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Fixed bug #14292: performance degradation for a benchmark query.

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This performance degradation was due to the fact that some
cost evaluation code added into 4.1 in the function find_best was
not merged into the code of the function best_access_path added
together with other code for greedy optimizer.
Added a parameter to the function print_plan. The parameter contains
accumulated cost for a given partial join.
 
The patch does not include a special test case since this performance
degradation is hard to reproduse with a simple example.

TODO: make the function find_best use the function best_access_path
in order to remove duplication of code which might result in incomplete
merges in the future.


mysql-test/r/delete.result:
  Fixed bug #14292: performance degradation for a benchmark query.
  Adjusted test results.
mysql-test/r/subselect.result:
  Fixed bug #14292: performance degradation for a benchmark query.
  Adjusted test results.
sql/mysql_priv.h:
  Fixed bug #14292: performance degradation for a benchmark query.
  Added a parameter to the function print_plan. The parameter contains
  accumulated cost for a given partial join.
sql/sql_select.cc:
  Fixed bug #14292: performance degradation for a benchmark query.
  This performance degradation was due to the fact that some
  cost evaluation code added into 4.1 in the function find_best was
  not merged into the code of the function best_access_path added
  together with other code for greedy optimizer.
sql/sql_test.cc:
  Fixed bug #14292: performance degradation for a benchmark query.
  Added a parameter to the function print_plan. The parameter contains
  accumulated cost for a given partial join.
This commit is contained in:
unknown
2006-05-02 18:31:20 -07:00
parent 6692dcf718
commit 21d61c2be7
5 changed files with 76 additions and 46 deletions
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4
mysql-test/r/delete.result
View File

@ -186,8 +186,8 @@ a b a b a b
explain select * from t1,t2,t3 where t1.a=t2.a AND t2.b=t3.a and t1.b=t3.b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 index PRIMARY PRIMARY 8 NULL 3 Using where; Using index
1 SIMPLE t3 index PRIMARY PRIMARY 8 NULL 3 Using where; Using index
1 SIMPLE t2 ref PRIMARY PRIMARY 4 test.t1.a 1 Using index
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 8 test.t2.b,test.t1.b 1 Using index
delete t2.*,t3.* from t1,t2,t3 where t1.a=t2.a AND t2.b=t3.a and t1.b=t3.b;
select * from t3;
a b

6
mysql-test/r/subselect.result
View File

@ -1354,10 +1354,10 @@ a
explain extended select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 index NULL a 5 NULL 4 Using where; Using index
2 DEPENDENT SUBQUERY t3 index a a 5 NULL 3 Using index
2 DEPENDENT SUBQUERY t1 ref a a 10 func,test.t3.a 1167 Using where; Using index
2 DEPENDENT SUBQUERY t1 ref a a 5 func 1001 Using where; Using index
2 DEPENDENT SUBQUERY t3 index a a 5 NULL 3 Using where; Using index
Warnings:
Note 1003 select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t1` join `test`.`t3` where ((`test`.`t1`.`b` = `test`.`t3`.`a`) and (<cache>(`test`.`t2`.`a`) = `test`.`t1`.`a`))))
Note 1003 select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t1` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t1`.`b`) and (<cache>(`test`.`t2`.`a`) = `test`.`t1`.`a`))))
insert into t1 values (3,31);
select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
a