If instead the goal is to have a URL that works even after a target document moves... heh stick a UUID in the page, and let Google or any other Search Engine be your engine... (for other people's pages where this isn't possible, copy/paste an Excerpt)
Not quite UUID.
Tantek Celik's Whistle shortener is algorithmic (meaning you don't really need to do a Data Store lookup), which works IFF your underlying Data Store (hmm, inconsistent?) tracks the post-number-of-the-day.
Google ran one, but shut it down in 2019.
options in 2020
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