From: Alexander Korotkov <akorotkov@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Implement WAIT FOR command
Date: Wed, 05 Nov 2025 09:44:46 +0000
Message-ID: <E1vGa4M-0058H1-2k@gemulon.postgresql.org> (raw)
Implement WAIT FOR command
WAIT FOR is to be used on standby and specifies waiting for
the specific WAL location to be replayed. This option is useful when
the user makes some data changes on primary and needs a guarantee to see
these changes are on standby.
WAIT FOR needs to wait without any snapshot held. Otherwise, the snapshot
could prevent the replay of WAL records, implying a kind of self-deadlock.
This is why separate utility command seems appears to be the most robust
way to implement this functionality. It's not possible to implement this as
a function. Previous experience shows that stored procedures also have
limitation in this aspect.
Discussion: https://www.postgresql.org/message-id/flat/CAPpHfdsjtZLVzxjGT8rJHCYbM0D5dwkO+BBjcirozJ6nYbOW8Q@mail....
Discussion: https://www.postgresql.org/message-id/flat/CABPTF7UNft368x-RgOXkfj475OwEbp%2BVVO-wEXz7StgjD_%3D6sw%4...
Author: Kartyshov Ivan <i.kartyshov@postgrespro.ru>
Author: Alexander Korotkov <aekorotkov@gmail.com>
Author: Xuneng Zhou <xunengzhou@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Euler Taveira <euler@eulerto.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: jian he <jian.universality@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com>
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/447aae13b0305780e87cac7b0dd669db6fab3d9d
Modified Files
--------------
doc/src/sgml/high-availability.sgml | 54 ++++++
doc/src/sgml/ref/allfiles.sgml | 1 +
doc/src/sgml/ref/wait_for.sgml | 234 +++++++++++++++++++++++
doc/src/sgml/reference.sgml | 1 +
src/backend/access/transam/xact.c | 6 +
src/backend/access/transam/xlog.c | 7 +
src/backend/access/transam/xlogrecovery.c | 11 ++
src/backend/commands/Makefile | 3 +-
src/backend/commands/meson.build | 1 +
src/backend/commands/wait.c | 212 +++++++++++++++++++++
src/backend/parser/gram.y | 33 +++-
src/backend/storage/lmgr/proc.c | 6 +
src/backend/tcop/pquery.c | 12 +-
src/backend/tcop/utility.c | 22 +++
src/include/commands/wait.h | 22 +++
src/include/nodes/parsenodes.h | 8 +
src/include/parser/kwlist.h | 2 +
src/include/tcop/cmdtaglist.h | 1 +
src/test/recovery/meson.build | 3 +-
src/test/recovery/t/049_wait_for_lsn.pl | 302 ++++++++++++++++++++++++++++++
src/tools/pgindent/typedefs.list | 1 +
21 files changed, 931 insertions(+), 11 deletions(-)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-committers@postgresql.org
Cc: akorotkov@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Implement WAIT FOR command
In-Reply-To: <E1vGa4M-0058H1-2k@gemulon.postgresql.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox