Fixed review comments and updated FunctionParameterValuesVisitor to use visitFunction - 40907 Parameterized views as table functions

src/Interpreters/InterpreterSelectQuery.cpp

@@ -510,9 +510,10 @@ InterpreterSelectQuery::InterpreterSelectQuery(
         if (view)
         {
             query_info.is_parameterized_view = view->isParameterizedView();
-            /// We need to fetch the parameters set for SELECT parameterized view before the query is replaced.
+            /// We need to fetch the parameters set for SELECT ... FROM parameterized_view(<params>) before the query is replaced.
             /// replaceWithSubquery replaces the function child and adds the subquery in its place.
-            /// the parameters are children of function child, if function is replaced the parameters are also gone from tree
+            /// the parameters are children of function child, if function (which corresponds to parametrised view and has
+            /// parameters in its arguments: `parametrised_view(<params>)`) is replaced the parameters are also gone from tree
             /// So we need to get the parameters before they are removed from the tree
             /// and after query is replaced, we use these parameters to substitute in the parameterized view query
             if (query_info.is_parameterized_view)

src/Parsers/FunctionParameterValuesVisitor.cpp

@@ -27,8 +27,8 @@ public:
 
     void visit(const ASTPtr & ast)
     {
-        if (const auto * expression = ast->as<ASTExpressionList>())
+        if (const auto * function = ast->as<ASTFunction>())
-            visitExpressionList(*expression);
+            visitFunction(*function);
         for (const auto & child : ast->children)
             visit(child);
     }
@@ -36,18 +36,23 @@ public:
 private:
     NameToNameMap & parameter_values;
 
-    void visitExpressionList(const ASTExpressionList & expression_list)
+    void visitFunction(const ASTFunction & parameter_function)
     {
-        if (expression_list.children.size() != 2)
+        if (parameter_function.name != "equals" && parameter_function.children.size() != 1)
             return;
 
-        if (const auto * identifier = expression_list.children[0]->as<ASTIdentifier>())
+        const auto * expression_list = parameter_function.children[0]->as<ASTExpressionList>();
+
+        if (expression_list && expression_list->children.size() != 2)
+            return;
+
+        if (const auto * identifier = expression_list->children[0]->as<ASTIdentifier>())
         {
-            if (const auto * literal = expression_list.children[1]->as<ASTLiteral>())
+            if (const auto * literal = expression_list->children[1]->as<ASTLiteral>())
             {
                 parameter_values[identifier->name()] = convertFieldToString(literal->value);
             }
-            else if (const auto * function = expression_list.children[1]->as<ASTFunction>())
+            else if (const auto * function = expression_list->children[1]->as<ASTFunction>())
             {
                 if (isFunctionCast(function))
                 {

src/Storages/StorageSnapshot.cpp

@@ -117,10 +117,11 @@ Block StorageSnapshot::getSampleBlockForColumns(const Names & column_names,const
     Block res;
 
     const auto & columns = getMetadataForQuery()->getColumns();
-    for (const auto & name : column_names)
+    for (const auto & column_name : column_names)
     {
-        const std::string & column_name  = name;
+        /// substituted_column_name is used for parameterized view (which are created using query parameters
-        std::string substituted_column_name = name;
+        /// and SELECT is used with substitution of these query parameters )
+        std::string substituted_column_name = column_name;
         std::string::size_type pos = 0u;
         for (const auto & parameter : parameter_values)
         {
@@ -141,17 +142,17 @@ Block StorageSnapshot::getSampleBlockForColumns(const Names & column_names,const
         {
             res.insert({object_column->type->createColumn(), object_column->type, column_name});
         }
-        else if (auto it = virtual_columns.find(name); it != virtual_columns.end())
+        else if (auto it = virtual_columns.find(column_name); it != virtual_columns.end())
         {
             /// Virtual columns must be appended after ordinary, because user can
             /// override them.
             const auto & type = it->second;
-            res.insert({type->createColumn(), type, name});
+            res.insert({type->createColumn(), type, column_name});
         }
         else
         {
             throw Exception(ErrorCodes::NOT_FOUND_COLUMN_IN_BLOCK,
-                "Column {} not found in table {}", backQuote(name), storage.getStorageID().getNameForLogs());
+                "Column {} not found in table {}", backQuote(substituted_column_name), storage.getStorageID().getNameForLogs());
         }
     }
     return res;