Re: Skipping logical replication transactions on subscriber side

On Wed, Aug 18, 2021 at 5:39 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Wed, Aug 18, 2021 at 3:33 PM houzj(dot)fnst(at)fujitsu(dot)com
> <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> >
> > On Tues, Aug 17, 2021 1:01 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> > > On Mon, Aug 16, 2021 at 3:59 PM houzj(dot)fnst(at)fujitsu(dot)com <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> > > > 3)
> > > > Do we need to invoke set_apply_error_context_xact() in the function
> > > > apply_handle_stream_prepare() to save the xid and timestamp ?
> > >
> > > Yes. I think that v8-0001 patch already set xid and timestamp just after parsing
> > > stream_prepare message. You meant it's not necessary?
> >
> > Sorry, I thought of something wrong, please ignore the above comment.
> >
> > >
> > > I'll submit the updated patches soon.
> >
> > I was thinking about the place to set the errcallback.callback.
> >
> > apply_dispatch(StringInfo s)
> > {
> > LogicalRepMsgType action = pq_getmsgbyte(s);
> > + ErrorContextCallback errcallback;
> > + bool set_callback = false;
> > +
> > + /*
> > + * Push apply error context callback if not yet. Other fields will be
> > + * filled during applying the change. Since this function can be called
> > + * recursively when applying spooled changes, we set the callback only
> > + * once.
> > + */
> > + if (apply_error_callback_arg.command == 0)
> > + {
> > + errcallback.callback = apply_error_callback;
> > + errcallback.previous = error_context_stack;
> > + error_context_stack = &errcallback;
> > + set_callback = true;
> > + }
> > ...
> > + /* Pop the error context stack */
> > + if (set_callback)
> > + error_context_stack = errcallback.previous;
> >
> > It seems we can put the above code in the function LogicalRepApplyLoop()
> > around invoking apply_dispatch(), and in that approach we don't need to worry
> > about the recursively case. What do you think ?
>
> Thank you for the comment!
>
> I think you're right. Maybe we can set the callback before entering to
> the main loop and pop it after breaking from it. It would also fix the
> problem reported by Tang[1]. But one thing we need to note that since
> we want to reset apply_error_callback_arg.command at the end of
> apply_dispatch() (otherwise we could end up setting the apply error
> context to an irrelevant error such as network error), when
> apply_dispatch() is called recursively probably we need to save the
> apply_error_callback_arg.command before setting the new command and
> then revert back to the saved command. Is that right?

I've attached the updated version patches that incorporated all
comments I got so far unless I'm missing something. Please review
them.

Regards,

--
Masahiko Sawada
EDB: https://www.enterprisedb.com/