[PATCH] Fix always false check in evaluateConstantExpression

0001-Fix-always-false-check-in-evaluateConstantExpression.patch

From 111f1566e13efd03c4b72b2325b2254284d17fe8 Mon Sep 17 00:00:00 2001
From: Azat Khuzhin <a3at.mail@gmail.com>
Date: Mon, 9 Aug 2021 23:23:39 +0300
Subject: [PATCH] Fix always false check in evaluateConstantExpression

---
 .../evaluateConstantExpression.cpp            | 22 +++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/Interpreters/evaluateConstantExpression.cpp b/src/Interpreters/evaluateConstantExpression.cpp
index 6a2e559a07..5ce68bab68 100644
--- a/src/Interpreters/evaluateConstantExpression.cpp
+++ b/src/Interpreters/evaluateConstantExpression.cpp
@@ -18,6 +18,7 @@
 #include <Interpreters/FunctionNameNormalizer.h>
 #include <Interpreters/ReplaceQueryParameterVisitor.h>
 #include <Poco/Util/AbstractConfiguration.h>
+#include <unordered_map>
 
 namespace
 {
@@ -368,6 +369,7 @@ std::optional<Blocks> evaluateExpressionOverConstantCondition(const ASTPtr & nod
 
     if (const auto * fn = node->as<ASTFunction>())
     {
+        std::unordered_map<std::string, bool> always_false_map;
         const auto dnf = analyzeFunction(fn, target_expr, limit);
 
         if (dnf.empty() || !limit)
@@ -420,8 +422,19 @@ std::optional<Blocks> evaluateExpressionOverConstantCondition(const ASTPtr & nod
                         Field prev_value = assert_cast<const ColumnConst &>(*prev.column).getField();
                         Field curr_value = assert_cast<const ColumnConst &>(*elem.column).getField();
 
-                        if (prev_value != curr_value)
-                            return Blocks{};
+                        if (!always_false_map.count(elem.name))
+                        {
+                            always_false_map[elem.name] = prev_value != curr_value;
+                        }
+                        else
+                        {
+                            auto & always_false = always_false_map[elem.name];
+                            /// If at least one of conjunct is not always false, we should preserve this.
+                            if (always_false)
+                            {
+                                always_false = prev_value != curr_value;
+                            }
+                        }
                     }
                 }
             }
@@ -449,6 +462,11 @@ std::optional<Blocks> evaluateExpressionOverConstantCondition(const ASTPtr & nod
                 return {};
             }
         }
+
+        bool any_always_false = std::any_of(always_false_map.begin(), always_false_map.end(), [](const auto & v) { return v.second; });
+        if (any_always_false)
+            return Blocks{};
+
     }
     else if (const auto * literal = node->as<ASTLiteral>())
     {
-- 
2.32.0