DWS Sink Stream (JDBC Mode)

Function

DLI outputs the Flink job output data to Data Warehouse Service (DWS). DWS database kernel is compliant with PostgreSQL. The PostgreSQL database can store data of more complex types and delivers space information services, multi-version concurrent control (MVCC), and high concurrency. It applies to location applications, financial insurance, and e-commerce.

DWS is an online data processing database based on the cloud infrastructure and platform and helps you mine and analyze massive sets of data. For more information about DWS, see the Data Warehouse Service Management Guide.

Prerequisites

Ensure that you have created a DWS cluster on DWS using your account.
For details about how to create a DWS cluster, see Creating a Cluster in the Data Warehouse Service Management Guide.
Ensure that a DWS database table has been created.
In this scenario, jobs must run on the dedicated queue of DLI. Therefore, DLI must interconnect with the enhanced datasource connection that has been connected with DWS clusters. You can also set the security group rules as required.
For details about how to create an enhanced datasource connection, see Enhanced Datasource Connections in the Data Lake Insight User Guide.

For details about how to configure security group rules, see Security Group in the Virtual Private Cloud User Guide.

Syntax

    
         CREATE SINK STREAM stream_id (attr_name attr_type (',' attr_name attr_type)* )
  WITH (
    type = "rds",
    username = "",
    password = "",
    db_url = "",
    table_name = ""
  );

Keywords

Table 1 Keywords

Parameter

Mandatory

Description

type

Yes

Output channel type. rds indicates that data is exported to RDS or DWS.

username

Yes

Username for connecting to a database.

password

Yes

Password for connecting to a database.

db_url

Yes

Database connection address, for example, postgresql://ip:port/database.

table_name

Yes

Name of the table where data will be inserted. You need to create the database table in advance.

db_columns

Mapping between attributes in the output stream and those in the database table. This parameter must be configured based on the sequence of attributes in the output stream.

Example:

         
              create sink stream a3(student_name  string, student_age int) 
  with (
    type = "rds",
    username = "root",
    password = "xxxxxxxx",
    db_url = "postgresql://192.168.0.102:8000/test1",
    db_columns = "name,age",
    table_name = "t1"
  );

In the example, student_name corresponds to the name attribute in the database, and student_age corresponds to the age attribute in the database.

NOTE:

If db_columns is not configured, it is normal that the number of attributes in the output stream is less than that of attributes in the database table and the extra attributes in the database table are all nullable or have default values.

primary_key

To update data in the table in real time by using the primary key, add the primary_key configuration item (c_timeminute in the following example) when creating a table. During the data writing operation, data is updated if the specified primary_key exists. Otherwise, data is inserted.

Example:

         
              CREATE SINK STREAM test(c_timeminute LONG, c_cnt LONG)
  WITH (
    type = "rds",
    username = "root",
    password = "xxxxxxxx",
    db_url = "postgresql://192.168.0.12:8000/test",
    table_name = "test",
    primary_key = "c_timeminute"
  );

Precautions

The stream format defined by stream_id must be the same as the table format.

Example

Data of stream audi_cheaper_than_30w is exported to the audi_cheaper_than_30w table in the test database.

    
         CREATE SINK STREAM audi_cheaper_than_30w (
  car_id STRING,
  car_owner STRING,
  car_brand STRING,
  car_price INT
)
  WITH (
    type = "rds",
    username = "root",
    password = "xxxxxx",
    db_url = "postgresql://192.168.1.1:8000/test",
    table_name = "audi_cheaper_than_30w"
  ); 

insert into audi_cheaper_than_30w select "1","2","3",4;