PostgreSQL change data capture and delivery to YDS

You can track data changes in a Managed Service for PostgreSQL source cluster and send them to a Data Streams target cluster using Change Data Capture (CDC).

To set up CDC using Data Transfer:

1. Set up the transfer.
2. Activate the transfer.
3. Test the replication process.

If you no longer need the resources you created, delete them.

Getting startedGetting started

Prepare the infrastructure:

Set up the transferSet up the transfer

1. Create a Data Streams data stream named mpg-stream.

2. Connect to the Managed Service for PostgreSQL cluster, create a table named measurements in the db1 database, and populate it with data:

   CREATE TABLE measurements (
       device_id varchar(200) NOT NULL,
       datetime timestamp NOT NULL,
       latitude real NOT NULL,
       longitude real NOT NULL,
       altitude real NOT NULL,
       speed real NOT NULL,
       battery_voltage real,
       cabin_temperature real NOT NULL,
       fuel_level real,
       PRIMARY KEY (device_id)
   );
   INSERT INTO measurements VALUES
       ('iv9a94th6rzt********', '2022-06-05 17:27:00', 55.70329032, 37.65472196,  427.5,    0, 23.5, 17, NULL),
       ('rhibbh3y08qm********', '2022-06-06 09:49:54', 55.71294467, 37.66542005, 429.13, 55.5, NULL, 18, 32);
   

3. Create a target endpoint of the Data Streams type with the following settings:

   • Database: ydb-example.
   • Stream: mpg-stream.
   • Service account: yds-sa.

4. Create a source endpoint and a transfer.

   Manually

   Terraform

   1. Create a source endpoint of the PostgreSQL type and specify the cluster connection parameters in it:

      • Installation type: Managed Service for PostgreSQL cluster.
      • Managed Service for PostgreSQL cluster: <PostgreSQL_source_cluster_name> from the drop-down list.
      • Database: db1.
      • User: pg-user.
      • Password: pg-user user password.

   2. Create a transfer of the Replication type that will use the created endpoints.

   1. In the postgresql-yds.tf file, specify these variables:

      • yds_endpoint_id: Target endpoint ID.
      • transfer_enabled: 1 to create a transfer.

   2. Make sure the Terraform configuration files are correct using this command:

      terraform validate
      

      If there are any errors in the configuration files, Terraform will point them out.

   3. Create the required infrastructure:

      1. Run the command to view planned changes:

         terraform plan
         

         If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

      2. If you are happy with the planned changes, apply them:

         1. Run the command:

            terraform apply
            

         2. Confirm the update of resources.

         3. Wait for the operation to complete.

Activate the transferActivate the transfer

1. Activate the transfer and wait for its status to change to Replicating.

2. Make sure the data from the source has been moved to the Data Streams stream:

   Management console

   AWS CLI

   1. In the management console, select Data Streams.
   2. Select the target stream from the list and go to Data viewer.
   3. Make sure shard-000000 contains messages with the source table rows. To view message details, click .

   1. Install the AWS CLI.

   2. Configure the environment for Data Streams.

   3. Read the stream data using:

      • AWS CLI.
      • AWS SDK.

Test the replication processTest the replication process

1. Connect to the source cluster.

2. Add a new row to the measurements table:

   INSERT INTO measurements VALUES
       ('ad02l5ck6sdt********', '2022-06-05 17:27:00', 55.70329032, 37.65472196,  427.5,    0, 23.5, 19, 45);
   

3. Make sure the new row is shown in the Data Streams stream.

Delete the resources you createdDelete the resources you created

Some resources are not free of charge. To avoid paying for them, delete the resources you no longer need:

1. Delete the transfer.
2. Delete the target endpoint.
3. Delete the Data Streams stream.

Delete the other resources depending on how they were created: