From 68684f6fa6233f3e35f2a2e5e4d441a02177710b Mon Sep 17 00:00:00 2001
From: t99-i <tim.limmer@campus.tu-berlin.de>
Date: Sun, 19 Jul 2026 16:16:07 +0200
Subject: [PATCH] [MINOR] fixed incorrect column name indexing (off-by-one
 error) in CSV header writing

---
 .../instructions/spark/utils/FrameRDDConverterUtils.java    | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/apache/sysds/runtime/instructions/spark/utils/FrameRDDConverterUtils.java b/src/main/java/org/apache/sysds/runtime/instructions/spark/utils/FrameRDDConverterUtils.java
index 9371d43094c..3a35e43a98c 100644
--- a/src/main/java/org/apache/sysds/runtime/instructions/spark/utils/FrameRDDConverterUtils.java
+++ b/src/main/java/org/apache/sysds/runtime/instructions/spark/utils/FrameRDDConverterUtils.java
@@ -663,9 +663,9 @@ public Iterator<String> call(Tuple2<Long, FrameBlock> arg0)
 			//handle header information and frame meta data
 			if( ix==1 ) {
 				if( _props.hasHeader() ) {
-					for(int j = 1; j <= blk.getNumColumns(); j++) {
-						sb.append(blk.getColumnNames()[j] 
-							+ ((j<blk.getNumColumns()-1)?_props.getDelim():""));
+					for(int j = 0; j < blk.getNumColumns(); j++) {
+						sb.append(blk.getColumnNames()[j])
+								.append(j < blk.getNumColumns() - 1 ? _props.getDelim() : "");
 					}
 					ret.add(sb.toString());
 					sb.setLength(0); //reset