postgresql/src/include/tcop
Alexander Korotkov 447aae13b0 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.gmail.com
Discussion: https://www.postgresql.org/message-id/flat/CABPTF7UNft368x-RgOXkfj475OwEbp%2BVVO-wEXz7StgjD_%3D6sw%40mail.gmail.com
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>
2025-11-05 11:44:13 +02:00
..
backend_startup.h Sync typedefs.list with the buildfarm. 2025-06-15 13:04:24 -04:00
cmdtag.h Update copyright for 2025 2025-01-01 11:21:55 -05:00
cmdtaglist.h Implement WAIT FOR command 2025-11-05 11:44:13 +02:00
deparse_utility.h Update copyright for 2025 2025-01-01 11:21:55 -05:00
dest.h Update copyright for 2025 2025-01-01 11:21:55 -05:00
fastpath.h Update copyright for 2025 2025-01-01 11:21:55 -05:00
pquery.h Update various forward declarations to use typedef 2025-09-15 11:04:10 +02:00
tcopprot.h Add ExplainState argument to pg_plan_query() and planner(). 2025-10-08 08:33:29 -04:00
utility.h Update copyright for 2025 2025-01-01 11:21:55 -05:00