From c52adc22ddb83f3eb6d4514405a955569e18a0a9 Mon Sep 17 00:00:00 2001
From: wforget <643348094@qq.com>
Date: Thu, 25 Sep 2025 18:38:28 +0800
Subject: [PATCH 1/2] Fix ARROW_STRUCT_CONFLICT_POLICY env not work

---
 .../apache/arrow/vector/complex/AbstractStructVector.java   | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/vector/src/main/java/org/apache/arrow/vector/complex/AbstractStructVector.java b/vector/src/main/java/org/apache/arrow/vector/complex/AbstractStructVector.java
index 2921e43cb6..0d4675e902 100644
--- a/vector/src/main/java/org/apache/arrow/vector/complex/AbstractStructVector.java
+++ b/vector/src/main/java/org/apache/arrow/vector/complex/AbstractStructVector.java
@@ -46,11 +46,13 @@ public abstract class AbstractStructVector extends AbstractContainerVector {
   private ConflictPolicy conflictPolicy;
 
   static {
-    String conflictPolicyStr =
-        System.getProperty(STRUCT_CONFLICT_POLICY_JVM, ConflictPolicy.CONFLICT_REPLACE.toString());
+    String conflictPolicyStr = System.getProperty(STRUCT_CONFLICT_POLICY_JVM);
     if (conflictPolicyStr == null) {
       conflictPolicyStr = System.getenv(STRUCT_CONFLICT_POLICY_ENV);
     }
+    if (conflictPolicyStr == null) {
+      conflictPolicyStr = ConflictPolicy.CONFLICT_REPLACE.toString();
+    }
     ConflictPolicy conflictPolicy;
     try {
       conflictPolicy = ConflictPolicy.valueOf(conflictPolicyStr.toUpperCase(Locale.ROOT));

From db2dc19a395ec2b885a9bca005e6602fc239986d Mon Sep 17 00:00:00 2001
From: wforget <643348094@qq.com>
Date: Thu, 25 Sep 2025 20:55:23 +0800
Subject: [PATCH 2/2] address comment

---
 .../org/apache/arrow/vector/complex/AbstractStructVector.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/vector/src/main/java/org/apache/arrow/vector/complex/AbstractStructVector.java b/vector/src/main/java/org/apache/arrow/vector/complex/AbstractStructVector.java
index 0d4675e902..a57fbe473f 100644
--- a/vector/src/main/java/org/apache/arrow/vector/complex/AbstractStructVector.java
+++ b/vector/src/main/java/org/apache/arrow/vector/complex/AbstractStructVector.java
@@ -64,11 +64,11 @@ public abstract class AbstractStructVector extends AbstractContainerVector {
 
   /** Policy to determine how to react when duplicate columns are encountered. */
   public enum ConflictPolicy {
-    // Ignore the conflict and append the field. This is the default behaviour
+    // Ignore the conflict and append the field.
     CONFLICT_APPEND,
     // Keep the existing field and ignore the newer one.
     CONFLICT_IGNORE,
-    // Replace the existing field with the newer one.
+    // Replace the existing field with the newer one. This is the default behaviour
     CONFLICT_REPLACE,
     // Refuse the new field and error out.
     CONFLICT_ERROR