Interconnecting FlinkServer with JDBC

Scenario

FlinkServer can interconnect with JDBC. This topic uses FlinkServer and Kafka in security mode as an example to describe the DDL definition for JDBC MySQL source tables, sink tables, and dimension tables. This topic also explains the WITH parameters for creating a table and code examples. You will learn how to connect to JDBC on the FlinkServer job management page.

Mapping between Flink SQL and JDBC data types

Flink SQL	MySQL	Oracle	PostgreSQL	SQL Server
BOOLEAN	BOOLEAN TINYINT(1)	-	BOOLEAN	BIT
TINYINT	TINYINT	-	-	TINYINT
SMALLINT	SMALLINT TINYINT UNSIGNED	-	SMALLINT INT2 SMALLSERIAL SERIAL2	SMALLINT
INT	INT MEDIUMINT SMALLINT UNSIGNED	-	INTEGER SERIAL	INT
BIGINT	BIGINT INT UNSIGNED	-	BIGINT BIGSERIAL	BIGINT
FLOAT	FLOAT	BINARY_FLOAT	REAL FLOAT4	REAL
DOUBLE	DOUBLE DOUBLE PRECISION	BINARY_DOUBLE	FLOAT8 DOUBLE PRECISION	FLOAT
STRING	CHAR(n) VARCHAR(n) TEXT	CHAR(n) VARCHAR(n) CLOB	CHAR(n) CHARACTER(n) VARCHAR(n) CHARACTER VARYING(n) TEXT	CHAR(n) NCHAR(n) VARCHAR(n) NVARCHAR(n) TEXT NTEXT
BYTES	BINARY VARBINARY BLOB	RAW(s) BLOB	BYTEA	BINARY(n) VARBINARY(n)
ARRAY	-	-	ARRAY	-
DATE	DATE	DATE	DATE	DATE
TIME [(p)] [WITHOUT TIMEZONE]	TIME [(p)]	DATE	TIME [(p)] [WITHOUT TIMEZONE]	TIME(0)
TIMESTAMP [(p)] [WITHOUT TIMEZONE]	DATETIME [(p)]	TIMESTAMP [(p)] [WITHOUT TIMEZONE]	TIMESTAMP [(p)] [WITHOUT TIMEZONE]	DATETIME DATETIME2
DECIMAL(20, 0)	BIGINT UNSIGNED	-	-	-
DECIMAL(p, s)	NUMERIC(p, s) DECIMAL(p, s)	SMALLINT FLOAT(s) DOUBLE PRECISION REAL NUMBER(p, s)	NUMERIC(p, s) DECIMAL(p, s)	DECIMAL(p, s)

Prerequisites

Cluster where FlinkServer resides:

HDFS, Yarn, Kafka, ZooKeeper, and Flink have been installed in the cluster.
The client that contains the Kafka service has been installed, for example, in the /opt/client directory.
You have created a user with the FlinkServer Admin Privilege (for example, flinkuser) for accessing the Flink web UI.

JDBC Sink Table (MySQL as an Example)

Create an empty table for receiving data in a database, for example, MySQL database customer_t1.
Log in to Manager as user flinkuser and choose Cluster > Services > Flink. In the Basic Information area, click the link next to Flink WebUI to access the Flink web UI.
Create a Flink SQL job by referring to Creating a Job. On the job development page, configure the job parameters as follows and start the job.

In Basic Parameter, select Enable CheckPoint, set Time Interval(ms) to 60000, and retain the default value for Mode.
```
CREATE TABLE MyUserTable(
  c_customer_sk INTEGER,
  c_customer_name VARCHAR(32)
) WITH(
  'connector' = 'jdbc',
  'url' = 'jdbc:mysql://IP address of the MySQL server:MySQL server port/mysql',
  'table-name' = 'customer_t1',
  'username' ='MySQL database username',
  'password' ='Password of the MySQL database user'
);
CREATE TABLE KafkaSource (
  c_customer_sk INTEGER,
  c_customer_name VARCHAR(32)
) WITH (
  'connector' = 'kafka',
  'topic' = 'customer_source',
  'properties.bootstrap.servers' = 'Service IP address of the Kafka Broker instance:Kafka port number',
  'properties.group.id' = 'testGroup',
  'scan.startup.mode' = 'latest-offset',
  'value.format' = 'csv',
  'properties.sasl.kerberos.service.name' = 'kafka',  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
  'properties.security.protocol' = 'SASL_PLAINTEXT',  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
  'properties.kerberos.domain.name' = 'hadoop.System domain name'  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
);
Insert into
  MyUserTable
select
  *
from
  KafkaSource;
```
- The IP address and port number of the Kafka broker instance are as follows:
  - To obtain the instance IP address, log in to FusionInsight Manager, choose Cluster > Services > Kafka, click Instance, and query the instance IP address on the instance list page.
  - If Kerberos authentication is enabled for the cluster (the cluster is in security mode), the Broker port number is the value of sasl.port. The default value is 21007.
  - If Kerberos authentication is disabled for the cluster (the cluster is in normal mode), the broker port number is the value of port. The default value is 9092. If the port number is set to 9092, set allow.everyone.if.no.acl.found to true. The procedure is as follows:
    Log in to FusionInsight Manager and choose Cluster > Services > Kafka. Click Configurations then All Configurations. On the page that is displayed, search for allow.everyone.if.no.acl.found, set it to true, and click Save.
- System domain name: To obtain the value, log in to FusionInsight Manager, choose System > Permission > Domain and Mutual Trust, and check the value of Local Domain.
- properties.group.id indicates the Kafka user group ID. This parameter is mandatory when Kafka functions as the source.
- properties.kerberos.domain.name: Set it to hadoop.System domain name. To obtain the actual domain name of the cluster, log in to FusionInsight Manager and choose System > Permission > Domain and Mutual Trust.
On the job management page, check whether the job status is Running.
Execute the following commands to view the topic and write data to Kafka. For details, see Managing Messages in Kafka Topics.

./kafka-topics.sh --list --bootstrap-server Service IP address of the Kafka Broker instance:Kafka port --command-config Client directory/Kafka/kafka/config/client.properties

sh kafka-console-producer.sh --broker-list IP address of the node where Kafka Broker instances reside:Kafka port --topic Topic name --producer.config Client directory/Kafka/kafka/config/producer.properties

In this example, the topic name is customer_source.

sh kafka-console-producer.sh --broker-list IP address of the node where the Kafka Broker instance is located:Kafka port --topic customer_source --producer.config /opt/client/Kafka/kafka/config/producer.properties

Enter the message content.
```
3,zhangsan
4,wangwu
8,zhaosi
```
Press Enter to send the message.
Log in to the MySQL client and run the following statement to check whether the sink table received data:

Select * from customer_t1;

JDBC Source Table (MySQL as an Example)

Log in to Manager as user flinkuser and choose Cluster > Services > Flink. In the Basic Information area, click the link next to Flink WebUI to access the Flink web UI.
Create a Flink SQL job by referring to Creating a Job. On the job development page, configure the job parameters as follows and start the job.

In Basic Parameter, select Enable CheckPoint, set Time Interval(ms) to 5000, and retain the default value for Mode.
```
CREATE TABLE MyUserTable(
  --MySQL source table
  c_customer_sk INTEGER,
  c_customer_name VARCHAR(32)
) WITH(
  'connector' = 'jdbc',
  'url' = 'jdbc:mysql://IP address of the MySQL server:MySQL server port/mysql',
  'table-name' = 'customer_t1',
  'username' ='MySQL database username',
  'password' ='Password of the MySQL database user'
);
CREATE TABLE KafkaSink (
  -- Kafka functions as a sink table.
  c_customer_sk INTEGER,
  c_customer_name VARCHAR(32)
) WITH (
  'connector' = 'kafka',
  'topic' = 'customer_sink',
  'properties.bootstrap.servers' = 'Service IP address of the Kafka Broker instance:Kafka port number',
  'properties.group.id' = 'testGroup',
  'scan.startup.mode' = 'latest-offset',
  'value.format' = 'csv',
  'properties.sasl.kerberos.service.name' = 'kafka',  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
  'properties.security.protocol' = 'SASL_PLAINTEXT',  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
  'properties.kerberos.domain.name' = 'hadoop.System domain name'  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
);
Insert into
  KafkaSink
select
  *
from
  MyUserTable;
```
- The IP address and port number of the Kafka broker instance are as follows:
  - To obtain the instance IP address, log in to FusionInsight Manager, choose Cluster > Services > Kafka, click Instance, and query the instance IP address on the instance list page.
  - If Kerberos authentication is enabled for the cluster (the cluster is in security mode), the Broker port number is the value of sasl.port. The default value is 21007.
  - If Kerberos authentication is disabled for the cluster (the cluster is in normal mode), the broker port number is the value of port. The default value is 9092. If the port number is set to 9092, set allow.everyone.if.no.acl.found to true. The procedure is as follows:
    Log in to FusionInsight Manager and choose Cluster > Services > Kafka. Click Configurations then All Configurations. On the page that is displayed, search for allow.everyone.if.no.acl.found, set it to true, and click Save.
- System domain name: You can log in to FusionInsight Manager, choose System > Permission > Domain and Mutual Trust, and check the value of Local Domain.
- properties.group.id indicates the Kafka user group ID. This parameter is mandatory when Kafka functions as the source.
- properties.kerberos.domain.name: Set it to hadoop.System domain name. You can log in to FusionInsight Manager and choose System > Permission > Domain and Mutual Trust to view the actual domain name of the cluster.
On the job management page, check whether the job status is Running.
Obtain the required Kafka IP address and port by referring to Managing Messages in Kafka Topics, and run the following command to check whether data is written from the Kafka topic to the sink table:

sh kafka-console-consumer.sh --topic customer_sink --bootstrap-server IP address of the node where the Kafka instance is deployed:Kafka port number --consumer.config /opt/client/Kafka/kafka/config/ consumer.properties

JDBC Dimension Table (MySQL as an Example)

kafkaSource is used as the fact table, customer_t2 is used as the dimension table, and the result is written to kafkaSink.

Create the dimension table customer_t2 on the MySQL client. An example of the table creation statement is as follows:

CREATE TABLE customer_t2(
c_customer_sk INTEGER PRIMARY KEY,
c_customer_age INTEGER,
c_customer_address VARCHAR(32)
);
 
INSERT INTO customer_t2 VALUES(1,18,'city a');
INSERT INTO customer_t2 VALUES(2,14,'city b');
INSERT INTO customer_t2 VALUES(3,16,'city c');
INSERT INTO customer_t2 VALUES(4,24,'city d');
INSERT INTO customer_t2 VALUES(5,32,'city e');
INSERT INTO customer_t2 VALUES(6,27,'city f');
INSERT INTO customer_t2 VALUES(7,41,'city a');
INSERT INTO customer_t2 VALUES(8,35,'city h');
INSERT INTO customer_t2 VALUES(9,16,'city j');

Log in to Manager as user flinkuser and choose Cluster > Services > Flink. In the Basic Information area, click the link next to Flink WebUI to access the Flink web UI.

Create a Flink SQL job by referring to Creating a Job. On the job development page, configure the job parameters as follows and start the job.

In Basic Parameter, select Enable CheckPoint, set Time Interval(ms) to 5000, and retain the default value for Mode.

CREATE TABLE KafkaSource (
  -- Kafka as a source table
  c_customer_sk INTEGER,
  c_customer_name VARCHAR(32),
  proctime as proctime()
) WITH (
  'connector' = 'kafka',
  'topic' = 'customer_source',
  'properties.bootstrap.servers' = 'Service IP address of the Kafka Broker instance:Kafka port',
  'properties.group.id' = 'testGroup',
  'scan.startup.mode' = 'latest-offset',
  'value.format' = 'csv',
  'properties.sasl.kerberos.service.name' = 'kafka',  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
  'properties.security.protocol' = 'SASL_PLAINTEXT',  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
  'properties.kerberos.domain.name' = 'hadoop.System domain name'  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
);
CREATE TABLE KafkaSink (
  -- Kafka sink table.
  c_customer_sk INTEGER,
  c_customer_name VARCHAR(32),
  c_customer_age INTEGER,
  c_customer_address VARCHAR(32)
) WITH (
  'connector' = 'kafka',
  'topic' = 'customer_sink',
  'properties.bootstrap.servers' = 'Service IP address of the Kafka Broker instance:Kafka port',
  'properties.group.id' = 'testGroup',
  'scan.startup.mode' = 'latest-offset',
  'value.format' = 'csv',
  'properties.sasl.kerberos.service.name' = 'kafka',  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
  'properties.security.protocol' = 'SASL_PLAINTEXT',  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
  'properties.kerberos.domain.name' = 'hadoop.System domain name'  --Delete this parameter if the cluster where FlinkServer is deployed is in non-security mode.
);
CREATE TABLE MyUserTable (
  -- MySQL dimension table
  c_customer_sk INTEGER PRIMARY KEY NOT ENFORCED,
  c_customer_age INTEGER,
  c_customer_address VARCHAR(32)
) WITH (
  'connector' = 'jdbc',
  'url' = 'jdbc:mysql://IP address of the MySQL server:MySQL server port/mysql',
  'table-name' = 'customer_t2',
  'username' ='MySQL database username',
  'password' ='Password of the MySQL database user'
);
INSERT INTO
  KafkaSink
SELECT
  t.c_customer_sk,
  t.c_customer_name,
  d.c_customer_age,
  d.c_customer_address
FROM
  KafkaSource as t
  JOIN MyUserTable FOR SYSTEM_TIME AS OF t.proctime as d ON t.c_customer_sk = d.c_customer_sk;

The IP address and port number of the Kafka broker instance are as follows:
- To obtain the instance IP address, log in to FusionInsight Manager, choose Cluster > Services > Kafka, click Instance, and query the instance IP address on the instance list page.
- If Kerberos authentication is enabled for the cluster (the cluster is in security mode), the Broker port number is the value of sasl.port. The default value is 21007.
- If Kerberos authentication is disabled for the cluster (the cluster is in normal mode), the broker port number is the value of port. The default value is 9092. If the port number is set to 9092, set allow.everyone.if.no.acl.found to true. The procedure is as follows:
  Log in to FusionInsight Manager and choose Cluster > Services > Kafka. Click Configurations then All Configurations. On the page that is displayed, search for allow.everyone.if.no.acl.found, set it to true, and click Save.

System domain name: You can log in to FusionInsight Manager, choose System > Permission > Domain and Mutual Trust, and check the value of Local Domain.
properties.group.id indicates the Kafka user group ID. This parameter is mandatory when Kafka functions as the source.
properties.kerberos.domain.name: Set it to hadoop.System domain name. You can log in to FusionInsight Manager and choose System > Permission > Domain and Mutual Trust to view the actual domain name of the cluster.

Run the following command to check whether data is received in the sink table, that is, check whether data is properly written to the Kafka topic after 5 is performed. For details, see Managing Messages in Kafka Topics.

sh kafka-console-consumer.sh --topic customer_sink --bootstrap-server IP address of the node where the Kafka instance is deployed:Kafka port number --consumer.config /opt/client/Kafka/kafka/config/ consumer.properties
View the topic and write data to the Kafka topic by referring to Managing Messages in Kafka Topics. After the data is written, view the execution result in the window in 4.

./kafka-topics.sh --list Service IP address of the Kafka Broker instance:Kafka port --command-config Client directory/Kafka/kafka/config/client.properties

sh kafka-console-producer.sh --broker-list IP address of the node where Kafka Broker instances are deployed:Kafka port --topic Topic name --producer.config Client directory/Kafka/kafka/config/producer.properties

In this example, the topic name is customer_source.

sh kafka-console-producer.sh --broker-list IP address of the node where the Kafka Broker instance is deployed:Kafka port --topic customer_source --producer.config /opt/client/Kafka/kafka/config/producer.properties

Enter the message content.
```
3,zhangsan
5,zhaosi
1,xiaoming
2,liuyang
7,liubei
10,guanyu
20,zhaoyun
```
Press Enter to send the message. The output in the kafka-console-consumer window in 4 is as follows:
```
3,zhangsan,16,city c
5,zhaosi,32,city e
1,xiaoming,18,city a
2,liuyang,14,city b
7,liubei,41,city a
```