|
| 1 | +# kingshard SQL黑名单功能介绍 |
| 2 | + |
| 3 | +## 1. 应用场景介绍 |
| 4 | +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： |
| 5 | + |
| 6 | +1. DBA定义一些比较危险的SQL，放在SQL黑名单文件中。可以避免前端应用发过来的SQL对数据库造成危害。这种SQL有可能是开发者粗心编写的，也有可能是被SQL注入生成的SQL。例如：`delete from mytable`，这种不带where条件的SQL，会把整个表删除。 |
| 7 | +2. 在kingshard项目上线后，通过log发现存在大量某条SQL给DB造成了很大的压力。这时候可以动态地将这条SQL加入黑名单，阻止该SQL的执行，从而使数据库压力降低。例如:`select count(*) from mytable where xxxx`,这类SQL如果没有优化得当，是很容易造成系统的IO过高的。 |
| 8 | + |
| 9 | +## 2. 功能介绍 |
| 10 | +在kingshard如果想使用SQL黑名单功能，只需要在配置中添加： |
| 11 | +``` |
| 12 | +blacklist_sql_file: /Users/flike/blacklist |
| 13 | +``` |
| 14 | +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。 |
| 15 | + |
| 16 | +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： |
| 17 | + |
| 18 | +``` |
| 19 | +SELECT c FROM t WHERE id=1 |
| 20 | +select c from t where id=? |
| 21 | +
|
| 22 | +SELECT * FROM prices.rt_5min where id=1 |
| 23 | +select * from prices.rt_5min where id=? |
| 24 | +
|
| 25 | +select null, 5.001, 5001. from foo |
| 26 | +select ?, ?, ? from foo |
| 27 | +
|
| 28 | +select 'hello', '\nhello\n', \"hello\", '\\'' from foo |
| 29 | +select ?, ?, ?, ? from foo |
| 30 | +
|
| 31 | +select 'hello'\n |
| 32 | +select ? |
| 33 | +
|
| 34 | +select * from t where (base.nid IN ('1412', '1410', '1411')) |
| 35 | +select * from t where (base.nid in(?+)) |
| 36 | +
|
| 37 | +select * from foo where a in (5) and b in (5, 8,9 ,9 , 10) |
| 38 | +select * from foo where a in(?+) and b in(?+) |
| 39 | +
|
| 40 | +select * from foo limit 5 |
| 41 | +select * from foo limit ? |
| 42 | +
|
| 43 | +select * from foo limit 5, 10 |
| 44 | +select * from foo limit ?, ? |
| 45 | +
|
| 46 | +select * from foo limit 5 offset 10 |
| 47 | +select * from foo limit ? offset ? |
| 48 | +
|
| 49 | +INSERT INTO t (ts) VALUES (NOW()) |
| 50 | +insert into t (ts) values(?+) |
| 51 | +
|
| 52 | +insert into foo(a, b, c) values(2, 4, 5) |
| 53 | +insert into foo(a, b, c) values(?+) |
| 54 | +
|
| 55 | +CALL foo(1, 2, 3) |
| 56 | +call foo |
| 57 | +
|
| 58 | +LOAD DATA INFILE '/tmp/foo.txt' INTO db.tbl |
| 59 | +load data infile ? into db.tbl |
| 60 | +
|
| 61 | +administrator command: Init DB |
| 62 | +administrator command: Init DB |
| 63 | +
|
| 64 | +use `foo` |
| 65 | +use ? |
| 66 | +
|
| 67 | +``` |
| 68 | + |
| 69 | +## 3.功能演示 |
| 70 | +在blacklist加入如下SQL: |
| 71 | + |
| 72 | +``` |
| 73 | +select count(*) from test_shard_hash where id > ? |
| 74 | +select count(*) from test_shard_range |
| 75 | +SELECT * FROM WORLD |
| 76 | +DELETE FROM WORLD |
| 77 | +``` |
| 78 | + |
| 79 | +连接kingshard，执行SQL显示如下： |
| 80 | + |
| 81 | +``` |
| 82 | +mysql> select * from world; |
| 83 | +ERROR 1105 (HY000): sql in blacklist. |
| 84 | +mysql> select * from world where a > 0; |
| 85 | ++------+------+ |
| 86 | +| a | b | |
| 87 | ++------+------+ |
| 88 | +| 10 | 23 | |
| 89 | +| 45 | 565 | |
| 90 | ++------+------+ |
| 91 | +2 rows in set (0.00 sec) |
| 92 | +
|
| 93 | +mysql> delete from world; |
| 94 | +ERROR 1105 (HY000): sql in blacklist. |
| 95 | +mysql> delete from world where a =10; |
| 96 | +Query OK, 1 row affected (0.00 sec) |
| 97 | +#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 |
| 98 | +mysql> select count(*) from test_shard_hash where id >1; |
| 99 | ++----------+ |
| 100 | +| count(*) | |
| 101 | ++----------+ |
| 102 | +| 24 | |
| 103 | ++----------+ |
| 104 | +1 row in set (0.02 sec) |
| 105 | +
|
| 106 | +mysql> select count(*) from test_shard_hash where id > 1; |
| 107 | +ERROR 1105 (HY000): sql in blacklist. |
| 108 | +``` |
| 109 | + |
| 110 | +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。 |
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