数据库垂直拆分，水平拆分利器，cobar升级版mycat

1，关于Mycat

Mycat情报
基于阿里的开源cobar ，可以用于生产系统中，目前在做如下的一些改进：
非阻塞IO的实现，相对于目前的cobar，并发性能大大提升，而且不会陷入假死状态
优化线程池的分配，目前cobar的线程池分配效率不高
修复cobar一些ＢＵＧ
参考impala中的impala front部分的Java代码，实现高效的Map-Reduce，能够处理上亿的大数据量
实现自动分片特性，目前cobar需要手工分片，并有一定的编程限制
官方网站：
https://github.com/MyCATApache/
好多文档，大多数都是word的，写的非常详细。
https://github.com/MyCATApache/Mycat-doc
Mycat是cobar重新优化开发的版本，和cobar的很多配置都类似。
可以参考之前写的cobar安装：
http://blog.csdn.net/freewebsys/article/details/44022421

2，安装Mycat服务

下载二进制安装文件
https://github.com/MyCATApache/Mycat-download
解压缩到/usr/local/mycat
修改配置文件：

<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://org.opencloudb/">
    #数据库名称是TESTDB，sqlMaxLimit设置limit防止错误sql查询大量数据
    <schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100">
        #自动分库规则
        <!-- auto sharding by id (long) -->
        <table name="travelrecord" dataNode="dn1,dn2,dn3" rule="auto-sharding-long" />
        #全局配置表，所有数据均同步到每个数据库。
        <!-- global table is auto cloned to all defined data nodes ,so can join 
            with any table whose sharding node is in the same data node -->
        <table name="company" primaryKey="ID" type="global" dataNode="dn1,dn2,dn3" />
        <table name="goods" primaryKey="ID" type="global" dataNode="dn1,dn2" />

        <!-- random sharding using mod sharind rule -->
        <table name="hotnews" primaryKey="ID" dataNode="dn1,dn2,dn3" rule="mod-long" /> 
        <table name="employee" primaryKey="ID" dataNode="dn1,dn2"
            rule="sharding-by-intfile" />
        #关联子表配置，不太明白
        <table name="customer" primaryKey="ID" dataNode="dn1,dn2"
            rule="sharding-by-intfile">
            <childTable name="orders" primaryKey="ID" joinKey="customer_id"
                parentKey="id">
                <childTable name="order_items" joinKey="order_id"
                    parentKey="id" />
            </childTable>
            <childTable name="customer_addr" primaryKey="ID" joinKey="customer_id"
                parentKey="id" />
        </table>
    </schema>
    #配置多个dataNode，制定dataHost和数据库名称。
    <dataNode name="dn1" dataHost="localhost1" database="db1" />
    <dataNode name="dn2" dataHost="localhost1" database="db2" />
    <dataNode name="dn3" dataHost="localhost1" database="db3" />
    #配置dataHost的读写分配。同时mysql也要配置好，Master-Slave或Master-Master
    <dataHost name="localhost1" maxCon="1000" minCon="10" balance="0"
        writeType="0" dbType="mysql" dbDriver="native">
        <heartbeat>select user()</heartbeat>
        <!-- can have multi write hosts -->
        <writeHost host="hostM1" url="localhost:3306" user="root"
            password="123456">
            <!-- can have multi read hosts -->
            <!-- <readHost host="hostS1" url="localhost:3306" user="root" password="123456" 
                /> -->
        </writeHost>
        <!-- <writeHost host="hostM2" url="localhost:3316" user="root" password="123456"/> -->
    </dataHost>


</mycat:schema>

wrapper.conf是mycat的配置文件启动参数等
rule.xml 是配置规则xml
还有几个配置文件慢慢研究
创建数据库

CREATE DATABASE db1 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE DATABASE db2 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE DATABASE db3 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

服务启动:/bin/mycat start
/bin/mycat这个问题同时可以作为service，拷贝到/etc/init.d/目录下即可。

3，登陆mycat服务和管理端

登陆mycat服务：（端口8066）

# mysql -utest -ptest -h 127.0.0.1 -P8066
Warning: USING a password ON the command line interface can be insecure.
Welcome TO the MySQL monitor.  Commands END WITH ; OR \g.
Your MySQL connection id IS 1
Server version: 5.5.8-mycat-1.3 MyCat Server (OpenCloundDB)

Copyright (c) 2000, 2015, 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> SHOW DATABASES;
+----------+
| DATABASE |
+----------+
| TESTDB   |
+----------+
1 ROW IN SET (0.02 sec)

mysql> USE TESTDB;
Reading TABLE information FOR completion OF TABLE AND COLUMN names
You can turn off this feature TO GET a quicker startup WITH -A

DATABASE changed
mysql> SHOW TABLES;
+------------------+
| TABLES IN TESTDB |
+------------------+
| company          |
| customer         |
| customer_addr    |
| employee         |
| goods            |
| hotnews          |
| orders           |
| order_items      |
| travelrecord     |
+------------------+
9 ROWS IN SET (0.00 sec)

mysql> CREATE TABLE company(id INT NOT NULL PRIMARY KEY,name VARCHAR(100));
Query OK, 0 ROWS affected (0.05 sec)

mysql> EXPLAIN CREATE TABLE company(id INT NOT NULL PRIMARY KEY,name VARCHAR(100));
+-----------+---------------------------------------------------------------------+
| DATA_NODE | SQL                                                                 |
+-----------+---------------------------------------------------------------------+
| dn1       | CREATE TABLE company(id INT NOT NULL PRIMARY KEY,name VARCHAR(100)) |
| dn2       | CREATE TABLE company(id INT NOT NULL PRIMARY KEY,name VARCHAR(100)) |
| dn3       | CREATE TABLE company(id INT NOT NULL PRIMARY KEY,name VARCHAR(100)) |
+-----------+---------------------------------------------------------------------+
3 ROWS IN SET (0.01 sec)

mysql> INSERT INTO company(id,name) VALUES(1,‘hp‘); INSERT INTO company(id,name) VALUES(2,‘ibm‘); INSERT INTO company(id,name) VALUES(3,‘oracle‘);
Query OK, 3 ROWS affected (0.37 sec)

Query OK, 3 ROWS affected (0.01 sec)

Query OK, 3 ROWS affected (0.00 sec)

mysql> SELECT * FROM company ;
+----+--------+
| id | name   |
+----+--------+
|  1 | hp     |
|  2 | ibm    |
|  3 | oracle |
+----+--------+
3 ROWS IN SET (0.01 sec)

使用管理端登陆：（端口9066）

#  mysql -utest -ptest -h 127.0.0.1 -P9066
Warning: USING a password ON the command line interface can be insecure.
Welcome TO the MySQL monitor.  Commands END WITH ; OR \g.
Your MySQL connection id IS 2
Server version: 5.5.8-mycat-1.3 CobarManager@Alibaba

Copyright (c) 2000, 2015, 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> SHOW @@help;
+--------------------------------------+-----------------------------------+
| STATEMENT                            | DESCRIPTION                       |
+--------------------------------------+-----------------------------------+
| clear @@slow WHERE datanode = ?      | Clear slow SQL BY datanode        |
| clear @@slow WHERE schema = ?        | Clear slow SQL BY schema          |
| KILL @@connection id1,id2,...        | KILL the specified connections    |
| offline                              | CHANGE MyCat STATUS TO OFF        |
| online                               | CHANGE MyCat STATUS TO ON         |
| reload @@config                      | Reload ALL config FROM file       |
| reload @@route                       | Reload route config FROM file     |
| reload @@USER                        | Reload USER config FROM file      |
| ROLLBACK @@config                    | ROLLBACK ALL config FROM memory   |
| ROLLBACK @@route                     | ROLLBACK route config FROM memory |
| ROLLBACK @@USER                      | ROLLBACK USER config FROM memory  |
| SHOW @@backend                       | Report backend connection STATUS  |
| SHOW @@cache                         | Report system cache usage         |
| SHOW @@command                       | Report commands STATUS            |
| SHOW @@connection                    | Report connection STATUS          |
| SHOW @@connection.SQL                | Report connection SQL             |
| SHOW @@DATABASE                      | Report DATABASES                  |
| SHOW @@datanode                      | Report dataNodes                  |
| SHOW @@datanode WHERE schema = ?     | Report dataNodes                  |
| SHOW @@datasource                    | Report dataSources                |
| SHOW @@datasource WHERE dataNode = ? | Report dataSources                |
| SHOW @@heartbeat                     | Report heartbeat STATUS           |
| SHOW @@parser                        | Report parser STATUS              |
| SHOW @@processor                     | Report processor STATUS           |
| SHOW @@router                        | Report router STATUS              |
| SHOW @@server                        | Report server STATUS              |
| SHOW @@SESSION                       | Report front SESSION details      |
| SHOW @@slow WHERE datanode = ?       | Report datanode slow SQL          |
| SHOW @@slow WHERE schema = ?         | Report schema slow SQL            |
| SHOW @@SQL WHERE id = ?              | Report specify SQL                |
| SHOW @@SQL.detail WHERE id = ?       | Report EXECUTE detail STATUS      |
| SHOW @@SQL.EXECUTE                   | Report EXECUTE STATUS             |
| SHOW @@SQL.slow                      | Report slow SQL                   |
| SHOW @@threadpool                    | Report threadPool STATUS          |
| SHOW @@TIME.CURRENT                  | Report CURRENT TIMESTAMP          |
| SHOW @@TIME.startup                  | Report startup TIMESTAMP          |
| SHOW @@version                       | Report Mycat Server version       |
| stop @@heartbeat name:TIME           | Pause dataNode heartbeat          |
| switch @@datasource name:INDEX       | Switch dataSource                 |
+--------------------------------------+-----------------------------------+
39 ROWS IN SET (0.03 sec)

mysql> SHOW @@backend;
+------------+------+---------+-----------------+------+--------+--------+---------+------+--------+----------+------------+--------+---------+------------+
| processor  | id   | mysqlId | host            | port | l_port | net_in | net_out | life | closed | borrowed | SEND_QUEUE | schema | txlevel | autocommit |
+------------+------+---------+-----------------+------+--------+--------+---------+------+--------+----------+------------+--------+---------+------------+
| Processor0 |   12 |      33 | 127.0.0.1 | 3306 |  42505 |    596 |     501 | 3384 | FALSE  | FALSE    |          0 
.......

17 ROWS IN SET (0.03 sec)

mysql> SHOW @@connection;
+------------+------+-----------+------+------------+--------+---------+--------+---------+---------------+-------------+------------+---------+------------+
| PROCESSOR  | ID   | HOST      | PORT | LOCAL_PORT | SCHEMA | CHARSET | NET_IN | NET_OUT | ALIVE_TIME(S) | RECV_BUFFER | SEND_QUEUE | txlevel | autocommit |
+------------+------+-----------+------+------------+--------+---------+--------+---------+---------------+-------------+------------+---------+------------+
| Processor0 |    2 | 127.0.0.1 | 9066 |      35952 | NULL   | utf8    |    156 |    4107 |            40 |        4096 |          0 | NULL    | NULL       |
| Processor0 |    1 | 127.0.0.1 | 8066 |      16525 | TESTDB | utf8    |   2005 |    5132 |          3461 |        4096 |          0 | 3       | TRUE       |
+------------+------+-----------+------+------------+--------+---------+--------+---------+---------------+-------------+------------+---------+------------+
2 ROWS IN SET (0.02 sec)

mysql> SHOW @@heartbeat;
+--------+-------+-----------------+------+---------+-------+--------+---------+--------------+---------------------+-------+
| NAME   | TYPE  | HOST            | PORT | RS_CODE | RETRY | STATUS | TIMEOUT | EXECUTE_TIME | LAST_ACTIVE_TIME    | STOP  |
+--------+-------+-----------------+------+---------+-------+--------+---------+--------------+---------------------+-------+
| hostM1 | mysql | 127.0.0.1 | 3306 |       1 |     0 | idle   |   30000 | 0,0,0        | 2015-03-03 14:45:00 | FALSE |
+--------+-------+-----------------+------+---------+-------+--------+---------+--------------+---------------------+-------+
1 ROW IN SET (0.01 sec)

mysql> SHOW @@datanode;
+------+----------------+-------+-------+--------+------+------+---------+------------+----------+---------+---------------+
| NAME | DATHOST        | INDEX | TYPE  | ACTIVE | IDLE | SIZE | EXECUTE | TOTAL_TIME | MAX_TIME | MAX_SQL | RECOVERY_TIME |
+------+----------------+-------+-------+--------+------+------+---------+------------+----------+---------+---------------+
| dn1  | localhost1/db1 |     0 | mysql |      0 |    9 |   50 |      27 |          0 |        0 |       0 |            -1 |
| dn2  | localhost1/db2 |     0 | mysql |      0 |    4 |   50 |      26 |          0 |        0 |       0 |            -1 |
| dn3  | localhost1/db3 |     0 | mysql |      0 |    3 |   50 |      17 |          0 |        0 |       0 |            -1 |
+------+----------------+-------+-------+--------+------+------+---------+------------+----------+---------+---------------+
3 ROWS IN SET (0.01 sec)

mysql> SHOW @@cache;
+-------------------------------------+-------+------+--------+------+------+---------------+---------------+
| CACHE                               | MAX   | CUR  | ACCESS | HIT  | PUT  | LAST_ACCESS   | LAST_PUT      |
+-------------------------------------+-------+------+--------+------+------+---------------+---------------+
| SQLRouteCache                       | 10000 |    1 |      8 |    0 |    1 | 1425364473193 | 1425363891040 |
| TableID2DataNodeCache.TESTDB_ORDERS | 50000 |    0 |      0 |    0 |    0 |             0 |             0 |
| ER_SQL2PARENTID                     |  1000 |    0 |      0 |    0 |    0 |             0 |             0 |
+-------------------------------------+-------+------+--------+------+------+---------------+---------------+
3 ROWS IN SET (0.05 sec)

4，总结

初步安装测试了下mycat组件，还是非常不错的，确实比起cobar有不少的进步。
同时他们开发团队也说了，解决了cobar之前存在的问题。
有了全局表，这样可以使用join了，同时增加读写分离。
规则增加了不少，能满足大部分需求。
和cobar一样，mycat可以直接伪装成一个mysql服务器，对业务进行垂直拆分，水平拆分。平滑的进行数据扩展。
保证在原有系统上进行优化。接下来继续研究mycat，非常好的解决方案。