Re: Implement waiting for wal lsn replay: reloaded

Hi,

On Wed, Oct 15, 2025 at 8:48 PM Xuneng Zhou <xunengzhou(at)gmail(dot)com> wrote:
>
> Hi,
>
> Thank you for the grammar review and the clear recommendation.
>
> On Wed, Oct 15, 2025 at 4:51 PM Álvaro Herrera <alvherre(at)kurilemu(dot)de> wrote:
> >
> > I didn't review the patch other than look at the grammar, but I disagree
> > with using opt_with in it. I think WITH should be a mandatory word, or
> > just not be there at all. The current formulation lets you do one of:
> >
> > 1. WAIT FOR LSN '123/456' WITH (opt = val);
> > 2. WAIT FOR LSN '123/456' (opt = val);
> > 3. WAIT FOR LSN '123/456';
> >
> > and I don't see why you need two ways to specify an option list.
>
> I agree with this as unnecessary choices are confusing.
>
> >
> > So one option is to remove opt_wait_with_clause and just use
> > opt_utility_option_list, which would remove the WITH keyword from there
> > (ie. only keep 2 and 3 from the above list). But I think that's worse:
> > just look at the REPACK grammar[1], where we have to have additional
> > productions for the optional parenthesized option list.
> >
> >
> >
> > So why not do just
> >
> > +opt_wait_with_clause:
> > + WITH '(' utility_option_list ')' { $$ = $3; }
> > + | /*EMPTY*/ { $$ = NIL; }
> > + ;
> >
> > which keeps options 1 and 3 of the list above.
>
> Your suggested approach of making WITH mandatory when options are
> present looks better.
> I've implemented the change as you recommended. Please see patch 3 in v16.
>
> >
> >
> >
> > Note: you don't need to worry about WITH_LA, because that's only going
> > to show up when the user writes WITH TIME or WITH ORDINALITY (see
> > parser.c), and that's a syntax error anyway.
> >
>
> Yeah, we require '(' immediately after WITH in our grammar, the
> lookahead mechanism will keep it as regular WITH, and any attempt to
> write "WITH TIME" or "WITH ORDINALITY" would be a syntax error anyway,
> which is expected.
>

The filename of patch 1 is incorrect due to coping. Just correct it.

Best,
Xuneng