tustvold opened a new issue #1281: URL: https://github.com/apache/arrow-rs/issues/1281
**Is your feature request related to a problem or challenge? Please describe what you are trying to do.** The current `DeltaBitPackDecoder` implementation decodes each value separately with a call to `BitReader::get_unaligned`. This prevents it from benefiting from the vectorized `unpack32` that is used by RLEDecoder, and makes for a complex inner body of the loop. It also seems to do a fair amount of memory allocation on the hot path, which is also unfortunate. **Describe the solution you'd like** The `DeltaBitPackDecoder` should be faster than `RLEDecoder` and theoretically should be even faster than `PlainDecoder` - the [algorithm](https://arxiv.org/pdf/1209.2137v5.pdf) is specifically designed to vectorize well. Most of the logic to achieve this already exists, it is just a matter of hooking it up. _One small detail is `unpack32` can only handle a bit width less than 32. This should be rare in non-degenerate data, but the logic will need to fallback in such a case_ -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
