Ordinary database engine is deprecated but there is no simple mean to change database engine to Atomic for existing databases.

Possible options:
- ALTER DATABASE MODIFY ENGINE query.
- Flag that triggers migration at ClickHouse startup.

The latter should be easier to implement. 

{
    writeIntBinary(rows, out);
    writeIntBinary(offset, out);
}
void StorageLog::Mark::read(ReadBuffer & in)
{
    readIntBinary(rows, in);
    readIntBinary(offset, in);
}
namespace
{
    
    
    
    
    
    
    
    constexpr size_t INDEX_WITH_REAL_ROW_COUNT = 0;
}
StorageLog::~StorageLog() = default;