I need to read a huge file (around 20G) that contains trade data, and I wonder if there's a good method to read the file without killing the memory.

My current method is loading the files by columns and join those columns together:

```
columnA:(" S "; 10 20 30)0:`filepath

```

The problem of this method is that although it is pretty fast, it uses a huge chunk of memory, and I want to improve its memory usage.

I have also tried to use .Q.fs, but it takes more than 3 hours to load the file... 

Is there a way to do this efficiently without consuming tons of memory?

Thanks