diff --git a/paimon-core/src/main/java/org/apache/paimon/append/AppendOnlyWriter.java b/paimon-core/src/main/java/org/apache/paimon/append/AppendOnlyWriter.java
index 4f011d9e31c5..0810f023bf64 100644
--- a/paimon-core/src/main/java/org/apache/paimon/append/AppendOnlyWriter.java
+++ b/paimon-core/src/main/java/org/apache/paimon/append/AppendOnlyWriter.java
@@ -279,9 +279,8 @@ public long memoryOccupancy() {
 
     @Override
     public void flushMemory() throws Exception {
-        if (sinkWriter.bufferSpillableWriter()) {
-            sinkWriter.spill();
-        } else {
+        boolean success = sinkWriter.flushMemory();
+        if (!success) {
             flush(false, false);
         }
     }
@@ -307,6 +306,8 @@ private interface SinkWriter {
 
         List<DataFileMeta> flush() throws IOException;
 
+        boolean flushMemory() throws IOException;
+
         long memoryOccupancy();
 
         void close();
@@ -314,8 +315,6 @@ private interface SinkWriter {
         void setMemoryPool(MemorySegmentPool memoryPool);
 
         boolean bufferSpillableWriter();
-
-        void spill() throws IOException;
     }
 
     /**
@@ -346,6 +345,11 @@ public List<DataFileMeta> flush() throws IOException {
             return flushedFiles;
         }
 
+        @Override
+        public boolean flushMemory() throws IOException {
+            return false;
+        }
+
         @Override
         public long memoryOccupancy() {
             return 0;
@@ -368,9 +372,6 @@ public void setMemoryPool(MemorySegmentPool memoryPool) {
         public boolean bufferSpillableWriter() {
             return false;
         }
-
-        @Override
-        public void spill() throws IOException {}
     }
 
     /**
@@ -441,8 +442,8 @@ public boolean bufferSpillableWriter() {
         }
 
         @Override
-        public void spill() throws IOException {
-            writeBuffer.spill();
+        public boolean flushMemory() throws IOException {
+            return writeBuffer.flushMemory();
         }
     }
 }
diff --git a/paimon-core/src/main/java/org/apache/paimon/disk/ExternalBuffer.java b/paimon-core/src/main/java/org/apache/paimon/disk/ExternalBuffer.java
index f799888c1ff2..5181a9ed8c72 100644
--- a/paimon-core/src/main/java/org/apache/paimon/disk/ExternalBuffer.java
+++ b/paimon-core/src/main/java/org/apache/paimon/disk/ExternalBuffer.java
@@ -87,6 +87,12 @@ public void reset() {
         addCompleted = false;
     }
 
+    @Override
+    public boolean flushMemory() throws IOException {
+        spill();
+        return true;
+    }
+
     @Override
     public boolean put(InternalRow row) throws IOException {
         checkState(!addCompleted, "This buffer has add completed.");
@@ -126,7 +132,7 @@ private void throwTooBigException(InternalRow row) throws IOException {
                         + memorySize());
     }
 
-    public void spill() throws IOException {
+    private void spill() throws IOException {
         FileIOChannel.ID channel = ioManager.createChannel();
 
         BufferFileWriter writer = ioManager.createBufferFileWriter(channel);
diff --git a/paimon-core/src/main/java/org/apache/paimon/disk/InMemoryBuffer.java b/paimon-core/src/main/java/org/apache/paimon/disk/InMemoryBuffer.java
index 04ed809c292c..83c4e423b03c 100644
--- a/paimon-core/src/main/java/org/apache/paimon/disk/InMemoryBuffer.java
+++ b/paimon-core/src/main/java/org/apache/paimon/disk/InMemoryBuffer.java
@@ -81,8 +81,8 @@ public void reset() {
     }
 
     @Override
-    public void spill() {
-        throw new UnsupportedOperationException();
+    public boolean flushMemory() throws IOException {
+        return false;
     }
 
     private void returnToSegmentPool() {
diff --git a/paimon-core/src/main/java/org/apache/paimon/disk/RowBuffer.java b/paimon-core/src/main/java/org/apache/paimon/disk/RowBuffer.java
index b78d213b6622..7589b45eab9c 100644
--- a/paimon-core/src/main/java/org/apache/paimon/disk/RowBuffer.java
+++ b/paimon-core/src/main/java/org/apache/paimon/disk/RowBuffer.java
@@ -39,7 +39,7 @@ public interface RowBuffer {
 
     void reset();
 
-    void spill() throws IOException;
+    boolean flushMemory() throws IOException;
 
     RowBufferIterator newIterator();