Re: Implement waiting for wal lsn replay: reloaded

Hi!

In Thu, Oct 16, 2025 at 10:12 AM Xuneng Zhou <xunengzhou(at)gmail(dot)com> wrote:
> 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.

Thank you for rebasing the patch.

I've revised it. The significant changes has been made to 0002, where
I reduced the code duplication. Also, I run pgindent and pgperltidy
and made other small improvements.
Please, check.

------
Regards,
Alexander Korotkov
Supabase