Re: Synchronizing slots from primary to standby

On Thu, Oct 26, 2023 at 12:38 PM Hayato Kuroda (Fujitsu)
<kuroda.hayato@fujitsu.com> wrote:
>
> > PFA v25 patch set. The changes are:
>
> Thanks for making the patch! It seems that there are lots of comments, so
> I can put some high-level comments for 0001.
> Sorry if there are duplicated comments.
>
> 1.
> The patch seemed not to consider the case that failover option between replication
> slot and subscription were different. Currently slot option will be overwritten
> by subscription one.
>
> Actually, I'm not sure what specification is better. Regarding the two_phase,
> 2PC will be decoded only when the both of settings are true. Should we follow?
>
> 2.
> Currently ctx->failover is set only in the pgoutput_startup(), but not sure it is OK.
> Can we change the parameter in CreateDecodingContext() or similar functions?
>
> Because IIUC it means that only slots which have pgoutput can wait. Other
> output plugins must understand the change and set faliover flag as well -
> I felt it is not good. E.g., you might miss to enable the parameter in test_decoding.
>
> Regarding the two_phase parameter, setting on plugin layer is good because it
> quite affects the output. As for the failover, it is not related with the
> content so that all of slots should be enabled.
>

Both of your points seem valid to me. However, I think they should be
addressed once we make option 'failover' behave similar to the '2PC'
option as per discussion [1].

[1] - https://www.postgresql.org/message-id/b099ebc2-68fd-4c08-87ce-65fc4cb24121%40gmail.com

--
With Regards,
Amit Kapila.