postgres.git / summary / log / commit / refs

commit    4545cee303c257e58195e3d033c05bf38e2cd4d6
Author:   Michael Paquier <michael@paquier.xyz>
Date:     Thu Sep 24 00:36:05 2026 +0000

    Forbid pg_get_multixact_stats() during recovery
    
    MultiXactState->oldestOffset is not maintained during recovery, so
    calling pg_get_multixact_stats() in this context would report misleading
    information.  We could try to work this out by adding this field to the
    control file, for example, but such a change would be too invasive at
    this stage of the v19 development cycle.
    
    The information of pg_get_multixact_stats() is usually useful to control
    the need of some VACUUM or some freezing, operations that cannot happen
    on a standby, so the argument to make the function work while recovery
    is in progress gets thinner with this point in the balance.
    
    The function is updated to return an ERROR when called under
    RecoveryInProgress().
    
    Per discussion with Heikki Linnakangas and Naga Appani.
    
    Reported-by: Noah Misch <noah@leadboat.com>
    Discussion: https://postgr.es/m/CA+QeY+DcnsZRL4GZD8JyJu5HD-d6p8_9M5kT4jgF3gq3Rh8n4w@mail.gmail.com
    Discussion: https://postgr.es/m/20260827231757.78.noahmisch@microsoft.com
    Backpatch-through: 19


 src/backend/utils/adt/multixactfuncs.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/backend/utils/adt/multixactfuncs.c b/src/backend/utils/adt/multixactfuncs.c
index d9aa58e821d..f51de47e879 100644
--- a/src/backend/utils/adt/multixactfuncs.c
+++ b/src/backend/utils/adt/multixactfuncs.c
@@ -17,6 +17,7 @@
 #include "access/htup_details.h"
 #include "access/multixact.h"
 #include "access/multixact_internal.h"
+#include "access/xlog.h"
 #include "catalog/pg_authid_d.h"
 #include "funcapi.h"
 #include "miscadmin.h"
@@ -103,6 +104,13 @@ pg_get_multixact_stats(PG_FUNCTION_ARGS)
 	Datum		values[4];
 	bool		nulls[4];
 
+	if (RecoveryInProgress())
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("recovery is in progress"),
+				 errhint("%s cannot be executed during recovery.",
+						 "pg_get_multixact_stats()")));
+
 	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),