Entries in read (1)

I have a very big text file. Can I read a text file in chunks?

By defining a function to handle one chunk

process_chunk: {[list_of_lines]
    // Split and parse each line in list_of_lines and
    // then - most likely - create some sort of output.
    // After all, the idea here is to avoid holding
    // all of the data in memory.
    }

and passing your chunk handler along with the file handle to .Q.fs:

bytes_read: .Q.fs[process_chunk; `:big_file_name]

For details on how to parse lines of text inside your chunk handler, see this related faq.