Re: Skipping logical replication transactions on subscriber side

On Fri, Jan 21, 2022 at 10:32 AM osumi(dot)takamichi(at)fujitsu(dot)com
<osumi(dot)takamichi(at)fujitsu(dot)com> wrote:
>
> On Friday, January 21, 2022 12:08 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> > I've attached an updated patch that incorporated these commends as well as
> > other comments I got so far.
> Thank you for your update !
>
> Few minor comments.
>
> (1) trivial question
>
> For the users,
> was it perfectly clear that in the cascading logical replication setup,
> we can't selectively skip an arbitrary transaction of one upper nodes,
> without skipping its all executions on subsequent nodes,
> when we refer to the current doc description of v9 ?
>
> IIUC, this is because we don't write changes WAL either and
> can't propagate the contents to subsequent nodes.
>
> I tested this case and it didn't, as I expected.
> This can apply to other measures for conflicts, though.
>

Right, there is nothing new as the user will same effect when she uses
existing function pg_replication_origin_advance(). So, not sure if we
want to add something specific to this.

>
> (3) minor question
>
> In the past, there was a discussion that
> it might be better if we reset the XID
> according to a change of subconninfo,
> which might be an opportunity to connect another
> publisher of a different XID space.
> Currently, we can regard it as user's responsibility.
> Was this correct ?
>

I think if the user points to another publisher, doesn't it similarly
needs to change slot_name as well? If so, I think this can be treated
in a similar way.

--
With Regards,
Amit Kapila.