minor improvements

dbms/src/Interpreters/DatabaseAndTableWithAlias.cpp

@@ -118,6 +118,22 @@ DatabaseAndTableWithAlias::DatabaseAndTableWithAlias(const ASTTableExpression &
         throw Exception("Logical error: no known elements in ASTTableExpression", ErrorCodes::LOGICAL_ERROR);
 }
 
+bool DatabaseAndTableWithAlias::satisfies(const DatabaseAndTableWithAlias & db_table, bool table_may_be_an_alias)
+{
+    /// table.*, alias.* or database.table.*
+
+    if (database.empty())
+    {
+        if (!db_table.table.empty() && table == db_table.table)
+            return true;
+
+        if (!db_table.alias.empty())
+            return (alias == db_table.alias) || (table_may_be_an_alias && table == db_table.alias);
+    }
+
+    return database == db_table.database && table == db_table.table;
+}
+
 String DatabaseAndTableWithAlias::getQualifiedNamePrefix() const
 {
     if (alias.empty() && table.empty())

dbms/src/Interpreters/DatabaseAndTableWithAlias.h

@@ -33,6 +33,9 @@ struct DatabaseAndTableWithAlias
 
     /// If ast is ASTIdentifier, prepend getQualifiedNamePrefix() to it's name.
     void makeQualifiedName(const ASTPtr & ast) const;
+
+    /// Check if it satisfies another db_table name. @note opterion is not symmetric.
+    bool satisfies(const DatabaseAndTableWithAlias & table, bool table_may_be_an_alias);
 };
 
 void stripIdentifier(DB::ASTPtr & ast, size_t num_qualifiers_to_strip);

dbms/src/Interpreters/TranslateQualifiedNamesVisitor.cpp

@@ -89,38 +89,17 @@ std::vector<ASTPtr *> TranslateQualifiedNamesMatcher::visit(const ASTIdentifier
 
 std::vector<ASTPtr *> TranslateQualifiedNamesMatcher::visit(const ASTQualifiedAsterisk & , const ASTPtr & ast, Data & data)
 {
-    const std::vector<DatabaseAndTableWithAlias> & tables = data.tables;
-
     if (ast->children.size() != 1)
         throw Exception("Logical error: qualified asterisk must have exactly one child", ErrorCodes::LOGICAL_ERROR);
 
-    ASTIdentifier * ident = typeid_cast<ASTIdentifier *>(ast->children[0].get());
-    if (!ident)
-        throw Exception("Logical error: qualified asterisk must have identifier as its child", ErrorCodes::LOGICAL_ERROR);
-
-    size_t num_components = ident->children.size();
-    if (num_components > 2)
-        throw Exception("Qualified asterisk cannot have more than two qualifiers", ErrorCodes::UNKNOWN_ELEMENT_IN_AST);
+    auto & ident = ast->children[0];
 
-    DatabaseAndTableWithAlias db_and_table(*ident);
+    /// @note it could contain table alias as table name.
+    DatabaseAndTableWithAlias db_and_table(ident);
 
-    for (const auto & table_names : tables)
-    {
-        /// database.table.*, table.* or alias.*
-        if (num_components == 2)
-        {
-            if (!table_names.database.empty() &&
-                db_and_table.database == table_names.database &&
-                db_and_table.table == table_names.table)
-                return {};
-        }
-        else if (num_components == 0)
-        {
-            if ((!table_names.table.empty() && db_and_table.table == table_names.table) ||
-                (!table_names.alias.empty() && db_and_table.table == table_names.alias))
-                return {};
-        }
-    }
+    for (const auto & known_table : data.tables)
+        if (db_and_table.satisfies(known_table, true))
+            return {};
 
     throw Exception("Unknown qualified identifier: " + ident->getAliasOrColumnName(), ErrorCodes::UNKNOWN_IDENTIFIER);
 }