本篇前提：
mycat配置正确，且能正常启动。
1、schema.xml
<table>标签：
dataNode -- 分片节点指定（取值：dataNode中的name属性值）rule ------ 分片规则选择（取值：rule标签中的name属性值）
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[[email protected] conf]# vim schema.xml 1 <?xml version="1.0"?> 2 <!DOCTYPE mycat:schema SYSTEM "schema.dtd"> 3 <mycat:schema xmlns:mycat="http://io.mycat/"> 4 <schema name="mycatdb" checkSQLschema="false" sqlMaxLimit="100"> 5 <!-- auto sharding by id (long) --> 6 <table name="t_person" dataNode="dn1,dn2" rule="mod-long" /> 7 <table name="t_user" primaryKey="id" dataNode="dn1,dn2" rule="sharding-by-murmur" /> <!-- 全局表 --> 8 <!-- table name="province" type="global" dataNode="dn1,dn2,dn3" /> 9 10 <table name="student" dataNode="dn1,dn2" rule="auto-sharding-long-sharejoin" /> 11 <table name="score" dataNode="dn2,dn3" rule="auto-sharding-long-sharejoin" /> 12 <table name="score" dataNode="dn1,dn2" rule="auto-sharding-long-sharejoin" /> 13 <!-- ER分片 --> 14 <table name="customer" dataNode="dn1,dn2,dn3" rule="auto-sharding-long-customer"> 15 <childTable name="orders" joinKey="customer_id" parentKey="id"/> 16 </table --> 17 18 <table name="user" primaryKey="id" dataNode="dn1,dn2" rule="mod-long-test"> 19 <childTable name="cell" joinKey="user_id" parentKey="id"/> 20 <childTable name="note" joinKey="user_id" parentKey="id"/> 21 <childTable name="lit" joinKey="user_id" parentKey="id"/> 22 <childTable name="lit_usr" joinKey="user_id" parentKey="id"/> 23 </table> 24 25 </schema> 26 27 <dataNode name="dn1" dataHost="localhost1" database="db1" /> 28 <dataNode name="dn2" dataHost="localhost1" database="db2" /> 29 <dataNode name="dn3" dataHost="localhost1" database="db3" /> 30 31 <dataHost name="localhost1" maxCon="500" minCon="100" balance="2" 32 writeType="1" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100"> 33 <heartbeat>select user()</heartbeat> 34 35 <writeHost host="hostM1" url="localhost:3306" user="root" 36 password="" > 37 </writeHost> 38 39 </dataHost> 40 </mycat:schema>
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2、rule.xml
<tablerule>标签
columns—— 指定分片列的列名；
algorithm—- 选择分片算法（function标签中的name属性） <function>标签
定义算法，class–分片算法类名及路径；
<count> 分片数，需要分成多少片；
<mapFile> 范围分片时使用的规则；
<type>默认值是0，表示分片列的值是整数，非0表示是字符串。
[[email protected] conf]# vim rule.xml <?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mycat:rule SYSTEM "rule.dtd"><mycat:rule xmlns:mycat="http://io.mycat/"> <tableRule name="mod-long"> <rule> <columns>person_id</columns> <algorithm>mod-long</algorithm> </rule> </tableRule> <tableRule name="mod-long-test"> <rule> <columns>id</columns> <algorithm>mod-long</algorithm> </rule> </tableRule> <tableRule name="auto-sharding-long-customer"> <rule> <columns>id</columns> <algorithm>auto-sharding-long-customer</algorithm> </rule> </tableRule> <tableRule name="auto-sharding-long-sharejoin"> <rule> <columns>id</columns> <algorithm>auto-sharding-long-sharejoin</algorithm> </rule> </tableRule> <tableRule name="sharding-by-murmur"> <rule> <columns>uuid</columns> <algorithm>murmur</algorithm> </rule> </tableRule> <function name="mod-long" class="io.mycat.route.function.PartitionByMod"> <!-- how many data nodes --> <property name="count">2</property> </function> <function name="auto-sharding-long-customer" class="io.mycat.route.function.AutoPartitionByLong"> <property name="mapFile">autopartition-long.txt</property> </function> <function name="auto-sharding-long-sharejoin" class="io.mycat.route.function.AutoPartitionByLong"> <property name="mapFile">autopartition-long-sharejoin.txt</property> </function> <function name="murmur" class="io.mycat.route.function.PartitionByMurmurHash"> <property name="seed">0</property><!-- 默认是0 --> <property name="type">1</property><!-- 默认是0, 表示integer, 非0表示string--> <property name="count">2</property><!-- 要分片的数据库节点数量，必须指定，否则没法分片 --> <property name="virtualBucketTimes">160</property><!-- 一个实际的数据库节点被映射为这么多虚拟节点，默认是160倍，也就是虚拟节点数是物理节点数的160倍 --> <!-- <property name="weightMapFile">weightMapFile</property> 节点的权重，没有指定权重的节点默认是1。以properties文件的格式填写，以从0开始到count-1的整数值也就是节点索引为key，以节点权重值为值。>所有权重值必须是正整数，否则以1代替 --> <property name="bucketMapPath">/usr/local/mycat/logs/bucketMapPath</property> <!-- 用于测试时观察各物理节点与虚拟节点的分布情况，如果指定了这个属性，会把虚拟节点的murmur hash值与物理节点的映射按行输出到这个文件，没有默认值，如果不指定，就不会输出任何东西 --> </function></mycat:rule>
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3、说明
对于以上配置文件，选择一个来说明，其他类推。
对t_person表：
在sechma.xml中：
<table name="t_person" dataNode="dn1,dn2" rule="mod-long" />
说明，将其分别存在分片节点dn1和dn2上， 分别对应实际MySQL数据库的db1和db2：
<dataNode name="dn1" dataHost="localhost1" database="db1" /> <dataNode name="dn2" dataHost="localhost1" database="db2" />
数据库db1和db2又在分片主机localhost1上，localhost1是连接的实际MySQL服务器，
<writeHost host="hostM1" url="localhost:3306" user="root" password="" >
因此，t_person表会被按照rule=’mod-long’被分别存储在实际MySQL服务器的db1和db2中。
在rule.xml中，
mod-long算法指定其分片里是id，分片算法是mod-long，对id列进行取模。
count=2，说明对2取模，
取模后值为0，存入dn1，取模后值为1，存入dn2.
4、验证
在mycat数据库中创建含id列的t_person表，插入5条数据：
[[email protected] ~]# mysql -uroot -p123456 -h127.0.0.1 -P8066Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 1Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.mysql> show databases;+----------+| DATABASE |+----------+| mycatdb |+----------+1 row in set (0.00 sec)mysql> use mycatdb;Database changedmysql> mysql> create table t_person(id int(11) primary key, name varchar(32));Query OK, 0 rows affected (0.04 sec)mysql> desc t_person;+-------+-------------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra |+-------+-------------+------+-----+---------+-------+| id | int(11) | NO | PRI | NULL | || name | varchar(32) | YES | | NULL | |+-------+-------------+------+-----+---------+-------+2 rows in set (0.01 sec)mysql> mysql> insert into t_person(id,name) values(1,"Moxiao1"),(2,"Moxiao2"),(3,"Moxiao3"),(4,"Moxiao4"),(5,"Moxiao5");Query OK, 5 rows affected (0.02 sec)Records: 3 Duplicates: 0 Warnings: 0mysql> mysql> select * from t_person;+----+---------+| id | name |+----+---------+| 2 | Moxiao2 || 4 | Moxiao4 || 1 | Moxiao1 || 3 | Moxiao3 || 5 | Moxiao5 |+----+---------+5 rows in set (0.04 sec)
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在实际的物理MySQL服务器中，查看：
[[email protected] conf]# mysql -uroot -pEnter password: Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 522063Server version: 5.1.71-log Source distributionCopyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.mysql> show databases;+--------------------+| Database |+--------------------+| information_schema || db1 || db2 || db3 || estudy || mysql || test || yundras |+--------------------+8 rows in set (0.00 sec)mysql> select * from db1.t_person;+----+---------+| id | name |+----+---------+| 2 | Moxiao2 || 4 | Moxiao4 |+----+---------+2 rows in set (0.00 sec)mysql> select * from db2.t_person;+----+---------+| id | name |+----+---------+| 1 | Moxiao1 || 3 | Moxiao3 || 5 | Moxiao5 |+----+---------+3 rows in set (0.00 sec)
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t_person表成功被mycat自动分散到db1和db2两个库的t_person中。
解决单表数据量大的问题。在以分片列为条件进行查询时，会先查找其所在的分片，缩小查找范围。
mysql> explain select * from t_person where id=3;+-----------+-----------------------------------------------+| DATA_NODE | SQL |+-----------+-----------------------------------------------+| dn2 | SELECT * FROM t_person WHERE id = 3 LIMIT 100 |+-----------+-----------------------------------------------+1 row in set (0.01 sec)
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原文地址：https://www.cnblogs.com/jpfss/p/8205385.html
时间： 2024-08-14 20:21:49