kingshard SQL黑名單功能介紹

1. 應用場景介紹

在kingshard開源之后，有用戶多次提到能不能在kingshard中加入SQL黑名單機制，讓kingshard能夠根據特定的規則來攔截在黑名單中的SQL。有幾個比較典型的應用場景：

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

2. 功能介紹

在kingshard如果想使用SQL黑名單功能，只需要在配置中添加：

blacklist_sql_file: /Users/flike/blacklist

然后我們在blacklist定義SQL黑名單，這樣kingshard在轉發的時候，就會阻止黑名單中SQL的轉發。

黑名單SQL以正則表達式的形式定義。對于SQL中的值用 ? 或 ?+ 代替。為保證黑名單有效，最好手動驗證一下，kingshard是否正確攔截了黑名單中的SQL。定義規則（上一條是原SQL，對應的下一條是黑名單形式的SQL）可以參考下列例子：

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 ?</pre> 
 
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
 
 
連接kingshard，執行SQL顯示如下：

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黑名單中該SQL是大于后面有個空格，必須要嚴格匹配，否則#kingshard不會認為是黑名單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.</pre> 
 
用sysbench測試了一下存在blacklist時kingshad的性能，發現性能并沒有明顯下降，所以可以放心使用該功能。
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