Re: Time delayed LR (WAS Re: logical replication restrictions)

On Fri, Apr 28, 2023 at 2:35 PM Hayato Kuroda (Fujitsu)
<kuroda.hayato@fujitsu.com> wrote:
>
> Dear hackers,
>
> I rebased and refined my PoC. Followings are the changes:
>

1. Is my understanding correct that this patch creates the delay files
for each transaction? If so, did you consider other approaches such as
using one file to avoid creating many files?
2. For streaming transactions, first the changes are written in the
temp file and then moved to the delay file. It seems like there is a
double work. Is it possible to unify it such that when min_apply_delay
is specified, we just use the delay file without sacrificing the
advantages like stream sub-abort can truncate the changes?
3. Ideally, there shouldn't be a performance impact of this feature on
regular transactions because the delay file is created only when
min_apply_delay is active but better to do some testing of the same.

Overall, I think such an approach can address comments by Sawada-San
[1] but not sure if Sawada-San or others have any better ideas to
achieve this feature. It would be good to see what others think of
this approach.

[1] - https://www.postgresql.org/message-id/CAD21AoAeG2%2BRsUYD9%2BmEwr8-rrt8R1bqpe56T2D%3DeuO-Qs-GAg%40mail.gmail.com

--
With Regards,
Amit Kapila.