When I used ClickHouse's MaterializeMySQL feature to synchronize data from MySQL to ClickHouse, I had some problems. The Click House version I'm using is 20.10.3.30, and the MySQL version I'm using is 5.7.28-log.

The SQL statement I executed is as follows:
> SET allow_experimental_database_materialize_mysql = 1;
drop database if exists ck_test;
CREATE DATABASE if not exists ck_test ENGINE = MaterializeMySQL('x.x.x.x:3306', 'test', 'user', 'test');


After I executed the SQL statement, I saw the following information from the error log /var/log/clickhouse-server/clickhouse-server.err. Log:

> 2020.11.10 20:27:39.611578 [ 33057 ] {} <Error> MaterializeMySQLSyncThread: Code: 20, e.displayText() = DB::Exception: mysqlxx::UseQueryResult contains 4 columns while 2 expected, Stack trace (when copying this message, always include the lines below):

> 0. DB::MySQLBlockInputStream::MySQLBlockInputStream(mysqlxx::Pool::Entry const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, DB::Block const&, unsigned long, bool) @ 0xe587457 in /usr/bin/clickhouse

> 1. DB::MaterializeMetadata::MaterializeMetadata(mysqlxx::Pool::Entry&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) @ 0xdb1cbf3 in /usr/bin/clickhouse

> 2. DB::MaterializeMySQLSyncThread::prepareSynchronized(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) @ 0xdaf8bf1 in /usr/bin/clickhouse

> 3. DB::MaterializeMySQLSyncThread::synchronization(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) @ 0xdaf836a in /usr/bin/clickhouse

> 4. ? @ 0xdb1480d in /usr/bin/clickhouse

> 5. ThreadPoolImpl<std::__1::thread>::worker(std::__1::__list_iterator<std::__1::thread, void*>) @ 0x7b8963d in /usr/bin/clickhouse

> 6. ? @ 0x7b8d153 in /usr/bin/clickhouse

> 7. start_thread @ 0x7dd5 in /usr/lib64/libpthread-2.17.so

> 8. __clone @ 0xfdead in /usr/lib64/libc-2.17.so

>  (version 20.10.3.30 (official build))


Does anybody have a problem like this?
{"binlog_format", "binlog_format='ROW'"},
            {"binlog_row_image", "binlog_row_image='FULL'"},
            {"default_authentication_plugin", "default_authentication_plugin='mysql_native_password'"}
        };
        ColumnPtr variable_name_column = variables_block.getByName("Variable_name").column;
        for (size_t index = 0; index < variables_block.rows(); ++index)
        {
            const auto & error_message_it = variables_error_message.find(variable_name_column->getDataAt(index).toString());
            if (error_message_it != variables_error_message.end())
                variables_error_message.erase(error_message_it);
        }
        bool first = true;
        WriteBufferFromOwnString error_message;
        error_message << "Illegal MySQL variables, the MaterializeMySQL engine requires ";
        for (const auto & [variable_name, variable_error_message] : variables_error_message)
        {
            error_message << (first ? "" : ", ") << variable_error_message;
            if (first)
                first = false;
        }
        throw Exception(error_message.str(), ErrorCodes::ILLEGAL_MYSQL_VARIABLE);
    }
    Block version_header{{std::make_shared<DataTypeString>(), "version"}};
    MySQLBlockInputStream version_input(connection, "SELECT version() AS version;", version_header, DEFAULT_BLOCK_SIZE);
    Block version_block = version_input.read();
    if (!version_block || version_block.rows() != 1)
        throw Exception("LOGICAL ERROR: cannot get mysql version.", ErrorCodes::LOGICAL_ERROR);
    return version_block.getByPosition(0).column->getDataAt(0).toString();
}
MaterializeMySQLSyncThread::MaterializeMySQLSyncThread(