Re: Synchronizing slots from primary to standby

Hi,

On 7/24/23 4:32 AM, Bharath Rupireddy wrote:
> On Fri, Jul 21, 2023 at 5:16 PM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:

> Here are my thoughts about this feature:

Thanks for looking at it!

>
> Important considerations:
>
> 1. Does this design guarantee the row versions required by subscribers
> aren't removed on candidate standbys as raised here -
> https://www.postgresql.org/message-id/20220218222319.yozkbhren7vkjbi5%40alap3.anarazel.de?
>
> It seems safe with logical decoding on standbys feature. Also, a
> test-case from upthread is already in patch sets (in v9 too)
> https://www.postgresql.org/message-id/CAAaqYe9FdKODa1a9n%3Dqj%2Bw3NiB9gkwvhRHhcJNginuYYRCnLrg%40mail.gmail.com.
> However, we need to verify the use cases extensively.

Agree. We also discussed up-thread that we'd have to drop any "sync" slots if they
are invalidated. And they should be re-created based on the synchronize_slot_names.

> Please feel free to add the list if I'm missing anything.
>

We'd also have to ensure that "sync" slots can't be consumed on the standby (this has been
discussed up-thread).

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com