【Mycat】Mycat核心開發者帶你輕鬆掌握Mycat路由轉發！！
阿新 • • 發佈：2020-11-14
## 寫在前面
> 熟悉Mycat的小夥伴都知道，Mycat一個很重要的功能就是路由轉發，那麼，這篇文章就帶著大家一起來看看Mycat是如何進行路由轉發的，好了，不多說了，我們直接進入主題。
## 環境準備
### 軟體版本
作業系統：CentOS-6.8
JDK版本：jdk1.8
Mycat版本：Mycat-server-1.6
MySQL：5.7
注意：這裡，我將Mycat和MySQL安裝在同一臺虛擬機器(IP：192.168.209.140 主機名為:binghe140)，大家也可以將Mycat和MySQL安裝到不同的主機上，測試效果是一樣的。
### 建立物理庫
```sql
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
```xml
```
### server.xml配置
```xml
```
### rule.xml配置
```xml
```
## 登入Mycat
### 登入Mycat
命令列輸入以下命令登入Mycat
```sql
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>
```
## 建立表測試
輸入以下命令檢視建立表的路由
```sql
create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int);
```
結果如下：
```sql
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>
```
說明建立表的SQL語句被Mycat路由到dn1,dn2,dn3三個節點上，也就是說在3個節點上都執行了建立表的SQL。
我們輸入建表語句：
```sql
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)
```
此時，將會在dn1,dn2,dn3三個節點上建立travelrecord表。
## 錄入資料測試
**錄入到dn1節點**
我們在命令列輸入如下SQL語句
```sql
explain insert into travelrecord (id,user_id,traveldate,fee,days) values(100001,'binghe','2020-11-10',510.5,3);
```
結果如下：
```sql
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)
```
說明Mycat將SQL路由到了dn1節點。
我們執行插入語句：
```sql
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>
```
**錄入到dn2節點**
我們在命令列輸入如下語句：
```sql
explain insert into travelrecord (id,user_id,traveldate,fee,days) values(8000004,'binghe','2020-11-10',510.5,3);
```
結果如下：
```sql
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)
```
說明Mycat將SQL路由到了dn2節點，我們執行插入語句：
```sql
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節點**
我們在命令列輸入如下語句
```sql
explain insert into travelrecord (id,user_id,traveldate,fee,days) values(10000004,'binghe','2020-11-10',510.5,3);
```
結果為：
```sql
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)
```
說明Mycat將SQL路由到了dn3節點，我們同樣執行插入語句的操作
```sql
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)
```
## 查詢測試
### 查詢所有資料
在命令列執行如下語句：
```sql
explain select * from travelrecord;
```
結果為：
```sql
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)
```
說明查詢所有的資料，Mycat是將SQL語句路由到了所有的資料分片，即dn1,dn2,dn3節點上。
### 根據id查詢指定資料
我們分別在命令列中執行如下SQL:
```sql
explain select * from travelrecord where id = 1000004;
explain select * from travelrecord where id = 8000004;
explain select * from travelrecord where id = 10000004;
```
得到的結果依次如下：
```sql
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)
```
說明：按照分片欄位查詢，Mycat只會將SQL路由到指定的資料分片。
## 刪表測試
在命令列輸入如下SQL：
```sql
explain drop table travelrecord;
```
結果如下
```sql
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)
```
有結果可知，刪表操作和建立表操作一樣，Mycat在本例項中都會將SQL路由到所有的資料分片。
**注意：本文的Mycat路由結果針對本文的配置例項，其他配置下，Mycat的路由結果可能會有不同。**
**好了，我們今天就到這兒吧，我是冰河，我們下期見~~**
## 重磅福利
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