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Bug#18411494 WRONG COMPARSION ON BIG DECIMAL VALUES

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Problem: integer literals may be converted to floats for
comparison with decimal data. If the integers are large,
we may lose precision, and give wrong results.

Fix: for
  <non-const decimal expression> <cmp> <const string expression>
  or
  <const string expression> <cmp> <non-const decimal expression>
we override the compare_type chosen by item_cmp_type(), and
do comparison as decimal rather than float.

(cherry picked from commit 1cf3489ba4 and edited by Johannes Weißl <jargon@molb.org>)
This commit is contained in:
Tor Didriksen 2015-04-21 08:32:31 +02:00 committed by holyfoot
parent 68d632bc5a
commit e823023e4b
3 changed files with 82 additions and 0 deletions
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39
mysql-test/r/type_newdecimal.result
View File

@ -2243,3 +2243,42 @@ DROP TABLE t1;
#
# End of 10.1 tests
#
#
# Bug#18408499 UNSIGNED BIGINT HIGH VALUES
# WRONG NUMERICAL COMPARISON RESULTS
#
CREATE TABLE t1(value DECIMAL(24,0) NOT NULL);
INSERT INTO t1(value)
VALUES('100000000000000000000001'),
('100000000000000000000002'),
('100000000000000000000003');
SELECT * FROM t1 WHERE value = '100000000000000000000002';
value
100000000000000000000002
SELECT * FROM t1 WHERE '100000000000000000000002' = value;
value
100000000000000000000002
SELECT * FROM t1 WHERE value + 0 = '100000000000000000000002';
value
100000000000000000000002
SELECT * FROM t1 WHERE value = 100000000000000000000002;
value
100000000000000000000002
SELECT * FROM t1 WHERE value + 0 = 100000000000000000000002;
value
100000000000000000000002
PREPARE stmt FROM 'SELECT * FROM t1 WHERE value = ?';
set @a="100000000000000000000002";
EXECUTE stmt using @a;
value
100000000000000000000002
set @a=100000000000000000000002;
EXECUTE stmt using @a;
value
100000000000000000000002
DEALLOCATE PREPARE stmt;
ALTER TABLE t1 ADD INDEX value (value);
SELECT * FROM t1 WHERE value = '100000000000000000000002';
value
100000000000000000000002
DROP TABLE t1;

27
mysql-test/t/type_newdecimal.test
View File

@ -1738,3 +1738,30 @@ DROP TABLE t1;
--echo #
--echo # End of 10.1 tests
--echo #
--echo #
--echo # Bug#18408499 UNSIGNED BIGINT HIGH VALUES
--echo # WRONG NUMERICAL COMPARISON RESULTS
--echo #
CREATE TABLE t1(value DECIMAL(24,0) NOT NULL);
INSERT INTO t1(value)
VALUES('100000000000000000000001'),
('100000000000000000000002'),
('100000000000000000000003');
SELECT * FROM t1 WHERE value = '100000000000000000000002';
SELECT * FROM t1 WHERE '100000000000000000000002' = value;
SELECT * FROM t1 WHERE value + 0 = '100000000000000000000002';
SELECT * FROM t1 WHERE value = 100000000000000000000002;
SELECT * FROM t1 WHERE value + 0 = 100000000000000000000002;
PREPARE stmt FROM 'SELECT * FROM t1 WHERE value = ?';
set @a="100000000000000000000002";
EXECUTE stmt using @a;
set @a=100000000000000000000002;
EXECUTE stmt using @a;
DEALLOCATE PREPARE stmt;
ALTER TABLE t1 ADD INDEX value (value);
SELECT * FROM t1 WHERE value = '100000000000000000000002';
DROP TABLE t1;

16
sql/item_cmpfunc.cc
View File

@ -655,6 +655,22 @@ int Arg_comparator::set_cmp_func(Item_func_or_sum *owner_arg,
return 0;
}
if (m_compare_type == REAL_RESULT &&
(((*a)->result_type() == DECIMAL_RESULT && !(*a)->const_item() &&
(*b)->result_type() == STRING_RESULT && (*b)->const_item()) ||
((*b)->result_type() == DECIMAL_RESULT && !(*b)->const_item() &&
(*a)->result_type() == STRING_RESULT && (*a)->const_item())))
{
/*
<non-const decimal expression> <cmp> <const string expression>
or
<const string expression> <cmp> <non-const decimal expression>
Do comparison as decimal rather than float, in order not to lose precision.
*/
m_compare_type= DECIMAL_RESULT;
}
if (m_compare_type == INT_RESULT &&
(*a)->field_type() == MYSQL_TYPE_YEAR &&
(*b)->field_type() == MYSQL_TYPE_YEAR)