From 61653f0ce563c420d68bdc5d0ddf243c3e6d28b7 Mon Sep 17 00:00:00 2001
From: Konstantin Burkalev <KSDaemon@gmail.com>
Date: Wed, 2 Jul 2025 20:49:55 +0300
Subject: [PATCH] fix(clickhouse-driver): Fix headers check

---
 packages/cubejs-clickhouse-driver/src/ClickHouseDriver.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/cubejs-clickhouse-driver/src/ClickHouseDriver.ts b/packages/cubejs-clickhouse-driver/src/ClickHouseDriver.ts
index 80570c8a21f3b..b5a783023553c 100644
--- a/packages/cubejs-clickhouse-driver/src/ClickHouseDriver.ts
+++ b/packages/cubejs-clickhouse-driver/src/ClickHouseDriver.ts
@@ -268,7 +268,9 @@ export class ClickHouseDriver extends BaseDriver implements DriverInterface {
           abort_signal: signal,
         });
 
-        if (resultSet.response_headers['x-clickhouse-format'] !== format) {
+        // response_headers['x-clickhouse-format'] is optional, but if it exists,
+        // it should match the requested format.
+        if (resultSet.response_headers['x-clickhouse-format'] && resultSet.response_headers['x-clickhouse-format'] !== format) {
           throw new Error(`Unexpected x-clickhouse-format in response: expected ${format}, received ${resultSet.response_headers['x-clickhouse-format']}`);
         }