Debezium的基本使用（以MySQL为例）

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GreatSQL是MySQL的国产分支版本，使用上与MySQL一致。
一、Debezium介绍
摘自官网:

Debezium is a set of distributed services to capture changes in your databases so that your applications can see those changes and respond to them. Debezium records all row-level changes within each database table in a _change event stream_, and applications simply read these streams to see the change events in the same order in which they occurred.

简单理解就是Debezium可以捕获数据库中所有行级的数据变化并包装成事件流顺序输出。

二、基本使用

下面以MySQL为例介绍Debezium的基本使用。

1. MySQL的准备工作

准备一个MySQL用户并且拥有相应权限，像这样：

CREATE USER 'dbz'@'%' IDENTIFIED BY 'dbzpwd';

GRANT SELECT, RELOAD, SHOW DATABASES, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'dbz' IDENTIFIED BY 'dbzpwd';

检查MySQL是否开启log-bin

SELECT variable_value as "BINARY LOGGING STATUS (log-bin) ::" FROM information_schema.global_variables WHERE variable_name='log_bin';

-- If the following error occurs: The 'INFORMATION_SCHEMA.GLOBAL_VARIABLES' feature is disabled...
-- please execute the given SQL again after execute this SQL: set global show_compatibility_56=on;

如果是OFF则需要修改MySQL配置文件，类似下面这样：

server-id         = 223344        #必须有
log_bin           = mysql-bin    #log_bin的值是binlog文件序列的基本名称
binlog_format     = ROW                #必须是ROW
binlog_row_image  = FULL            #必须是FULL
expire_logs_days  = 10                #依据实际情况而定

准备数据库&表

create database inventory;
create table inventory.a (id bigint primary key auto_increment, name varchar(32));
insert into inventory.a values (null, 'n1'),(null, 'n2'),(null, 'n3');

2. 编写程序

2.1. 工程依赖（Maven）

pom.xml


    io.debezium
    debezium-api
    ${version.debezium}


    io.debezium
    debezium-embedded
    ${version.debezium}



    io.debezium
    debezium-connector-mysql
    ${version.debezium}

目前Debezium最新稳定版本为：1.9.5.Final

2.2. 准备数据库&表

create database inventory;
create table inventory.a (id bigint primary key, name varchar(32));
insert into inventory.a values (1, 'n1'),(2, 'n2'),(3, 'n3');

2.3. 代码编写

package com.greatdb.dbzdemo;

import java.io.IOException;
import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import io.debezium.engine.ChangeEvent;
import io.debezium.engine.DebeziumEngine;
import io.debezium.engine.format.Json;

/**
 * @author wang.jianwen
 * @version 1.0
 * @date 2022/07/29
 */
public class DebeziumTest {

    private static DebeziumEngine> engine;

    public static void main(String[] args) throws Exception {
        final Properties props = new Properties();
        props.setProperty("name", "dbz-engine");
        props.setProperty("connector.class", "io.debezium.connector.mysql.MySqlConnector");

        //offset config begin - 使用文件来存储已处理的binlog偏移量
        props.setProperty("offset.storage", "org.apache.kafka.connect.storage.FileOffsetBackingStore");
        props.setProperty("offset.storage.file.filename", "/tmp/dbz/storage/mysql_offsets.dat");
        props.setProperty("offset.flush.interval.ms", "0");
        //offset config end

        props.setProperty("database.server.name", "mysql-connector");
        props.setProperty("database.history", "io.debezium.relational.history.FileDatabaseHistory");
        props.setProperty("database.history.file.filename", "/tmp/dbz/storage/mysql_dbhistory.txt");

        props.setProperty("database.server.id", "122112");    //需要与MySQL的server-id不同
        props.setProperty("database.hostname", "tmg");
        props.setProperty("database.port", "3306");
        props.setProperty("database.user", "mysqluser");
        props.setProperty("database.password", "mysqlpw");
        props.setProperty("database.include.list", "inventory");//要捕获的数据库名
        props.setProperty("table.include.list", "inventory.a");//要捕获的数据表

        props.setProperty("snapshot.mode", "initial");//全量+增量

        // 使用上述配置创建Debezium引擎，输出样式为Json字符串格式
        engine = DebeziumEngine.create(Json.class)
                .using(props)
                .notifying(record -> {
                    System.out.println(record);//输出到控制台
                })
                .using((success, message, error) -> {
                    if (error != null) {
                        // 报错回调
                        System.out.println("------------error, message:" + message + "exception:" + error);
                    }
                    closeEngine(engine);
                })
                .build();

        ExecutorService executor = Executors.newSingleThreadExecutor();
        executor.execute(engine);
        addShutdownHook(engine);
        awaitTermination(executor);

        System.out.println("------------main finished.");
    }

    private static void closeEngine(DebeziumEngine> engine) {
        try {
            engine.close();
        } catch (IOException ignored) {
        }
    }

    private static void addShutdownHook(DebeziumEngine> engine) {
        Runtime.getRuntime().addShutdownHook(new Thread(() -> closeEngine(engine)));
    }

    private static void awaitTermination(ExecutorService executor) {
        if (executor != null) {
            try {
                executor.shutdown();
                while (!executor.awaitTermination(5, TimeUnit.SECONDS)) {
                }
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
        }
    }
}

3. 测试

程序跑起来后，可以看到控制台输出：

...（省略）
EmbeddedEngineChangeEvent [key={"schema":{"type":"struct","fields":[{"type":"int64","optional":false,"field":"id"}],"optional":false,"name":"mysql_connector.inventory.a.Key"},"payload":{"id":1}}, value={"schema":{"type":"struct","fields":[{"type":"struct","fields":[{"type":"int64","optional":false,"field":"id"},{"type":"string","optional":true,"field":"name"}],"optional":true,"name":"mysql_connector.inventory.a.Value","field":"before"},{"type":"struct","fields":[{"type":"int64","optional":false,"field":"id"},{"type":"string","optional":true,"field":"name"}],"optional":true,"name":"mysql_connector.inventory.a.Value","field":"after"},{"type":"struct","fields":[{"type":"string","optional":false,"field":"version"},{"type":"string","optional":false,"field":"connector"},{"type":"string","optional":false,"field":"name"},{"type":"int64","optional":false,"field":"ts_ms"},{"type":"string","optional":true,"name":"io.debezium.data.Enum","version":1,"parameters":{"allowed":"true,last,false,incremental"},"default":"false","field":"snapshot"},{"type":"string","optional":false,"field":"db"},{"type":"string","optional":true,"field":"sequence"},{"type":"string","optional":true,"field":"table"},{"type":"int64","optional":false,"field":"server_id"},{"type":"string","optional":true,"field":"gtid"},{"type":"string","optional":false,"field":"file"},{"type":"int64","optional":false,"field":"pos"},{"type":"int32","optional":false,"field":"row"},{"type":"int64","optional":true,"field":"thread"},{"type":"string","optional":true,"field":"query"}],"optional":false,"name":"io.debezium.connector.mysql.Source","field":"source"},{"type":"string","optional":false,"field":"op"},{"type":"int64","optional":true,"field":"ts_ms"},{"type":"struct","fields":[{"type":"string","optional":false,"field":"id"},{"type":"int64","optional":false,"field":"total_order"},{"type":"int64","optional":false,"field":"data_collection_order"}],"optional":true,"field":"transaction"}],"optional":false,"name":"mysql_connector.inventory.a.Envelope"},"payload":{"before":null,"after":{"id":1,"name":"n1"},"source":{"version":"1.8.1.Final","connector":"mysql","name":"mysql-connector","ts_ms":1659064005186,"snapshot":"true","db":"inventory","sequence":null,"table":"a","server_id":0,"gtid":null,"file":"mysql-bin.000001","pos":154,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1659064005191,"transaction":null}}, sourceRecord=SourceRecord{sourcePartition={server=mysql-connector}, sourceOffset={ts_sec=1659064005, file=mysql-bin.000001, pos=154, snapshot=true}} ConnectRecord{topic='mysql-connector.inventory.a', kafkaPartition=null, key=Struct{id=1}, keySchema=Schema{mysql_connector.inventory.a.Key:STRUCT}, value=Struct{after=Struct{id=1,name=n1},source=Struct{version=1.8.1.Final,connector=mysql,name=mysql-connector,ts_ms=1659064005186,snapshot=true,db=inventory,table=a,server_id=0,file=mysql-bin.000001,pos=154,row=0},op=r,ts_ms=1659064005191}, valueSchema=Schema{mysql_connector.inventory.a.Envelope:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)}]
EmbeddedEngineChangeEvent [key={"schema":{"type":"struct","fields":[{"type":"int64","optional":false,"field":"id"}],"optional":false,"name":"mysql_connector.inventory.a.Key"},"payload":{"id":2}}, value={"schema":{"type":"struct","fields":[{"type":"struct","fields":[{"type":"int64","optional":false,"field":"id"},{"type":"string","optional":true,"field":"name"}],"optional":true,"name":"mysql_connector.inventory.a.Value","field":"before"},{"type":"struct","fields":[{"type":"int64","optional":false,"field":"id"},{"type":"string","optional":true,"field":"name"}],"optional":true,"name":"mysql_connector.inventory.a.Value","field":"after"},{"type":"struct","fields":[{"type":"string","optional":false,"field":"version"},{"type":"string","optional":false,"field":"connector"},{"type":"string","optional":false,"field":"name"},{"type":"int64","optional":false,"field":"ts_ms"},{"type":"string","optional":true,"name":"io.debezium.data.Enum","version":1,"parameters":{"allowed":"true,last,false,incremental"},"default":"false","field":"snapshot"},{"type":"string","optional":false,"field":"db"},{"type":"string","optional":true,"field":"sequence"},{"type":"string","optional":true,"field":"table"},{"type":"int64","optional":false,"field":"server_id"},{"type":"string","optional":true,"field":"gtid"},{"type":"string","optional":false,"field":"file"},{"type":"int64","optional":false,"field":"pos"},{"type":"int32","optional":false,"field":"row"},{"type":"int64","optional":true,"field":"thread"},{"type":"string","optional":true,"field":"query"}],"optional":false,"name":"io.debezium.connector.mysql.Source","field":"source"},{"type":"string","optional":false,"field":"op"},{"type":"int64","optional":true,"field":"ts_ms"},{"type":"struct","fields":[{"type":"string","optional":false,"field":"id"},{"type":"int64","optional":false,"field":"total_order"},{"type":"int64","optional":false,"field":"data_collection_order"}],"optional":true,"field":"transaction"}],"optional":false,"name":"mysql_connector.inventory.a.Envelope"},"payload":{"before":null,"after":{"id":2,"name":"n2"},"source":{"version":"1.8.1.Final","connector":"mysql","name":"mysql-connector","ts_ms":1659064005195,"snapshot":"true","db":"inventory","sequence":null,"table":"a","server_id":0,"gtid":null,"file":"mysql-bin.000001","pos":154,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1659064005196,"transaction":null}}, sourceRecord=SourceRecord{sourcePartition={server=mysql-connector}, sourceOffset={ts_sec=1659064005, file=mysql-bin.000001, pos=154, snapshot=true}} ConnectRecord{topic='mysql-connector.inventory.a', kafkaPartition=null, key=Struct{id=2}, keySchema=Schema{mysql_connector.inventory.a.Key:STRUCT}, value=Struct{after=Struct{id=2,name=n2},source=Struct{version=1.8.1.Final,connector=mysql,name=mysql-connector,ts_ms=1659064005195,snapshot=true,db=inventory,table=a,server_id=0,file=mysql-bin.000001,pos=154,row=0},op=r,ts_ms=1659064005196}, valueSchema=Schema{mysql_connector.inventory.a.Envelope:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)}]
EmbeddedEngineChangeEvent [key={"schema":{"type":"struct","fields":[{"type":"int64","optional":false,"field":"id"}],"optional":false,"name":"mysql_connector.inventory.a.Key"},"payload":{"id":3}}, value={"schema":{"type":"struct","fields":[{"type":"struct","fields":[{"type":"int64","optional":false,"field":"id"},{"type":"string","optional":true,"field":"name"}],"optional":true,"name":"mysql_connector.inventory.a.Value","field":"before"},{"type":"struct","fields":[{"type":"int64","optional":false,"field":"id"},{"type":"string","optional":true,"field":"name"}],"optional":true,"name":"mysql_connector.inventory.a.Value","field":"after"},{"type":"struct","fields":[{"type":"string","optional":false,"field":"version"},{"type":"string","optional":false,"field":"connector"},{"type":"string","optional":false,"field":"name"},{"type":"int64","optional":false,"field":"ts_ms"},{"type":"string","optional":true,"name":"io.debezium.data.Enum","version":1,"parameters":{"allowed":"true,last,false,incremental"},"default":"false","field":"snapshot"},{"type":"string","optional":false,"field":"db"},{"type":"string","optional":true,"field":"sequence"},{"type":"string","optional":true,"field":"table"},{"type":"int64","optional":false,"field":"server_id"},{"type":"string","optional":true,"field":"gtid"},{"type":"string","optional":false,"field":"file"},{"type":"int64","optional":false,"field":"pos"},{"type":"int32","optional":false,"field":"row"},{"type":"int64","optional":true,"field":"thread"},{"type":"string","optional":true,"field":"query"}],"optional":false,"name":"io.debezium.connector.mysql.Source","field":"source"},{"type":"string","optional":false,"field":"op"},{"type":"int64","optional":true,"field":"ts_ms"},{"type":"struct","fields":[{"type":"string","optional":false,"field":"id"},{"type":"int64","optional":false,"field":"total_order"},{"type":"int64","optional":false,"field":"data_collection_order"}],"optional":true,"field":"transaction"}],"optional":false,"name":"mysql_connector.inventory.a.Envelope"},"payload":{"before":null,"after":{"id":3,"name":"n3"},"source":{"version":"1.8.1.Final","connector":"mysql","name":"mysql-connector","ts_ms":1659064005196,"snapshot":"last","db":"inventory","sequence":null,"table":"a","server_id":0,"gtid":null,"file":"mysql-bin.000001","pos":154,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1659064005196,"transaction":null}}, sourceRecord=SourceRecord{sourcePartition={server=mysql-connector}, sourceOffset={ts_sec=1659064005, file=mysql-bin.000001, pos=154}} ConnectRecord{topic='mysql-connector.inventory.a', kafkaPartition=null, key=Struct{id=3}, keySchema=Schema{mysql_connector.inventory.a.Key:STRUCT}, value=Struct{after=Struct{id=3,name=n3},source=Struct{version=1.8.1.Final,connector=mysql,name=mysql-connector,ts_ms=1659064005196,snapshot=last,db=inventory,table=a,server_id=0,file=mysql-bin.000001,pos=154,row=0},op=r,ts_ms=1659064005196}, valueSchema=Schema{mysql_connector.inventory.a.Envelope:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)}]
...（省略）

可以看到全量的数据已经输出，关键的数据如下：

..."payload":{"before":null,"after":{"id":1,"name":"n1"}..."op":"r"...
..."payload":{"before":null,"after":{"id":2,"name":"n2"}..."op":"r"...
..."payload":{"before":null,"after":{"id":3,"name":"n3"}..."op":"r"...

接下来新增一条数据：

insert into inventory.a values (4, 'n4');

控制台输出：

..."payload":{"before":null,"after":{"id":4,"name":"n4"}..."op":"c"...

修改一条数据：

update inventory.a set name = 'n4-upd' where id = 4;

控制台输出：

..."payload":{"before":{"id":4,"name":"n4"},"after":{"id":4,"name":"n4-upd"}..."op":"u"...

删除一条数据：
```
delete from inventory.a where id = 1;
```
控制台输出：
```
..."payload":{"before":{"id":1,"name":"n1"},"after":null..."op":"d"...
```
三、总结
本文以MySQL为例介绍了Debezium在代码中基本使用流程，对MySQL的数据进行常见的增删改操作，Debezium将捕获这些数据行的变化，并记录了数据行变化前后的数据，并对外提供事件流，外部可以获取并对事件进行相应处理。

参考：https://debezium.io/documenta...