From 52171b1b100e80f5efe4dd09bcbd18c3245a1fea Mon Sep 17 00:00:00 2001
From: Jah-yee <166608075+Jah-yee@users.noreply.github.com>
Date: Sat, 3 Oct 2026 15:50:42 +0800
Subject: [PATCH] Fix S3 block size error messages to match their checks

- s3.py: Fix message to say 'at least 5 MiB (5242880 bytes)' instead of
  incorrectly showing byte count with MB suffix
- s3.py & s3_async.py: Fix 'greater than' to 'at least' and 'less than' to
  'at most' since the checks use inclusive bounds [<, >]

Fixes #926.
---
 pyathena/filesystem/s3.py       | 4 ++--
 pyathena/filesystem/s3_async.py | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/pyathena/filesystem/s3.py b/pyathena/filesystem/s3.py
index 3d039832c..58ac57a02 100644
--- a/pyathena/filesystem/s3.py
+++ b/pyathena/filesystem/s3.py
@@ -1275,7 +1275,7 @@ def _copy_object_with_multipart_upload(
             block_size < self.MULTIPART_UPLOAD_MIN_PART_SIZE
             or block_size > self.MULTIPART_UPLOAD_MAX_PART_SIZE
         ):
-            raise ValueError("Block size must be greater than 5MiB and less than 5GiB.")
+            raise ValueError("Block size must be at least 5 MiB (5242880 bytes) and at most 5 GiB (5368709120 bytes).")
 
         copy_source = {
             "Bucket": bucket1,
@@ -2322,7 +2322,7 @@ def __init__(
         if "r" not in mode and block_size < self.fs.MULTIPART_UPLOAD_MIN_PART_SIZE:
             # When writing occurs, the block size should not be smaller
             # than the minimum size of a part in a multipart upload.
-            raise ValueError(f"Block size must be >= {self.fs.MULTIPART_UPLOAD_MIN_PART_SIZE}MB.")
+            raise ValueError(f"Block size must be >= 5 MiB ({self.fs.MULTIPART_UPLOAD_MIN_PART_SIZE} bytes).")
 
         self.append_block = False
         if "a" in mode and self.fs.exists(path):
diff --git a/pyathena/filesystem/s3_async.py b/pyathena/filesystem/s3_async.py
index 77deccc2a..eb1f624c9 100644
--- a/pyathena/filesystem/s3_async.py
+++ b/pyathena/filesystem/s3_async.py
@@ -281,7 +281,7 @@ async def _copy_object_with_multipart_upload(
             block_size < S3FileSystem.MULTIPART_UPLOAD_MIN_PART_SIZE
             or block_size > S3FileSystem.MULTIPART_UPLOAD_MAX_PART_SIZE
         ):
-            raise ValueError("Block size must be greater than 5MiB and less than 5GiB.")
+            raise ValueError("Block size must be at least 5 MiB (5242880 bytes) and at most 5 GiB (5368709120 bytes).")
 
         copy_source: dict[str, Any] = {
             "Bucket": bucket1,