cosmos-sdk/orm/encoding
Aaron Craelius 1944a0883e
feat(orm)!: ordered variable length encoding for uint32 and uint64 types (#11090)
## Description

`uint64` values are used in the ORM as auto-incrementing primary keys. Always using 8 bytes for these values is a bit of a waste of space. Unfortunately, varint encoding does not support ordered prefix iteration.

This PR introduces a compact, well-ordered variable length encoding for `uint32` and `uint64` types. `fixed32` and `fixed64` integers are still encoded as 4 and 8 byte fixed-length big-endian arrays. With this, users have a choice of encoding based on what type of data they are storing. An auto-incrementing primary key should prefer the variable length `uint64` whereas a fixed precision decimal might want to use `fixed64`.

See the golden test updates to see how this reduces key lengths.

This encoding works by using the first two bits to encode the buffer length (4 possible lengths). I'm not sure if my choice of 2,4,6 and 9 bytes is the right choice of 4 lenths for `uint64` - there are many alternate choices. I could have also chosen 3 bits and allowed for 8 possible lengths, but way waste an extra bit? Input on the right design parameters would be appreciated.



---

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- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
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### Reviewers Checklist

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- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
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2022-02-07 17:58:55 +00:00
..
encodeutil
ormfield feat(orm)!: ordered variable length encoding for uint32 and uint64 types (#11090) 2022-02-07 17:58:55 +00:00
ormkv fix(orm): bad error messages (#11059) 2022-01-28 19:28:51 +00:00
docs.go feat(orm): ModuleDB JSON import/export/default/validate methods (#11101) 2022-02-03 20:36:21 -08:00