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commit    ebc53ca7b2ff339a9455ccdc368d39ebb39a0762
Author:   Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date:     Wed Feb 11 16:50:57 2026 +0000
First released in: 14.22, 15.17, 16.13, 17.9, 18.3

    Fix pg_stat_get_backend_wait_event() for aux processes
    
    The pg_stat_activity view shows information for aux processes, but the
    pg_stat_get_backend_wait_event() and
    pg_stat_get_backend_wait_event_type() functions did not. To fix, call
    AuxiliaryPidGetProc(pid) if BackendPidGetProc(pid) returns NULL, like
    we do in pg_stat_get_activity().
    
    In version 17 and above, it's a little silly to use those functions
    when we already have the ProcNumber at hand, but it was necessary
    before v17 because the backend ID was different from ProcNumber. I
    have other plans for wait_event_info on master, so it doesn't seem
    worth applying a different fix on different versions now.
    
    Reviewed-by: Sami Imseih <samimseih@gmail.com>
    Reviewed-by: Chao Li <li.evan.chao@gmail.com>
    Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
    Discussion: https://www.postgresql.org/message-id/c0320e04-6e85-4c49-80c5-27cfb3a58108@iki.fi
    Backpatch-through: 14


 src/backend/utils/adt/pgstatfuncs.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 614654fd025..29f2f4562ad 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -987,8 +987,14 @@ pg_stat_get_backend_wait_event_type(PG_FUNCTION_ARGS)
 		wait_event_type = "<backend information not available>";
 	else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
 		wait_event_type = "<insufficient privilege>";
-	else if ((proc = BackendPidGetProc(beentry->st_procpid)) != NULL)
-		wait_event_type = pgstat_get_wait_event_type(proc->wait_event_info);
+	else
+	{
+		proc = BackendPidGetProc(beentry->st_procpid);
+		if (!proc)
+			proc = AuxiliaryPidGetProc(beentry->st_procpid);
+		if (proc)
+			wait_event_type = pgstat_get_wait_event_type(proc->wait_event_info);
+	}
 
 	if (!wait_event_type)
 		PG_RETURN_NULL();
@@ -1008,8 +1014,14 @@ pg_stat_get_backend_wait_event(PG_FUNCTION_ARGS)
 		wait_event = "<backend information not available>";
 	else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
 		wait_event = "<insufficient privilege>";
-	else if ((proc = BackendPidGetProc(beentry->st_procpid)) != NULL)
-		wait_event = pgstat_get_wait_event(proc->wait_event_info);
+	else
+	{
+		proc = BackendPidGetProc(beentry->st_procpid);
+		if (!proc)
+			proc = AuxiliaryPidGetProc(beentry->st_procpid);
+		if (proc)
+			wait_event = pgstat_get_wait_event(proc->wait_event_info);
+	}
 
 	if (!wait_event)
 		PG_RETURN_NULL();


[parent: c10535fbea02]