feat: Allow specifying the hex width to use when generating shard ranges.

[arthurschreiber]

Description

This adds a new --hex-width cli flag to vtctldclient GenerateShardRanges. This flag allows specifying how many characters to use for start and end parts of the shard range labels. This can be used to reduce the shard size differences when using a shard count that is not a power of 2.

I'm not super happy with the naming of the CLI flag, suggestions for alternative naming are welcome.

Related Issue(s)

Fixes: #15744
References: #17688

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

Tests

• Bug fixes should have at least one unit or end-to-end test, enhancement and new features should have a sufficient number of tests.

Documentation

• Apply the release notes (needs details) label if users need to know about this change.
• New features should be documented.
• There should be some code comments as to why things are implemented the way they are.
• There should be a comment at the top of each new or modified test to explain what the test does.

New flags

• Is this flag really necessary?
• Flag names must be clear and intuitive, use dashes (-), and have a clear help text.

If a workflow is added or modified:

• Each item in Jobs should be named in order to mark it as required.
• If the workflow needs to be marked as required, the maintainer team must be notified.

Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from vitess-operator and arewefastyet, if used there.
• vtctl command output order should be stable and awk-able.

[codecov]

Codecov Report

❌ Patch coverage is 93.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.48%. Comparing base (7398277) to head (a43a090).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
go/cmd/vtctldclient/command/shards.go	66.66%	1 Missing ⚠️
go/vt/vtctl/vtctl.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #18633   +/-   ##
=======================================
  Coverage   67.48%   67.48%           
=======================================
  Files        1613     1613           
  Lines      263962   263948   -14     
=======================================
- Hits       178146   178137    -9     
+ Misses      85816    85811    -5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[nickvanw]

This looks good to me, will wait for feedback from others on the command line flag.

It would be good to add some more exhaustive tests for common scenarios, I think - passing 0 in for various values, and overriding to 3 or 4 at smaller shard values.

[nickvanw]

I think --chars makes sense. Other things I thought about:

• --num-digits
• --digits
• --hex-char-count
• --char-count
• --range-digits

Let me know if you or anyone thinks any of those are better.

[GrahamCampbell]

Claude likes --digits. It also suggests --width.

[harshit-gangal]

what about --hex-format-length or --format-length

[arthurschreiber]

It would be good to add some more exhaustive tests for common scenarios, I think - passing 0 in for various values, and overriding to 3 or 4 at smaller shard values.

I added another test case for 512 shards (to verify that using a shard number > 256 uses 4 characters).

[harshit-gangal]

LGTM
Like @nickvanw said, need some test with different hex length passed to the function and finalizing on the flag name

[harshit-gangal]

It would be good to add some more exhaustive tests for common scenarios, I think - passing 0 in for various values, and overriding to 3 or 4 at smaller shard values.

I added another test case for 512 shards (to verify that using a shard number > 256 uses 4 characters).

A test like 8 shards with 4 length

[arthurschreiber]

A test like 8 shards with 4 length

Isn't this covered by https://github.com/vitessio/vitess/pull/18633/files#diff-742b022d7e1f659dd60ba4e410fa90b9597aa4c941e0edc19b56e8ab068d6f6bR1596-R1637?

[arthurschreiber]

I renamed the option to --hex-width.

[nickvanw]