diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 9d3ca4dc7e..eb86bb4420 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -93,6 +93,7 @@
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "storage/reinit.h"
+#include "storage/sinvaladt.h"
 #include "storage/spin.h"
 #include "storage/sync.h"
 #include "utils/guc_hooks.h"
@@ -6040,6 +6041,30 @@ StartupXLOG(void)
 	XLogCtl->LogwrtRqst.Write = EndOfLog;
 	XLogCtl->LogwrtRqst.Flush = EndOfLog;
 
+	/*
+	 * Invalidate all sinval-managed caches before READ WRITE transactions
+	 * begin.  The xl_heap_inplace WAL record doesn't store sufficient data
+	 * for invalidations.  The commit record, if any, has the invalidations.
+	 * However, the inplace update is permanent, whether or not we reach a
+	 * commit record.  Fortunately, read-only transactions tolerate caches not
+	 * reflecting the latest inplace updates.  Read-only transactions
+	 * experience the notable inplace updates as follows:
+	 *
+	 * - relhasindex=true affects readers only after the CREATE INDEX
+	 * transaction commit makes an index fully available to them.
+	 *
+	 * - datconnlimit=DATCONNLIMIT_INVALID_DB affects readers only at
+	 * InitPostgres() time, and that read does not use a cache.
+	 *
+	 * - relfrozenxid, datfrozenxid, relminmxid, and datminmxid have no effect
+	 * on readers.
+	 *
+	 * Hence, hot standby queries (all READ ONLY) function correctly without
+	 * the missing invalidations.  This avoided changing the WAL format in
+	 * back branches.
+	 */
+	SIResetAll();
+
 	/*
 	 * Preallocate additional log files, if wanted.
 	 */
diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index b486d8ddd1..271212987e 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -683,6 +683,48 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	}
 }
 
+/*
+ * SIResetAll
+ *		Mark all active backends as "reset"
+ *
+ * Use this when we don't know what needs to be invalidated.  It's a
+ * cluster-wide InvalidateSystemCaches().  This was a back-branch-only remedy
+ * to avoid a WAL format change.
+ *
+ * The implementation is like SICleanupQueue(false, MAXNUMMESSAGES + 1), with
+ * one addition.  SICleanupQueue() assumes minFree << MAXNUMMESSAGES, so it
+ * assumes hasMessages==true for any backend it resets.  We're resetting even
+ * fully-caught-up backends, so we set hasMessages.
+ */
+void
+SIResetAll(void)
+{
+	SISeg	   *segP = shmInvalBuffer;
+	int			i;
+
+	LWLockAcquire(SInvalWriteLock, LW_EXCLUSIVE);
+	LWLockAcquire(SInvalReadLock, LW_EXCLUSIVE);
+
+	for (i = 0; i < segP->numProcs; i++)
+	{
+		ProcState  *stateP = &segP->procState[segP->pgprocnos[i]];
+
+		Assert(stateP->procPid != 0);
+		if (stateP->sendOnly)
+			continue;
+
+		/* Consuming the reset will update "nextMsgNum" and "signaled". */
+		stateP->resetState = true;
+		stateP->hasMessages = true;
+	}
+
+	segP->minMsgNum = segP->maxMsgNum;
+	segP->nextThreshold = CLEANUP_MIN;
+
+	LWLockRelease(SInvalReadLock);
+	LWLockRelease(SInvalWriteLock);
+}
+
 
 /*
  * GetNextLocalTransactionId --- allocate a new LocalTransactionId
diff --git a/src/include/storage/sinvaladt.h b/src/include/storage/sinvaladt.h
index c3c97b3f8b..7c8f450db7 100644
--- a/src/include/storage/sinvaladt.h
+++ b/src/include/storage/sinvaladt.h
@@ -35,6 +35,7 @@ extern void SharedInvalBackendInit(bool sendOnly);
 extern void SIInsertDataEntries(const SharedInvalidationMessage *data, int n);
 extern int	SIGetDataEntries(SharedInvalidationMessage *data, int datasize);
 extern void SICleanupQueue(bool callerHasWriteLock, int minFree);
+extern void SIResetAll(void);
 
 extern LocalTransactionId GetNextLocalTransactionId(void);