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Fixed bug #28188: performance degradation for outer join queries to which

Browse Source 
'not exists' optimization is applied.

In fact 'not exists' optimization did not work anymore after the patch
introducing the evaluate_join_record function had been applied.

Corrected the evaluate_join_record function to respect the 'not_exists'
optimization.


mysql-test/r/join_outer.result:
  Added a test case for bug #28188.
mysql-test/t/join_outer.test:
  Added a test case for bug #28188.
sql/sql_select.cc:
  Fixed bug #28188: performance degradation for outer join queries to which
  'not exists' optimization is applied.
  
  Corrected the evaluate_join_record function to respect the 'not_exists'
  optimization.
This commit is contained in:
unknown 2007-05-01 23:34:14 -07:00
parent 5352b41d29
commit 8e8ece72eb
3 changed files with 47 additions and 3 deletions
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25
mysql-test/r/join_outer.result
View File

@ -1214,3 +1214,28 @@ SELECT * FROM t1 LEFT JOIN t2 USING(f1) WHERE f1='Bla';
f1 f2 f3
bla blah sheep
DROP TABLE t1,t2;
CREATE TABLE t1 (id int PRIMARY KEY, a varchar(8));
CREATE TABLE t2 (id int NOT NULL, b int NOT NULL, INDEX idx(id));
INSERT INTO t1 VALUES
(1,'aaaaaaa'), (5,'eeeeeee'), (4,'ddddddd'), (2,'bbbbbbb'), (3,'ccccccc');
INSERT INTO t2 VALUES
(3,10), (2,20), (5,30), (3,20), (5,10), (3,40), (3,30), (2,10), (2,40);
EXPLAIN
SELECT t1.id, a FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.b IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 5
1 SIMPLE t2 ref idx idx 4 test.t1.id 2 Using where; Not exists
flush status;
SELECT t1.id, a FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.b IS NULL;
id a
1 aaaaaaa
4 ddddddd
show status like 'Handler_read%';
Variable_name Value
Handler_read_first 0
Handler_read_key 5
Handler_read_next 0
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 6
DROP TABLE t1,t2;

20
mysql-test/t/join_outer.test
View File

@ -825,3 +825,23 @@ SELECT * FROM t1 LEFT JOIN t2 USING(f1) WHERE f1='bla';
SELECT * FROM t1 LEFT JOIN t2 USING(f1) WHERE f1='Bla';
DROP TABLE t1,t2;
#
# Bug 28188: 'not exists' optimization for outer joins
#
CREATE TABLE t1 (id int PRIMARY KEY, a varchar(8));
CREATE TABLE t2 (id int NOT NULL, b int NOT NULL, INDEX idx(id));
INSERT INTO t1 VALUES
(1,'aaaaaaa'), (5,'eeeeeee'), (4,'ddddddd'), (2,'bbbbbbb'), (3,'ccccccc');
INSERT INTO t2 VALUES
(3,10), (2,20), (5,30), (3,20), (5,10), (3,40), (3,30), (2,10), (2,40);
EXPLAIN
SELECT t1.id, a FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.b IS NULL;
flush status;
SELECT t1.id, a FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.b IS NULL;
show status like 'Handler_read%';
DROP TABLE t1,t2;

5
sql/sql_select.cc
View File

@ -10526,7 +10526,6 @@ static enum_nested_loop_state
evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
int error, my_bool *report_error)
{
bool not_exists_optimize= join_tab->table->reginfo.not_exists_optimize;
bool not_used_in_distinct=join_tab->not_used_in_distinct;
ha_rows found_records=join->found_records;
COND *select_cond= join_tab->select_cond;
@ -10563,6 +10562,8 @@ 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
@ -10608,8 +10609,6 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
if (found)
{
enum enum_nested_loop_state rc;
if (not_exists_optimize)
return NESTED_LOOP_NO_MORE_ROWS;
/* A match from join_tab is found for the current partial join. */
rc= (*join_tab->next_select)(join, join_tab+1, 0);
if (rc != NESTED_LOOP_OK && rc != NESTED_LOOP_NO_MORE_ROWS)