mycat配置全局系列号，采用db方式

先要在对应datanode节点上创建相关表(我这里用的是dn1):

#创建表
CREATE TABLE MYCAT_SEQUENCE (
name VARCHAR (50) NOT NULL comment "名称",
current_value INT NOT NULL comment "当前值",
increment INT NOT NULL DEFAULT 100 comment "步长",
PRIMARY KEY (name)
) ENGINE = INNODB;

#插入对应自增长表
insert into MYCAT_SEQUENCE(name,current_value,increment) values('T_USER',19,5);

#取当前squence的值
DROP FUNCTION IF EXISTS mycat_seq_currval;
DELIMITER $$
CREATE FUNCTION mycat_seq_currval(seq_name VARCHAR(50))RETURNS VARCHAR(64) CHARSET 'utf8'
BEGIN
DECLARE retval VARCHAR(64);
SET retval='-999999999,NULL';
SELECT CONCAT(CAST(current_value AS CHAR),',',CAST(increment AS CHAR)) INTO retval FROM
MYCAT_SEQUENCE WHERE NAME = seq_name;
RETURN retval;
END$$
DELIMITER ;

#设置 sequence 值
DROP FUNCTION IF EXISTS mycat_seq_setval;
DELIMITER $$
CREATE FUNCTION mycat_seq_setval(seq_name VARCHAR(50),VALUE INTEGER) RETURNS VARCHAR(64) CHARSET 'utf8'
BEGIN
UPDATE MYCAT_SEQUENCE SET current_value = VALUE WHERE NAME = seq_name;
RETURN mycat_seq_currval(seq_name);
END$$
DELIMITER ;

#取下一个sequence的值
DROP FUNCTION IF EXISTS mycat_seq_nextval;
DELIMITER $$
CREATE FUNCTION mycat_seq_nextval(seq_name VARCHAR(50)) RETURNS VARCHAR(64) CHARSET 'utf8'
BEGIN
UPDATE MYCAT_SEQUENCE SET current_value = current_value + increment
WHERE NAME = seq_name;
RETURN mycat_seq_currval(seq_name);
END$$
DELIMITER ;修改数据库my.cnf：
数据库配置文件修改my.ini

log_bin_trust_function_creators=1
# 忽略大小写
lower_case_table_names=1修改schema.xml：(添加主键和自增长配置primarykey和autoIncrement属性)
<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">

<schema name="tanlei" checkSQLschema="false" sqlMaxLimit="100">
<table name="t_user" subTables="t_user$1-3" dataNode="dn1" rule="mod-long" primaryKey="id" autoIncrement="true"/>
</schema>
<dataNode name="dn1" dataHost="localhost1" database="tanleidb" />
<dataHost name="localhost1" maxCon="1000" minCon="10" balance="0" writeType="0" dbType="mysql"
dbDriver="native" switchType="1" slaveThreshold="100">
<heartbeat>select user()</heartbeat>
<writeHost host="hostM1" url="localhost:3306" user="root" password="root" />
</dataHost>

</mycat:schema>修改sequence_db_conf.properties：
注意对应shcema.xml中table的表名要大写，我这里是T_USER, 对应创建sequence表和存储函数的节点是dn1.

#sequence stored in datanode
GLOBAL=dn1
T_USER=dn1
CUSTOMER=dn1
ORDERS=dn1进入mycat客户端，插入数据:
insert into t_user(userName,age,createTime,updateTime) values('tanlei2',23,now(),now());

查询数据会发现该条数据id已经自增长:

select * from t_user;

不过我们线上id都是用一个只有一列主键自增长id的表维护的！