From 0fa864aa7150ca55919c7323aa1d495afed394ac Mon Sep 17 00:00:00 2001
From: Julian Maicher <julian.maicher@gmail.com>
Date: Fri, 29 Aug 2025 16:15:58 +0200
Subject: [PATCH] Fail when all replicas are unavailable for *cluster functions

---
 src/Storages/IStorageCluster.cpp                   | 11 ++++++++---
 tests/config/config.d/clusters.xml                 | 14 ++++++++++++++
 ...ding_s3_cluster_all_nodes_unavailable.reference |  0
 ...03_reading_s3_cluster_all_nodes_unavailable.sql |  4 ++++
 4 files changed, 26 insertions(+), 3 deletions(-)
 create mode 100644 tests/queries/0_stateless/03603_reading_s3_cluster_all_nodes_unavailable.reference
 create mode 100644 tests/queries/0_stateless/03603_reading_s3_cluster_all_nodes_unavailable.sql

diff --git a/src/Storages/IStorageCluster.cpp b/src/Storages/IStorageCluster.cpp
index 7c8d410cee53..0789c2993e74 100644
--- a/src/Storages/IStorageCluster.cpp
+++ b/src/Storages/IStorageCluster.cpp
@@ -42,6 +42,11 @@ namespace Setting
     extern const SettingsNonZeroUInt64 max_parallel_replicas;
 }
 
+namespace ErrorCodes
+{
+    extern const int ALL_CONNECTION_TRIES_FAILED;
+}
+
 IStorageCluster::IStorageCluster(
     const String & cluster_name_,
     const StorageID & table_id_,
@@ -239,10 +244,10 @@ void ReadFromCluster::initializePipeline(QueryPipelineBuilder & pipeline, const
         pipes.emplace_back(std::move(pipe));
     }
 
-    auto pipe = Pipe::unitePipes(std::move(pipes));
-    if (pipe.empty())
-        pipe = Pipe(std::make_shared<NullSource>(getOutputHeader()));
+    if (pipes.empty())
+        throw Exception(ErrorCodes::ALL_CONNECTION_TRIES_FAILED, "Cannot connect to any replica for query execution");
 
+    auto pipe = Pipe::unitePipes(std::move(pipes));
     for (const auto & processor : pipe.getProcessors())
         processors.emplace_back(processor);
 
diff --git a/tests/config/config.d/clusters.xml b/tests/config/config.d/clusters.xml
index 0ee6ce774e43..1a507a76fd85 100644
--- a/tests/config/config.d/clusters.xml
+++ b/tests/config/config.d/clusters.xml
@@ -325,5 +325,19 @@
                 </replica>
             </shard>
         </test_shard_bind_host_fail>
+        <test_cluster_multiple_nodes_all_unavailable>
+            <node>
+                <host>127.0.0.1</host>
+                <port>1234</port>
+            </node>
+            <node>
+                <host>127.0.0.2</host>
+                <port>1234</port>
+            </node>
+            <node>
+                <host>127.0.0.3</host>
+                <port>1234</port>
+            </node>
+        </test_cluster_multiple_nodes_all_unavailable>
     </remote_servers>
 </clickhouse>
diff --git a/tests/queries/0_stateless/03603_reading_s3_cluster_all_nodes_unavailable.reference b/tests/queries/0_stateless/03603_reading_s3_cluster_all_nodes_unavailable.reference
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/tests/queries/0_stateless/03603_reading_s3_cluster_all_nodes_unavailable.sql b/tests/queries/0_stateless/03603_reading_s3_cluster_all_nodes_unavailable.sql
new file mode 100644
index 000000000000..80da21ffacf8
--- /dev/null
+++ b/tests/queries/0_stateless/03603_reading_s3_cluster_all_nodes_unavailable.sql
@@ -0,0 +1,4 @@
+-- Tags: no-fasttest
+-- s3Cluster is not used in fast tests
+
+SELECT * FROM s3Cluster('test_cluster_multiple_nodes_all_unavailable', 'http://localhost:11111/test/a.tsv'); -- { serverError ALL_CONNECTION_TRIES_FAILED }