From 54cc8e1d2797f11e5af00d08c35372f9db44af38 Mon Sep 17 00:00:00 2001
From: Nikolai Kochetov <nik-kochetov@yandex-team.ru>
Date: Fri, 22 Oct 2021 16:19:49 +0300
Subject: [PATCH] Fix LimitStep header after limit push down optimization.

---
 src/Processors/QueryPlan/LimitStep.cpp        |  2 +-
 .../02100_limit_push_down_bug.reference       |  0
 .../0_stateless/02100_limit_push_down_bug.sql | 21 +++++++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 tests/queries/0_stateless/02100_limit_push_down_bug.reference
 create mode 100644 tests/queries/0_stateless/02100_limit_push_down_bug.sql

diff --git a/src/Processors/QueryPlan/LimitStep.cpp b/src/Processors/QueryPlan/LimitStep.cpp
index 8c5e3e3c87c..aff7472e4aa 100644
--- a/src/Processors/QueryPlan/LimitStep.cpp
+++ b/src/Processors/QueryPlan/LimitStep.cpp
@@ -40,7 +40,7 @@ void LimitStep::updateInputStream(DataStream input_stream)
 {
     input_streams.clear();
     input_streams.emplace_back(std::move(input_stream));
-    output_stream = createOutputStream(input_streams.front(), output_stream->header, getDataStreamTraits());
+    output_stream = createOutputStream(input_streams.front(), input_streams.front().header, getDataStreamTraits());
 }
 
 void LimitStep::transformPipeline(QueryPipelineBuilder & pipeline, const BuildQueryPipelineSettings &)
diff --git a/tests/queries/0_stateless/02100_limit_push_down_bug.reference b/tests/queries/0_stateless/02100_limit_push_down_bug.reference
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/tests/queries/0_stateless/02100_limit_push_down_bug.sql b/tests/queries/0_stateless/02100_limit_push_down_bug.sql
new file mode 100644
index 00000000000..2ba9d2b8818
--- /dev/null
+++ b/tests/queries/0_stateless/02100_limit_push_down_bug.sql
@@ -0,0 +1,21 @@
+drop table if exists tbl_repr;
+
+CREATE TABLE tbl_repr(
+ts DateTime,
+x  String)
+ENGINE=MergeTree ORDER BY ts;
+
+
+SELECT *
+FROM
+(
+    SELECT
+        x,
+        length(x)
+    FROM tbl_repr
+    WHERE ts > now()
+    LIMIT 1
+)
+WHERE x != '';
+
+drop table if exists tbl_repr;