ISSUES-4006 add rewrite alter query

src/Interpreters/InterpreterExternalDDLQuery.cpp

@@ -11,6 +11,7 @@
 #include <Parsers/ASTExternalDDLQuery.h>
 
 #ifdef USE_MYSQL
+#    include <Parsers/MySQL/ASTAlterQuery.h>
 #    include <Parsers/MySQL/ASTCreateQuery.h>
 #    include <Interpreters/MySQL/InterpretersMySQLDDLQuery.h>
 #endif
@@ -49,6 +50,10 @@ BlockIO InterpreterExternalDDLQuery::execute()
             return MySQLInterpreter::InterpreterMySQLRenameQuery(
                 external_ddl_query.external_ddl, context, getIdentifierName(arguments[0]),
                 getIdentifierName(arguments[1])).execute();
+        else if (external_ddl_query.external_ddl->as<MySQLParser::ASTAlterQuery>())
+            return MySQLInterpreter::InterpreterMySQLAlterQuery(
+                external_ddl_query.external_ddl, context, getIdentifierName(arguments[0]),
+                getIdentifierName(arguments[1])) .execute();
         else if (external_ddl_query.external_ddl->as<MySQLParser::ASTCreateQuery>())
             return MySQLInterpreter::InterpreterMySQLCreateQuery(
                 external_ddl_query.external_ddl, context, getIdentifierName(arguments[0]),

src/Interpreters/MySQL/InterpretersMySQLDDLQuery.cpp

@@ -4,8 +4,10 @@
 #include <Parsers/ASTLiteral.h>
 #include <Parsers/ASTFunction.h>
 #include <Parsers/ASTIdentifier.h>
+#include <Parsers/ASTAlterQuery.h>
 #include <Parsers/ASTCreateQuery.h>
 #include <Parsers/MySQL/ASTCreateQuery.h>
+#include <Parsers/MySQL/ASTAlterCommand.h>
 #include <Parsers/MySQL/ASTDeclareColumn.h>
 #include <Parsers/MySQL/ASTDeclareOption.h>
 #include <Parsers/MySQL/ASTCreateDefines.h>
@@ -338,6 +340,89 @@ ASTPtr InterpreterRenameImpl::getRewrittenQuery(
     return rewritten_query;
 }
 
+void InterpreterAlterImpl::validate(const InterpreterAlterImpl::TQuery & /*query*/, const Context & /*context*/)
+{
+}
+
+ASTPtr InterpreterAlterImpl::getRewrittenQuery(
+    const InterpreterAlterImpl::TQuery & alter_query, const Context & context, const String & clickhouse_db, const String & filter_mysql_db)
+{
+    const auto & database_name = context.resolveDatabase(alter_query.database);
+
+    if (database_name != filter_mysql_db)
+        return {};
+
+    auto rewritten_query = std::make_shared<ASTAlterQuery>();
+    rewritten_query->database = clickhouse_db;
+    rewritten_query->table = alter_query.table;
+    rewritten_query->set(rewritten_query->command_list, std::make_shared<ASTAlterCommandList>());
+
+    for (const auto & command_query : alter_query.command_list->children)
+    {
+        const auto & alter_command = command_query->as<MySQLParser::ASTAlterCommand>();
+
+        if (alter_command->type == MySQLParser::ASTAlterCommand::ADD_COLUMN)
+        {
+            const auto & additional_columns = getColumnsList(alter_command->additional_columns);
+
+            for (const auto & additional_column : InterpreterCreateQuery::formatColumns(additional_columns)->children)
+            {
+                auto rewritten_command = std::make_shared<ASTAlterCommand>();
+                rewritten_command->type = ASTAlterCommand::ADD_COLUMN;
+                rewritten_command->first = alter_command->first;
+                rewritten_command->col_decl = additional_column;
+                rewritten_command->column = std::make_shared<ASTIdentifier>(alter_command->column_name);
+                rewritten_query->command_list->add(rewritten_command);
+            }
+        }
+        else if (alter_command->type == MySQLParser::ASTAlterCommand::DROP_COLUMN)
+        {
+            auto rewritten_command = std::make_shared<ASTAlterCommand>();
+            rewritten_command->type = ASTAlterCommand::DROP_COLUMN;
+            rewritten_command->column = std::make_shared<ASTIdentifier>(alter_command->column_name);
+            rewritten_query->command_list->add(rewritten_command);
+        }
+        else if (alter_command->type == MySQLParser::ASTAlterCommand::RENAME_COLUMN)
+        {
+            auto rewritten_command = std::make_shared<ASTAlterCommand>();
+            rewritten_command->type = ASTAlterCommand::RENAME_COLUMN;
+            rewritten_command->column = std::make_shared<ASTIdentifier>(alter_command->old_name);
+            rewritten_command->rename_to = std::make_shared<ASTIdentifier>(alter_command->column_name);
+            rewritten_query->command_list->add(rewritten_command);
+        }
+        else if (alter_command->type == MySQLParser::ASTAlterCommand::MODIFY_COLUMN)
+        {
+            String new_column_name;
+
+            {
+                auto rewritten_command = std::make_shared<ASTAlterCommand>();
+                rewritten_command->type = ASTAlterCommand::MODIFY_COLUMN;
+                rewritten_command->first = alter_command->first;
+                rewritten_command->column = std::make_shared<ASTIdentifier>(alter_command->column_name);
+                const auto & modify_columns = getColumnsList(alter_command->additional_columns);
+
+                if (modify_columns.size() != 1)
+                    throw Exception("It is a bug", ErrorCodes::LOGICAL_ERROR);
+
+                new_column_name = modify_columns.front().name;
+                rewritten_command->col_decl = InterpreterCreateQuery::formatColumns(modify_columns)->children[0];
+                rewritten_query->command_list->add(rewritten_command);
+            }
+
+            if (!alter_command->old_name.empty())
+            {
+                auto rewritten_command = std::make_shared<ASTAlterCommand>();
+                rewritten_command->type = ASTAlterCommand::RENAME_COLUMN;
+                rewritten_command->column = std::make_shared<ASTIdentifier>(alter_command->old_name);
+                rewritten_command->rename_to = std::make_shared<ASTIdentifier>(new_column_name);
+                rewritten_query->command_list->add(rewritten_command);
+            }
+        }
+    }
+
+    return rewritten_query;
+}
+
 }
 
 }

src/Interpreters/MySQL/InterpretersMySQLDDLQuery.h

@@ -6,6 +6,7 @@
 #include <Interpreters/executeQuery.h>
 #include <Parsers/ASTDropQuery.h>
 #include <Parsers/ASTRenameQuery.h>
+#include <Parsers/MySQL/ASTAlterQuery.h>
 #include <Parsers/MySQL/ASTCreateQuery.h>
 
 namespace DB
@@ -23,6 +24,15 @@ struct InterpreterDropImpl
     static ASTPtr getRewrittenQuery(const TQuery & drop_query, const Context & context, const String & clickhouse_db, const String & filter_mysql_db);
 };
 
+struct InterpreterAlterImpl
+{
+    using TQuery = MySQLParser::ASTAlterQuery;
+
+    static void validate(const TQuery & query, const Context & context);
+
+    static ASTPtr getRewrittenQuery(const TQuery & alter_query, const Context & context, const String & clickhouse_db, const String & filter_mysql_db);
+};
+
 struct InterpreterRenameImpl
 {
     using TQuery = ASTRenameQuery;
@@ -71,6 +81,7 @@ private:
 };
 
 using InterpreterMySQLDropQuery = InterpreterMySQLDDLQuery<InterpreterDropImpl>;
+using InterpreterMySQLAlterQuery = InterpreterMySQLDDLQuery<InterpreterAlterImpl>;
 using InterpreterMySQLRenameQuery = InterpreterMySQLDDLQuery<InterpreterRenameImpl>;
 using InterpreterMySQLCreateQuery = InterpreterMySQLDDLQuery<InterpreterCreateImpl>;
 

src/Parsers/ParserExternalDDLQuery.cpp

@@ -10,6 +10,7 @@
 #include <Parsers/ParserRenameQuery.h>
 
 #ifdef USE_MYSQL
+#    include <Parsers/MySQL/ASTAlterQuery.h>
 #    include <Parsers/MySQL/ASTCreateQuery.h>
 #endif
 
@@ -38,11 +39,12 @@ bool ParserExternalDDLQuery::parseImpl(IParser::Pos & pos, ASTPtr & node, Expect
 #ifdef USE_MYSQL
         ParserDropQuery p_drop_query;
         ParserRenameQuery p_rename_query;
+        MySQLParser::ParserAlterQuery p_alter_query;
         MySQLParser::ParserCreateQuery p_create_query;
-        /// TODO: alter table
 
         res = p_create_query.parse(pos, external_ddl_query->external_ddl, expected)
             || p_drop_query.parse(pos, external_ddl_query->external_ddl, expected)
+            || p_alter_query.parse(pos, external_ddl_query->external_ddl, expected)
             || p_rename_query.parse(pos, external_ddl_query->external_ddl, expected);
 
         if (external_ddl_query->external_ddl)