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Back-port from 6.0 of the fix for

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BUG#38049 "incorrect rows estimations with references from preceding table"
(from revid:sergefp@mysql.com-20090126194259-ue20il3qro529l4d).
Compared to 6.0 where EXPLAIN indicates "Using index condition", here in join_optimizer.result
we see "Using where"; it's normal; 6.0 shows the same if disabling Index Condition Pushdown.
This commit is contained in:
Guilhem Bichot 2009-10-19 15:14:43 +02:00
parent ed8aaec764
commit b1f6a8e72f
4 changed files with 86 additions and 3 deletions
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37
mysql-test/r/join_optimizer.result Normal file
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@ -0,0 +1,37 @@
drop table if exists t0,t1,t2,t3;
#
# BUG#38049 incorrect rows estimations with references from preceding table
#
create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (a varchar(32));
insert into t1 values ('owner'),('requester'),('admincc'),('cc');
CREATE TABLE t2 (
id int(11) NOT NULL,
type varchar(32) default NULL,
PRIMARY KEY (id)
);
insert into t2 values (1,'owner'), (2,'admincc');
CREATE TABLE t3 (
id int(11) NOT NULL,
domain varchar(32) default NULL,
type varchar(32) default NULL,
PRIMARY KEY (id)
);
set @domain='system';
set @pk=0;
INSERT INTO t3 select @pk:=@pk+1, 'system', t1.a from t1;
INSERT INTO t3 select @pk:=@pk+1, 'queue', t1.a from t1, t0 where t0.a<3;
INSERT INTO t3 select @pk:=@pk+1, 'ticket', t1.a from t1, t0 A, t0 B, t0 C;
CREATE INDEX groups_d ON t3(domain);
CREATE INDEX groups_t ON t3(type);
CREATE INDEX groups_td ON t3(type, domain);
CREATE INDEX groups_dt ON t3(domain, type);
For table g this must use ref(groups_dt) and #rows should be around 15 and not 335:
explain
SELECT STRAIGHT_JOIN g.id FROM t2 a, t3 g USE INDEX(groups_dt)
WHERE g.domain = 'queue' AND g.type = a.type;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE a ALL NULL NULL NULL NULL 2
1 SIMPLE g ref groups_dt groups_dt 70 const,test.a.type 13 Using where
drop table t0,t1,t2,t3;

4
mysql-test/r/view.result
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@ -2342,11 +2342,11 @@ CREATE VIEW v2 AS SELECT t3.* FROM t1,t3 WHERE t1.a=t3.a;
EXPLAIN SELECT t1.* FROM t1 JOIN t2 WHERE t1.a=t2.a AND t1.b=t2.b AND t1.a=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 5 const 1 Using where; Using index
1 SIMPLE t2 ref a a 10 const,test.t1.b 2 Using where; Using index
1 SIMPLE t2 ref a a 10 const,test.t1.b 1 Using where; Using index
EXPLAIN SELECT * FROM v1 WHERE a=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 5 const 1 Using where; Using index
1 SIMPLE t2 ref a a 10 const,test.t1.b 2 Using where; Using index
1 SIMPLE t2 ref a a 10 const,test.t1.b 1 Using where; Using index
EXPLAIN SELECT * FROM v2 WHERE a=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref a a 5 const 1 Using where; Using index

45
mysql-test/t/join_optimizer.test Normal file
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@ -0,0 +1,45 @@
--disable_warnings
drop table if exists t0,t1,t2,t3;
--enable_warnings
--echo #
--echo # BUG#38049 incorrect rows estimations with references from preceding table
--echo #
create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (a varchar(32));
insert into t1 values ('owner'),('requester'),('admincc'),('cc');
CREATE TABLE t2 (
id int(11) NOT NULL,
type varchar(32) default NULL,
PRIMARY KEY (id)
);
insert into t2 values (1,'owner'), (2,'admincc');
CREATE TABLE t3 (
id int(11) NOT NULL,
domain varchar(32) default NULL,
type varchar(32) default NULL,
PRIMARY KEY (id)
);
set @domain='system';
set @pk=0;
INSERT INTO t3 select @pk:=@pk+1, 'system', t1.a from t1;
INSERT INTO t3 select @pk:=@pk+1, 'queue', t1.a from t1, t0 where t0.a<3;
INSERT INTO t3 select @pk:=@pk+1, 'ticket', t1.a from t1, t0 A, t0 B, t0 C;
CREATE INDEX groups_d ON t3(domain);
CREATE INDEX groups_t ON t3(type);
CREATE INDEX groups_td ON t3(type, domain);
CREATE INDEX groups_dt ON t3(domain, type);
--echo For table g this must use ref(groups_dt) and #rows should be around 15 and not 335:
explain
SELECT STRAIGHT_JOIN g.id FROM t2 a, t3 g USE INDEX(groups_dt)
WHERE g.domain = 'queue' AND g.type = a.type;
drop table t0,t1,t2,t3;

3
sql/sql_select.cc
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@ -4328,7 +4328,8 @@ best_access_path(JOIN *join,
in ReuseRangeEstimateForRef-3.
*/
if (table->quick_keys.is_set(key) &&
const_part & (1 << table->quick_key_parts[key]) &&
(const_part & ((1 << table->quick_key_parts[key])-1)) ==
((1 << table->quick_key_parts[key])-1) &&
table->quick_n_ranges[key] == 1 &&
records > (double) table->quick_rows[key])
{