Why checksum? [was Re: Fuzzy Lookups]

[Erik Max Francis]

Steven D'Aprano wrote:

> This isn't a criticism, it is a genuine question. Why do people compare
> local files with MD5 instead of doing a byte-to-byte compare? Is it purely
> a caching thing (once you have the checksum, you don't need to read the
> file again)? Are there any other reasons?

Because if you store a hash, then you can keep that around even when the 
original file is archived, moved elsewhere, or deleted.  It's awfully 
helpful for building databases of files you've seen before.

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