From 4e77c0a8b82492a434bcc1b275b1eaaf05102261 Mon Sep 17 00:00:00 2001
From: 1ambda <1amb4a@gmail.com>
Date: Mon, 17 Apr 2017 17:08:41 +0900
Subject: [PATCH] fix: Convert old notebook format only once

---
 .../src/main/java/org/apache/zeppelin/notebook/Notebook.java  | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/Notebook.java b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/Notebook.java
index e7f7e49a437..de48befab3e 100644
--- a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/Notebook.java
+++ b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/Notebook.java
@@ -414,6 +414,10 @@ public Note getNoteByRevision(String noteId, String revisionId, AuthenticationIn
   public void convertFromSingleResultToMultipleResultsFormat(Note note) {
     for (Paragraph p : note.paragraphs) {
       Object ret = p.getPreviousResultFormat();
+      if (ret != null && p.results != null) {
+        continue; // already converted
+      }
+
       try {
         if (ret != null && ret instanceof Map) {
           Map r = ((Map) ret);