Subject: Logical replication without direct link between publisher and subscriber?

From: Koen De Groote <[email-masked]>
Date: Mon, 9 Sep 2024 16:36:26 +0200

I want to have a PG instance receive logical replication from a publisher.

However, the subscriber should not have network access to the publisher, in
any way. This is for security reasons. No VPN or any setup that allows the
subscriber to send traffic to the publisher host.

The publisher, however, can reach the subscriber IP and send traffic to it.

Is there a way to start a logical replication setup without having the
subscriber create a subscription? Run a few commands on the publisher and
the subscriber suddenly starts receiving data?

>From what I've googled, an option would be to use pgrecvlogical:
https://www.postgresql.org/docs/current/app-pgrecvlogical.html

Dumping changes periodically, sending them directly or uploading to cloud
storage and then downloading and applying them on the subscriber side.

But maybe there's a simpler option someone here knows about?

Any help and/or suggestions appreciated.

Thanks,
Koen

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From: Greg Sabino Mullane <[email-masked]>
Date: Wed, 11 Sep 2024 09:19:37 -0400

> But maybe there's a simpler option someone here knows about?

How about using WAL shipping to populate a replica, and either query that
directly or use that as the publisher to your sequestered node?

Cheers,
Greg

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From: Koen De Groote <[email-masked]>
Date: Thu, 12 Sep 2024 20:47:21 +0200

I've considered it, but it sounds like a lot of work and failure prone.
Even projects like Debezium seem like it's a ton to set up.

Thanks for the suggestions.

Regards,
Koen