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Item::print(): remove redundant parentheses

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by introducing new Item::precedence() method and using it
to decide whether parentheses are required
This commit is contained in:
Sergei Golubchik
2016-11-27 19:50:10 +01:00
parent 1db438c833
commit 180065ebb0
188 changed files with 2684 additions and 2553 deletions
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8
mysql-test/r/range.result
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@ -2258,26 +2258,26 @@ explain extended select * from t2 where (b > 25 and b < 15) or a<44;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 range a,b a 5 NULL 43 100.00 Using index condition
Warnings:
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` where (`test`.`t2`.`a` < 44)
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` where `test`.`t2`.`a` < 44
# EXPLAIN EXTENDED should show that 'b > 25 and b < 15' is removed from the WHERE:
explain extended select * from t2 where a < 44 or (b > 25 and b < 15);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 range a,b a 5 NULL 43 100.00 Using index condition
Warnings:
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` where (`test`.`t2`.`a` < 44)
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` where `test`.`t2`.`a` < 44
# Here, conditions b will not be removed, because "c<44" is not sargable
# and hence (b.. and .. b) part is not analyzed at all:
explain extended select * from t2 where c < 44 or (b > 25 and b < 15);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL b NULL NULL NULL 1000 100.00 Using where
Warnings:
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` where ((`test`.`t2`.`c` < 44) or ((`test`.`t2`.`b` > 25) and (`test`.`t2`.`b` < 15)))
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` where `test`.`t2`.`c` < 44 or `test`.`t2`.`b` > 25 and `test`.`t2`.`b` < 15
# EXPLAIN EXTENDED should show that 'b > 25 and b < 15' is removed from the WHERE:
explain extended select * from t2 where (b > 25 and b < 15) or c < 44;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL b NULL NULL NULL 1000 100.00 Using where
Warnings:
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` where ((`test`.`t2`.`c` < 44))
Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` where `test`.`t2`.`c` < 44
# Try a case where both OR parts produce SEL_ARG::IMPOSSIBLE:
explain extended select * from t2 where (b > 25 and b < 15) or (a>55 and a<44);
id select_type table type possible_keys key key_len ref rows filtered Extra