Mycat使用之MySQL單庫分表及均分數據

#wget http://dl.mycat.io/1.6.5/Mycat-server-1.6.5-release-20180122220033-linux.tar.gz

#tar zxvf Mycat-server-1.6.5-release-20180122220033-linux.tar.gz
#vi /usr/local/mycat/conf/schema.xml

<table name="orderlog" dataNode="dn1" primaryKey="id" subTables="orderlog$1-3" rule="mod-long" />

<dataNode name="dn1" dataHost="localhost1" database="db1" />

#vi /usr/local/mycat/conf/rule.xml

<tableRule name="mod-long">
<rule>
<columns>id</columns>
<algorithm>mod-long</algorithm>
</rule>
</tableRule>
<function name="mod-long" class="io.mycat.route.function.PartitionByMod">
<!-- how many data nodes -->
<property name="count">3</property>
</function>

 

在db1數據庫上建立3個表
CREATE TABLE `orderlog1` (
`id` int(10) NOT NULL,
`order_id` int(10) unsigned NOT NULL,
`create_time` int(10) unsigned NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `orderlog2` (
`id` int(10) NOT NULL,
`order_id` int(10) unsigned NOT NULL,
`create_time` int(10) unsigned NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `orderlog3` (
`id` int(10) NOT NULL,
`order_id` int(10) unsigned NOT NULL,
`create_time` int(10) unsigned NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

#/usr/local/mycat/bin/mycat stop
#/usr/local/mycat/bin/mycat start

mysql> explain insert into orderlog(id,order_id,create_time) VALUES(1,5200,86784523);
+-----------+------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+------------------------------------------------------------------------------+
| dn1 | INSERT INTO orderlog2 (id, order_id, create_time) VALUES (1, 5200, 86784523) |
+-----------+------------------------------------------------------------------------------+
1 row in set (0.01 sec)

mysql> explain insert into orderlog(id,order_id,create_time) VALUES(2,5200,86784523);
+-----------+------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+------------------------------------------------------------------------------+
| dn1 | INSERT INTO orderlog3 (id, order_id, create_time) VALUES (2, 5200, 86784523) |
+-----------+------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> explain insert into orderlog(id,order_id,create_time) VALUES(3,5200,86784523);
+-----------+------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+------------------------------------------------------------------------------+
| dn1 | INSERT INTO orderlog1 (id, order_id, create_time) VALUES (3, 5200, 86784523) |
+-----------+------------------------------------------------------------------------------+
1 row in set (0.01 sec)

查詢：

mysql> explain select * from orderlog;
+-----------+-----------------------------------+
| DATA_NODE | SQL |
+-----------+-----------------------------------+
| dn1 | SELECT * FROM orderlog1 LIMIT 100 |
| dn1 | SELECT * FROM orderlog2 LIMIT 100 |
| dn1 | SELECT * FROM orderlog3 LIMIT 100 |
+-----------+-----------------------------------+
3 rows in set (0.09 sec)

 

實現方式：切分規則根據配置中輸入的數值n。此種分片規則將數據分成n份（通常dn節點也為n），從而將數據均勻的分布於各節點上。
優點：這種策略可以很好的分散數據庫寫的壓力。比較適合於單點查詢的情景
缺點：不方便擴展；出現了范圍查詢，就需要MyCAT去合並結果，當數據量偏高的時候，這種跨庫查詢+合並結果消耗的時間有可能會增加很多，尤其是還出現了order by的時候