Let us take a closer look at the AWS DMS task using PostgreSQL fails. With the support of our PostgreSQL support services at Bobcares we will give you a complete overview of the process.

Description: AWS DMS task using PostgreSQL fails

AWS DMS performs logical replication for change data capture on Amazon RDS for PostgreSQL instances using native replication slots (CDC).

The max replication slots option governs the number of replication slots available to a PostgreSQL instance. RDS PostgreSQL instances have five replication slots by default.

When we reach the maximum number of replication slots, we observe the following log entries:

Remove the utilized replication slots or raise the value of the max replication slots option to remedy these problems.

Resolution: Remove used replication slots

We have to remove used replication slots if we are running multiple Amazon DMS jobs or if we have old tasks running on the same Database instance. These replication slots continue to use up space, so by eliminating them, we may free up spaces for new activities.

To begin, determine the maximum number of replication slots. Then, delete or “drop” the previously utilized replication slots.

Execute the following query to get the maximum number of replication slots:

Execute the following query to remove a previously utilized replication slot:

Increase the value of the max_replication_slots parameter

Change the DB parameter in the custom DB parameter groups associated with the Amazon RDS DB instance. Then, raise the max replication slots option value. As this is a static parameter, we must restart the Database instance after altering the parameter value.

Restart the process when we delete the utilized replication slots or raise the value of the max replication slots parameter.

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Conclusion

To sum up, we have now gone through AWS DMS task using PostgreSQL fails. WIht the support of our PostgreSQL support services at Bobcares we have gone through the whole porcess.