写在前面
熟悉Mycat的小伙伴都知道，Mycat一个很重要的功能就是路由转发，那么，这篇文章就带着大家一起来看看Mycat是如何进行路由转发的，好了，不多说了，我们直接进入主题。
环境准备
软件版本
操作系统：CentOS-6.8
JDK版本：jdk1.8
Mycat版本：Mycat-server-1.6
MySQL：5.7
注意：这里，我将Mycat和MySQL安装在同一台虚拟机(IP：192.168.209.140 主机名为:binghe140)，大家也可以将Mycat和MySQL安装到不同的主机上，测试效果是一样的。
创建物理库
mysql -uroot -proot -h192.168.209.140 -P3306
drop database if exists db1;
create database db1;
drop database if exists db2;
create database db2;
drop database if exists db3;
create database db3;配置Mycat
schema.xml配置
select user()
server.xml配置
druidparser
binghe.123
binghe
test
binghe
true
rule.xml配置
id
func1
user_id
func1
sharding_id
hash-int
id
rang-long
id
mod-long
id
murmur
create_date
partbymonth
calldate
latestMonth
id
rang-mod
id
jump-consistent-hash
0
2
160
partition-hash-int.txt
autopartition-long.txt
3
8
128
24
yyyy-MM-dd
2020-01-01
partition-range-mod.txt
3
登录Mycat
登录Mycat
命令行输入以下命令登录Mycat
D:\>mysql -ubinghe -pbinghe.123 -h192.168.209.140 -P8066
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.5.8-mycat-1.6.1-RELEASE-20170807215126 MyCat Server (OpenCloundDB)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>创建表测试
输入以下命令查看创建表的路由
create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int); 结果如下：
mysql> explain create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int);
+-----------+-----------------------------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+-----------------------------------------------------------------------------------------------------------------------+
| dn1 | create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int) |
| dn2 | create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int) |
| dn3 | create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int) |
+-----------+-----------------------------------------------------------------------------------------------------------------------+
3 rows in set (0.00 sec)
mysql>说明创建表的SQL语句被Mycat路由到dn1,dn2,dn3三个节点上，也就是说在3个节点上都执行了创建表的SQL。
我们输入建表语句：
mysql> create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int);
Query OK, 0 rows affected (0.18 sec)此时，将会在dn1,dn2,dn3三个节点上创建travelrecord表。
录入数据测试
录入到dn1节点
我们在命令行输入如下SQL语句
explain insert into travelrecord (id,user_id,traveldate,fee,days) values(100001,'binghe','2020-11-10',510.5,3);结果如下：
mysql> explain insert into travelrecord (id,user_id,traveldate,fee,days) values(100001,'binghe','2020-11-10',510.5,3);
+-----------+-------------------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+-------------------------------------------------------------------------------------------------------------+
| dn1 | insert into travelrecord (id,user_id,traveldate,fee,days) values(100001,'binghe','2020-11-10',510.5,3) |
+-----------+-------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)说明Mycat将SQL路由到了dn1节点。
我们执行插入语句：
mysql> insert into travelrecord (id,user_id,traveldate,fee,days) values(100001,'binghe','2020-11-10',510.5,3);
Query OK, 1 row affected, 1 warning (0.01 sec)
mysql>录入到dn2节点
我们在命令行输入如下语句：
explain insert into travelrecord (id,user_id,traveldate,fee,days) values(8000004,'binghe','2020-11-10',510.5,3);结果如下：
mysql> explain insert into travelrecord (id,user_id,traveldate,fee,days) values(8000004,'binghe','2020-11-10',510.5,3);
+-----------+--------------------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+--------------------------------------------------------------------------------------------------------------+
| dn2 | insert into travelrecord (id,user_id,traveldate,fee,days) values(8000004,'binghe','2020-11-10',510.5,3) |
+-----------+--------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)说明Mycat将SQL路由到了dn2节点，我们执行插入语句：
mysql> insert into travelrecord (id,user_id,traveldate,fee,days) values(8000004,'binghe','2020-11-10',510.5,3);
Query OK, 1 row affected, 1 warning (0.06 sec)路由到dn3节点
我们在命令行输入如下语句
explain insert into travelrecord (id,user_id,traveldate,fee,days) values(10000004,'binghe','2020-11-10',510.5,3);结果为：
mysql> explain insert into travelrecord (id,user_id,traveldate,fee,days) values(10000004,'binghe','2020-11-10',510.5,3);
+-----------+---------------------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+---------------------------------------------------------------------------------------------------------------+
| dn3 | insert into travelrecord (id,user_id,traveldate,fee,days) values(10000004,'binghe','2020-11-10',510.5,3) |
+-----------+---------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)说明Mycat将SQL路由到了dn3节点，我们同样执行插入语句的操作
mysql> insert into travelrecord (id,user_id,traveldate,fee,days) values(10000004,'binghe','2020-11-10',510.5,3);
Query OK, 1 row affected, 1 warning (0.01 sec)查询测试
查询所有数据
在命令行执行如下语句：
explain select * from travelrecord;结果为：
mysql> explain select * from travelrecord;
+-----------+--------------------------------------+
| DATA_NODE | SQL |
+-----------+--------------------------------------+
| dn1 | SELECT * FROM travelrecord LIMIT 100 |
| dn2 | SELECT * FROM travelrecord LIMIT 100 |
| dn3 | SELECT * FROM travelrecord LIMIT 100 |
+-----------+--------------------------------------+
3 rows in set (0.01 sec)说明查询所有的数据，Mycat是将SQL语句路由到了所有的数据分片，即dn1,dn2,dn3节点上。
根据id查询指定数据
我们分别在命令行中执行如下SQL:
explain select * from travelrecord where id = 1000004;
explain select * from travelrecord where id = 8000004;
explain select * from travelrecord where id = 10000004;得到的结果依次如下：
mysql> explain select * from travelrecord where id = 1000004;
+-----------+---------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+---------------------------------------------------------+
| dn1 | SELECT * FROM travelrecord WHERE id = 1000004 LIMIT 100 |
+-----------+---------------------------------------------------------+
1 row in set (0.06 sec)
mysql> explain select * from travelrecord where id = 8000004;
+-----------+---------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+---------------------------------------------------------+
| dn2 | SELECT * FROM travelrecord WHERE id = 8000004 LIMIT 100 |
+-----------+---------------------------------------------------------+
1 row in set (0.00 sec)
mysql> explain select * from travelrecord where id = 10000004;
+-----------+----------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+----------------------------------------------------------+
| dn3 | SELECT * FROM travelrecord WHERE id = 10000004 LIMIT 100 |
+-----------+----------------------------------------------------------+
1 row in set (0.00 sec)说明：按照分片字段查询，Mycat只会将SQL路由到指定的数据分片。
删表测试
在命令行输入如下SQL：
explain drop table travelrecord;结果如下
mysql> explain drop table travelrecord;
+-----------+-------------------------+
| DATA_NODE | SQL |
+-----------+-------------------------+
| dn1 | drop table travelrecord |
| dn2 | drop table travelrecord |
| dn3 | drop table travelrecord |
+-----------+-------------------------+
3 rows in set (0.00 sec)有结果可知，删表操作和创建表操作一样，Mycat在本实例中都会将SQL路由到所有的数据分片。
注意：本文的Mycat路由结果针对本文的配置实例，其他配置下，Mycat的路由结果可能会有不同。
好了，我们今天就到这儿吧，我是冰河，我们下期见~~
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