diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index 89df585b87..d6f3fd5436 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -3835,12 +3835,31 @@ RemoveTempRelationsCallback(int code, Datum arg)
 
 /*
  * Remove all temp tables from the temporary namespace.
+ *
+ * If we haven't set up one yet, but one exists from a previous crashed
+ * backend, clean that one; but only do this once in a session's life.
  */
 void
 ResetTempTableNamespace(void)
 {
+	static bool	TempNamespaceCleaned = false;
+
 	if (OidIsValid(myTempNamespace))
 		RemoveTempRelations(myTempNamespace);
+	else if (MyBackendId != InvalidBackendId && !RecoveryInProgress() &&
+			 !TempNamespaceCleaned)
+	{
+		char		namespaceName[NAMEDATALEN];
+		Oid			namespaceId;
+
+		snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d",
+				 MyBackendId);
+		namespaceId = get_namespace_oid(namespaceName, true);
+		if (OidIsValid(namespaceId))
+			RemoveTempRelations(namespaceId);
+	}
+
+	TempNamespaceCleaned = true;
 }
 
 
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index c18285d690..62a06add56 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -2108,11 +2108,18 @@ do_autovacuum(void)
 		if (classForm->relpersistence == RELPERSISTENCE_TEMP)
 		{
 			int			backendID;
+			PGPROC	   *proc;
 
 			backendID = GetTempNamespaceBackendId(classForm->relnamespace);
 
-			/* We just ignore it if the owning backend is still active */
-			if (backendID == MyBackendId || BackendIdGetProc(backendID) == NULL)
+			/*
+			 * We just ignore it if the owning backend is still active in the
+			 * same database.
+			 */
+			if (backendID != InvalidBackendId &&
+				(backendID == MyBackendId ||
+				 (proc = BackendIdGetProc(backendID)) == NULL ||
+				 proc->databaseId != MyDatabaseId))
 			{
 				/*
 				 * We found an orphan temp table (which was probably left