kingshard SQL黑名单功能介绍

1. 应用场景介绍

在kingshard开源之后，有用户多次提到能不能在kingshard中加入SQL黑名单机制，让kingshard能够根据特定的规则来拦截在黑名单中的SQL。有几个比较典型的应用场景：

delete from mytable  select count(*) from mytable where xxxx

2. 功能介绍

在kingshard如果想使用SQL黑名单功能，只需要在配置中添加：

blacklist_sql_file: /Users/flike/blacklist

然后我们在blacklist定义SQL黑名单，这样kingshard在转发的时候，就会阻止黑名单中SQL的转发。

黑名单SQL以正则表达式的形式定义。对于SQL中的值用 ? 或 ?+ 代替。为保证黑名单有效，最好手动验证一下，kingshard是否正确拦截了黑名单中的SQL。定义规则（上一条是原SQL，对应的下一条是黑名单形式的SQL）可以参考下列例子：

SELECT c FROM t WHERE id=1  select c from t where id=?    SELECT * FROM prices.rt_5min where id=1  select * from prices.rt_5min where id=?    select null, 5.001, 5001. from foo  select ?, ?, ? from foo    select 'hello', '\nhello\n', \"hello\", '\\'' from foo  select ?, ?, ?, ? from foo    select 'hello'\n  select ?    select * from t where (base.nid IN  ('1412', '1410', '1411'))  select * from t where (base.nid in(?+))    select * from foo where a in (5) and b in (5, 8,9 ,9 , 10)  select * from foo where a in(?+) and b in(?+)    select * from foo limit 5  select * from foo limit ?    select * from foo limit 5, 10  select * from foo limit ?, ?    select * from foo limit 5 offset 10  select * from foo limit ? offset ?    INSERT INTO t (ts) VALUES (NOW())  insert into t (ts) values(?+)    insert into foo(a, b, c) values(2, 4, 5)  insert into foo(a, b, c) values(?+)    CALL foo(1, 2, 3)  call foo    LOAD DATA INFILE '/tmp/foo.txt' INTO db.tbl  load data infile ? into db.tbl    administrator command: Init DB  administrator command: Init DB    use `foo`  use ?

3.功能演示

在blacklist加入如下SQL:

select count(*) from test_shard_hash where id > ?  select count(*) from test_shard_range  SELECT * FROM WORLD  DELETE FROM WORLD

连接kingshard，执行SQL显示如下：

mysql> select * from world;  ERROR 1105 (HY000): sql in blacklist.  mysql> select * from world where a > 0;  +------+------+  | a    | b    |  +------+------+  |   10 |   23 |  |   45 |  565 |  +------+------+  2 rows in set (0.00 sec)    mysql> delete from world;  ERROR 1105 (HY000): sql in blacklist.  mysql> delete from world where a =10;  Query OK, 1 row affected (0.00 sec)  #注意在SQL黑名单中该SQL是大于后面有个空格，必须要严格匹配，否则#kingshard不会认为是黑名单SQL  mysql> select count(*) from test_shard_hash where id >1;  +----------+  | count(*) |  +----------+  |       24 |  +----------+  1 row in set (0.02 sec)    mysql> select count(*) from test_shard_hash where id > 1;  ERROR 1105 (HY000): sql in blacklist.

用sysbench测试了一下存在blacklist时kingshad的性能，发现性能并没有明显下降，所以可以放心使用该功能。