Feedback-ID: ie3de48e3:Fastmail
Date: Wed, 15 Oct 2025 10:51:42 +0200
From: =?utf-8?Q?=C3=81lvaro?= Herrera <alvherre@kurilemu.de>
To: Xuneng Zhou <xunengzhou@gmail.com>
Cc: Alexander Korotkov <aekorotkov@gmail.com>,
	Michael Paquier <michael@paquier.xyz>, jian he <jian.universality@gmail.com>,
	Tomas Vondra <tomas@vondra.me>, Yura Sokolov <y.sokolov@postgrespro.ru>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: Implement waiting for wal lsn replay: reloaded
Message-ID: <202510150831.g75i32rzddor@alvherre.pgsql>
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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.

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.

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.


[1] https://postgr.es/m/202510101352.vvp4p3p2dblu@alvherre.pgsql

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
"La virtud es el justo medio entre dos defectos" (Aristóteles)