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Commit fa3570f9 authored by Sergey Glukhov's avatar Sergey Glukhov
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Bug#52005 'JOIN_TAB->dependent' may be incorrectly propageted for multilevel outer joins 

There are two problems:
1. In simplify_joins function we calculate table dependencies. If STRAIGHT_JOIN hint
is used for whole SELECT we do not count it and as result some dependendecies
might be lost. It leads to incorrect table order which is returned by
join_tab_cmp_straight() function.
2. make_join_statistics() calculate the transitive closure for relations a particular
JOIN_TAB is 'dependent on'.
We aggregate the dependent table_map of a JOIN_TAB by adding dependencies from other
tables which we depend on. However, this may also cause new dependencies to be
available after we have completed processing a certain JOIN_TAB.
Both these problems affect condition pushdown and as result condition might be pushed
into wrong table which leads to crash or even omitted which leads to wrong result.
The fix:
1. Use modified 'transitive closure' algorithm provided by Ole John Aske
2. Update table dependences in simplify_joins according to 
   global STRAIGHT_JOIN hint.
Note: the patch also fixes bugs 46091 & 51492
parent 54a006fa
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Showing with 137 additions and 10 deletions
mysql-test/r/join_outer.result
View file @ fa3570f9
......@@ -1338,4 +1338,63 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE tt9 ALL NULL NULL NULL NULL 2 Using join buffer
SET optimizer_search_depth = DEFAULT;
DROP TABLE t1;
#
# Bug#46091 STRAIGHT_JOIN + RIGHT JOIN returns different result
#
CREATE TABLE t1 (f1 INT NOT NULL);
INSERT INTO t1 VALUES (9),(0);
CREATE TABLE t2 (f1 INT NOT NULL);
INSERT INTO t2 VALUES
(5),(3),(0),(3),(1),(0),(1),(7),(1),(0),(0),(8),(4),(9),(0),(2),(0),(8),(5),(1);
SELECT STRAIGHT_JOIN COUNT(*) FROM t1 TA1
RIGHT JOIN t2 TA2 JOIN t2 TA3 ON TA2.f1 ON TA3.f1;
COUNT(*)
476
EXPLAIN SELECT STRAIGHT_JOIN COUNT(*) FROM t1 TA1
RIGHT JOIN t2 TA2 JOIN t2 TA3 ON TA2.f1 ON TA3.f1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE TA2 ALL NULL NULL NULL NULL 20 Using where
1 SIMPLE TA3 ALL NULL NULL NULL NULL 20 Using join buffer
1 SIMPLE TA1 ALL NULL NULL NULL NULL 2
DROP TABLE t1, t2;
#
# Bug#48971 Segfault in add_found_match_trig_cond () at sql_select.cc:5990
#
CREATE TABLE t1(f1 INT, PRIMARY KEY (f1));
INSERT INTO t1 VALUES (1),(2);
EXPLAIN EXTENDED SELECT STRAIGHT_JOIN T1.f1 FROM t1 AS T1
LEFT JOIN t1 AS T2
RIGHT JOIN t1 AS T3
JOIN t1 AS T4 ON 1
LEFT JOIN t1 AS T5 ON 1
ON 1
RIGHT JOIN t1 AS T6 ON T6.f1
ON 1;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE T1 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T6 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T3 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T4 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T5 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T2 index NULL PRIMARY 4 NULL 2 100.00 Using index
Warnings:
Note 1003 select straight_join `test`.`T1`.`f1` AS `f1` from `test`.`t1` `T1` left join (`test`.`t1` `T6` left join (`test`.`t1` `T3` join `test`.`t1` `T4` left join `test`.`t1` `T5` on(1) left join `test`.`t1` `T2` on(1)) on((`test`.`T6`.`f1` and 1))) on(1) where 1
EXPLAIN EXTENDED SELECT STRAIGHT_JOIN T1.f1 FROM t1 AS T1
RIGHT JOIN t1 AS T2
RIGHT JOIN t1 AS T3
JOIN t1 AS T4 ON 1
LEFT JOIN t1 AS T5 ON 1
ON 1
RIGHT JOIN t1 AS T6 ON T6.f1
ON 1;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE T6 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T3 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T4 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T5 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T2 index NULL PRIMARY 4 NULL 2 100.00 Using index
1 SIMPLE T1 index NULL PRIMARY 4 NULL 2 100.00 Using index
Warnings:
Note 1003 select straight_join `test`.`T1`.`f1` AS `f1` from `test`.`t1` `T6` left join (`test`.`t1` `T3` join `test`.`t1` `T4` left join `test`.`t1` `T5` on(1) left join `test`.`t1` `T2` on(1)) on((`test`.`T6`.`f1` and 1)) left join `test`.`t1` `T1` on(1) where 1
DROP TABLE t1;
End of 5.1 tests
mysql-test/t/join_outer.test
View file @ fa3570f9
......@@ -936,4 +936,49 @@ FROM t1 tt3 LEFT OUTER JOIN t1 tt4 ON 1
SET optimizer_search_depth = DEFAULT;
DROP TABLE t1;
--echo #
--echo # Bug#46091 STRAIGHT_JOIN + RIGHT JOIN returns different result
--echo #
CREATE TABLE t1 (f1 INT NOT NULL);
INSERT INTO t1 VALUES (9),(0);
CREATE TABLE t2 (f1 INT NOT NULL);
INSERT INTO t2 VALUES
(5),(3),(0),(3),(1),(0),(1),(7),(1),(0),(0),(8),(4),(9),(0),(2),(0),(8),(5),(1);
SELECT STRAIGHT_JOIN COUNT(*) FROM t1 TA1
RIGHT JOIN t2 TA2 JOIN t2 TA3 ON TA2.f1 ON TA3.f1;
EXPLAIN SELECT STRAIGHT_JOIN COUNT(*) FROM t1 TA1
RIGHT JOIN t2 TA2 JOIN t2 TA3 ON TA2.f1 ON TA3.f1;
DROP TABLE t1, t2;
--echo #
--echo # Bug#48971 Segfault in add_found_match_trig_cond () at sql_select.cc:5990
--echo #
CREATE TABLE t1(f1 INT, PRIMARY KEY (f1));
INSERT INTO t1 VALUES (1),(2);
EXPLAIN EXTENDED SELECT STRAIGHT_JOIN T1.f1 FROM t1 AS T1
LEFT JOIN t1 AS T2
RIGHT JOIN t1 AS T3
JOIN t1 AS T4 ON 1
LEFT JOIN t1 AS T5 ON 1
ON 1
RIGHT JOIN t1 AS T6 ON T6.f1
ON 1;
EXPLAIN EXTENDED SELECT STRAIGHT_JOIN T1.f1 FROM t1 AS T1
RIGHT JOIN t1 AS T2
RIGHT JOIN t1 AS T3
JOIN t1 AS T4 ON 1
LEFT JOIN t1 AS T5 ON 1
ON 1
RIGHT JOIN t1 AS T6 ON T6.f1
ON 1;
DROP TABLE t1;
--echo End of 5.1 tests
sql/sql_select.cc
View file @ fa3570f9
......@@ -2709,31 +2709,53 @@ make_join_statistics(JOIN *join, TABLE_LIST *tables_arg, COND *conds,
/*
Build transitive closure for relation 'to be dependent on'.
This will speed up the plan search for many cases with outer joins,
as well as allow us to catch illegal cross references/
as well as allow us to catch illegal cross references.
Warshall's algorithm is used to build the transitive closure.
As we use bitmaps to represent the relation the complexity
of the algorithm is O((number of tables)^2).
As we may restart the outer loop upto 'table_count' times, the
complexity of the algorithm is O((number of tables)^3).
However, most of the iterations will be shortcircuited when
there are no pedendencies to propogate.
*/
for (i= 0, s= stat ; i < table_count ; i++, s++)
for (i= 0 ; i < table_count ; i++)
{
for (uint j= 0 ; j < table_count ; j++)
uint j;
table= stat[i].table;
if (!table->reginfo.join_tab->dependent)
continue;
/* Add my dependencies to other tables depending on me */
for (j= 0, s= stat ; j < table_count ; j++, s++)
{
table= stat[j].table;
if (s->dependent & table->map)
{
table_map was_dependent= s->dependent;
s->dependent |= table->reginfo.join_tab->dependent;
/*
If we change dependencies for a table we already have
processed: Redo dependency propagation from this table.
*/
if (i > j && s->dependent != was_dependent)
{
i = j-1;
break;
}
}
}
if (outer_join & s->table->map)
s->table->maybe_null= 1;
}
/* Catch illegal cross references for outer joins */
for (i= 0, s= stat ; i < table_count ; i++, s++)
{
/* Catch illegal cross references for outer joins */
if (s->dependent & s->table->map)
{
join->tables=0; // Don't use join->table
my_message(ER_WRONG_OUTER_JOIN, ER(ER_WRONG_OUTER_JOIN), MYF(0));
goto error;
}
if (outer_join & s->table->map)
s->table->maybe_null= 1;
s->key_dependent= s->dependent;
}
}
......@@ -8704,6 +8726,7 @@ simplify_joins(JOIN *join, List<TABLE_LIST> *join_list, COND *conds, bool top)
NESTED_JOIN *nested_join;
TABLE_LIST *prev_table= 0;
List_iterator<TABLE_LIST> li(*join_list);
bool straight_join= test(join->select_options & SELECT_STRAIGHT_JOIN);
DBUG_ENTER("simplify_joins");
/*
......@@ -8814,7 +8837,7 @@ simplify_joins(JOIN *join, List<TABLE_LIST> *join_list, COND *conds, bool top)
if (prev_table)
{
/* The order of tables is reverse: prev_table follows table */
if (prev_table->straight)
if (prev_table->straight || straight_join)
prev_table->dep_tables|= used_tables;
if (prev_table->on_expr)
{
......
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