diff --git a/internal/topo/node/window_op.go b/internal/topo/node/window_op.go
index 88d426c43b..15114330d9 100644
--- a/internal/topo/node/window_op.go
+++ b/internal/topo/node/window_op.go
@@ -608,11 +608,21 @@ func (o *WindowOperator) handleInputs(ctx api.StreamContext, inputs []*xsql.Tupl
 }
 
 func (o *WindowOperator) gcInputs(inputs []*xsql.Tuple, triggerTime time.Time, ctx api.StreamContext) []*xsql.Tuple {
-	var discard []*xsql.Tuple
-	inputs, discard, _ = o.handleInputs(ctx, inputs, triggerTime)
-	ctx.GetLogger().Debugf("after scan %v", inputs)
-	o.handleTraceDiscardTuple(ctx, discard)
-	return inputs
+	length := o.window.Length + o.window.Delay
+	gcIndex := -1
+	for i, tuple := range inputs {
+		if tuple.Timestamp.Add(length).Compare(triggerTime) >= 0 {
+			break
+		}
+		gcIndex = i
+	}
+	if gcIndex == len(inputs)-1 {
+		return inputs[:0]
+	}
+	if gcIndex == -1 {
+		return inputs
+	}
+	return inputs[gcIndex+1:]
 }
 
 func (o *WindowOperator) scan(inputs []*xsql.Tuple, triggerTime time.Time, ctx api.StreamContext) []*xsql.Tuple {