Create an OpenSearch®-based Apache Flink® table

To build data pipelines, Apache Flink® requires you to map source and target data structures as Flink tables within an application. You can accomplish this through the Aiven Console or Aiven CLI.

You can define a Flink table over an existing or new Aiven for OpenSearch® index, to sink streaming data. To define a table over an OpenSearch® index, specify the index name, column data formats, and the Flink table name you want to use as a reference when building data pipelines.

Warning

• To use Flink tables an existing integration must be available between the Aiven for Flink® service and one or more Aiven for OpenSearch® services.

• You can use Aiven for OpenSearch® can only as the target of a data pipeline. You can create Flink applications that write data to an OpenSearch® index. However, reading data from an OpenSearch® index is currently not possible.

Create an OpenSearch®-based Apache Flink® table with Aiven Console

To create an Apache Flink table based on an Aiven for OpenSearch® index via Aiven console:

1. In the Aiven for Apache Flink service page, select Application from the left sidebar.

2. Create a new application or select an existing one with Aiven for OpenSearch® integration.

   Note

   If editing an existing application, create a new version to make changes to the source or sink tables.

3. In the Create new version screen, select Add sink tables.

4. Select Add new table or select Edit if you want to edit an existing source table.

5. In the Add new sink table or Edit sink table screen, select the Aiven for OpenSearch® as the integrated service.

6. In the Table SQL section, enter the SQL statement to create the OpenSearch-based Apache Flink table.

   • Define the Flink table name, which will represent the Flink reference to the topic and will be used during the data pipeline definition.

7. In the Create statement section, write the SQL schema that defines the fields to be pushed for each message in the OpenSearch index.

Example: Define an Apache Flink® table to OpenSearch®

We want to push the result of an Apache Flink® application to an index named metrics in an Aiven for OpenSearch® service named demo-opensearch. The application result should generate the following data:

{'hostname': 'sleepy', 'cpu': 'cpu3', 'usage': 93.30629927475789, 'occurred_at': 1637775077782}
{'hostname': 'dopey', 'cpu': 'cpu4', 'usage': 88.39531418706092, 'occurred_at': 1637775078369}
{'hostname': 'happy', 'cpu': 'cpu2', 'usage': 77.90860728236156, 'occurred_at': 1637775078964}
{'hostname': 'dopey', 'cpu': 'cpu4', 'usage': 81.17372993952847, 'occurred_at': 1637775079054}

We can define a metrics_out Apache Flink® table with:

• demo-opensearch as integration service

• metrics as OpenSearch® index name

• metrics_out as Flink table name

• the following as SQL schema

CREATE TABLE metrics_out (
cpu VARCHAR,
hostname VARCHAR,
usage DOUBLE,
occurred_at BIGINT
) WITH (
'connector' = 'elasticsearch-7',
'hosts' = '',
'index' = 'metrics'
)

The hosts will be substituted with the appropriate address during runtime.