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Bug#22331: Wrong WHERE in EXPLAIN EXTENDED when all expressions were optimized

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away.

During optimization stage the WHERE conditions can be changed or even
be removed at all if they know for sure to be true of false. Thus they aren't
showed in the EXPLAIN EXTENDED which prints conditions after optimization.

Now if all elements of an Item_cond were removed this Item_cond is substituted
for an Item_int with the int value of the Item_cond.
If there were conditions that were totally optimized away then values of the
saved cond_value and having_value will be printed instead.


mysql-test/t/explain.test:
  Added a test case for the bug#22331: Wrong WHERE in EXPLAIN EXTENDED when all expressions were optimized away.
mysql-test/r/subselect.result:
  Corrected test case result after fix for bug#22331.
mysql-test/r/func_test.result:
  Corrected test case result after fix for bug#22331.
mysql-test/r/explain.result:
  Added a test case for the bug#22331: Wrong WHERE in EXPLAIN EXTENDED when all expressions were optimized away.
sql/sql_select.cc:
  Bug#22331: Wrong WHERE in EXPLAIN EXTENDED when all expressions were optimized
  away.
  Now if all elements of an Item_cond were removed this Item_cond is substituted
  for an Item_int with the int value of the Item_cond.
  If there were conditions that were totally optimized away then values of the
  saved cond_value and having_value will be printed instead.
sql/sql_lex.h:
  Bug#22331: Wrong WHERE in EXPLAIN EXTENDED when all expressions were optimized
  away.
  The cond_value and the having_value variables are
  added to the SELECT_LEX class.
sql/sql_lex.cc:
  Bug#22331: Wrong WHERE in EXPLAIN EXTENDED when all expressions were optimized
  away.
  The initialization of the cond_value and the having_value variables.
sql/sql_select.h:
  Bug#22331: Wrong WHERE in EXPLAIN EXTENDED when all expressions were optimized
  away.
  Now having_value is also stored in the JOIN class.
This commit is contained in:
unknown
2007-03-07 21:44:58 +03:00
parent e656c582bc
commit 6de277910b
8 changed files with 74 additions and 15 deletions
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29
mysql-test/r/explain.result
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@ -57,3 +57,32 @@ select 3 into @v1;
explain select 3 into @v1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL No tables used
create table t1(f1 int, f2 int);
insert into t1 values (1,1);
create view v1 as select * from t1 where f1=1;
explain extended select * from v1 where f2=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 system NULL NULL NULL NULL 1
Warnings:
Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f2` AS `f2` from `test`.`t1` where 1
explain extended select * from t1 where 0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
Warnings:
Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f2` AS `f2` from `test`.`t1` where 0
explain extended select * from t1 where 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 system NULL NULL NULL NULL 1
Warnings:
Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f2` AS `f2` from `test`.`t1` where 1
explain extended select * from t1 having 0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible HAVING
Warnings:
Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f2` AS `f2` from `test`.`t1` having 0
explain extended select * from t1 having 1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 system NULL NULL NULL NULL 1
Warnings:
Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f2` AS `f2` from `test`.`t1` having 1
drop table t1;