fst files can be streamed on a row by row basis

[MarcusKlik]

That would involve creating a fst file-connection object (similar to base-R file method). With that object data can be streamed row-by-row until the file is depleted (or the connection is closed). The binary file format allows for streaming from compressed fst files as well. In addition, a connection object could also be used to stream to a fst file. The fst format needs to accommodate multiple chunks for that options and the connection object needs a (custom sized) buffer for maximum performance.