In recent ClickHouse versions (21.3) Avro format for kafka does not work at all.
In ClickHouse 20.3 one Avro formatted kafka message can read, than stall forever.
Reportedly in ClickHouse prior 20.3 Avro formatted kafka messages work Ok while contain only single record
{
    uint8_t magic;
    uint32_t schema_id;
    try
    {
        readBinaryBigEndian(magic, in);
        readBinaryBigEndian(schema_id, in);
    }
    catch (const Exception & e)
    {
        if (e.code() == ErrorCodes::CANNOT_READ_ALL_DATA)
        {
            
            throw Exception("Missing AvroConfluent magic byte or schema identifier.", ErrorCodes::INCORRECT_DATA);
        }
        else
            throw;
    }
    if (magic != 0x00)
    {
        throw Exception("Invalid magic byte before AvroConfluent schema identifier."
            " Must be zero byte, found " + std::to_string(int(magic)) + " instead", ErrorCodes::INCORRECT_DATA);
    }
    return schema_id;
}
AvroConfluentRowInputFormat::AvroConfluentRowInputFormat(