3 ms·

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 Tri

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 run out the 63-char limit if we introduce more knobs. A demonstration of it is here, in case the above didn't explain it well: https://rethinkdns.com/configure https://rethinkdns.com/configure (choose blocklists, and see the selection generate a path appended to the base-url shown in the search-bar).

maxdemarzi 5y ago
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
- ignoramous 5y ago
  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.
shepik 5y ago
Oh. No, i don't think it's possible - i'd suggest to just use multiple subdomains. Technically, you can squeeze out some bits: there are 36-37 possible characters of which you are using only 32, so with arithmetic coding you would be looking at about 1 extra bit for 5 characters, but it's a nightmare to code. And after those extra bits run out, you will get the same problem anyway.

maxdemarzi 5y ago

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

ignoramous 5y ago
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.

shepik 5y ago

Oh. No, i don't think it's possible - i'd suggest to just use multiple subdomains. Technically, you can squeeze out some bits: there are 36-37 possible characters of which you are using only 32, so with arithmetic coding you would be looking at about 1 extra bit for 5 characters, but it's a nightmare to code. And after those extra bits run out, you will get the same problem anyway.