Flink-cdc实时读postgresql

由于公司业务需要，需要实时同步pgsql数据，我们选择使用flink-cdc方式进行

架构图：

前提步骤:

1，更改配置文件postgresql.conf

# 更改wal日志方式为logical
wal_level = logical # minimal, replica, or 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 # max number of replication slots

# 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 # max number of walsender processes
# 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）
wal_sender_timeout = 180s # in milliseconds; 0 disable　　

wal_level是必须更改的，其它参数选着性更改，如果同步表数量超过10张建议修改为合适的值

更改配置文件postgresql.conf完成，需要重启pg服务生效，所以一般是在业务低峰期更改

2，新建用户并且给用户复制流权限

-- pg新建用户
CREATE USER user WITH PASSWORD 'pwd';

-- 给用户复制流权限
ALTER ROLE user replication;

-- 给用户登录数据库权限
grant CONNECT ON DATABASE test to user;

-- 把当前库public下所有表查询权限赋给用户
GRANT SELECT ON ALL TABLES IN SCHEMA public TO user;

3，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;

4，更改表的复制标识包含更新和删除的值

-- 更改复制标识包含更新和删除之前值
ALTER TABLE test0425 REPLICA IDENTITY FULL;
-- 查看复制标识（为f标识说明设置成功）
select relreplident from pg_class where relname='test0425';

 OK，到这一步，设置已经完全可以啦，上面步骤都是必须的

常用的pgsql命令（备忘）

-- pg新建用户
CREATE USER ODPS_ETL WITH PASSWORD 'odpsETL@2021';
-- 给用户复制流权限
ALTER ROLE ODPS_ETL replication;
-- 给用户数据库权限
grant CONNECT ON DATABASE test to ODPS_ETL;
-- 设置发布开关
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;
-- 给表查询权限
grant select on TABLE aa to ODPS_ETL;
-- 给用户读写权限
grant select,insert,update,delete ON  ALL TABLES IN SCHEMA public to bd_test;
-- 把当前库所有表查询权限赋给用户
GRANT SELECT ON ALL TABLES IN SCHEMA public TO ODPS_ETL;
-- 把当前库以后新建的表查询权限赋给用户
alter default privileges in schema public grant select on tables to ODPS_ETL;
-- 更改复制标识包含更新和删除之前值
ALTER TABLE test0425 REPLICA IDENTITY FULL;
-- 查看复制标识
select relreplident from pg_class where relname='test0425';
-- 查看solt使用情况
SELECT * FROM pg_replication_slots;
-- 删除solt
SELECT pg_drop_replication_slot('zd_org_goods_solt');
-- 查询用户当前连接数
select usename, count(*) from pg_stat_activity group by usename order by count(*) desc;
-- 设置用户最大连接数
alter role odps_etl connection limit 200;

5，下面开始上代码：,

maven依赖

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-scala_2.11</artifactId>
            <version>1.13.0</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.flink/flink-streaming-scala -->
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-scala_2.11</artifactId>
            <version>1.13.0</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba.ververica</groupId>
            <artifactId>flink-connector-postgres-cdc</artifactId>
            <version>1.1.0</version>
        </dependency>

java代码

package flinkTest.connect;

import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.table.api.EnvironmentSettings;
import org.apache.flink.table.api.TableResult;
import org.apache.flink.table.api.bridge.java.StreamTableEnvironment;

public class PgsqlToMysqlTest {
    public static void main(String[] args) {
        //设置flink表环境变量
        EnvironmentSettings fsSettings = EnvironmentSettings.newInstance()
                .useBlinkPlanner()
                .inStreamingMode()
                .build();

        //获取flink流环境变量
        StreamExecutionEnvironment exeEnv = StreamExecutionEnvironment.getExecutionEnvironment();
        exeEnv.setParallelism(1);

        //表执行环境
        StreamTableEnvironment tableEnv = StreamTableEnvironment.create(exeEnv, fsSettings);

        //拼接souceDLL
        String sourceDDL =
                "CREATE TABLE pgsql_source (
" +
                        " id int,
" +
                        " name STRING,
" +
                        " py_code STRING,
" +
                        " seq_no int,
" +
                        " description STRING
" +
                        ") WITH (
" +
                        " 'connector' = 'postgres-cdc',
" +
                        " 'hostname' = '***',
" +
                        " 'port' = '5432',
" +
                        " 'username' = 'bd_test',
" +
                        " 'password' = '***',
" +
                        " 'database-name' = 'bd_test',
" +
                        " 'schema-name' = 'public',
" +
                        " 'debezium.snapshot.mode' = 'never',
" +
                        " 'decoding.plugin.name' = 'pgoutput',
" +
                        " 'debezium.slot.name' = 'test',
" +
                        " 'table-name' = 'test'
" +
                        ")";

        String sinkDDL =
                "CREATE TABLE mysql_sink (
" +
                        " id int,
" +
                        " name STRING,
" +
                        " py_code STRING,
" +
                        " seq_no int,
" +
                        " description STRING,
" +
                        " PRIMARY KEY (id) NOT ENFORCED
" +
                        ") WITH (
" +
                        " 'connector' = 'jdbc',
" +
                        " 'url' = 'jdbc:mysql://ip:3306/test_db?rewriteBatchedStatements=true&useUnicode=true&characterEncoding=UTF-8',
" +
                        " 'username' = 'bd_test',
" +
                        " 'password' = '***',
" +
                        " 'table-name' = 'test'
" +
                        ")";

        String transformSQL =
                "INSERT INTO mysql_sink " +
                        "SELECT id,name,py_code,seq_no,description " +
                        "FROM pgsql_source";

        //执行source表ddl
        tableEnv.executeSql(sourceDDL);
        //执行sink表ddl
        tableEnv.executeSql(sinkDDL);
        //执行逻辑sql语句
        TableResult tableResult = tableEnv.executeSql(transformSQL);

        //控制塔输出
//        tableResult.print();
    }
}

表机构奉上：

-- pgsql表结构
CREATE TABLE "public"."test" (
  "id" int4 NOT NULL,
  "name" varchar(50) COLLATE "pg_catalog"."default" NOT NULL,
  "py_code" varchar(50) COLLATE "pg_catalog"."default",
  "seq_no" int4 NOT NULL,
  "description" varchar(200) COLLATE "pg_catalog"."default",
  CONSTRAINT "pk_zd_business_type" PRIMARY KEY ("id")
)
;

-- mysql表结构
CREATE TABLE `test` (
  `id` int(11) NOT NULL DEFAULT '0' COMMENT 'ID',
  `name` varchar(50) DEFAULT NULL COMMENT '名称',
  `py_code` varchar(50) DEFAULT NULL COMMENT '助记码',
  `seq_no` int(11) DEFAULT NULL COMMENT '排序',
  `description` varchar(200) DEFAULT NULL COMMENT '备注',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

 6，下面就可以进行操作原表，然后增删改操作

WITH参数

类型映射

Postgres CDC和Flink字段类型对应关系如下。