Fixed bug #52636.

Applied the fix for bug #47217 from the mysql-6.0 codebase.
The patch adds not null predicates generated for the left parts
of the equality predicates used for ref accesses. This is done
for such predicates both in where conditions and on conditions.
For the where conditions the not null predicates were generated
but in 5.0/5.1 they actually never were used due to some lame
merge from 4.1 to 5.0. The fix for bug #47217 made these 
predicates to be used in the condition pushed to the tables.
Yet only this patch generates not null predicates for equality
predicated from on conditions of outer joins.
This patch introduces a performance regression that can be
observed on a test case from null_key.test. The regression
will disappear after the fix for bug #57024 from mariadb-5.1
is pulled into mariadb-5.3.
The patch contains many changes in the outputs of the EXPLAIN 
commands since generated not null predicates are considered as
parts of the conditions pushed to join tables and may add
'Usingwhere' in some rows of EXPLAINs where there used
to be no such comments.

1 files changed, 9 insertions, 9 deletions

diff --git a/mysql-test/r/table_elim.result b/mysql-test/r/table_elim.result
index a1b8ba0018d..282ae4cb55d 100644
--- a/mysql-test/r/table_elim.result
+++ b/mysql-test/r/table_elim.result
@@ -26,17 +26,17 @@ a
 explain select * from t1 left join t2 on t2.a=t1.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
 # This will not be eliminated as t2.b is in in order list:
 explain select t1.a from t1 left join t2 on t2.a=t1.a order by t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
 # This will not be eliminated as t2.b is in group list:
 explain select t1.a from t1 left join t2 on t2.a=t1.a group by t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
 # This will not be eliminated as t2.b is in the WHERE
 explain select t1.a from t1 left join t2 on t2.a=t1.a where t2.b < 3 or t2.b is null;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -75,7 +75,7 @@ This must not use elimination:
 explain select count(1) from t1 left join t2 on t2.a=t1.a group by t2.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where; Using index
 drop table t0, t1, t2, t3;
 create table t0 ( id integer, primary key (id));
 create table t1 (
@@ -128,7 +128,7 @@ Note	1003	select `f`.`id` AS `id` from `test`.`t0` `f` where (`f`.`id` in (1,2,3
 This should use facts and a1 tables:
 explain extended select id from v1 where attr1 between 12 and 14;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition; Using MRR
+1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition; Using where; Using MRR
 1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a1.id	1	100.00	Using index
 Warnings:
 Note	1276	Field or reference 'test.a2.id' of SELECT #3 was resolved in SELECT #1
@@ -156,7 +156,7 @@ Note	1003	select `f`.`id` AS `id` from `test`.`t0` `f` where (`f`.`id` in (1,2,3
 This should use facts and a1 tables:
 explain extended select id from v2 where attr1 between 12 and 14;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition; Using MRR
+1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition; Using where; Using MRR
 1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a1.id	1	100.00	Using index
 Warnings:
 Note	1276	Field or reference 'test.f.id' of SELECT #3 was resolved in SELECT #1
@@ -164,7 +164,7 @@ Note	1003	select `f`.`id` AS `id` from `test`.`t0` `f` join `test`.`t1` `a1` whe
 This should use facts, a2 and its subquery:
 explain extended select id from v2 where attr2 between 12 and 14;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	a2	range	PRIMARY,attr2	attr2	5	NULL	5	100.00	Using index condition; Using MRR
+1	PRIMARY	a2	range	PRIMARY,attr2	attr2	5	NULL	5	100.00	Using index condition; Using where; Using MRR
 1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a2.id	1	100.00	Using where; Using index
 3	DEPENDENT SUBQUERY	t2	ref	PRIMARY	PRIMARY	4	test.f.id	2	100.00	Using index
 Warnings:
@@ -217,7 +217,7 @@ explain
 select t1.*, t2.* from t1 left join (t2 left join t3 on t3.pk=t2.col) on t2.pk=t1.col;
 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	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	Using where
 explain select t1.* 
 from 
 t1 left join ( t2 left join t3 on t3.pk=t2.col or t3.pk=t2.col) 
@@ -232,7 +232,7 @@ t1 left join
 on t2.pk=t1.col or t2.pk=t1.col;
 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	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	Using where
 drop table t1, t2, t3;
 # 
 # Check things that look like functional dependencies but really are not