Backward compatible

src/Core/Settings.h

@@ -383,6 +383,7 @@ class IColumn;
     M(Bool, optimize_if_chain_to_multiif, false, "Replace if(cond1, then1, if(cond2, ...)) chains to multiIf. Currently it's not beneficial for numeric types.", 0) \
     M(Bool, optimize_if_transform_strings_to_enum, false, "Replaces string-type arguments in If and Transform to enum. Disabled by default cause it could make inconsistent change in distributed query that would lead to its fail.", 0) \
     M(Bool, optimize_monotonous_functions_in_order_by, true, "Replace monotonous function with its argument in ORDER BY", 0) \
+    M(Bool, normalize_function_names, true, "Normalize function names to their canonical names", 0) \
     M(Bool, allow_experimental_alter_materialized_view_structure, false, "Allow atomic alter on Materialized views. Work in progress.", 0) \
     M(Bool, enable_early_constant_folding, true, "Enable query optimization where we analyze function and subqueries results and rewrite query if there're constants there", 0) \
     M(Bool, deduplicate_blocks_in_dependent_materialized_views, false, "Should deduplicate blocks for materialized views if the block is not a duplicate for the table. Use true to always deduplicate in dependent tables.", 0) \

src/Interpreters/TreeRewriter.cpp

@@ -936,7 +936,8 @@ void TreeRewriter::normalize(ASTPtr & query, Aliases & aliases, const Settings &
     MarkTableIdentifiersVisitor(identifiers_data).visit(query);
 
     /// Rewrite function names to their canonical ones.
-    FunctionNameNormalizer().visit(query.get());
+    if (settings.normalize_function_names)
+        FunctionNameNormalizer().visit(query.get());
 
     /// Common subexpression elimination. Rewrite rules.
     QueryNormalizer::Data normalizer_data(aliases, settings);

src/Interpreters/evaluateConstantExpression.cpp

@@ -36,7 +36,10 @@ std::pair<Field, std::shared_ptr<const IDataType>> evaluateConstantExpression(co
     auto ast = node->clone();
     ReplaceQueryParameterVisitor param_visitor(context.getQueryParameters());
     param_visitor.visit(ast);
-    FunctionNameNormalizer().visit(ast.get());
+
+    if (context.getSettingsRef().normalize_function_names)
+        FunctionNameNormalizer().visit(ast.get());
+
     String name = ast->getColumnName();
     auto syntax_result = TreeRewriter(context).analyze(ast, source_columns);
     ExpressionActionsPtr expr_for_constant_folding = ExpressionAnalyzer(ast, syntax_result, context).getConstActions();

src/Server/TCPHandler.cpp

@@ -1133,6 +1133,12 @@ void TCPHandler::receiveQuery()
     }
     query_context->applySettingsChanges(settings_changes);
 
+    /// Disable function name normalization it's not an initial query.
+    if (client_info.query_kind != ClientInfo::QueryKind::INITIAL_QUERY)
+    {
+        query_context->setSetting("normalize_function_names", Field(0));
+    }
+
     // Use the received query id, or generate a random default. It is convenient
     // to also generate the default OpenTelemetry trace id at the same time, and
     // set the trace parent.