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Fixed LP #bug 660963.

Browse source 
The condition that was supposed to check whether a join table
is an inner table of a nested outer join or semi-join was not
quite correct in the code of the function check_join_cache_usage.
That's why some queries with nested outer joins triggered 
an assertion failure.
Encapsulated this condition in the new method called
JOIN_TAB::is_nested_inner and provided a proper code for it.

Also corrected a bug in the code of check_join_cache_usage()
that caused a downgrade of not first join buffers of the
level 5 and 7 to level 4 and 6 correspondingly.
This commit is contained in:
Igor Babaev 2010-11-19 06:20:28 -08:00
parent e25ac681c9
commit 0a3922fca8
4 changed files with 90 additions and 15 deletions
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41
mysql-test/r/join_cache.result
View file

@ -2104,7 +2104,7 @@ CountryLanguage.Percentage > 50;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE CountryLanguage ALL PRIMARY,Percentage NULL NULL NULL 984 Using where
1 SIMPLE Country eq_ref PRIMARY PRIMARY 3 world.CountryLanguage.Country 1 Using where; Using join buffer (flat, BKAH join)
1 SIMPLE City ref Country Country 3 world.Country.Code 18 Using index condition(BKA); Using where; Using join buffer (incremental, BKA join)
1 SIMPLE City ref Country Country 3 world.Country.Code 18 Using index condition(BKA); Using where; Using join buffer (flat, BKAH join)
SELECT City.Name, Country.Name, CountryLanguage.Language
FROM City,Country,CountryLanguage
WHERE City.Country=Country.Code AND
@ -3578,7 +3578,7 @@ CountryLanguage.Percentage > 50;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE CountryLanguage ALL PRIMARY,Percentage NULL NULL NULL 984 Using where
1 SIMPLE Country eq_ref PRIMARY PRIMARY 3 world.CountryLanguage.Country 1 Using where; Using join buffer (flat, BKAH join)
1 SIMPLE City ref Country Country 3 world.Country.Code 18 Using index condition(BKA); Using where; Using join buffer (incremental, BKA join)
1 SIMPLE City ref Country Country 3 world.Country.Code 18 Using index condition(BKA); Using where; Using join buffer (flat, BKAH join)
SELECT City.Name, Country.Name, CountryLanguage.Language
FROM City,Country,CountryLanguage
WHERE City.Country=Country.Code AND
@ -4661,7 +4661,7 @@ t1.b IS NULL AND t2.b IS NULL AND t3.b IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 16384 Using where
1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 Using where; Using join buffer (flat, BKAH join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 Using where; Using join buffer (incremental, BKA join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 Using where; Using join buffer (flat, BKAH join)
SELECT COUNT(*) FROM t1,t2,t3
WHERE t1.a=t2.a AND t2.a=t3.a AND
t1.b IS NULL AND t2.b IS NULL AND t3.b IS NULL;
@ -5969,4 +5969,39 @@ a1 b1 c1 a2 a3 b3 c3 a4 b4 c4
SET SESSION optimizer_switch = 'outer_join_with_cache=off';
SET SESSION join_cache_level = DEFAULT;
DROP TABLE t1,t2,t3,t4;
#
# Bug #660963: nested outer join with join_cache_level set to 5
#
CREATE TABLE t1 (a1 int) ;
INSERT INTO t1 VALUES (0),(0);
CREATE TABLE t2 (a2 int, b2 int, PRIMARY KEY (a2)) ;
INSERT INTO t2 VALUES (2,1);
CREATE TABLE t3 (a3 int, b3 int, PRIMARY KEY (a3)) ;
INSERT INTO t3 VALUES (2,1);
SET SESSION optimizer_switch = 'outer_join_with_cache=on';
SET SESSION join_cache_level = 6;
EXPLAIN
SELECT * FROM t1 LEFT JOIN t2 JOIN t3 ON t3.a3 = t2.a2 ON t3.b3 <> 0 ;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 1 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t2.a2 1 Using where; Using join buffer (incremental, BKA join)
SELECT * FROM t1 LEFT JOIN t2 JOIN t3 ON t3.a3 = t2.a2 ON t3.b3 <> 0 ;
a1 a2 b2 a3 b3
0 2 1 2 1
0 2 1 2 1
SET SESSION join_cache_level = 5;
EXPLAIN
SELECT * FROM t1 LEFT JOIN t2 JOIN t3 ON t3.a3 = t2.a2 ON t3.b3 <> 0 ;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
1 SIMPLE t2 ALL PRIMARY NULL NULL NULL 1 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t2.a2 1 Using where; Using join buffer (incremental, BNLH join)
SELECT * FROM t1 LEFT JOIN t2 JOIN t3 ON t3.a3 = t2.a2 ON t3.b3 <> 0 ;
a1 a2 b2 a3 b3
0 2 1 2 1
0 2 1 2 1
SET SESSION optimizer_switch = 'outer_join_with_cache=off';
SET SESSION join_cache_level = DEFAULT;
DROP TABLE t1,t2,t3;
set @@optimizer_switch=@save_optimizer_switch;

30
mysql-test/t/join_cache.test
View file

@ -2625,5 +2625,35 @@ SET SESSION join_cache_level = DEFAULT;
DROP TABLE t1,t2,t3,t4;
--echo #
--echo # Bug #660963: nested outer join with join_cache_level set to 5
--echo #
CREATE TABLE t1 (a1 int) ;
INSERT INTO t1 VALUES (0),(0);
CREATE TABLE t2 (a2 int, b2 int, PRIMARY KEY (a2)) ;
INSERT INTO t2 VALUES (2,1);
CREATE TABLE t3 (a3 int, b3 int, PRIMARY KEY (a3)) ;
INSERT INTO t3 VALUES (2,1);
SET SESSION optimizer_switch = 'outer_join_with_cache=on';
SET SESSION join_cache_level = 6;
EXPLAIN
SELECT * FROM t1 LEFT JOIN t2 JOIN t3 ON t3.a3 = t2.a2 ON t3.b3 <> 0 ;
SELECT * FROM t1 LEFT JOIN t2 JOIN t3 ON t3.a3 = t2.a2 ON t3.b3 <> 0 ;
SET SESSION join_cache_level = 5;
EXPLAIN
SELECT * FROM t1 LEFT JOIN t2 JOIN t3 ON t3.a3 = t2.a2 ON t3.b3 <> 0 ;
SELECT * FROM t1 LEFT JOIN t2 JOIN t3 ON t3.a3 = t2.a2 ON t3.b3 <> 0 ;
SET SESSION optimizer_switch = 'outer_join_with_cache=off';
SET SESSION join_cache_level = DEFAULT;
DROP TABLE t1,t2,t3;
# this must be the last command in the file
set @@optimizer_switch=@save_optimizer_switch;

21
sql/sql_select.cc
View file

@ -7635,8 +7635,7 @@ uint check_join_cache_usage(JOIN_TAB *tab,
if (cache_level == 0 || i == join->const_tables || !prev_tab)
return 0;
if (force_unlinked_cache &&
(cache_level & JOIN_CACHE_INCREMENTAL_BIT))
if (force_unlinked_cache && (cache_level%2 == 0))
cache_level--;
if (options & SELECT_NO_JOIN_CACHE)
@ -7658,13 +7657,14 @@ uint check_join_cache_usage(JOIN_TAB *tab,
/*
Non-linked join buffers can't guarantee one match
*/
if ((force_unlinked_cache || cache_level == 1) &&
((tab->is_inner_table_of_semi_join_with_first_match() &&
!tab->is_single_inner_of_semi_join_with_first_match()) ||
(tab->is_inner_table_of_outer_join() &&
!tab->is_single_inner_of_outer_join())))
goto no_join_cache;
if (tab->is_nested_inner())
{
if (force_unlinked_cache || cache_level == 1)
goto no_join_cache;
if (cache_level & 1)
cache_level--;
}
/*
Don't use join buffering if we're dictated not to by no_jbuf_after (this
...)
@ -7757,9 +7757,6 @@ uint check_join_cache_usage(JOIN_TAB *tab,
(cache_level <= 6 || no_hashed_cache))
goto no_join_cache;
if (prev_tab->cache && cache_level==7)
cache_level= 6;
if ((rows != HA_POS_ERROR) && !(flags & HA_MRR_USE_DEFAULT_IMPL))
{
if (cache_level <= 6 || no_hashed_cache)

13
sql/sql_select.h
View file

@ -359,6 +359,19 @@ typedef struct st_join_table {
return (first_inner && first_inner->last_inner == this) ||
last_sj_inner_tab == this;
}
/*
Check whether the table belongs to a nest of inner tables of an
outer join or to a nest of inner tables of a semi-join
*/
bool is_nested_inner()
{
if (first_inner &&
(first_inner != first_inner->last_inner || first_inner->first_upper))
return TRUE;
if (first_sj_inner_tab && first_sj_inner_tab != last_sj_inner_tab)
return TRUE;
return FALSE;
}
struct st_join_table *get_first_inner_table()
{
if (first_inner)