for larger files, this can be very costly and for relatively little benefit. Often the column types guessed based on a subset of the file are “good enough”.</p>
<p>Note also that <code>guess_max = n</code>, for finite <code>n</code>, works better in the second edition parser. Due to its different design, vroom is able to sub-sample <code>n</code> rows throughout the file and it always includes the last row, whereas earlier versions of readr just consulted the first <code>n</code> rows. In practice, the 