Hi, On Tue, Jun 4, 2024 at 5:40 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > Even if we decode it periodically (say each time we decode the > checkpoint record) then also we need to send the entire set of > sequences at shutdown. This is because the sequences may have changed > from the last time we sent them.
Agree. How about decoding and sending only the sequences that are changed from the last time when they were sent? I know it requires a bit of tracking and more work, but all I'm looking for is to reduce the amount of work that walsenders need to do during the shutdown. Having said that, I like the idea of letting the user sync the sequences via ALTER SUBSCRIPTION command and not weave the logic into the shutdown checkpoint path. As Peter Eisentraut said here https://www.postgresql.org/message-id/42e5cb35-4aeb-4f58-8091-90619c7c3ecc%40eisentraut.org, this can be a good starting point to get going. > > I can imagine a case where there are tens > > of thousands of sequences in a production server, and surely decoding > > and sending them just during the shutdown can take a lot of time > > hampering the overall server uptime. > > It is possible but we will send only the sequences that belong to > publications for which walsender is supposed to send the required > data. Right, but what if all the publication tables can have tens of thousands of sequences. > Now, we can also imagine providing option 2 (Alter Subscription > ... Replicate Sequences) so that users can replicate sequences before > shutdown and then disable the subscriptions so that there won't be a > corresponding walsender. As stated above, I like this idea to start with. -- Bharath Rupireddy PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
