- GreatSQL社区原创内容未经授权不得随意使用，转载请联系小编并注明来源。
- 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
<dependency>
<groupId>io.debezium</groupId>
<artifactId>debezium-api</artifactId>
<version>${version.debezium}</version>
</dependency>
<dependency>
<groupId>io.debezium</groupId>
<artifactId>debezium-embedded</artifactId>
<version>${version.debezium}</version>
</dependency>
<dependency>
<groupId>io.debezium</groupId>
<artifactId>debezium-connector-mysql</artifactId>
<version>${version.debezium}</version>
</dependency>
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<ChangeEvent<String, String>> 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<ChangeEvent<String, String>> engine) {
try {
engine.close();
} catch (IOException ignored) {
}
}
private static void addShutdownHook(DebeziumEngine<ChangeEvent<String, String>> 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"...
insert into inventory.a values (4, 'n4');
控制台输出：
..."payload":{"before":null,"after":{"id":4,"name":"n4"}..."op":"c"...
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"...
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/documentation/reference/1.8/index.html
