hi all:
I have a problem about the type cast when I have read the source of Maria &
MySQL
I notice that when cast from string into int, Maria & MySQL do it like the C
function atoi
code:
for (ul= 0 ; str < end9 && (ch= (uchar) (*str - '0')) < 10; str++)
{
ul= ul * 10 + ch;
}
but cast from hex into int, the code is:
code:
char *end=(char*) str_value.ptr()+str_value.length(),
*ptr=end-min(str_value.length(),sizeof(longlong));
ulonglong value=0;
for (; ptr != end ; ptr++)
value=(value << 8)+ (ulonglong) (uchar) *ptr;
so I do the test blew:
create table t(id int auto_increment primary key, a int)engine=innodb;
insert into t(a) values('1');
insert into t(a) values(0x31);
everything is ok, I get the result:
mysql> select * from t;
+----+------+
| id | a |
+----+------+
| 1 | 1 |
| 2 | 49 |
+----+------+
the value 0x31 is the ascii of the string '1', but we got the different result
after inserting
maybe it's not a problem, but in the replication environment, it maybe cause
the data of slave not the same as master
In the master, when we set the connection characterset into multi-bytes
characterset and this characterset may escape with backslash is dangerous (like
gbk, cp932) and then we use the prepared statement to do the insert, the string
value in the insert must be cast into hex before write into the binlog, so we
do the insert(insert into t(a) values('1')) on the master, but in the slave it
does the another(insert into t(a) values(0x31)) , the data is not the same.
how to reappear:
master(binlog format=statement):
create table t(id int auto_increment primay key, a int) engine=innodb;
set names gbk;
prepare stmt from 'insert into t(a) values(?)';
set @a='1';
execute stmt using @a;
the result in master is:
mysql> select * from t;
+----+------+
| id | a |
+----+------+
| 1 | 1 |
+----+------+
and result in slave is:
mysql> select * from t;
+----+------+
| id | a |
+----+------+
| 1 | 49 |
+----+------+
I test the newest release version mariadb-10.0.2 and MySQL-5.6.10, the problem
is still exist, is this a bug?
2013-04-28
jhx1008 @netease_______________________________________________
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