Re: Skipping logical replication transactions on subscriber side

On Mon, Jan 17, 2022 at 6:22 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> >
> > (5)
> >
> > I can miss something here but, in one of
> > the past discussions, there seems a consensus that
> > if the user specifies XID of a subtransaction,
> > it would be better to skip only the subtransaction.
> >
> > This time, is it out of the range of the patch ?
> > If so, I suggest you include some description about it
> > either in the commit message or around codes related to it.
>
> How can the user know subtransaction XID? I suppose you refer to
> streaming protocol cases but while applying spooled changes we don't
> report subtransaction XID neither in server log nor
> pg_stat_subscription_workers.
>

I also think in the current system users won't be aware of
subtransaction's XID but I feel Osumi-San's point is valid that we
should at least add it in docs that we allow to skip only top-level
xacts. Also, in the future, it won't be impossible to imagine that we
can have subtransaction's XID info also available to users as we have
that in the case of streaming xacts (See subxact_data).

Few minor points:
===============
1.
+ * the subscription if hte user has specified skip_xid.

Typo. /hte/the

2.
+ * PREPARED won’t be resent but subskipxid is left.

In diffmerge tool, won't is showing some funny chars. When I manually
removed 't and added it again, everything is fine. I am not sure why
it is so? I think Osumi-San has also raised this complaint.

3.
+ /*
+ * We don't expect that the user set the XID of the transaction that is
+ * rolled back but if the skip XID is set, clear it.
+ */

/user set/user to set/

--
With Regards,
Amit Kapila.