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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.
This commit is contained in:
igor@rurik.mysql.com
2006-05-02 18:31:20 -07:00
parent 806564d754
commit ae4eb6b50f
5 changed files with 76 additions and 46 deletions
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4
mysql-test/r/delete.result
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@@ -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