diff --git a/dbms/include/DB/Interpreters/ExpressionAnalyzer.h b/dbms/include/DB/Interpreters/ExpressionAnalyzer.h
index 5d2c326566a..7bb679b57bf 100644
--- a/dbms/include/DB/Interpreters/ExpressionAnalyzer.h
+++ b/dbms/include/DB/Interpreters/ExpressionAnalyzer.h
@@ -232,7 +232,7 @@ private:
 
 	/// remove Function_if AST if condition is constant
 	void optimizeIfWithConstantCondition();
-	void optimizeIfWithConstantConditionImpl(ASTPtr & current_ast) const;
+	void optimizeIfWithConstantConditionImpl(ASTPtr & current_ast, Aliases & aliases) const;
 	bool tryExtractConstValueFromCondition(const ASTPtr & condition, bool & value) const;
 
 	/// Превратить перечисление значений или подзапрос в ASTSet. node - функция in или notIn.
diff --git a/dbms/src/Interpreters/ExpressionAnalyzer.cpp b/dbms/src/Interpreters/ExpressionAnalyzer.cpp
index f10352fcfca..042ff4cd0bb 100644
--- a/dbms/src/Interpreters/ExpressionAnalyzer.cpp
+++ b/dbms/src/Interpreters/ExpressionAnalyzer.cpp
@@ -200,7 +200,7 @@ void ExpressionAnalyzer::init()
 
 void ExpressionAnalyzer::optimizeIfWithConstantCondition()
 {
-	optimizeIfWithConstantConditionImpl(ast);
+	optimizeIfWithConstantConditionImpl(ast, aliases);
 }
 
 bool ExpressionAnalyzer::tryExtractConstValueFromCondition(const ASTPtr & condition, bool & value) const
@@ -237,7 +237,7 @@ bool ExpressionAnalyzer::tryExtractConstValueFromCondition(const ASTPtr & condit
 	return false;
 }
 
-void ExpressionAnalyzer::optimizeIfWithConstantConditionImpl(ASTPtr & current_ast) const
+void ExpressionAnalyzer::optimizeIfWithConstantConditionImpl(ASTPtr & current_ast, ExpressionAnalyzer::Aliases & aliases) const
 {
 	if (!current_ast)
 		return;
@@ -247,11 +247,11 @@ void ExpressionAnalyzer::optimizeIfWithConstantConditionImpl(ASTPtr & current_as
 		ASTFunction * function_node = typeid_cast<ASTFunction *>(child.get());
 		if (!function_node || function_node->name != FunctionIf::name)
 		{
-			optimizeIfWithConstantConditionImpl(child);
+			optimizeIfWithConstantConditionImpl(child, aliases);
 			continue;
 		}
 
-		optimizeIfWithConstantConditionImpl(function_node->arguments);
+		optimizeIfWithConstantConditionImpl(function_node->arguments, aliases);
 		ASTExpressionList * args = typeid_cast<ASTExpressionList *>(function_node->arguments.get());
 
 		ASTPtr condition_expr = args->children.at(0);
@@ -262,10 +262,24 @@ void ExpressionAnalyzer::optimizeIfWithConstantConditionImpl(ASTPtr & current_as
 		bool condition;
 		if (tryExtractConstValueFromCondition(condition_expr, condition))
 		{
-			if (condition)
-				child = then_expr;
+			ASTPtr replace_ast = condition ? then_expr : else_expr;
+			String replace_alias = replace_ast->tryGetAlias();
+			String if_alias = child->tryGetAlias();
+
+			if (replace_alias.empty())
+			{
+				replace_ast->setAlias(if_alias);
+				child = replace_ast;
+			}
 			else
-				child = else_expr;
+			{
+				/// Only copy of one node is required here.
+				/// But IAST has only method for deep copy of subtree.
+				/// This can be a reason of performance degradation in case of deep queries.
+				ASTPtr replace_ast_deep_copy = replace_ast->clone();
+				replace_ast_deep_copy->setAlias(if_alias);
+				child = replace_ast_deep_copy;
+			}
 		}
 	}
 }
diff --git a/dbms/tests/queries/0_stateless/00393_if_with_constant_condition.reference b/dbms/tests/queries/0_stateless/00393_if_with_constant_condition.reference
index 019389c1815..69685047337 100644
--- a/dbms/tests/queries/0_stateless/00393_if_with_constant_condition.reference
+++ b/dbms/tests/queries/0_stateless/00393_if_with_constant_condition.reference
@@ -1,7 +1,8 @@
 1
 1
 2
-42
-1	0
-0	5
-1	2	3
+1
+d=2	a=1	b=2	c=3	d=2
+d=3	a=0	b=2	c=3	d=3
+d=2	a=1	b=2	c=3	d=2
+not_existing=42
diff --git a/dbms/tests/queries/0_stateless/00393_if_with_constant_condition.sql b/dbms/tests/queries/0_stateless/00393_if_with_constant_condition.sql
index af4051f34a4..c35e4ff24e3 100644
--- a/dbms/tests/queries/0_stateless/00393_if_with_constant_condition.sql
+++ b/dbms/tests/queries/0_stateless/00393_if_with_constant_condition.sql
@@ -1,10 +1,15 @@
 SELECT 1 ? 1 : 0;
 SELECT 0 ? not_existing_column : 1 FROM system.numbers LIMIT 1;
-SELECT if(1, if(0, not_existing_column, 2), 0) FROM system.numbers LIMIT 1;
+SELECT 1 ? (0 ? not_existing_column : 2) : 0 FROM system.numbers LIMIT 1;
 
-SELECT (SELECT hasColumnInTable('system', 'numbers', 'not_existing')) ? not_existing : 42 FROM system.numbers LIMIT 1;
+/* scalar subquery optimization */
+SELECT (SELECT toUInt8(number + 1) FROM system.numbers LIMIT 1) ? 1 : 2 FROM system.numbers LIMIT 1;
 
 /* alias test */
-SELECT 1 ? 1 : (0 as n), n FROM system.numbers LIMIT 1;
-SELECT 0 ? (number + 5 as n) : 0, n FROM system.numbers LIMIT 1;
-SELECT (2 as n) ?  1 : (number + 3 as nn), n, nn FROM system.numbers LIMIT 1;
\ No newline at end of file
+SELECT (1 as a) ? (2 as b) : (3 as c) as d, a, b, c, d FORMAT TSKV;
+SELECT (0 as a) ? (2 as b) : (3 as c) as d, a, b, c, d FORMAT TSKV;
+
+SELECT (1 as a) ? (number + 2 as b) : (number + 3 as c) as d, a, b, c, d FROM system.numbers LIMIT 1 FORMAT TSKV;
+
+/* intergration test */
+SELECT (SELECT hasColumnInTable('system', 'numbers', 'not_existing')) ? not_existing : 42 as not_existing FROM system.numbers LIMIT 1 FORMAT TSKV;
\ No newline at end of file