From f8eab28c5dac47a917c92ed3ddfe79132be4d7ca Mon Sep 17 00:00:00 2001
From: arnavb <arnavb@uber.com>
Date: Mon, 18 Aug 2025 05:35:55 +0000
Subject: [PATCH 1/2] update

---
 .../column/values/plain/BinaryPlainValuesReader.java   |  8 ++++++++
 .../parquet/column/values/plain/PlainValuesWriter.java | 10 +++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/parquet-column/src/main/java/org/apache/parquet/column/values/plain/BinaryPlainValuesReader.java b/parquet-column/src/main/java/org/apache/parquet/column/values/plain/BinaryPlainValuesReader.java
index 6ce2f31a43..569d0af675 100644
--- a/parquet-column/src/main/java/org/apache/parquet/column/values/plain/BinaryPlainValuesReader.java
+++ b/parquet-column/src/main/java/org/apache/parquet/column/values/plain/BinaryPlainValuesReader.java
@@ -27,6 +27,14 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+/**
+ * ValuesReader for variable-length {@code BYTE_ARRAY} columns.
+ *
+ * <p>When the column carries the logical type {@code DECIMAL}, the bytes read
+ * here are the big-endian two's-complement form of the un-scaled integer.
+ * It slices the requested number of bytes without flipping and
+ * returns them as a {@link org.apache.parquet.io.api.Binary}.
+ */
 public class BinaryPlainValuesReader extends ValuesReader {
   private static final Logger LOG = LoggerFactory.getLogger(BinaryPlainValuesReader.class);
   private ByteBufferInputStream in;
diff --git a/parquet-column/src/main/java/org/apache/parquet/column/values/plain/PlainValuesWriter.java b/parquet-column/src/main/java/org/apache/parquet/column/values/plain/PlainValuesWriter.java
index c7069bc092..3965286f32 100644
--- a/parquet-column/src/main/java/org/apache/parquet/column/values/plain/PlainValuesWriter.java
+++ b/parquet-column/src/main/java/org/apache/parquet/column/values/plain/PlainValuesWriter.java
@@ -32,7 +32,15 @@
 import org.slf4j.LoggerFactory;
 
 /**
- * Plain encoding except for booleans
+ * Plain encoding except for booleans.
+ *
+ * <p>Endianness note for DECIMAL: when a DECIMAL value is stored in a
+ * BYTE_ARRAY column, the {@link org.apache.parquet.io.api.Binary}
+ * passed to this writer already contains the big-endian two's-complement bytes
+ * of the un-scaled integer (the same bytes produced by
+ * {@link java.math.BigInteger#toByteArray()}).  This writer keeps those bytes
+ * exactly as they are and only adds the 4-byte little-endian length prefix
+ * required by the PLAIN encoding.  Bytes are not re-ordered..</p>
  */
 public class PlainValuesWriter extends ValuesWriter {
   private static final Logger LOG = LoggerFactory.getLogger(PlainValuesWriter.class);

From b3430d0cf5a3509472167d34b0b829d72f5cea39 Mon Sep 17 00:00:00 2001
From: arnavb <arnavb@uber.com>
Date: Mon, 18 Aug 2025 05:39:23 +0000
Subject: [PATCH 2/2] update

---
 .../apache/parquet/column/values/plain/PlainValuesWriter.java   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/parquet-column/src/main/java/org/apache/parquet/column/values/plain/PlainValuesWriter.java b/parquet-column/src/main/java/org/apache/parquet/column/values/plain/PlainValuesWriter.java
index 3965286f32..ec725597cf 100644
--- a/parquet-column/src/main/java/org/apache/parquet/column/values/plain/PlainValuesWriter.java
+++ b/parquet-column/src/main/java/org/apache/parquet/column/values/plain/PlainValuesWriter.java
@@ -40,7 +40,7 @@
  * of the un-scaled integer (the same bytes produced by
  * {@link java.math.BigInteger#toByteArray()}).  This writer keeps those bytes
  * exactly as they are and only adds the 4-byte little-endian length prefix
- * required by the PLAIN encoding.  Bytes are not re-ordered..</p>
+ * required by the PLAIN encoding.  Bytes are not re-ordered.</p>
  */
 public class PlainValuesWriter extends ValuesWriter {
   private static final Logger LOG = LoggerFactory.getLogger(PlainValuesWriter.class);