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Fix for bug#58490, 'Incorrect result in multi level OUTER JOIN

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in combination with IS NULL'
      
As this bug is a duplicate of bug#49322, it also includes test cases
covering this bugreport
      
Qualifying an OUTER JOIN with the condition 'WHERE <column> IS NULL',
where <column> is declared as 'NOT NULL' causes the
'not_exists_optimize' to be enabled by the optimizer.
      
In evaluate_join_record() the 'not_exists_optimize' caused
'NESTED_LOOP_NO_MORE_ROWS' to be returned immediately
when a matching row was found.
      
However, as the 'not_exists_optimize' is derived from
'JOIN_TAB::select_cond', the usual rules for condition guards
also applies for 'not_exist_optimize'. It is therefore incorrect
to check 'not_exists_optimize' without ensuring that all guards
protecting it is 'open'.
      
This fix uses the fact that 'not_exists_optimize' is derived from
a 'is_null' predicate term in 'tab->select_cond'. Furthermore,
'is_null' will evaluate to 'false' for any 'non-null' rows
once all guards protecting the is_null is open.
      
We can use this knowledge as an implicit guard check for the
'not_exists_optimize' by moving 'if (...not_exists_optimize)'
inside the handling of 'select_cond==false'. It will then
not take effect before its guards are open.
      
We also add an assert which requires that a
'not_exists_optimize' always comes together with
a select_cond. (containing 'is_null').
This commit is contained in:
Ole John Aske
2011-02-01 15:19:34 +01:00
parent 4b8888f6f0
commit ed74edada2
3 changed files with 291 additions and 2 deletions
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142
mysql-test/r/join_outer.result
View File

@ -1502,4 +1502,146 @@ WHERE 7;
col_datetime_key
NULL
DROP TABLE BB;
#
# Bug#58490: Incorrect result in multi level OUTER JOIN
# in combination with IS NULL
#
CREATE TABLE t1 (i INT NOT NULL);
INSERT INTO t1 VALUES (0), (2),(3),(4);
CREATE TABLE t2 (i INT NOT NULL);
INSERT INTO t2 VALUES (0),(1), (3),(4);
CREATE TABLE t3 (i INT NOT NULL);
INSERT INTO t3 VALUES (0),(1),(2), (4);
CREATE TABLE t4 (i INT NOT NULL);
INSERT INTO t4 VALUES (0),(1),(2),(3) ;
SELECT * FROM
t1 LEFT JOIN
( t2 LEFT JOIN
( t3 LEFT JOIN
t4
ON t4.i = t3.i
)
ON t3.i = t2.i
)
ON t2.i = t1.i
;
i i i i
0 0 0 0
2 NULL NULL NULL
3 3 NULL NULL
4 4 4 NULL
SELECT * FROM
t1 LEFT JOIN
( t2 LEFT JOIN
( t3 LEFT JOIN
t4
ON t4.i = t3.i
)
ON t3.i = t2.i
)
ON t2.i = t1.i
WHERE t4.i IS NULL;
i i i i
2 NULL NULL NULL
3 3 NULL NULL
4 4 4 NULL
SELECT * FROM
t1 LEFT JOIN
( ( t2 LEFT JOIN
t3
ON t3.i = t2.i
)
)
ON t2.i = t1.i
WHERE t3.i IS NULL;
i i i
2 NULL NULL
3 3 NULL
SELECT * FROM
t1 LEFT JOIN
( ( t2 LEFT JOIN
t3
ON t3.i = t2.i
)
JOIN t4
ON t4.i=t2.i
)
ON t2.i = t1.i
WHERE t3.i IS NULL;
i i i i
2 NULL NULL NULL
3 3 NULL 3
4 NULL NULL NULL
SELECT * FROM
t1 LEFT JOIN
( ( t2 LEFT JOIN
t3
ON t3.i = t2.i
)
JOIN (t4 AS t4a JOIN t4 AS t4b ON t4a.i=t4b.i)
ON t4a.i=t2.i
)
ON t2.i = t1.i
WHERE t3.i IS NULL;
i i i i i
2 NULL NULL NULL NULL
3 3 NULL 3 3
4 NULL NULL NULL NULL
SELECT * FROM
t1 LEFT JOIN
( ( t2 LEFT JOIN
t3
ON t3.i = t2.i
)
JOIN (t4 AS t4a, t4 AS t4b)
ON t4a.i=t2.i
)
ON t2.i = t1.i
WHERE t3.i IS NULL;
i i i i i
2 NULL NULL NULL NULL
3 3 NULL 3 0
3 3 NULL 3 1
3 3 NULL 3 2
3 3 NULL 3 3
4 NULL NULL NULL NULL
DROP TABLE t1,t2,t3,t4;
#
# Bug#49322(Duplicate): Server is adding extra NULL row
# on processing a WHERE clause
#
CREATE TABLE h (pk INT NOT NULL, col_int_key INT);
INSERT INTO h VALUES (1,NULL),(4,2),(5,2),(3,4),(2,8);
CREATE TABLE m (pk INT NOT NULL, col_int_key INT);
INSERT INTO m VALUES (1,2),(2,7),(3,5),(4,7),(5,5),(6,NULL),(7,NULL),(8,9);
CREATE TABLE k (pk INT NOT NULL, col_int_key INT);
INSERT INTO k VALUES (1,9),(2,2),(3,5),(4,2),(5,7),(6,0),(7,5);
SELECT TABLE1.pk FROM k TABLE1
RIGHT JOIN h TABLE2 ON TABLE1.col_int_key=TABLE2.col_int_key
RIGHT JOIN m TABLE4 ON TABLE2.col_int_key=TABLE4.col_int_key;
pk
2
4
2
4
NULL
NULL
NULL
NULL
NULL
NULL
NULL
SELECT TABLE1.pk FROM k TABLE1
RIGHT JOIN h TABLE2 ON TABLE1.col_int_key=TABLE2.col_int_key
RIGHT JOIN m TABLE4 ON TABLE2.col_int_key=TABLE4.col_int_key
WHERE TABLE1.pk IS NULL;
pk
NULL
NULL
NULL
NULL
NULL
NULL
NULL
DROP TABLE h,m,k;
End of 5.1 tests

124
mysql-test/t/join_outer.test
View File

@ -1092,4 +1092,128 @@ FROM BB table1 RIGHT JOIN BB table2
DROP TABLE BB;
--echo #
--echo # Bug#58490: Incorrect result in multi level OUTER JOIN
--echo # in combination with IS NULL
--echo #
CREATE TABLE t1 (i INT NOT NULL);
INSERT INTO t1 VALUES (0), (2),(3),(4);
CREATE TABLE t2 (i INT NOT NULL);
INSERT INTO t2 VALUES (0),(1), (3),(4);
CREATE TABLE t3 (i INT NOT NULL);
INSERT INTO t3 VALUES (0),(1),(2), (4);
CREATE TABLE t4 (i INT NOT NULL);
INSERT INTO t4 VALUES (0),(1),(2),(3) ;
SELECT * FROM
t1 LEFT JOIN
( t2 LEFT JOIN
( t3 LEFT JOIN
t4
ON t4.i = t3.i
)
ON t3.i = t2.i
)
ON t2.i = t1.i
;
SELECT * FROM
t1 LEFT JOIN
( t2 LEFT JOIN
( t3 LEFT JOIN
t4
ON t4.i = t3.i
)
ON t3.i = t2.i
)
ON t2.i = t1.i
WHERE t4.i IS NULL;
# Most simplified testcase to reproduce the bug.
# (Has to be at least a two level nested outer join)
SELECT * FROM
t1 LEFT JOIN
( ( t2 LEFT JOIN
t3
ON t3.i = t2.i
)
)
ON t2.i = t1.i
WHERE t3.i IS NULL;
# Extended testing:
# We then add some equi-join inside the query above:
# (There Used to be some problems here with first
# proposed patch for this bug)
SELECT * FROM
t1 LEFT JOIN
( ( t2 LEFT JOIN
t3
ON t3.i = t2.i
)
JOIN t4
ON t4.i=t2.i
)
ON t2.i = t1.i
WHERE t3.i IS NULL;
SELECT * FROM
t1 LEFT JOIN
( ( t2 LEFT JOIN
t3
ON t3.i = t2.i
)
JOIN (t4 AS t4a JOIN t4 AS t4b ON t4a.i=t4b.i)
ON t4a.i=t2.i
)
ON t2.i = t1.i
WHERE t3.i IS NULL;
SELECT * FROM
t1 LEFT JOIN
( ( t2 LEFT JOIN
t3
ON t3.i = t2.i
)
JOIN (t4 AS t4a, t4 AS t4b)
ON t4a.i=t2.i
)
ON t2.i = t1.i
WHERE t3.i IS NULL;
DROP TABLE t1,t2,t3,t4;
## Bug#49322 & bug#58490 are duplicates. However, we include testcases
## for both.
--echo #
--echo # Bug#49322(Duplicate): Server is adding extra NULL row
--echo # on processing a WHERE clause
--echo #
CREATE TABLE h (pk INT NOT NULL, col_int_key INT);
INSERT INTO h VALUES (1,NULL),(4,2),(5,2),(3,4),(2,8);
CREATE TABLE m (pk INT NOT NULL, col_int_key INT);
INSERT INTO m VALUES (1,2),(2,7),(3,5),(4,7),(5,5),(6,NULL),(7,NULL),(8,9);
CREATE TABLE k (pk INT NOT NULL, col_int_key INT);
INSERT INTO k VALUES (1,9),(2,2),(3,5),(4,2),(5,7),(6,0),(7,5);
# Baseline query wo/ 'WHERE ... IS NULL' - was correct
SELECT TABLE1.pk FROM k TABLE1
RIGHT JOIN h TABLE2 ON TABLE1.col_int_key=TABLE2.col_int_key
RIGHT JOIN m TABLE4 ON TABLE2.col_int_key=TABLE4.col_int_key;
# Adding 'WHERE ... IS NULL' -> incorrect result
SELECT TABLE1.pk FROM k TABLE1
RIGHT JOIN h TABLE2 ON TABLE1.col_int_key=TABLE2.col_int_key
RIGHT JOIN m TABLE4 ON TABLE2.col_int_key=TABLE4.col_int_key
WHERE TABLE1.pk IS NULL;
DROP TABLE h,m,k;
--echo End of 5.1 tests

27
sql/sql_select.cc
View File

@ -11767,17 +11767,40 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
first_unmatched->found= 1;
for (JOIN_TAB *tab= first_unmatched; tab <= join_tab; tab++)
{
if (tab->table->reginfo.not_exists_optimize)
return NESTED_LOOP_NO_MORE_ROWS;
/* Check all predicates that has just been activated. */
/*
Actually all predicates non-guarded by first_unmatched->found
will be re-evaluated again. It could be fixed, but, probably,
it's not worth doing now.
*/
/*
not_exists_optimize has been created from a
select_cond containing 'is_null'. This 'is_null'
predicate is still present on any 'tab' with
'not_exists_optimize'. Furthermore, the usual rules
for condition guards also applies for
'not_exists_optimize' -> When 'is_null==false' we
know all cond. guards are open and we can apply
the 'not_exists_optimize'.
*/
DBUG_ASSERT(!(tab->table->reginfo.not_exists_optimize &&
!tab->select_cond));
if (tab->select_cond && !tab->select_cond->val_int())
{
/* The condition attached to table tab is false */
if (tab->table->reginfo.not_exists_optimize)
{
/*
When not_exists_optimize is set: No need to further
explore more rows of 'tab' for this partial result.
Any found 'tab' matches are known to evaluate to 'false'.
Returning .._NO_MORE_ROWS will skip rem. 'tab' rows.
*/
return NESTED_LOOP_NO_MORE_ROWS;
}
if (tab == join_tab)
found= 0;
else