From a2fe0711e7f5366831f1db78b6a14f825252674f Mon Sep 17 00:00:00 2001
From: yujun <yujun@selectdb.com>
Date: Mon, 15 Jun 2026 12:05:56 +0800
Subject: [PATCH] [fix](mtmv) Add null-safety to getBaseViewsOneLevel for
 backward compatibility (#64412)

Introduced by #56423, the field baseViewsOneLevel may be null for MTMVs
created before that PR. This causes NPE when querying
information_schema.view_dependency:

Cannot invoke java.util.Set.stream() because the return value of
org.apache.doris.mtmv.MTMVRelation.getBaseViewsOneLevel() is null

baseViewsOneLevel is currently only used for
tablefunction/MetadataGenerator, so this change is safe.

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
---
 .../java/org/apache/doris/mtmv/MTMVRelation.java    | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/mtmv/MTMVRelation.java b/fe/fe-core/src/main/java/org/apache/doris/mtmv/MTMVRelation.java
index 46caf032f53dc7..452733cf7a7486 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/mtmv/MTMVRelation.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/mtmv/MTMVRelation.java
@@ -18,13 +18,16 @@
 package org.apache.doris.mtmv;
 
 import org.apache.doris.datasource.CatalogMgr;
+import org.apache.doris.persist.gson.GsonPostProcessable;
 
 import com.google.gson.annotations.SerializedName;
 import org.apache.commons.collections4.CollectionUtils;
 
+import java.io.IOException;
+import java.util.HashSet;
 import java.util.Set;
 
-public class MTMVRelation {
+public class MTMVRelation implements GsonPostProcessable {
     // t1 => v1 => v2
     // t2 => mv1
     // mv1 join v2 => mv2
@@ -80,6 +83,14 @@ public Set<BaseTableInfo> getBaseViews() {
         return baseViews;
     }
 
+    @Override
+    public void gsonPostProcess() throws IOException {
+        // For backward compatibility: previously created MTMV may not have baseViewsOneLevel
+        if (baseViewsOneLevel == null) {
+            baseViewsOneLevel = baseViews == null ? new HashSet<>() : new HashSet<>(baseViews);
+        }
+    }
+
     // toString() is not easy to find where to call the method
     public String toInfoString() {
         return "MTMVRelation{"