From 82e39c4010245f35f2d126ae212cbd8fff94d652 Mon Sep 17 00:00:00 2001
From: hutiefang76 <137664623+hutiefang76@users.noreply.github.com>
Date: Wed, 9 Sep 2026 04:45:04 +0800
Subject: [PATCH] fix(client-v2): report LZ4 byte counts

Fixes #3108
---
 CHANGELOG.md                                  |  2 ++
 .../internal/ClickHouseLZ4InputStream.java    |  2 +-
 .../ClickHouseLZ4InputStreamTest.java         | 25 +++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 client-v2/src/test/java/com/clickhouse/client/api/internal/ClickHouseLZ4InputStreamTest.java

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9eff8d530..098f1a172 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -137,6 +137,8 @@
 
 ### Bug Fixes 
 
+- **[client-v2]** Fixed truncated LZ4 stream errors reporting literal `{0}` and `{1}` placeholders instead of the
+  number of bytes read and expected. (https://github.com/ClickHouse/clickhouse-java/issues/3108)
 - **[jdbc-v2]** Fixed `DatabaseMetaData#getTables` reporting `TABLE_TYPE = TABLE` for a table with the `BigQuery`
   engine (present in `system.table_engines` since ClickHouse `26.8`). The engine was missing from the
   engine-to-table-type mapping, so it fell back to the default `TABLE`, and `getTables(..., types = {"REMOTE TABLE"})`
diff --git a/client-v2/src/main/java/com/clickhouse/client/api/internal/ClickHouseLZ4InputStream.java b/client-v2/src/main/java/com/clickhouse/client/api/internal/ClickHouseLZ4InputStream.java
index 8550fb6c2..980b06cf9 100644
--- a/client-v2/src/main/java/com/clickhouse/client/api/internal/ClickHouseLZ4InputStream.java
+++ b/client-v2/src/main/java/com/clickhouse/client/api/internal/ClickHouseLZ4InputStream.java
@@ -83,7 +83,7 @@ private boolean readFully(byte[] b, int off, int len) throws IOException {
                 if (n == 0) {
                     return false;
                 }
-                throw new IOException(ClickHouseUtils.format("Incomplete read: {0} of {1}", n, len));
+                throw new IOException(ClickHouseUtils.format("Incomplete read: %s of %s", n, len));
             }
             n += count;
         }
diff --git a/client-v2/src/test/java/com/clickhouse/client/api/internal/ClickHouseLZ4InputStreamTest.java b/client-v2/src/test/java/com/clickhouse/client/api/internal/ClickHouseLZ4InputStreamTest.java
new file mode 100644
index 000000000..e6ab846e5
--- /dev/null
+++ b/client-v2/src/test/java/com/clickhouse/client/api/internal/ClickHouseLZ4InputStreamTest.java
@@ -0,0 +1,25 @@
+package com.clickhouse.client.api.internal;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+
+import net.jpountz.lz4.LZ4Factory;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+public class ClickHouseLZ4InputStreamTest {
+
+    @Test
+    public void reportsActualByteCountsForTruncatedHeader() {
+        byte[] truncatedHeader = new byte[10];
+        ClickHouseLZ4InputStream input = new ClickHouseLZ4InputStream(
+                new ByteArrayInputStream(truncatedHeader),
+                LZ4Factory.fastestJavaInstance().fastDecompressor(),
+                8192);
+
+        IOException exception = Assert.expectThrows(IOException.class,
+                () -> input.read(new byte[1], 0, 1));
+
+        Assert.assertEquals(exception.getMessage(), "Incomplete read: 10 of 25");
+    }
+}