From 447aae13b0305780e87cac7b0dd669db6fab3d9d Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Wed, 5 Nov 2025 11:43:55 +0200 Subject: Implement WAIT FOR command MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Author: Alexander Korotkov Author: Xuneng Zhou Reviewed-by: Michael Paquier Reviewed-by: Peter Eisentraut Reviewed-by: Dilip Kumar Reviewed-by: Amit Kapila Reviewed-by: Alexander Lakhin Reviewed-by: Bharath Rupireddy Reviewed-by: Euler Taveira Reviewed-by: Heikki Linnakangas Reviewed-by: Kyotaro Horiguchi Reviewed-by: jian he Reviewed-by: Álvaro Herrera Reviewed-by: Xuneng Zhou --- src/include/nodes/parsenodes.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'src/include/nodes/parsenodes.h') diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index ecbddd12e1b..d14294a4ece 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -4385,4 +4385,12 @@ typedef struct DropSubscriptionStmt DropBehavior behavior; /* RESTRICT or CASCADE behavior */ } DropSubscriptionStmt; +typedef struct WaitStmt +{ + NodeTag type; + char *lsn_literal; /* LSN string from grammar */ + List *options; /* List of DefElem nodes */ +} WaitStmt; + + #endif /* PARSENODES_H */ -- cgit v1.2.3