1.Debezium和postgres介绍

Debezium

是一个开源项目，为捕获数据更改(change data capture,CDC)提供了一个低延迟的流式处理平台。你可以安装并且配置Debezium去监控你的数据库，然后你的应用就可以消费对数据库的每一个行级别(row-level)的更改。只有已提交的更改才是可见的，所以你的应用不用担心事务(transaction)或者更改被回滚(roll back)。Debezium为所有的数据库更改事件提供了一个统一的模型，所以你的应用不用担心每一种数据库管理系统的错综复杂性。另外，由于Debezium用持久化的、有副本备份的日志来记录数据库数据变化的历史，因此，你的应用可以随时停止再重启，而不会错过它停止运行时发生的事件，保证了所有的事件都能被正确地、完全地处理掉

postgres介绍

PostgreSQL是一个功能强大的开源数据库系统。经过长达15年以上的积极开发和不断改进，PostgreSQL已在可靠性、稳定性、数据一致性等获得了业内极高的声誉。目前PostgreSQL可以运行在所有主流操作系统上，包括Linux、Unix（AIX、BSD、HP-UX、SGI IRIX、Mac OS X、Solaris和Tru64）和Windows。PostgreSQL是完全的事务安全性数据库，完整地支持外键、联合、视图、触发器和存储过程（并支持多种语言开发存储过程）。它支持了大多数的SQL:2008标准的数据类型，包括整型、数值型、布尔型、字节型、字符型、日期型、时间间隔型和时间型，它也支持存储二进制的大对像，包括图片、声音和视频。PostgreSQL对很多高级开发语言有原生的编程接口，如C/C++、Java、.Net、Perl、Python、Ruby、Tcl 和ODBC以及其他语言等，也包含各种文档。

2.postgres测试环境搭建

1.安装

step1： 拉取 PostgreSQL 10.6 版本的镜像：

docker pull postgres:10.6

step2：创建并启动 PostgreSQL 容器，

在这里，我们将把容器的端口 5432 映射到主机的端口 30028，账号密码设置为postgres，并将 pgoutput 插件加载到 PostgreSQL 实例中：

 docker run -d -p 30028:5432 --name postgres-10.6 -e POSTGRES_PASSWORD=postgres postgres:10.6 -c 'shared_preload_libraries=pgoutput'

step3： 查看容器是否创建成功：

docker ps | grep postgres-10.6

2.配置

step1：docker进去Postgresql数据的容器：

docker exec -it postgres-10.6 bash

step2：编辑postgresql.conf配置文件：

vi /var/lib/postgresql/data/postgresql.conf

配置内容如下：

# 更改wal日志方式为logical（方式有：minimal、replica 、logical  ）
wal_level = logical

# 更改solts最大数量（默认值为10），flink-cdc默认一张表占用一个slots
max_replication_slots = 20

# 更改wal发送最大进程数（默认值为10），这个值和上面的solts设置一样
max_wal_senders = 20

# 中断那些停止活动超过指定毫秒数的复制连接，可以适当设置大一点（默认60s，0表示禁用）
wal_sender_timeout = 180s

step3：重启容器：

docker restart postgres-10.6

连接数据库，如果查询一下语句，返回logical表示修改成功：

SHOW wal_level

3.新建用户并赋权

使用创建容器时的账号密码（postgres/postgres）登录Postgresql数据库。

先创建数据库和表：

-- 创建数据库test_db

 CREATE DATABASE test_db;

-- 连接到新创建的数据库 test_db

\c test_db

-- 创建 t_user 表

CREATE TABLE "public"."t_user" (
"id" int8 NOT NULL,
"name" varchar(255),
"age" int2,
PRIMARY KEY ("id")
); 

新建用户并且给用户权限：

-- pg新建用户

CREATE USER test1 WITH PASSWORD 'test123';

-- 给用户复制流权限

ALTER ROLE test1 replication;

-- 给用户登录数据库权限

 GRANT CONNECT ON DATABASE test_db to test1;

-- 把当前库public下所有表查询权限赋给用户

GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO test1;

5. 发布表

-- 设置发布为true

update pg_publication set puballtables=true where pubname is not null;

-- 把所有表进行发布

CREATE PUBLICATION dbz_publication FOR ALL TABLES;

-- 查询哪些表已经发布

select * from pg_publication_tables;

-- 更改复制标识包含更新和删除之前值（目的是为了确保表 t_user 在实时同步过程中能够正确地捕获并同步更新和删除的数据变化。如果不执行这两条语句，那么 t_user 表的复制标识可能默认为 NOTHING，这可能导致实时同步时丢失更新和删除的数据行信息，从而影响同步的准确性）

ALTER TABLE t_user REPLICA IDENTITY FULL;

-- 查看复制标识（为f标识说明设置成功，f（表示 full），否则为 n（表示 nothing），即复制标识未设置）

select relreplident from pg_class where relname='t_user';

3.代码工程

实验目标：测试读取postgres数据库中t_user增量数据

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springboot-demo</artifactId>
        <groupId>com.et</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>postgre</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <debezium.version>1.9.4.Final</debezium.version>

    </properties>
    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

        <!-- debezium -->
        <dependency>
            <groupId>io.debezium</groupId>
            <artifactId>debezium-api</artifactId>
            <version>${debezium.version}</version>
        </dependency>
        <dependency>
            <groupId>io.debezium</groupId>
            <artifactId>debezium-embedded</artifactId>
            <version>${debezium.version}</version>
        </dependency>
        <dependency>
            <groupId>io.debezium</groupId>
            <artifactId>debezium-connector-postgres</artifactId>
            <version>${debezium.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.12.0</version>
        </dependency>

    </dependencies>
</project>

DebeziumConnectorConfig.java

package com.et.postgres.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;

import java.io.File;
import java.io.IOException;

@Configuration
public class DebeziumConnectorConfig {

    @Bean
    public io.debezium.config.Configuration customerConnector(Environment env) throws IOException {
        File offsetStorageTempFile = File.createTempFile("offsets_", ".dat");
        return io.debezium.config.Configuration.create()
            .with("name", "customer_postgres_connector")
            .with("connector.class", "io.debezium.connector.postgresql.PostgresConnector")
            .with("offset.storage", "org.apache.kafka.connect.storage.FileOffsetBackingStore")
            .with("offset.storage.file.filename", offsetStorageTempFile.getAbsolutePath())
            .with("offset.flush.interval.ms", "60000")
            .with("database.hostname", env.getProperty("customer.datasource.host"))
            .with("database.port", env.getProperty("customer.datasource.port")) // defaults to 5432
            .with("database.user", env.getProperty("customer.datasource.username"))
            .with("database.password", env.getProperty("customer.datasource.password"))
            .with("database.dbname", env.getProperty("customer.datasource.database"))
            .with("database.server.id", "10181")
            .with("database.server.name", "customer-postgres-db-server")
            .with("database.history", "io.debezium.relational.history.MemoryDatabaseHistory")
            .with("table.include.list", "public.t_user")
            .with("column.include.list", "public.t_user.name,public.t_user.age")
            .with("publication.autocreate.mode", "filtered")
            .with("plugin.name", "pgoutput")
            .with("slot.name", "dbz_customerdb_listener")
            .build();
    }
}

DebeziumListener.java

package com.et.postgres.listener;

import io.debezium.config.Configuration;
import io.debezium.embedded.Connect;
import io.debezium.engine.DebeziumEngine;
import io.debezium.engine.RecordChangeEvent;
import io.debezium.engine.format.ChangeEventFormat;
import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.connect.data.Struct;
import org.apache.kafka.connect.source.SourceRecord;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import java.io.IOException;
import java.util.Objects;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

@Slf4j
@Component
public class DebeziumListener {

    private final Executor executor = Executors.newSingleThreadExecutor();    
    private final DebeziumEngine<RecordChangeEvent<SourceRecord>> debeziumEngine;

    public DebeziumListener(Configuration customerConnectorConfiguration) {
        this.debeziumEngine = DebeziumEngine.create(ChangeEventFormat.of(Connect.class))
            .using(customerConnectorConfiguration.asProperties())
            .notifying(this::handleChangeEvent)
            .build();
    }

    private void handleChangeEvent(RecordChangeEvent<SourceRecord> sourceRecordRecordChangeEvent) {
        SourceRecord sourceRecord = sourceRecordRecordChangeEvent.record();
        log.info("Key = {}, Value = {}", sourceRecord.key(), sourceRecord.value());
        Object sourceRecordChangeValue= (Struct) sourceRecord.value();
        log.info("SourceRecordChangeValue = '{}'",sourceRecordRecordChangeEvent);
        // if (sourceRecordChangeValue != null) {
        //     Operation operation = Operation.forCode((String) sourceRecordChangeValue.get(OPERATION));

        // Operation.READ operation events are always triggered when application initializes
        // We're only interested in CREATE operation which are triggered upon new insert registry
        //     if(operation != Operation.READ) {
        //         String record = operation == Operation.DELETE ? BEFORE : AFTER; // Handling Update & Insert operations.

        //         Struct struct = (Struct) sourceRecordChangeValue.get(record);
        //         Map<String, Object> payload = struct.schema().fields().stream()
        //             .map(Field::name)
        //             .filter(fieldName -> struct.get(fieldName) != null)
        //             .map(fieldName -> Pair.of(fieldName, struct.get(fieldName)))
        //             .collect(toMap(Pair::getKey, Pair::getValue));

        //         // this.customerService.replicateData(payload, operation);
        //         log.info("Updated Data: {} with Operation: {}", payload, operation.name());
        //     }
        // }
    }

    @PostConstruct
    private void start() {
        this.executor.execute(debeziumEngine);
    }

    @PreDestroy
    private void stop() throws IOException {
        if (Objects.nonNull(this.debeziumEngine)) {
            this.debeziumEngine.close();
        }
    }

}

DemoApplication.java

package com.et.postgres;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}

application.properties

customer.datasource.host=localhost
customer.datasource.port=30028
customer.datasource.database=test_db
customer.datasource.username=test1
customer.datasource.password=test123

logging.level.root=INFO
logging.level.io.debezium.postgres.BinlogReader=INFO
logging.level.io.davidarhcanjo=DEBUG

以上只是一些关键代码，所有代码请参见下面代码仓库

代码仓库

• https://github.com/Harries/springboot-demo

4.测试

• 启动spring boot应用程序

• 在表里面插入一些数据

  INSERT INTO public.t_user(id, "name", age) VALUES(1, 'harries', 18);

• 观察控制台输出

  2024-04-07 14:22:01.621 INFO 29260 --- [pool-1-thread-1] i.d.connector.common.BaseSourceTask : 1 records sent during previous 00:00:42.015, last recorded offset: {transaction_id=null, lsn_proc=23559864, lsn=23559864, txId=575, ts_usec=1712470921044339} 2024-04-07 14:22:01.622 INFO 29260 --- [pool-1-thread-1] c.et.postgres.listener.DebeziumListener : Key = Struct{id=1}, Value = Struct{after=Struct{name=harries,age=18},source=Struct{version=1.9.4.Final,connector=postgresql,name=customer-postgres-db-server,ts_ms=1712470921044,db=test_db,sequence=[null,"23559864"],schema=public,table=t_user,txId=575,lsn=23559864},op=c,ts_ms=1712470921607} 2024-04-07 14:22:01.622 INFO 29260 --- [pool-1-thread-1] c.et.postgres.listener.DebeziumListener : SourceRecordChangeValue = 'EmbeddedEngineChangeEvent [key=null, value=SourceRecord{sourcePartition={server=customer-postgres-db-server}, sourceOffset={transaction_id=null, lsn_proc=23559864, lsn=23559864, txId=575, ts_usec=1712470921044339}} ConnectRecord{topic='customer-postgres-db-server.public.t_user', kafkaPartition=null, key=Struct{id=1}, keySchema=Schema{customer_postgres_db_server.public.t_user.Key:STRUCT}, value=Struct{after=Struct{name=harries,age=18},source=Struct{version=1.9.4.Final,connector=postgresql,name=customer-postgres-db-server,ts_ms=1712470921044,db=test_db,sequence=[null,"23559864"],schema=public,table=t_user,txId=575,lsn=23559864},op=c,ts_ms=1712470921607}, valueSchema=Schema{customer_postgres_db_server.public.t_user.Envelope:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)}, sourceRecord=SourceRecord{sourcePartition={server=customer-postgres-db-server}, sourceOffset={transaction_id=null, lsn_proc=23559864, lsn=23559864, txId=575, ts_usec=1712470921044339}} ConnectRecord{topic='customer-postgres-db-server.public.t_user', kafkaPartition=null, key=Struct{id=1}, keySchema=Schema{customer_postgres_db_server.public.t_user.Key:STRUCT}, value=Struct{after=Struct{name=harries,age=18},source=Struct{version=1.9.4.Final,connector=postgresql,name=customer-postgres-db-server,ts_ms=1712470921044,db=test_db,sequence=[null,"23559864"],schema=public,table=t_user,txId=575,lsn=23559864},op=c,ts_ms=1712470921607}, valueSchema=Schema{customer_postgres_db_server.public.t_user.Envelope:STRUCT}, timestamp=null, headers=ConnectHeaders(headers=)}]'

5.引用

• https://github.com/davidarchanjo/spring-boot-debezium-postgres
• http://www.liuhaihua.cn/archives/710398.html
• https://debezium.io/documentation/reference/0.10/features.html