mysql故障转移读写分离_使用ProxySQL实现MySQL Group Replication的故障转移、读写分离（二）...

在上一篇文章《使用ProxySQL实现MySQL Group Replication的故障转移、读写分离(一) 》 中，已经完成了MGR+ProxySQL集群的搭建，也测试了ProxySQL实现业务层面的故障转移，接下来继续测试读写分离。

王国维大师笔下的人生三境界：

第一重境界：昨夜西风凋碧树。独上高楼，望尽天涯路；

第二重境界：衣带渐宽终不悔，为伊消得人憔悴；

第三重境界：众里寻他千百度，蓦然回首，那人却在灯火阑珊处。

作为一个一根筋的学渣程序员,我还没能想透彻。但是数据库读写分离的三境界却有了一定的了解，我们不妨来看一看MySQL数据库读写分离的三境界。

第一重境界：人工实现读写分离。通过IP、端口读写分离，业务层面人工识别读写语句，然后将其分配到不同的主机，实现读写分离；

第二重境界：正则实现读写分离。通过路由中间件识别SQL语句，通过正则表达式匹配SQL语句，然后根据匹配结果分发到不同的主机；

第三重境界：识别TOP SQL，将高负载SQL分发到不同的主机；

(一)第一境界：人工实现读写分离

通过IP、端口读写分离，业务层面人工识别读写语句，然后使用不同的连接数据库配置信息，将其分配到不同的主机，实现读写分离。在ProxySQL里面，我们是通过端口来实现读写分离的。具体操作如下：

STEP1：配置ProxySQL在两个端口上侦听，并且重新启动ProxySQL

mysql -uadmin -padmin -h127.0.0.1 -P6032

mysql> SET mysql-interfaces='0.0.0.0:6401;0.0.0.0:6402';-- save it on disk and restart proxysqlmysql> SAVE MYSQL VARIABLES TO DISK;

mysql> PROXYSQL RESTART;

STEP2：配置路由规则，通过端口将请求分发到不同的组

mysql> INSERT INTO mysql_query_rules (rule_id,active,proxy_port,destination_hostgroup,apply) VALUES (1,1,6401,10,1), (3,1,6402,20,1);

mysql> LOAD MYSQL QUERY RULES TORUNTIME;

mysql> SAVE MYSQL QUERY RULES TO DISK;

这样，通过6401端口访问数据库的请求就会被转发到组1(写组)中，通过6402端口访问数据库的请求会被转发到组3(读组)中，从而实现读写分离，具体使用6401端口还是6402端口访问数据库，取决于开发人员人工识别SQL的读写特性。

(二)第二境界：使用正则表达式实现读写分离

通过路由中间件识别SQL语句，通过正则表达式匹配SQL语句，然后根据匹配结果分发到不同的主机。操作过程如下

STEP1:为避免干扰测试，删除之前定义的规则

DELETE FROM mysql_query_rules;

STEP2:定义新的读写分离规则

INSERT INTO mysql_query_rules (rule_id,active,match_digest,destination_hostgroup,apply) VALUES(1,1,'^SELECT.*FOR UPDATE$',1,1);INSERT INTO mysql_query_rules (rule_id,active,match_digest,destination_hostgroup,apply) VALUES(2,1,'^SELECT',3,1);LOAD MYSQL QUERY RULES TORUNTIME;SAVE MYSQL QUERY RULES TO DISK;

现在，ProxySQL的路由规则为：SELECT FOR UPDATE操作将被路由到组1(写组);

其它的SELECT语句将被路由到组3(读组);

其它的路由到默认组，即组1。

这里对使用正则表达式方式进行测试，整个过程如下：

(1)测试之前读写组信息修改

--根据组的规则：最多1个写节点，其余的写节点放入备用写组。目前我们可以看到节点192.168.10.13是写节点，其余2个节点是备用写节点，没有读节点

mysql> select * frommysql_group_replication_hostgroups;+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

| writer_hostgroup | backup_writer_hostgroup | reader_hostgroup | offline_hostgroup | active | max_writers | writer_is_also_reader | max_transactions_behind | comment |

+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

| 1 | 2 | 3 | 4 | 1 | 1 | 0 | 100 | NULL |

+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

1 row in set (0.00sec)

mysql> mysql> select * fromruntime_mysql_servers;+--------------+---------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+

| hostgroup_id | hostname | port | gtid_port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |

+--------------+---------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+

| 1 | 192.168.10.13 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | |

| 2 | 192.168.10.12 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | |

| 2 | 192.168.10.11 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | |

+--------------+---------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+

3 rows in set (0.01sec)--为了实现读写分离，需要有读节点，我们可以修改writer_is_also_reader参数，让backup_writer_hostgroup中的节点既做备用写节点，又做读节点mysql> update mysql_group_replication_hostgroups set writer_is_also_reader = 2;

Query OK,1 row affected (0.00sec)

mysql> select * frommysql_group_replication_hostgroups;+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

| writer_hostgroup | backup_writer_hostgroup | reader_hostgroup | offline_hostgroup | active | max_writers | writer_is_also_reader | max_transactions_behind | comment |

+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

| 1 | 2 | 3 | 4 | 1 | 1 | 2 | 100 | NULL |

+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

1 row in set (0.00sec)

mysql>mysql> select * fromruntime_mysql_group_replication_hostgroups;+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

| writer_hostgroup | backup_writer_hostgroup | reader_hostgroup | offline_hostgroup | active | max_writers | writer_is_also_reader | max_transactions_behind | comment |

+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

| 1 | 2 | 3 | 4 | 1 | 1 | 0 | 100 | NULL |

+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

1 row in set (0.00sec)--需要生效、永久保存mysql server配置

mysql> load mysql servers toruntime;

Query OK,0 rows affected (0.01sec)

mysql> save mysql servers to disk;

Query OK,0 rows affected (0.03sec)

mysql> select * fromruntime_mysql_group_replication_hostgroups;+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

| writer_hostgroup | backup_writer_hostgroup | reader_hostgroup | offline_hostgroup | active | max_writers | writer_is_also_reader | max_transactions_behind | comment |

+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

| 1 | 2 | 3 | 4 | 1 | 1 | 2 | 100 | NULL |

+------------------+-------------------------+------------------+-------------------+--------+-------------+-----------------------+-------------------------+---------+

1 row in set (0.01sec)--最终mysql server的组信息如下

mysql> select * fromruntime_mysql_servers;+--------------+---------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+

| hostgroup_id | hostname | port | gtid_port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |

+--------------+---------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+

| 1 | 192.168.10.13 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | |

| 3 | 192.168.10.12 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | |

| 3 | 192.168.10.11 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | |

| 2 | 192.168.10.11 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | |

| 2 | 192.168.10.12 | 3306 | 0 | ONLINE | 1 | 0 | 1000 | 0 | 0 | 0 | |

+--------------+---------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+

5 rows in set (0.00 sec)

(2)导入规则

--为避免测试干扰，先删除之前的规则

DELETE FROMmysql_query_rules;--导入规则

INSERT INTO mysql_query_rules (rule_id,active,match_digest,destination_hostgroup,apply) VALUES(1,1,'^SELECT.*FOR UPDATE$',1,1);INSERT INTO mysql_query_rules (rule_id,active,match_digest,destination_hostgroup,apply) VALUES(2,1,'^SELECT',3,1);--生效、保存规则

LOAD MYSQL QUERY RULES TORUNTIME;SAVE MYSQL QUERY RULES TO DISK;

(3)测试规则是否生效

测试SQL语句：

mysql -uusera -p123456 -h192.168.10.10 -P6033--写测试

insert into testdb.test01 values(3,'c');--读测试

SELECT * fromtestdb.test01;--正则大小写测试

select * fromtestdb.test01;--select for update测试

SELECT * from testdb.test01 FOR UPDATE;select * from testdb.test01 FOR UPDATE;exit;

ProxySQL将SQL语句分发到哪一台主机上执行，可以查看统计视图：stats_mysql_query_digest和stats_mysql_query_digest_reset。两个表的内容和结构相同，但是查询stats_mysql_query_digest_reset表会自动将内部统计信息重置为零，即执行了stats_mysql_query_digest_reset的查询后，2个表的数据都会被完全清除。这里我们直接使用stats_mysql_query_digest_reset来查询上面的测试：

mysql> select hostgroup,schemaname,username,digest_text,count_star fromstats_mysql_query_digest_reset;+-----------+--------------------+----------+----------------------------------------+------------+

| hostgroup | schemaname | username | digest_text | count_star |

+-----------+--------------------+----------+----------------------------------------+------------+

| 1 | information_schema | usera | SELECT * from testdb.test01 FOR UPDATE | 1 |

| 3 | information_schema | usera | select * from testdb.test01 | 1 |

| 3 | information_schema | usera | SELECT * from testdb.test01 | 1 |

| 1 | information_schema | usera | select * from testdb.test01 FOR UPDATE | 1 |

| 1 | information_schema | usera | insert into testdb.test01 values(?,?) | 1 |

| 1 | information_schema | usera | select @@version_comment limit ? | 1 |

+-----------+--------------------+----------+----------------------------------------+------------+

6 rows in set (0.00 sec)

可以看到，正则表达式规则不区分大小写，并且根据匹配规则，已经将SQL发到了对应的主机上执行。

个人觉得基于正则表达式路由SQL语句到不同主机执行已经十分智能了，然而ProxySQL官方并不建议这么干，因为我们无法准确知道各类型的SQL语句的开销，从而可能会导致流量分布不均。

接下来我们来看看ProxySQL推荐的方法，基于正则表达式和摘要进行读写拆分。

(三)第三境界：使用正则表达式和digest实现读写分离

以下是ProxySQL推荐的有效设置读写分离的配置过程：

(1)配置ProxySQL以将所有流量仅发送到一个MySQL主节点，写和读都发送到一个节点；

(2)检查stats_mysql_query_digest哪些是最昂贵的SELECT语句；

(3)确定哪些昂贵的语句应移至读节点；

(4)配置mysql_query_rules(创建规则)以仅将昂贵的SELECT语句发送给读者

总之，想法非常简单：仅发送那些你想发送的SQL给读节点，而不是发送所有SELECT语句。

我们来整理一下整个过程：

STEP1:去除规则，让所有SQL语句都在默认组上执行

mysql> delete frommysql_query_rules;

Query OK,2 rows affected (0.00sec)

mysql> LOAD MYSQL QUERY RULES TORUNTIME;

Query OK,0 rows affected (0.00sec)

mysql> SAVE MYSQL QUERY RULES TO DISK;

Query OK,0 rows affected (0.01 sec)

STEP2:查找最昂贵的SQL

假设目前所有读写操作都在同一台机器上执行，且执行了很久，读写比例都具有代表性，我们可以使用stats_mysql_query_digest查找最昂贵的SQL，可以多维度进行查找。

(1)查找查询总耗时最多的5个SQL

mysql> SELECT digest,SUBSTR(digest_text,0,25),count_star,sum_time FROM stats_mysql_query_digest WHERE digest_text LIKE 'SELECT%' ORDER BY sum_time DESC LIMIT 5;+--------------------+--------------------------+------------+----------+

| digest | SUBSTR(digest_text,0,25) | count_star | sum_time |

+--------------------+--------------------------+------------+----------+

| 0xBF001A0C13781C1D | SELECT c FROM sbtest1 WH | 9594 | 9837782 |

| 0xC4771449056AB3AC | SELECT c FROM sbtest14 W | 9984 | 9756595 |

| 0xD84E4E04982951C1 | SELECT c FROM sbtest9 WH | 9504 | 9596185 |

| 0x9B090963F41AD781 | SELECT c FROM sbtest10 W | 9664 | 9530433 |

| 0x9AF59B998A3688ED | SELECT c FROM sbtest2 WH | 9744 | 9513180 |

+--------------------+--------------------------+------------+----------+

5 rows in set (0.00 sec)

(2)查看执行次数最多的5个SQL语句

mysql> SELECT digest,SUBSTR(digest_text,0,25),count_star,sum_time FROM stats_mysql_query_digest WHERE digest_text LIKE 'SELECT%' ORDER BY count_star DESC LIMIT 5;+--------------------+--------------------------+------------+----------+

| digest | SUBSTR(digest_text,0,25) | count_star | sum_time |

+--------------------+--------------------------+------------+----------+

| 0xC4771449056AB3AC | SELECT c FROM sbtest14 W | 9984 | 9756595 |

| 0x9AF59B998A3688ED | SELECT c FROM sbtest2 WH | 9744 | 9513180 |

| 0x9B090963F41AD781 | SELECT c FROM sbtest10 W | 9664 | 9530433 |

| 0x03744DC190BC72C7 | SELECT c FROM sbtest5 WH | 9604 | 9343514 |

| 0x1E7B7AC5611F30C2 | SELECT c FROM sbtest6 WH | 9594 | 9245838 |

+--------------------+--------------------------+------------+----------+

(3)查看平均执行时间最长的5个SQL语句

mysql> SELECT digest,SUBSTR(digest_text,0,25),count_star,sum_time, sum_time/count_star as avg_time FROM stats_mysql_query_digest WHERE digest_text LIKE 'SELECT%' ORDER BY avg_time DESC LIMIT 5;+--------------------+--------------------------+------------+----------+----------+

| digest | SUBSTR(digest_text,0,25) | count_star | sum_time | avg_time |

+--------------------+--------------------------+------------+----------+----------+

| 0x0DCAF47B4A363A7A | SELECT * from testdb.tes | 1 | 11400 | 11400 |

| 0x2050E81DB9C7038E | select * from testdb.tes | 1 | 10817 | 10817 |

| 0xF340A73F6EDA5B20 | SELECT c FROM sbtest11 W | 964 | 1726994 | 1791 |

| 0xC867A28C90150A81 | SELECT DISTINCT c FROM s | 929 | 1282699 | 1380 |

| 0x283AA9863F85EFC8 | SELECT DISTINCT c FROM s | 963 | 1318362 | 1369 |

+--------------------+--------------------------+------------+----------+----------+

(4)查看平均执行时间最长的5个SQL语句，且满足平均执行时间大于1s，并显示该SQL执行时间占所有SQL执行时间的百分比

SELECT digest,SUBSTR(digest_text,0,25),count_star,sum_time,sum_time/count_star as avg_time,round(sum_time/1000000*100/(SELECT sum(sum_time/1000000) FROM stats_mysql_query_digest ),3) aspctFROMstats_mysql_query_digestWHERE digest_text LIKE 'SELECT%'

AND sum_time/count_star > 1000000

ORDER BY avg_time DESC LIMIT 5;

说明：在测试该语句时，是使用sysbench压测出来的数据，发现存在一个sum_time非常大的SQL，导致在求sum(sum_time)时返回NULL值，故先做了预处理，把sum_time/1000000变为进行计算。

STEP3:结合digest和正则表达式实现路由

我们先观察一下，未使用路由规则时候的流量分布，可以看到，所有流量都到了hostgroup1

mysql> select hostgroup,schemaname,username,digest_text,count_star fromstats_mysql_query_digest_reset;+-----------+--------------------+----------+---------------------------------------------------------------------+------------+

| hostgroup | schemaname | username | digest_text | count_star |

+-----------+--------------------+----------+---------------------------------------------------------------------+------------+

| 1 | information_schema | usera | SET PROFILING = ? | 1 |

| 1 | information_schema | usera | SHOW DATABASES | 3 |

| 1 | information_schema | usera | SHOW VARIABLES LIKE ?; | 2 |

| 1 | information_schema | usera | SET NAMES utf8mb4 | 3 |

| 1 | tssysbench | usera | INSERT INTO sbtest15 (id, k, c, pad) VALUES (?, ?, ?, ?) | 1285 |

| 1 | tssysbench | usera | INSERT INTO sbtest14 (id, k, c, pad) VALUES (?, ?, ?, ?) | 1309 |

| 1 | tssysbench | usera | INSERT INTO sbtest13 (id, k, c, pad) VALUES (?, ?, ?, ?) | 1303 |

| 1 | tssysbench | usera | INSERT INTO sbtest12 (id, k, c, pad) VALUES (?, ?, ?, ?) | 1240 |

| 1 | tssysbench | usera | UPDATE sbtest3 SET k=k+? WHERE id=? | 1280 |

| 1 | tssysbench | usera | UPDATE sbtest2 SET k=k+? WHERE id=? | 1280 |

| 1 | tssysbench | usera | UPDATE sbtest1 SET k=k+? WHERE id=? | 1219 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest15 WHERE id BETWEEN ? AND ? ORDER BY c | 1207 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest14 WHERE id BETWEEN ? AND ? ORDER BY c | 1262 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest11 WHERE id BETWEEN ? AND ? ORDER BY c | 1227 |

插入路由规则：

--根据digest插入规则，匹配特定的SQL语句

INSERT INTO mysql_query_rules (rule_id,active,digest,destination_hostgroup,apply) VALUES(1,1,'0x0DCAF47B4A363A7A',3,1);INSERT INTO mysql_query_rules (rule_id,active,digest,destination_hostgroup,apply) VALUES(2,1,'0x63F9BD89D906209B',3,1);INSERT INTO mysql_query_rules (rule_id,active,digest,destination_hostgroup,apply) VALUES(3,1,'0x10D8D9CC551E199B',3,1);INSERT INTO mysql_query_rules (rule_id,active,digest,destination_hostgroup,apply) VALUES(4,1,'0xC867A28C90150A81',3,1);INSERT INTO mysql_query_rules (rule_id,active,digest,destination_hostgroup,apply) VALUES(5,1,'0x283AA9863F85EFC8',3,1);INSERT INTO mysql_query_rules (rule_id,active,digest,destination_hostgroup,apply) VALUES(6,1,'0x16BD798E66615299',3,1);--根据正则表达式插入规则，匹配所有SELECT 开头的语句

INSERT INTO mysql_query_rules (rule_id,active,match_digest,destination_hostgroup,apply) VALUES(7,1,'^SELECT COUNT\(\*\)',3,1);--使规则生效、保存

LOAD MYSQL QUERY RULES TORUNTIME;SAVE MYSQL QUERY RULES TO DISK;

STEP4:使用sysbench查询，再次查看流量分布，可以看到，符合路由条件的SQL语句已经转移到了hostgroup3执行。

mysql> select hostgroup,schemaname,username,digest_text,count_star fromstats_mysql_query_digest_reset;+-----------+------------+----------+---------------------------------------------------------------------+------------+

| hostgroup | schemaname | username | digest_text | count_star |

+-----------+------------+----------+---------------------------------------------------------------------+------------+

| 1 | tssysbench | usera | UPDATE sbtest3 SET k=k+? WHERE id=? | 863 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest14 WHERE id BETWEEN ? AND ? ORDER BY c | 841 |

| 3 | tssysbench | usera | SELECT DISTINCT c FROM sbtest13 WHERE id BETWEEN ? AND ? ORDER BY c | 765 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest12 WHERE id BETWEEN ? AND ? ORDER BY c | 837 |

| 3 | tssysbench | usera | SELECT DISTINCT c FROM sbtest11 WHERE id BETWEEN ? AND ? ORDER BY c | 813 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest10 WHERE id BETWEEN ? AND ? ORDER BY c | 861 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest9 WHERE id BETWEEN ? AND ? ORDER BY c | 835 |

| 3 | tssysbench | usera | SELECT DISTINCT c FROM sbtest8 WHERE id BETWEEN ? AND ? ORDER BY c | 823 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest6 WHERE id BETWEEN ? AND ? ORDER BY c | 834 |

| 1 | tssysbench | usera | UPDATE sbtest5 SET c=? WHERE id=? | 870 |

| 3 | tssysbench | usera | SELECT DISTINCT c FROM sbtest4 WHERE id BETWEEN ? AND ? ORDER BY c | 802 |

| 1 | tssysbench | usera | UPDATE sbtest1 SET c=? WHERE id=? | 835 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest3 WHERE id BETWEEN ? AND ? ORDER BY c | 838 |

| 1 | tssysbench | usera | SELECT DISTINCT c FROM sbtest2 WHERE id BETWEEN ? AND ? ORDER BY c | 885

至此，以实现根据负载进行流量分发。

================================================================================================================

附1：读写分离路由规则表解析

读写分离路由解析信息存放在mysql_query_rules表中，表的语法如下：

CREATE TABLEmysql_query_rules (

rule_idINTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,

activeINT CHECK (active IN (0,1)) NOT NULL DEFAULT 0,

usernameVARCHAR,

schemanameVARCHAR,

flagININT CHECK (flagIN >= 0) NOT NULL DEFAULT 0,

client_addrVARCHAR,

proxy_addrVARCHAR,

proxy_portINT,

digestVARCHAR,

match_digestVARCHAR,

match_patternVARCHAR,

negate_match_patternINT CHECK (negate_match_pattern IN (0,1)) NOT NULL DEFAULT 0,

re_modifiersVARCHAR DEFAULT 'CASELESS',

flagOUTINT CHECK (flagOUT >= 0),

replace_patternVARCHAR CHECK(CASE WHEN replace_pattern IS NULL THEN 1 WHEN replace_pattern IS NOT NULL AND match_pattern IS NOT NULL THEN 1 ELSE 0 END),

destination_hostgroupINT DEFAULT NULL,

cache_ttlINT CHECK(cache_ttl > 0),

cache_empty_resultINT CHECK (cache_empty_result IN (0,1)) DEFAULT NULL,

reconnectINT CHECK (reconnect IN (0,1)) DEFAULT NULL,

timeoutINTUNSIGNED,

retriesINT CHECK (retries>=0 AND retries <=1000),

delayINTUNSIGNED,

next_query_flagININTUNSIGNED,

mirror_flagOUTINTUNSIGNED,

mirror_hostgroupINTUNSIGNED,

error_msgVARCHAR,

OK_msgVARCHAR,

sticky_connINT CHECK (sticky_conn IN (0,1)),

multiplexINT CHECK (multiplex IN (0,1,2)),

gtid_from_hostgroupINTUNSIGNED,log INT CHECK (log IN (0,1)),

applyINT CHECK(apply IN (0,1)) NOT NULL DEFAULT 0,

commentVARCHAR)

重要列的含义如下：rule_id         ：规则的id，是主键，具有唯一非空特性，规则匹配时，按照rule_id从小到大匹配；

active          ：规则是否启用，1代表启用；

username:   : 匹配来自特定用户的流量；

client_addr   ：匹配来自特定客户端的流量；

proxy_addr   : 匹配特定本地IP上的传入流量；

proxy_port    : 匹配特定本地端口上的传入流量，具体见上面使用端口进行读写分离的方案；

digest           : 将查询与特定摘要匹配，每个相同的SQL文本都会生成一个唯一的diagst码(类似Oracle的sql_id)，按照码进行匹配；

match_digest ：将查询摘要与正则表达式匹配；

match_pattern：将查询文本与正则表达式匹配；

destination_hostgroup：将匹配的查询路由到该主机组，除非存在已启动的事务并且已登录的用户将transaction_persistent标志设置为1(请参见表mysql_users)，否则将发生这种情况。

cache_ttl     ：查询结果缓存保留的时间(单位：s)；

timeout       ：执行匹配或重写的查询的最大超时(以毫秒为单位)。如果查询的运行时间超过特定阈值，则会自动终止该查询。如果未指定超时，则mysql-default_query_timeout应用全局变量

retries         : 在执行查询检测到失败的情况下，重新执行查询的次数

apply           : 如果这只为1，则不再匹配后面的查询规则。

附2：本次实验用到的sysbench脚本

-- 准备阶段sysbench /usr/share/sysbench/oltp_read_write.lua --mysql-host=192.168.10.10 --mysql-port=6033 --mysql-user=usera --mysql-password='123456' --mysql-db=tssysbench --db-driver=mysql --tables=15 --table-size=50000 --report-interval=10 --threads=4 --time=120prepare-- 测试阶段

sysbench/usr/share/sysbench/oltp_read_write.lua --mysql-host=192.168.10.10 --mysql-port=6033 --mysql-user=usera --mysql-password='123456' --mysql-db=tssysbench --db-driver=mysql --tables=15 --table-size=500000 --report-interval=10 --threads=4 --time=120run-- 清除阶段

sysbench/usr/share/sysbench/oltp_read_write.lua --mysql-host=192.168.10.10 --mysql-port=6033 --mysql-user=usera --mysql-password='123456' --mysql-db=tssysbench --db-driver=mysql --tables=15 --table-size=500000 --report-interval=10 --threads=4 --time=120 cleanup

【完】