Mycat學習實戰-Mycat全局主鍵

阿新 • • 發佈：2017-10-26

mysql mycat

Mycat學習實戰-Mycat全局主鍵

@(學習)[mycat, mysql]

Mycat學習實戰-Mycat全局主鍵
1. Mycat全局主鍵介紹
2. Mycat全局主鍵方式
- 2.1 本地文件方式
- 2.2 本地時間戳方式
- 2.3 數據庫方式
- 2.4 zookeeper方式

1. Mycat全局主鍵介紹

在分庫分表的情況下，數據庫自增主鍵無法保證自增主鍵的全局唯一。

全局序列號的語法符合標準SQL規範，其格式為：
next value for MYCATSEQ_XXX
MYCATSEQ_XXX 是序列號的名字，MyCAT自動創建新的序列號，免去了開發的復雜度，另外，MyCAT也提供了一個全局的序列號，名稱為：MYCATSEQ_GLOBAL

註意，MYCATSEQ_必須大寫才能正確識別。
MyCAT溫馨提示：實踐中，建議每個表用自己的序列號，序列號的命名建議為MYCATSEQ _tableName_ID_SEQ。

SQL中使用說明
自定義序列號的標識為：MYCATSEQ_XXX ,其中XXX為具體定義的sequence的名稱，應用舉例如下：
使用默認的全局sequence :
insert into tb1(id,name) values(next value for MYCATSEQ_GLOBAL,‘tb1‘);
使用自定義的 sequence:
insert into tb2(id,name) values(next value for MYCATSEQ_MY1,‘tb2‘);

獲取最新的值
select next value for MYCATSEQ_xxx

2. Mycat全局主鍵方式

Mycat提供的全局主鍵方式如下：

本地文件方式：使用服務器本地磁盤文件的方式
數據庫方式：使用數據庫的方式
本地時間戳方式：使用時間戳方式
分布式zookeeper生成ID

2.1 本地文件方式

vim conf/server.xml

<property name="sequnceHandlerType">0</property>

vim conf/sequence_conf.properties

#default global sequence
GLOBAL.HISIDS=
GLOBAL.MINID=10001
GLOBAL.MAXID=20000
GLOBAL.CURID=10000

# self define sequence
ID_LOCAL_FILE.HISIDS=
ID_LOCAL_FILE.MINID=1001
ID_LOCAL_FILE.MAXID=2000
ID_LOCAL_FILE.CURID=1000

以上配置文件中，自定義表名必須大寫書寫
HISIDS：表示使用過的歷史分段(一般
無特殊需要可不配置)
MINID ：最小ID 值
MAXID ：表示最大ID 值
CURID 表示當前ID 值。
當 sequence_conf.properties的配置名字與表名一致的時候sql可以不包含ID字段（此處表名為id_local_file）

vim conf/schema.xml

<?xml version="1.0"?><!DOCTYPE mycat:schema SYSTEM "schema.dtd"><mycat:schema xmlns:mycat="http://io.mycat/">

        <schema name="test" checkSQLschema="false" sqlMaxLimit="100">
                <table name="id_local_file" dataNode="test1" autoIncrement="true" primaryKey="id"></table>

        </schema>
        <dataNode name="test1" dataHost="testA" database="test" />

        <dataHost name="testA" maxCon="1000" minCon="10" balance="1"
                        writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
                        <heartbeat>select 1</heartbeat>
                        <writeHost host="hostM1" url="192.168.33.11:3306" user="root"
                                password="123456" />
        </dataHost></mycat:schema>

實驗驗證：

[root@testA conf]# mysql -uroot -p123456 -P8066 -h 127.0.0.1 test
mysql: [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 3
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)

Copyright (c) 2000, 2017, 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> CREATE TABLE `id_local_file` (`id` varchar(20) NOT NULL ,`nm` varchar(60) NULL ,PRIMARY KEY (`id`));    
Query OK, 0 rows affected (0.06 sec)

mysql> insert into id_local_file(id,nm) values(next value for MYCATSEQ_GLOBAL,‘id_local_file‘); 
Query OK, 1 row affected (0.03 sec)

mysql> insert into id_local_file(nm) values(‘id_local_file‘); /* 插入的sql語句裏沒有了自增ID字段 */
Query OK, 1 row affected (0.01 sec)

mysql> select * from id_local_file;
+-------+---------------+
| id    | nm            |
+-------+---------------+
| 10001 | id_local_file |
| 1001  | id_local_file |
+-------+---------------+
2 rows in set (0.08 sec)

mysql> select next value for MYCATSEQ_GLOBAL;
+-------+
| 10002 |
+-------+
| 10002 |
+-------+
1 row in set (0.00 sec)

mysql>

優點：本地加載，讀取速度較快，配置簡單
缺點：mycat重新發布時，seq文件需要替換，集群部署無法用此方式，路由到不同的mycat上無法保證id唯一，使mycat變成了有狀態的中間件。

2.2 本地時間戳方式

vim conf/server.xml

<property name="sequnceHandlerType">2</property>

vim conf/sequence_time_conf.properties

#sequence depend on TIME
WORKID=01
DATAACENTERID=01

兩個屬性值為：0-31 任意整數

vim conf/schema.xml

<?xml version="1.0"?><!DOCTYPE mycat:schema SYSTEM "schema.dtd"><mycat:schema xmlns:mycat="http://io.mycat/">

        <schema name="test" checkSQLschema="false" sqlMaxLimit="100">
                <table name="id_local_time" dataNode="test1" autoIncrement="true" primaryKey="id"></table>

        </schema>
        <dataNode name="test1" dataHost="testA" database="test" />

        <dataHost name="testA" maxCon="1000" minCon="10" balance="1"
                        writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
                        <heartbeat>select 1</heartbeat>
                        <writeHost host="hostM1" url="192.168.33.11:3306" user="root"
                                password="123456" />
        </dataHost></mycat:schema>

實驗驗證：

[root@testA conf]# mysql -uroot -p123456 -P8066 -h 127.0.0.1 test
mysql: [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: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)

Copyright (c) 2000, 2017, 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> CREATE TABLE `id_local_time` (`id` varchar(20) NOT NULL ,`nm` varchar(60) NULL ,PRIMARY KEY (`id`));
Query OK, 0 rows affected (0.02 sec)

mysql> insert into id_local_time(id,nm) values(next value for MYCATSEQ_GLOBAL,‘id_local_time‘); 
Query OK, 1 row affected (0.06 sec)

mysql> insert into id_local_time(nm) values(‘id_local_time‘); /* 插入的sql語句裏沒有了自增ID字段 */
Query OK, 1 row affected (0.01 sec)

mysql> select * from id_local_time;
+--------------------+---------------+
| id                 | nm            |
+--------------------+---------------+
| 922641363168792576 | id_local_time |
| 922641424359493632 | id_local_time |
+--------------------+---------------+
2 rows in set (0.06 sec)

mysql> select next value for MYCATSEQ_GLOBAL;
+--------------------+
| 922641542101995520 |
+--------------------+
| 922641542101995520 |
+--------------------+
1 row in set (0.00 sec)

本地時間戳計算方式
ID= 64 位二進制 (42(毫秒)+5(機器 ID)+5(業務編碼)+12(重復累加)
長度18位，因此下面提示非常重要。

註意
表字段長度必須大於等於18位

優點：不存在mycat重新發布影響seq的問題，
缺點：字段長度是18位。

2.3 數據庫方式

vim conf/server.xml

<property name="sequnceHandlerType">1</property>

vim conf/sequence_db_conf.properties

#sequence stored in datanode
GLOBAL=test1
ID_DB=test1

在test1節點本地數據庫添加函數和表，以下為sql內容：

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    DETERMINISTICBEGIN 
        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    DETERMINISTICBEGIN 
         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    DETERMINISTICBEGIN 
         UPDATE mycat_sequence  
                   SET current_value = value  
                   WHERE name = seq_name;  
         RETURN mycat_seq_currval(seq_name);  
END;;
DELIMITER ;

添加過程：

[root@testA mycat]# mysql -uroot -p123456 test
mysql: [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 102
Server version: 5.7.19-log Source distribution

Copyright (c) 2000, 2017, 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> DROP TABLE IF EXISTS mycat_sequence;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> 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);


Query OK, 0 rows affected (0.11 sec)

mysql> 
mysql> 
mysql> 
mysql> 
mysql> INSERT INTO mycat_sequence(name,current_value,increment) VALUES (‘GLOBAL‘, 100000, 100);
Query OK, 1 row affected (0.00 sec)

mysql> 
mysql> 
mysql> DROP FUNCTION IF EXISTS `mycat_seq_currval`;
Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER ;;
mysql> 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
    -> ;;
Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER ;
mysql> 
mysql> 
mysql> DROP FUNCTION IF EXISTS `mycat_seq_nextval`;
DELIMITER ;;
Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER ;;
mysql> 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
    -> ;;
Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER ;
mysql> 
mysql> 
mysql> 
mysql> 
mysql> DROP FUNCTION IF EXISTS `mycat_seq_setval`;
Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER ;;
mysql> 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
    -> ;;
Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER ;
mysql>

以下步驟非常關鍵，讓id_db表也支持數據庫序列號。

mysql> INSERT INTO mycat_sequence (‘ID_DB‘, 1, 100);
mysql> select * from mycat_sequence;
+--------+---------------+-----------+
| NAME   | current_value | increment |
+--------+---------------+-----------+
| GLOBAL |        100200 |       100 |
| ID_DB  |           301 |       100 |
+--------+---------------+-----------+
2 rows in set (0.00 sec)

vim conf/schema.xml

<?xml version="1.0"?><!DOCTYPE mycat:schema SYSTEM "schema.dtd"><mycat:schema xmlns:mycat="http://io.mycat/">

        <schema name="test" checkSQLschema="false" sqlMaxLimit="100">
                <table name="id_db" dataNode="test1" autoIncrement="true" primaryKey="id"></table>
                <table name="mycat_sequence" dataNode="test1" autoIncrement="true" primaryKey="id"></table>

        </schema>
        <dataNode name="test1" dataHost="testA" database="test" />

        <dataHost name="testA" maxCon="1000" minCon="10" balance="1"
                        writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
                        <heartbeat>select 1</heartbeat>
                        <writeHost host="hostM1" url="192.168.33.11:3306" user="root"
                                password="123456" />
        </dataHost></mycat:schema>

註意
將mycat_sequence表也放出來，且註意大小寫（數據庫默認區分大小寫）

實驗驗證：

[root@testA mycat]# mysql -uroot -p123456 -P8066 -h127.0.0.1 test
mysql: [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: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)

Copyright (c) 2000, 2017, 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 |
+----------+
| test     |
+----------+
1 row in set (0.00 sec)

mysql> show tables;
+----------------+
| Tables in test |
+----------------+
| id_db          |
| mycat_sequence |
+----------------+
2 rows in set (0.00 sec)

mysql> drop id_db;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘id_db‘ at line 1
mysql> drop table id_db;
Query OK, 0 rows affected (0.08 sec)

mysql> CREATE TABLE `id_db` (`id` int NOT NULL ,`nm` varchar(60) NULL ,PRIMARY KEY (`id`));
Query OK, 0 rows affected (0.02 sec)

mysql> insert into id_db(id,nm) values(next value for MYCATSEQ_GLOBAL,‘id_db‘);
Query OK, 1 row affected (0.10 sec)

mysql> insert into id_db(nm) values(‘db‘);
Query OK, 1 row affected (0.00 sec)

mysql> select next value for MYCATSEQ_GLOBAL;
+--------+
| 100201 |
+--------+
| 100201 |
+--------+
1 row in set (0.00 sec)

mysql> select * from id_db;
+--------+-------+
| id     | nm    |
+--------+-------+
|    303 | db    |
| 100200 | id_db |
+--------+-------+
2 rows in set (0.00 sec)

mysql> insert into id_db(nm) values(‘db‘);
Query OK, 1 row affected (0.01 sec)

mysql> select * from id_db;
+--------+-------+
| id     | nm    |
+--------+-------+
|    303 | db    |
|    304 | db    |
| 100200 | id_db |
+--------+-------+
3 rows in set (0.00 sec)

mysql>

優點：重新部署mycat不受影響
缺點：當配置節點的部署是主從復制，當主掛了切從後會有重復。

註意
節點如果是主從切換後，數據id可能會有異常（重復）

2.4 zookeeper方式

vim conf/server.xml

<property name="sequnceHandlerType">3</property>

vim conf/sequence_distributed_conf.properties

INSTANCEID=01
CLUSTERID=01

schema的table 增加屬性 autoIncrement="true"和 primaryKey="id"

基於ZK 與本地配置的分布式ID 生成器(可以通過ZK 獲取集群（機房）唯一InstanceID，也可以通過配置文件配置InstanceID)ID 結構：long 64 位，ID 最大可占63 位
current time millis(微秒時間戳38 位,可以使用17 年)
instanceId（實例ID，可以通過ZK 或者配置文件獲取，5 位，也就是十進制0-31）
threadId（線程ID，9 位）
increment(自增,6 位)
一共63 位，可以承受單機房單機器單線程1000*(2^6)=640000 的並發。

優點：無悲觀鎖，無強競爭，吞吐量更高
缺點：對zookeeper集群的要求增加。

參考資料：
[1] http://mycat.io/
[2] 《分布式數據庫架構及企業實踐——基於Mycat中間件》
[3] 龍哥官方課程課件、博客

本文出自 “ygqygq2” 博客，請務必保留此出處http://ygqygq2.blog.51cto.com/1009869/1976279

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Mycat學習實戰-Mycat全局主鍵

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