[bangonkeyboard]

For the quoted spreadsheet-like operations of filtering and rearranging, awk is perfect as a deferred editor. That the kludgy first step of your chosen solution ("First, you must create a CSV file contain only the first 10-20 lines of your large CSV file") isn't just `head very_large_nov_2019.csv > very_large_nov_2019_abridged.csv` seems to further indicate an unfamiliarity with the large set of built-in, battle-tested UNIX tools for dealing with text files.

The first tools I reach for when dealing with CSVs of these and larger magnitudes are less, cut, awk, etc. They also tend to be the last tools I end up needing.

[ygra]

How well do those tools work with arbitrary CSV files, e.g. containing line breaks or quotes in field data? I wasn't aware that they can actually parse CSV and instead you have to assume things about the content that may not end up being true.

[bangonkeyboard]

Every data processing task has to make assumptions about the well-formedness of its input. "Arbitrary CSV" is basically undefined; whether deviations are best dealt with by parsing, preprocessing, or different tools altogether depends on the source.