WHERE a =
+(SELECT 1 FROM t2 WHERE b =
+(SELECT 1 FROM t1 t11 WHERE c = 1 OR t1.a = 1 AND 1 = 2)
+ORDER BY b
+);
+1
+SELECT 1 FROM t1 WHERE a =
+(SELECT 1 FROM t2 WHERE b =
+(SELECT 1 FROM t1 t11 WHERE c = 1 OR t1.a = 1 AND 1 = 2)
+GROUP BY b
+);
+1
+DROP TABLE t1, t2;
set optimizer_switch=default;
=== modified file 'sql/sql_select.cc'
--- a/sql/sql_select.cc 2011-05-26 06:03:02 +0000
+++ b/sql/sql_select.cc 2011-05-26 11:09:57 +0000
@@ -1904,6 +1904,11 @@ JOIN::optimize()
thd->restore_active_arena(arena, &backup);
}
+ /*
+ Note: optimize_cond() makes changes to conds. Since
+ select_lex->where and conds points to the same condition, this
+ function call effectively changes select_lex->where as well.
+ */
conds= optimize_cond(this, conds, join_list, TRUE, &select_lex->cond_value);
if (thd->is_error())
{
@@ -1913,6 +1918,7 @@ JOIN::optimize()
}
{
+ // Note above about optimize_cond() also applies to selec_lex->having
having= optimize_cond(this, having, join_list, FALSE,
&select_lex->having_value);
if (thd->is_error())
@@ -14711,7 +14717,8 @@ optimize_cond(JOIN *join, Item *conds, L
SYNPOSIS
remove_eq_conds()
thd THD environment
- cond the condition to handle
+ cond the condition to handle. Note that cond
+ is changed by this function
cond_value the resulting value of the condition
RETURN
@@ -14773,9 +14780,34 @@ internal_remove_eq_conds(THD *thd, Item
*cond_value != Item::COND_OK)
return (Item*) 0;
if (((Item_cond*) cond)->argument_list()->elements == 1)
- { // Remove list
+ {
+ /*
+ BUG#11765699:
+ We're dealing with an AND or OR item that has only one
+ argument. However, it is not an option to empty the list
+ because:
+
+ - this function is called for either JOIN::conds or
+ JOIN::having, but these point to the same condition as
+ SELECT_LEX::where and SELECT_LEX::having do.
+
+ - The return value of remove_eq_conds() is assigned to
+ JOIN::conds and JOIN::having, so emptying the list and
+ returning the only remaining item "replaces" the AND or OR
+ with item for the variables in JOIN. However, the return
+ value is not assigned to the SELECT_LEX counterparts. Thus,
+ if argument_list is emptied, SELECT_LEX forgets the item in
+ argument_list()->head().
+
+ item is therefore returned, but argument_list is not emptied.
+ */
item= ((Item_cond*) cond)->argument_list()->head();
- ((Item_cond*) cond)->argument_list()->empty();
+ /*
+ Consider reenabling the line below when the optimizer has been
+ split into properly separated phases.
+
+ ((Item_cond*) cond)->argument_list()->empty();
+ */
return item;
}
}
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| Thread |
|---|
| • bzr push into mysql-trunk branch (jorgen.loland:3121 to 3122) Bug#11765699 | Jorgen Loland | 26 May |
