minor changes

dbms/src/Interpreters/AddDefaultDatabaseVisitor.h

@@ -90,12 +90,7 @@ private:
     void visit(ASTTableExpression & table_expression, ASTPtr &) const
     {
         if (table_expression.database_and_table_name)
-        {
             tryVisit<ASTIdentifier>(table_expression.database_and_table_name);
-
-            if (table_expression.database_and_table_name->children.size() != 2)
-                throw Exception("Logical error: more than two components in table expression", ErrorCodes::LOGICAL_ERROR);
-        }
         else if (table_expression.subquery)
             tryVisit<ASTSubquery>(table_expression.subquery);
     }

dbms/src/Interpreters/DatabaseAndTableWithAlias.cpp

@@ -209,21 +209,13 @@ std::optional<DatabaseAndTableWithAlias> getDatabaseAndTable(const ASTSelectQuer
     return DatabaseAndTableWithAlias(database_and_table_name);
 }
 
-ASTPtr getTableFunctionOrSubquery(const ASTSelectQuery & select, size_t table_number)
+ASTPtr extractTableExpression(const ASTSelectQuery & select, size_t table_number)
 {
-    const ASTTableExpression * table_expression = getTableExpression(select, table_number);
-    if (table_expression)
+    if (const ASTTableExpression * table_expression = getTableExpression(select, table_number))
     {
-#if 1   /// TODO: It hides some logical error in InterpreterSelectQuery & distributed tables
         if (table_expression->database_and_table_name)
-        {
-            if (table_expression->database_and_table_name->children.empty())
             return table_expression->database_and_table_name;
 
-            if (table_expression->database_and_table_name->children.size() == 2)
-                return table_expression->database_and_table_name->children[1];
-        }
-#endif
         if (table_expression->table_function)
             return table_expression->table_function;
 

dbms/src/Interpreters/DatabaseAndTableWithAlias.h

@@ -44,6 +44,6 @@ std::vector<DatabaseAndTableWithAlias> getDatabaseAndTables(const ASTSelectQuery
 std::optional<DatabaseAndTableWithAlias> getDatabaseAndTable(const ASTSelectQuery & select, size_t table_number);
 
 std::vector<const ASTTableExpression *> getSelectTablesExpression(const ASTSelectQuery & select_query);
-ASTPtr getTableFunctionOrSubquery(const ASTSelectQuery & select, size_t table_number);
+ASTPtr extractTableExpression(const ASTSelectQuery & select, size_t table_number);
 
 }

dbms/src/Interpreters/ExpressionAnalyzer.cpp

@@ -310,7 +310,7 @@ void ExpressionAnalyzer::makeSetsForIndexImpl(const ASTPtr & node, const Block &
 
             if (!prepared_sets.count(arg->range)) /// Not already prepared.
             {
-                if (typeid_cast<ASTSubquery *>(arg.get()) || typeid_cast<ASTIdentifier *>(arg.get()))
+                if (typeid_cast<ASTSubquery *>(arg.get()) || isIdentifier(arg))
                 {
                     if (settings.use_index_for_in_with_subqueries)
                         tryMakeSetForIndexFromSubquery(arg);

dbms/src/Interpreters/GlobalSubqueriesVisitor.h

@@ -55,7 +55,7 @@ public:
             ASTPtr table_name;
             ASTPtr subquery_or_table_name;
 
-            if (typeid_cast<const ASTIdentifier *>(subquery_or_table_name_or_table_expression.get()))
+            if (isIdentifier(subquery_or_table_name_or_table_expression))
             {
                 table_name = subquery_or_table_name_or_table_expression;
                 subquery_or_table_name = table_name;
@@ -86,7 +86,7 @@ public:
             if (table_name)
             {
                 /// If this is already an external table, you do not need to add anything. Just remember its presence.
-                if (external_tables.end() != external_tables.find(static_cast<const ASTIdentifier &>(*table_name).name))
+                if (external_tables.end() != external_tables.find(*getIdentifierName(table_name)))
                     return;
             }
 

dbms/src/Interpreters/InterpreterSelectQuery.cpp

@@ -147,14 +147,22 @@ InterpreterSelectQuery::InterpreterSelectQuery(
 
     max_streams = settings.max_threads;
 
-    ASTPtr table_expression = getTableFunctionOrSubquery(query, 0);
+    ASTPtr table_expression = extractTableExpression(query, 0);
+
+    bool is_table_func = false;
+    bool is_subquery = false;
+    if (table_expression)
+    {
+        is_table_func = typeid_cast<const ASTFunction *>(table_expression.get());
+        is_subquery = typeid_cast<const ASTSelectWithUnionQuery *>(table_expression.get());
+    }
 
     if (input)
     {
         /// Read from prepared input.
         source_header = input->getHeader();
     }
-    else if (table_expression && typeid_cast<const ASTSelectWithUnionQuery *>(table_expression.get()))
+    else if (is_subquery)
     {
         /// Read from subquery.
         interpreter_subquery = std::make_unique<InterpreterSelectWithUnionQuery>(
@@ -164,7 +172,7 @@ InterpreterSelectQuery::InterpreterSelectQuery(
     }
     else if (!storage)
     {
-        if (table_expression && typeid_cast<const ASTFunction *>(table_expression.get()))
+        if (is_table_func)
         {
             /// Read from table function.
             storage = context.getQueryContext().executeTableFunction(table_expression);
@@ -208,7 +216,7 @@ InterpreterSelectQuery::InterpreterSelectQuery(
         if (query_analyzer->isRewriteSubqueriesPredicate())
         {
             /// remake interpreter_subquery when PredicateOptimizer is rewrite subqueries and main table is subquery
-            if (table_expression && typeid_cast<ASTSelectWithUnionQuery *>(table_expression.get()))
+            if (is_subquery)
                 interpreter_subquery = std::make_unique<InterpreterSelectWithUnionQuery>(
                     table_expression, getSubqueryContext(context), required_columns, QueryProcessingStage::Complete, subquery_depth + 1,
                     only_analyze);
@@ -921,7 +929,7 @@ void InterpreterSelectQuery::executeFetchColumns(
         /// If we need less number of columns that subquery have - update the interpreter.
         if (required_columns.size() < source_header.columns())
         {
-            ASTPtr subquery = getTableFunctionOrSubquery(query, 0);
+            ASTPtr subquery = extractTableExpression(query, 0);
             if (!subquery)
                 throw Exception("Subquery expected", ErrorCodes::LOGICAL_ERROR);
 
@@ -1396,7 +1404,7 @@ bool hasWithTotalsInAnySubqueryInFromClause(const ASTSelectQuery & query)
       * In other cases, totals will be computed on the initiating server of the query, and it is not necessary to read the data to the end.
       */
 
-    if (auto query_table = getTableFunctionOrSubquery(query, 0))
+    if (auto query_table = extractTableExpression(query, 0))
     {
         if (auto ast_union = typeid_cast<const ASTSelectWithUnionQuery *>(query_table.get()))
         {

dbms/src/Storages/StorageMaterializedView.cpp

@@ -30,7 +30,7 @@ namespace ErrorCodes
 static void extractDependentTable(ASTSelectQuery & query, String & select_database_name, String & select_table_name)
 {
     auto db_and_table = getDatabaseAndTable(query, 0);
-    ASTPtr subquery = getTableFunctionOrSubquery(query, 0);
+    ASTPtr subquery = extractTableExpression(query, 0);
 
     if (!db_and_table && !subquery)
         return;
@@ -69,7 +69,7 @@ static void checkAllowedQueries(const ASTSelectQuery & query)
     if (query.prewhere_expression || query.final() || query.sample_size())
         throw Exception("MATERIALIZED VIEW cannot have PREWHERE, SAMPLE or FINAL.", DB::ErrorCodes::QUERY_IS_NOT_SUPPORTED_IN_MATERIALIZED_VIEW);
 
-    ASTPtr subquery = getTableFunctionOrSubquery(query, 0);
+    ASTPtr subquery = extractTableExpression(query, 0);
     if (!subquery)
         return;