CDC变化数据捕获——Debezium-Embedded

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#cdc #数据库 #debezium #embed #mysql

于 2021-05-07 21:39:39 首次发布

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本文详细介绍了如何配置MySQL主从同步并使用Debezium-Embedded在Java应用中捕获MySQL数据库的变化数据。通过示例代码展示了如何创建和使用DebeziumEngine，包括简单的数据通知、使用Connect类创建引擎以及批量处理CDC事件。适用于无需Kafka的场景，便于直接获取和处理数据库变更事件。

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CDC变化数据捕获——Debezium-Embedded

CDC变化数据捕获——Debezium-Embedded

0. 前言

CDC(Change Data Capture)是变化数据捕获的意思，可以捕获数据库数据的增加、更新、删除等记录，RedHat的 Debezium 正是这样一款产品。
对于数据库数据变化的监听，国内常用的一般是阿里的 Canal ，可惜目前仅支持MySQL。而相对来说，Debezium支持的数据库就非常丰富了，包括：MySQL、PostgreSQL、MongoDB、Oracle、SQL Server、Db2、Cassandra、Vitess。
使用Debezium比较麻烦的是，它通常需要用到 Apache Kafka 来保证数据的高容错性和高可靠性。但是，很多应用不需要这样的特性，或者不想连接Kafka，因此Debezium提供了debezium-embedded。利用它，可以在Java应用中连接到数据库，直接获取到数据库的CDC事件信息，不用额外进行其他操作。
debezium-embedded使用起来更为便捷、灵巧，目前国内已有阿里的Flink-CDC在使用它了（查看示例）。可惜的是Debezium在国内相对来说文档不多，其嵌入式使用方式的示例更是难找（官方英文文档有坑- -！！），本文的目的正是要写出此处的示例（MySQL），方便大家参阅。
官方文档地址: Debezium Engine

1. 配置MySQL主从同步

停止MySQL服务

修改配置文件，在[mysqld]处添加内容如下

# 一般情况下，Window修改mysql目录下的my.ini
# 一般情况下，Linux修改/etc/mysql下的my.cnf

[mysqld]
# 添加的部分，server-id随便填
server-id = 12345
log-bin = mysql-bin
# 必须为ROW
binlog_format = ROW
# 必须为FULL，MySQL-5.7后才有该参数
binlog_row_image  = FULL
expire_logs_days  = 10

启动MySQL服务
root 登入MySQL，查看binlog相关变量配置
```
SHOW VARIABLES LIKE '%binlog%';
```

root 登入MySQL，新增用于同步数据的用户

-- 设置拥有同步权限的用户
CREATE USER 'cdc_user' IDENTIFIED BY 'cdc_password';
-- 赋予同步相关权限
GRANT SELECT, RELOAD, SHOW DATABASES, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'cdc_user';

新用户 cdc_user 登入MySQL，查看主从同步情况

SHOW MASTER STATUS;
SHOW SLAVE STATUS;
SHOW BINARY LOGS;

建议再建个测试用的库和表（带主键），方便调试，例如Flink-CDC中的

2. Debezium-Embedded 代码开发

2.1 Maven导包

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <version.debezium>1.4.2.Final</version.debezium>
    </properties>

    <dependencies>
        <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>
    </dependencies>

2.2 代码-简单示例

import io.debezium.connector.mysql.MySqlConnector;
import io.debezium.engine.ChangeEvent;
import io.debezium.engine.DebeziumEngine;
import io.debezium.engine.format.Json;
import io.debezium.relational.history.FileDatabaseHistory;
import org.apache.kafka.connect.storage.FileOffsetBackingStore;

import java.util.Properties;
import java.util.UUID;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Demo01 {

    public static void main(String[] args) {
        // 0. 配置数据库，添加用户，赋予主从同步的权限

        // 1. 生成配置
        Properties props = genProps();

        // 2. 构建 DebeziumEngine
        // 使用 Json 格式
        DebeziumEngine<ChangeEvent<String, String>> engine = DebeziumEngine.create(Json.class)
                .using(props)
                .notifying(record -> {
                	// record中会有操作的类型（增、删、改）和具体的数据
                	// key是主键
                    System.out.println("record.key() = " + record.key());
                    System.out.println("record.value() = " + record.value());
                })
                .using((success, message, error) -> {
               		// 强烈建议加上此部分的回调代码，方便查看错误信息
                    
                    if (!success && error != null) {
                    	// 报错回调
                        System.out.println("----------error------");
                        System.out.println(message);
                    }
                }).build();

        // 3. 正式运行
        ExecutorService executor = Executors.newSingleThreadExecutor();
        executor.execute(engine);
    }

    private static Properties genProps() {
        // 配置
        Properties props = new Properties();
        // 在maven处引入其他数据库的连接器，例如debezium-connector-postgres，再修改此处的connector.class，即可使用其他数据库的CDC
        props.setProperty("connector.class", MySqlConnector.class.getCanonicalName());
        props.setProperty("database.server.name", "my_server_01"); // 可以任意修改
        props.setProperty("database.hostname", "localhost"); // IP
        props.setProperty("database.port", String.valueOf(3306)); // 端口
        props.setProperty("database.user", "cdc_user"); // 用户
        props.setProperty("database.password", "cdc_password"); // 密码
        props.setProperty("database.serverTimezone", "UTC"); // 时区
        // 下面两个是数据库和表，注意只能选择一种:
        // 1. 使用database.whitelist，只设置数据库（会通知全库的CDC信息）
        // 2. 使用table.whitelist，设置库名和表名（会通知单个库的单个表的CDC信息）
//        props.setProperty("database.whitelist", "db_inventory_cdc");
        props.setProperty("table.whitelist", "db_inventory_cdc.tb_products_cdc"); // 库.表名

        props.setProperty("name", "engine");
        props.setProperty("key.converter.schemas.enable", "false");
        props.setProperty("value.converter.schemas.enable", "false");
        props.setProperty("include.schema.changes", "false");
        props.setProperty("tombstones.on.delete", "false");
        props.setProperty("database.history", FileDatabaseHistory.class.getCanonicalName());
        props.setProperty("database.history.store.only.monitored.tables.ddl", "true");
        props.setProperty("database.history.file.filename", "./storage/dbhistory.dat");
        props.setProperty("database.history.instance.name", UUID.randomUUID().toString());
        props.setProperty("database.history.skip.unparseable.ddl", "true");
        // 偏移量持久化配置
		props.setProperty("offset.storage", FileOffsetBackingStore.class.getCanonicalName());
        props.setProperty("offset.storage.file.filename", "./tmp/offsets.dat");
        props.setProperty("offset.flush.interval.ms", "6000");
        return props;
    }
    
}

2.3 代码-使用Connect.class创建引擎

import io.debezium.embedded.Connect;

……

DebeziumEngine<ChangeEvent<SourceRecord, SourceRecord>> engine = DebeziumEngine.create(Connect.class)
        .using(props)
        .notifying(record -> {
              System.out.println("record.key = " + record.key());
              System.out.println("record.value = " + record.value());
              System.out.println("record.value.sourcePartition = " + record.value().sourcePartition());
              System.out.println("record.value.sourceOffset = " + record.value().sourceOffset());
              System.out.println("record.value.key = " + record.value().key());
              System.out.println("record.value.value = " + record.value().value());
              System.out.println("record.destination = " + record.destination());
          })
          .using((success, message, error) -> {
              // 省略代码
          }).build();

2.4 代码-批量处理CDC事件

DebeziumEngine<ChangeEvent<String, String>> engine = DebeziumEngine.create(Json.class)
        .using(props)
        .notifying((records, committer) -> {
        	// records是当前批次的数据
            for (ChangeEvent<String, String> record : records) {
                System.out.println("record.key() = " + record.key());
                System.out.println("record.value() = " + record.value());
            }
            // 当前批次处理完后，需要标记为完成
            committer.markBatchFinished();
        })
        .using((success, message, error) -> {
            // 省略代码
        }).build();

2.5 启动代码运行即可

控制台日志样例

record.key() = {"id":1}
record.value() = {"before":null,"after":{"id":1,"name":"xiaowang","age":34,"address":"beijing"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":2}
record.value() = {"before":null,"after":{"id":2,"name":"lilei","age":12,"address":"chongqing"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":3}
record.value() = {"before":null,"after":{"id":3,"name":"meimei","age":19,"address":"chengdu"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":4}
record.value() = {"before":null,"after":{"id":4,"name":"chunfang","age":18,"address":"chongqing"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":6}
record.value() = {"before":null,"after":{"id":6,"name":"lili","age":15,"address":"chongqing"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":7}
record.value() = {"before":null,"after":{"id":7,"name":"xiaoming","age":21,"address":"beijing"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":8}
record.value() = {"before":null,"after":{"id":8,"name":"wangwu","age":24,"address":"hunan"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":9}
record.value() = {"before":null,"after":{"id":9,"name":"tom","age":12,"address":"beijing"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":10}
record.value() = {"before":null,"after":{"id":10,"name":"whitee","age":55,"address":"hebei"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":11}
record.value() = {"before":null,"after":{"id":11,"name":"meimei","age":31,"address":"hebei"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":12}
record.value() = {"before":null,"after":{"id":12,"name":"hehe","age":13,"address":"nanjing"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":13}
record.value() = {"before":null,"after":{"id":13,"name":"liyang","age":16,"address":"beijing"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":14}
record.value() = {"before":null,"after":{"id":14,"name":"huahua","age":21,"address":"shandong"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"true","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
record.key() = {"id":15}
record.value() = {"before":null,"after":{"id":15,"name":"zhangsan","age":25,"address":"hubei"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":0,"snapshot":"last","db":"y1","table":"tb_test_from","server_id":0,"gtid":null,"file":"binlog.000030","pos":115750444,"row":0,"thread":null,"query":null},"op":"r","ts_ms":1679554873026,"transaction":null}
// 删除了一条带IP的日志
record.key() = {"id":14}
record.value() = {"before":{"id":14,"name":"huahua","age":21,"address":"shandong"},"after":{"id":14,"name":"huahua","age":10,"address":"shandong"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":1679554893000,"snapshot":"false","db":"y1","table":"tb_test_from","server_id":1,"gtid":null,"file":"binlog.000030","pos":115750677,"row":0,"thread":26773,"query":null},"op":"u","ts_ms":1679554893186,"transaction":null}
record.key() = {"id":16}
record.value() = {"before":null,"after":{"id":16,"name":"alice","age":18,"address":"dalian"},"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":1679554929000,"snapshot":"false","db":"y1","table":"tb_test_from","server_id":1,"gtid":null,"file":"binlog.000030","pos":115752466,"row":0,"thread":26773,"query":null},"op":"c","ts_ms":1679554929396,"transaction":null}
record.key() = {"id":6}
record.value() = {"before":{"id":6,"name":"lili","age":15,"address":"chongqing"},"after":null,"source":{"version":"1.4.2.Final","connector":"mysql","name":"my_server_01","ts_ms":1679554936000,"snapshot":"false","db":"y1","table":"tb_test_from","server_id":1,"gtid":null,"file":"binlog.000030","pos":115752780,"row":0,"thread":26773,"query":null},"op":"d","ts_ms":1679554936366,"transaction":null}