MyCat Tutorial Six: Global serial number - global growth since the primary key

  Earlier we introduced the sub-library sub-table operation MyCat, then the data in the same table will be stored in a different database, which involves the 主键maintenance problem, this time certainly can not use a single database in a manner id increment to handle , and then the way we can provide through MyCat to achieve growth in several

Global primary key increment

First, the local file increment mode

  First we look at Dir a way, that is 本地文件自增the way

1. Modify Partitioning Strategies

  Partitioning strategy of our original configuration crc32slotis not supported by the primary key increment, so we need to modify theauto-sharding-long

2. Modify the server.xml file

  server.xml file sequnceHandlerTypeis used to configure the generated key type

sequnceHandlerType value	Explanation
0	Local file increment mode
1	Database increment mode
2	Local timestamp increment mode

So we need to first modify the value of sequnceHandlerType0

3.sequence_conf.properties Introduction

  Conf directory under sequence_conf.propertiesthe relevant configuration information sequence

#Wed Oct 16 07:40:44 CST 2019
COMPANY.MAXID=2000
GLOBAL.MAXID=20000
COMPANY.HISIDS=
CUSTOMER.MAXID=2000
HOTNEWS.CURID=1000
ORDER.MINID=1001
CUSTOMER.HISIDS=
HOTNEWS.MINID=1001
GLOBAL.CURID=10002
ORDER.MAXID=2000
COMPANY.CURID=1000
CUSTOMER.CURID=1000
COMPANY.MINID=1001
GLOBAL.MINID=10001
HOTNEWS.MAXID=2000
CUSTOMER.MINID=1001
GLOBAL.HISIDS=
HOTNEWS.HISIDS=
ORDER.HISIDS=
ORDER.CURID=1000

  
  

The main thing is GLOBAL.MAXID=20000 GLOBAL.CURID=10002 GLOBAL.MINID=10001you can set your own

4. Test realization

Insert statement primary key field with next value for MYCATSEQ_GLOBALalternative

 insert into t_user(id,name,age)values(next value for MYCATSEQ_GLOBAL,'HG-93',23)

  
  

Second, the local timestamp increment mode

 Use the time stamp of the way, we do not need, or choose a different allocation strategy of partitioning strategy.

1. Modify the server.xml file

  The server.xml file is sequnceHandlerTypemodified to2

2. Restart mycat

  Modify the configuration file, you need to restart the service to make its entry into force.

3. Insert test data

 insert into t_user(id,name,age)values(next value for MYCATSEQ_GLOBAL,'HG-93',23)

  
  

Too long a time stamp will be idrevised to varchartype.

Generate success ~

Third, the database auto-increment mode

1. Create a sequence table and related functions

  The third way is to create in Mycat managed in a database table structure to increment a maintenance-related data, relevant official script, as follows:

DROP TABLE IF EXISTS MYCAT_SEQUENCE;
CREATE TABLE MYCAT_SEQUENCE (
NAME VARCHAR (50) NOT NULL,
current_value INT NOT NULL,
increment INT NOT NULL DEFAULT 100,
PRIMARY KEY (NAME)
) ENGINE = INNODB ;
INSERT INTO MYCAT_SEQUENCE(NAME,current_value,increment) VALUES ('GLOBAL', 100000, 100);
DROP FUNCTION IF EXISTS `mycat_seq_currval`;
DELIMITER ;;
CREATE FUNCTION `mycat_seq_currval`(seq_name VARCHAR(50)) 
RETURNS VARCHAR(64) CHARSET utf8
    DETERMINISTIC
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 ;
DROP FUNCTION IF EXISTS `mycat_seq_nextval`;
DELIMITER ;;
CREATE FUNCTION `mycat_seq_nextval`(seq_name VARCHAR(50)) RETURNS VARCHAR(64)
 CHARSET utf8
    DETERMINISTIC
BEGIN UPDATE MYCAT_SEQUENCE  
                 SET current_value = current_value + increment 
                  WHERE NAME = seq_name;  
         RETURN mycat_seq_currval(seq_name);  
END
;;
DELIMITER ;
DROP FUNCTION IF EXISTS `mycat_seq_setval`;
DELIMITER ;;
CREATE FUNCTION `mycat_seq_setval`(seq_name VARCHAR(50), VALUE INTEGER) 
RETURNS VARCHAR(64) CHARSET utf8
    DETERMINISTIC
BEGIN UPDATE MYCAT_SEQUENCE  
                   SET current_value = VALUE  
                   WHERE NAME = seq_name;  
         RETURN mycat_seq_currval(seq_name);  
END
;;
DELIMITER ;

  
  

We call these scripts demo2to perform on

2. Modify the server.xml

3. Modify sequence_db_conf.properties file

  Because the demo2corresponding logical library is dn2so we need to change here

4. Test

  Restart the service and insert test data

 insert into t_user(id,name,age)values(next value for MYCATSEQ_GLOBAL,'hg-93',23)

  
  

Successful primary key generation, in addition to these three methods may also be maintained by the auto-increment primary key `zookeeper`, this can be realized on their own