From 7b7e8acf4f2556f635a5373efeb148b660cc4eab Mon Sep 17 00:00:00 2001
From: Azat Khuzhin <a3at.mail@gmail.com>
Date: Wed, 21 Jul 2021 09:58:13 +0300
Subject: [PATCH] Fix excessive connect attempts with skip_unavailable_shards

Before this patch the query was sent from
RemoteBlockInputStream::readPrefix() and also from
RemoteBlockInputStream::read().

And since in case of skip_unavailable_shards=1 connection errors are
ignored, it tries to do x2 connect attempts.

Fix this, but removing RemoteBlockInputStream::readPrefix().

Fixes: #26511
---
 src/DataStreams/RemoteBlockInputStream.cpp          |  5 -----
 src/DataStreams/RemoteBlockInputStream.h            |  3 ---
 ..._unavailable_shards_excessive_attempts.reference |  1 +
 ...56_skip_unavailable_shards_excessive_attempts.sh | 13 +++++++++++++
 4 files changed, 14 insertions(+), 8 deletions(-)
 create mode 100644 tests/queries/0_stateless/01956_skip_unavailable_shards_excessive_attempts.reference
 create mode 100755 tests/queries/0_stateless/01956_skip_unavailable_shards_excessive_attempts.sh

diff --git a/src/DataStreams/RemoteBlockInputStream.cpp b/src/DataStreams/RemoteBlockInputStream.cpp
index c633600d37f..f3a66fb3a57 100644
--- a/src/DataStreams/RemoteBlockInputStream.cpp
+++ b/src/DataStreams/RemoteBlockInputStream.cpp
@@ -38,11 +38,6 @@ void RemoteBlockInputStream::init()
     query_executor.setLogger(log);
 }
 
-void RemoteBlockInputStream::readPrefix()
-{
-    query_executor.sendQuery();
-}
-
 void RemoteBlockInputStream::cancel(bool kill)
 {
     if (kill)
diff --git a/src/DataStreams/RemoteBlockInputStream.h b/src/DataStreams/RemoteBlockInputStream.h
index b0029da91bb..0c829cb6a67 100644
--- a/src/DataStreams/RemoteBlockInputStream.h
+++ b/src/DataStreams/RemoteBlockInputStream.h
@@ -52,9 +52,6 @@ public:
 
     void setMainTable(StorageID main_table_) { query_executor.setMainTable(std::move(main_table_)); }
 
-    /// Sends query (initiates calculation) before read()
-    void readPrefix() override;
-
     /// Prevent default progress notification because progress' callback is called by its own.
     void progress(const Progress & /*value*/) override {}
 
diff --git a/tests/queries/0_stateless/01956_skip_unavailable_shards_excessive_attempts.reference b/tests/queries/0_stateless/01956_skip_unavailable_shards_excessive_attempts.reference
new file mode 100644
index 00000000000..f2322e4ffc4
--- /dev/null
+++ b/tests/queries/0_stateless/01956_skip_unavailable_shards_excessive_attempts.reference
@@ -0,0 +1 @@
+Connection failed at try №1,
diff --git a/tests/queries/0_stateless/01956_skip_unavailable_shards_excessive_attempts.sh b/tests/queries/0_stateless/01956_skip_unavailable_shards_excessive_attempts.sh
new file mode 100755
index 00000000000..0e2f1857aed
--- /dev/null
+++ b/tests/queries/0_stateless/01956_skip_unavailable_shards_excessive_attempts.sh
@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+CLICKHOUSE_CLIENT_SERVER_LOGS_LEVEL=trace
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+opts=(
+    "--connections_with_failover_max_tries=1"
+    "--skip_unavailable_shards=1"
+)
+$CLICKHOUSE_CLIENT --query "select * from remote('255.255.255.255', system.one)" "${opts[@]}" 2>&1 | grep -o 'Connection failed at try.*,'