On Thu, 13 Jun 2024 at 10:27, Dilip Kumar <dilipbal...@gmail.com> wrote: > > On Thu, Jun 13, 2024 at 10:10 AM vignesh C <vignes...@gmail.com> wrote: > > > > > So, you're saying that when we synchronize the sequence values on the > > > subscriber side, we will create a new relfilenode to allow reverting > > > to the old state of the sequence in case of an error or transaction > > > rollback? But why would we want to do that? Generally, even if you > > > call nextval() on a sequence and then roll back the transaction, the > > > sequence value doesn't revert to the old value. So, what specific > > > problem on the subscriber side are we trying to avoid by operating on > > > a new relfilenode? > > > > Let's consider a situation where we have two sequences: seq1 with a > > value of 100 and seq2 with a value of 200. Now, let's say seq1 is > > synced and updated to 100, then we attempt to synchronize seq2, > > there's a failure due to the sequence not existing or encountering > > some other issue. In this scenario, we don't want to halt operations > > where seq1 is synchronized, but the sequence state for sequence isn't > > changed to "ready" in pg_subscription_rel. > > Thanks for the explanation, but I am still not getting it completely, > do you mean to say unless all the sequences are not synced any of the > sequences would not be marked "ready" in pg_subscription_rel? Is that > necessary? I mean why we can not sync the sequences one by one and > mark them ready? Why it is necessary to either have all the sequences > synced or none of them?
Since updating the sequence is one operation and setting pg_subscription_rel is another, I was trying to avoid a situation where the sequence is updated but its state is not reflected in pg_subscription_rel. It seems you are suggesting that it's acceptable for the sequence to be updated even if its state isn't updated in pg_subscription_rel, and in such cases, the sequence value does not need to be reverted. Regards, Vignesh
