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Re: Ask HN: How can I help you?

#42

Earlier quoted context omitted.

Thanks. > Why would you want to do that? We store user preferences (200+ yes/no knobs) in a bitmap (well, a bitmap-index like the one in Hash Mapped-Array Tries). We want to capture those prefs in a single sub-domain (limited to 63 lower-case alphanumeric chars) or a URL (limited to 200 mixed-case alphanumerics). Today, we simply convert the bitmap into url-b64 (or, b32 to store it in the subdomain), but we will soon…

Does another party need to decode the url? What about using a dictionary for the top 10k seen starting combinations and then encode the rest? What about run length encoding? 1-9 for positive sequences. a-i for negative sequences (max means pattern continues) and the rest for frequent patterns like alternating sequences, etc 9967b would be 24 yes, 1 no, 7 yes, 3 nos, 1 yes etc

Thanks. RLE is a hit-and-a-miss (101010101010 etc); top-k is heuristic-based. Those are viable solutions, nevertheless (esp, top-k). Puny Code, which DNS uses, I thought was pretty neat for fitting in a state-machine in printable characters. Takes a bunch of CPU resources to restore it, though.

I was wondering if there are other techniques that I may not be aware of.

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