Fixed LP bug #674431.

A non-incremental join buffer cannot be used for inner tables of nested
outer joins. That's why when join_cache_level is set to 7 it must
be downgraded to level 6 for the inner tables of nested outer joins.
For the same reason with join_cache_level set to 3 no join buffer is
used for the inner tables of outer joins (we could downgrade it to
level 2, but this level does not support ref access).

mysql-test/r/join_cache.result

@@ -870,7 +870,7 @@ 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, BNLH join)
-1	SIMPLE	City	ref	Country	Country	3	world.Country.Code	18	Using where; Using join buffer (flat, BNLH join)
+1	SIMPLE	City	ref	Country	Country	3	world.Country.Code	18	Using index condition; Using where
 SELECT City.Name, Country.Name, CountryLanguage.Language
 FROM City,Country,CountryLanguage
 WHERE City.Country=Country.Code AND
@@ -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 (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)
 SELECT City.Name, Country.Name, CountryLanguage.Language
 FROM City,Country,CountryLanguage
 WHERE City.Country=Country.Code AND
@@ -2722,7 +2722,7 @@ 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, BNLH join)
-1	SIMPLE	City	ref	Country	Country	3	world.Country.Code	18	Using where; Using join buffer (flat, BNLH join)
+1	SIMPLE	City	ref	Country	Country	3	world.Country.Code	18	Using index condition; Using where
 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 (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)
 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 (flat, BKAH join)
+1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where; Using join buffer (incremental, BKA 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;
@@ -5407,7 +5407,7 @@ WHERE t3.u <='a' AND t2.j < 5 AND t3.v = t2.u;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	16	
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer (flat, BNL join)
-1	SIMPLE	t3	ref	idx	idx	3	test.t2.u	2	Using where; Using join buffer (flat, BNLH join)
+1	SIMPLE	t3	ref	idx	idx	3	test.t2.u	2	Using where
 SELECT t1.i, t1.d,  t1.v, t2.i, t2.d, t2.t, t2.v FROM t1,t2,t3
 WHERE t3.u <='a' AND t2.j < 5 AND t3.v = t2.u;
 i	d	v	i	d	t	v
@@ -5769,4 +5769,44 @@ pk	a	pk	a
 2	aa	42	aa
 SET SESSION join_cache_level = DEFAULT;
 DROP TABLE t1,t2;
+#
+# Bug #674431: nested outer join when join_cache_level is set to 7
+#
+CREATE TABLE t1 (a int, b varchar(32)) ;
+INSERT INTO t1 VALUES (5,'h'), (NULL,'j');
+CREATE TABLE t2 (a int, b varchar(32), c int) ;
+INSERT INTO t2 VALUES (5,'h',100), (NULL,'j',200);
+CREATE TABLE t3 (a int, b varchar(32), INDEX idx(b));
+INSERT INTO t3 VALUES (77,'h'), (88,'g');
+SET SESSION optimizer_switch = 'outer_join_with_cache=on';
+SET SESSION join_cache_level = 7;
+SELECT t3.a
+FROM t1 LEFT JOIN
+(t2 LEFT OUTER JOIN t3 ON t2.b = t3.b) ON t2.a = t1.b
+WHERE t3.a BETWEEN 3 AND 11 OR t1.a <= t2.c;
+a
+SET SESSION optimizer_switch = 'outer_join_with_cache=off';
+SET SESSION join_cache_level = DEFAULT;
+DROP TABLE t1,t2,t3;
+#
+# Bug #52540: nested outer join when join_cache_level is set to 3
+#
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (2);
+CREATE TABLE t2 (a varchar(10));
+INSERT INTO t2 VALUES ('f'),('x');
+CREATE TABLE t3 (pk int(11) PRIMARY KEY);
+INSERT INTO t3 VALUES (2);
+CREATE TABLE t4 (a varchar(10));
+SET SESSION optimizer_switch = 'outer_join_with_cache=on';
+SET SESSION join_cache_level = 3;
+SELECT *
+FROM t2 LEFT JOIN
+((t1 JOIN t3 ON t1.a = t3.pk) LEFT JOIN t4 ON 1) ON 1;
+a	a	pk	a
+f	2	2	NULL
+x	2	2	NULL
+SET SESSION optimizer_switch = 'outer_join_with_cache=off';
+SET SESSION join_cache_level = DEFAULT;
+DROP TABLE t1,t2,t3,t4;
 set @@optimizer_switch=@save_optimizer_switch;

mysql-test/t/join_cache.test

@@ -2448,5 +2448,52 @@ SET SESSION join_cache_level = DEFAULT;
 
 DROP TABLE t1,t2;
 
+--echo #
+--echo # Bug #674431: nested outer join when join_cache_level is set to 7
+--echo #
+
+CREATE TABLE t1 (a int, b varchar(32)) ;
+INSERT INTO t1 VALUES (5,'h'), (NULL,'j');
+CREATE TABLE t2 (a int, b varchar(32), c int) ;
+INSERT INTO t2 VALUES (5,'h',100), (NULL,'j',200);
+CREATE TABLE t3 (a int, b varchar(32), INDEX idx(b));
+INSERT INTO t3 VALUES (77,'h'), (88,'g');
+
+SET SESSION optimizer_switch = 'outer_join_with_cache=on';
+SET SESSION join_cache_level = 7;
+SELECT t3.a
+  FROM t1 LEFT JOIN
+       (t2 LEFT OUTER JOIN t3 ON t2.b = t3.b) ON t2.a = t1.b
+    WHERE t3.a BETWEEN 3 AND 11 OR t1.a <= t2.c;
+
+SET SESSION optimizer_switch = 'outer_join_with_cache=off';
+SET SESSION join_cache_level = DEFAULT;
+
+DROP TABLE t1,t2,t3;
+
+--echo #
+--echo # Bug #52540: nested outer join when join_cache_level is set to 3
+--echo #
+
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (2);
+CREATE TABLE t2 (a varchar(10));
+INSERT INTO t2 VALUES ('f'),('x');
+CREATE TABLE t3 (pk int(11) PRIMARY KEY);
+INSERT INTO t3 VALUES (2);
+CREATE TABLE t4 (a varchar(10));
+
+SET SESSION optimizer_switch = 'outer_join_with_cache=on';
+SET SESSION join_cache_level = 3;
+
+SELECT *
+       FROM t2 LEFT JOIN
+           ((t1 JOIN t3 ON t1.a = t3.pk) LEFT JOIN t4 ON 1) ON 1;
+
+SET SESSION optimizer_switch = 'outer_join_with_cache=off';
+SET SESSION join_cache_level = DEFAULT;
+
+DROP TABLE t1,t2,t3,t4;
+
 # this must be the last command in the file
 set @@optimizer_switch=@save_optimizer_switch;

sql/sql_select.cc

@@ -7634,6 +7634,10 @@ 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))
+    cache_level--;
+
   if (options & SELECT_NO_JOIN_CACHE)
     goto no_join_cache;
   /* 
@@ -7732,7 +7736,11 @@ uint check_join_cache_usage(JOIN_TAB *tab,
           tab->make_scan_filter())
         goto no_join_cache;
       if (cache_level == 3)
+      {
+        if (prev_tab->cache)
+          goto no_join_cache;
         prev_cache= 0;
+      }
       if ((tab->cache= new JOIN_CACHE_BNLH(join, tab, prev_cache)) &&
           ((options & SELECT_DESCRIBE) || !tab->cache->init()))
       {
@@ -7747,6 +7755,9 @@ uint check_join_cache_usage(JOIN_TAB *tab,
     if ((flags & HA_MRR_NO_ASSOCIATION) &&
 	(cache_level <= 6 || no_hashed_cache))
       goto no_join_cache;
+
+    if (prev_tab->cache and cache_level==7)
+      cache_level= 6;
     
     if ((rows != HA_POS_ERROR) && !(flags & HA_MRR_USE_DEFAULT_IMPL))
     {

sql/sql_select.h

@@ -398,6 +398,10 @@ typedef struct st_join_table {
 } JOIN_TAB;
 
 
+#define JOIN_CACHE_INCREMENTAL_BIT           1
+#define JOIN_CACHE_HASHED_BIT                2
+#define JOIN_CACHE_BKA_BIT                   4
+
 /* 
   Categories of data fields of variable length written into join cache buffers.
   The value of any of these fields is written into cache together with the