Managing logical replication slots for RDS for PostgreSQL

Before you can perform a major version upgrade on an RDS for PostgreSQL DB instance that's serving as a publisher node in a logical replication scenario, you must drop the replication slots on the instance. The major version upgrade pre-check process notifies you that the upgrade can't proceed until the slots are dropped.

To drop slots from your RDS for PostgreSQL DB instance, first drop the subscription and then drop the slot.

To identify replication slots that were created using the pglogical extension, log in to each database and get the name of the nodes. When you query the subscriber node, you get both the publisher and the subscriber nodes in the output, as shown in this example.

SELECT * FROM pglogical.node;
node_id   |     node_name
------------+-------------------
 2182738256 | docs_lab_target
 3410995529 | docs_lab_provider
(2 rows)

You can get the details about the subscription with the following query.

SELECT sub_name,sub_slot_name,sub_target
  FROM pglogical.subscription;
 sub_name |         sub_slot_name          | sub_target
----------+--------------------------------+------------
  docs_lab_subscription     | pgl_labdb_docs_labcb4fa94_docs_lab3de412c | 2182738256
(1 row)

You can now drop the subscription, as follows.

SELECT pglogical.drop_subscription(subscription_name := 'docs_lab_subscription');
 drop_subscription
-------------------
                 1
(1 row)

After dropping the subscription, you can delete the node.

SELECT pglogical.drop_node(node_name := 'docs-lab-subscriber');
 drop_node
-----------
 t
(1 row)

You can verify that the node no longer exists, as follows.

SELECT * FROM pglogical.node;
 node_id | node_name
---------+-----------
(0 rows)