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?
{
        MutableColumnPtr col_to = IColumn::mutate(std::move(buffer.getByPosition(column).column));
        writeFieldsToColumn(*col_to, rows_data, column, writeable_rows_mask);
        buffer.getByPosition(column).column = std::move(col_to);
    }
    MutableColumnPtr sign_mutable_column = IColumn::mutate(std::move(buffer.getByPosition(buffer.columns() - 2).column));
    MutableColumnPtr version_mutable_column = IColumn::mutate(std::move(buffer.getByPosition(buffer.columns() - 1).column));
    ColumnInt8::Container & sign_column_data = assert_cast<ColumnInt8 &>(*sign_mutable_column).getData();
    ColumnUInt64::Container & version_column_data = assert_cast<ColumnUInt64 &>(*version_mutable_column).getData();
    for (size_t index = 0; index < rows_data.size(); index += 2)
    {
        if (likely(!writeable_rows_mask[index]))
        {
            sign_column_data.emplace_back(1);
            version_column_data.emplace_back(version);
        }
        else
        {
            
            sign_column_data.emplace_back(-1);
            sign_column_data.emplace_back(1);
            version_column_data.emplace_back(version);
            version_column_data.emplace_back(version);
        }
    }
    buffer.getByPosition(buffer.columns() - 2).column = std::move(sign_mutable_column);
    buffer.getByPosition(buffer.columns() - 1).column = std::move(version_mutable_column);
    return buffer.bytes() - prev_bytes;
}
void MaterializeMySQLSyncThread::onEvent(Buffers & buffers, const BinlogEventPtr & receive_event, MaterializeMetadata & metadata)