mirror of
https://github.com/MariaDB/server.git
synced 2025-10-27 05:56:07 +03:00
db03c7e89f
to estimate correctly cost of full table scan we should take into account rows read and skipped on each iteration. mysql-test/r/distinct.result: Fixed test suite: now full scan is used less often mysql-test/r/join_outer.result: Fixed test suite: now full scan is used less often mysql-test/r/select_safe.result: Fixed test suite: now full scan is used less often
82 lines
2.9 KiB
Plaintext
82 lines
2.9 KiB
Plaintext
drop table if exists t1;
|
|
SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=4, SQL_MAX_JOIN_SIZE=9;
|
|
create table t1 (a int auto_increment primary key, b char(20));
|
|
insert into t1 values(1,"test");
|
|
SELECT SQL_BUFFER_RESULT * from t1;
|
|
a b
|
|
1 test
|
|
update t1 set b="a" where a=1;
|
|
delete from t1 where a=1;
|
|
insert into t1 values(1,"test"),(2,"test2");
|
|
SELECT SQL_BUFFER_RESULT * from t1;
|
|
a b
|
|
1 test
|
|
2 test2
|
|
update t1 set b="a" where a=1;
|
|
select 1 from t1,t1 as t2,t1 as t3;
|
|
1
|
|
1
|
|
1
|
|
1
|
|
1
|
|
update t1 set b="a";
|
|
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
|
|
update t1 set b="a" where b="test";
|
|
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
|
|
delete from t1;
|
|
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
|
|
delete from t1 where b="test";
|
|
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
|
|
delete from t1 where a+0=1;
|
|
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
|
|
select 1 from t1,t1 as t2,t1 as t3,t1 as t4,t1 as t5;
|
|
The SELECT would examine more rows than MAX_JOIN_SIZE. Check your WHERE and use SET SQL_BIG_SELECTS=1 or SET SQL_MAX_JOIN_SIZE=# if the SELECT is ok
|
|
update t1 set b="a" limit 1;
|
|
update t1 set b="a" where b="b" limit 2;
|
|
delete from t1 where b="test" limit 1;
|
|
delete from t1 where a+0=1 limit 2;
|
|
alter table t1 add key b (b);
|
|
SET MAX_JOIN_SIZE=2;
|
|
SELECT @@MAX_JOIN_SIZE, @@SQL_BIG_SELECTS;
|
|
@@max_join_size @@sql_big_selects
|
|
2 0
|
|
insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
|
|
SELECT * from t1 order by a;
|
|
The SELECT would examine more rows than MAX_JOIN_SIZE. Check your WHERE and use SET SQL_BIG_SELECTS=1 or SET SQL_MAX_JOIN_SIZE=# if the SELECT is ok
|
|
SET SQL_BIG_SELECTS=1;
|
|
SELECT * from t1 order by a;
|
|
a b
|
|
2 test2
|
|
3 a
|
|
4 a
|
|
5 a
|
|
SET MAX_JOIN_SIZE=2;
|
|
SELECT * from t1;
|
|
The SELECT would examine more rows than MAX_JOIN_SIZE. Check your WHERE and use SET SQL_BIG_SELECTS=1 or SET SQL_MAX_JOIN_SIZE=# if the SELECT is ok
|
|
SET MAX_JOIN_SIZE=DEFAULT;
|
|
SELECT * from t1;
|
|
a b
|
|
2 test2
|
|
3 a
|
|
4 a
|
|
5 a
|
|
SELECT @@MAX_SEEKS_FOR_KEY;
|
|
@@max_seeks_for_key
|
|
4294967295
|
|
analyze table t1;
|
|
Table Op Msg_type Msg_text
|
|
test.t1 analyze status OK
|
|
insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
|
|
explain select STRAIGHT_JOIN * from t1,t1 as t2 where t1.b=t2.b;
|
|
table type possible_keys key key_len ref rows Extra
|
|
t1 ALL b NULL NULL NULL 21
|
|
t2 ref b b 21 t1.b 6 Using where
|
|
set MAX_SEEKS_FOR_KEY=1;
|
|
explain select STRAIGHT_JOIN * from t1,t1 as t2 where t1.b=t2.b;
|
|
table type possible_keys key key_len ref rows Extra
|
|
t1 ALL b NULL NULL NULL 21
|
|
t2 ref b b 21 t1.b 6 Using where
|
|
SET MAX_SEEKS_FOR_KEY=DEFAULT;
|
|
drop table t1;
|
|
SET SQL_SAFE_UPDATES=0,SQL_SELECT_LIMIT=DEFAULT, SQL_MAX_JOIN_SIZE=DEFAULT;
|