From ca237ee3c45cadfafa24230c30b8255d61149f3a Mon Sep 17 00:00:00 2001
From: Nikolai Kochetov <nk@clickhouse.com>
Date: Wed, 16 Oct 2024 19:33:23 +0000
Subject: [PATCH] Fix constant result for prewhere optimization.

---
 .../QueryPlan/Optimizations/filterPushDown.cpp   |  5 +----
 .../QueryPlan/Optimizations/optimizePrewhere.cpp | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/Processors/QueryPlan/Optimizations/filterPushDown.cpp b/src/Processors/QueryPlan/Optimizations/filterPushDown.cpp
index ba5ff89a653..63359d039e8 100644
--- a/src/Processors/QueryPlan/Optimizations/filterPushDown.cpp
+++ b/src/Processors/QueryPlan/Optimizations/filterPushDown.cpp
@@ -152,10 +152,7 @@ addNewFilterStepOrThrow(QueryPlan::Node * parent_node, QueryPlan::Nodes & nodes,
     node.step = std::make_unique<FilterStep>(
         node.children.at(0)->step->getOutputHeader(), std::move(split_filter), std::move(split_filter_column_name), can_remove_filter);
 
-    if (auto * join = typeid_cast<JoinStep *>(child.get()))
-        join->updateInputHeader(node.step->getOutputHeader(), child_idx);
-    else
-        child->updateInputHeader(node.step->getOutputHeader());
+    child->updateInputHeader(node.step->getOutputHeader(), child_idx);
 
     if (update_parent_filter)
     {
diff --git a/src/Processors/QueryPlan/Optimizations/optimizePrewhere.cpp b/src/Processors/QueryPlan/Optimizations/optimizePrewhere.cpp
index 4933026377f..d8771c268ed 100644
--- a/src/Processors/QueryPlan/Optimizations/optimizePrewhere.cpp
+++ b/src/Processors/QueryPlan/Optimizations/optimizePrewhere.cpp
@@ -194,6 +194,22 @@ void optimizePrewhere(Stack & stack, QueryPlan::Nodes &)
     }
     else
     {
+        if (!filter_step->removesFilterColumn())
+        {
+            const auto * node = split_result.second.tryFindInOutputs(filter_step->getFilterColumnName());
+            if (node && !node->column)
+            {
+                ColumnWithTypeAndName column;
+                column.type = node->result_type;
+                column.name = node->result_name;
+                column.column = column.type->createColumnConst(0, 1u);
+                const auto * replaced_const = &split_result.second.addColumn(column);
+
+                for (auto & output : split_result.second.getOutputs())
+                    if (output == node)
+                        output = replaced_const;
+            }
+        }
         /// Have to keep this expression to change column names to column identifiers
         filter_node->step = std::make_unique<ExpressionStep>(
             source_step_with_filter->getOutputHeader(),