Online DDL: publish vreplication_lag_seconds from vreplication progress

[shlomi-noach]

Description

A new column in schema_migrations: vreplication_lag_seconds publishes the vreplication (rather, vplayer) lag on a vreplication migration. This is computed by the higher difference of vreplication's time updted and transaction timestamp compared with time now.

This just adds more visibility into the underlying workflow.

Related Issue(s)

#17264

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

Attention: Patch coverage is 0% with 44 lines in your changes missing coverage. Please review.

Project coverage is 67.37%. Comparing base (c5d0ecc) to head (ba6d68a).
Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vttablet/onlineddl/executor.go	0.00%	34 Missing ⚠️
go/vt/vttablet/onlineddl/vrepl.go	0.00%	10 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #17263   +/-   ##
=======================================
  Coverage   67.37%   67.37%           
=======================================
  Files        1573     1573           
  Lines      253110   253114    +4     
=======================================
+ Hits       170535   170547   +12     
+ Misses      82575    82567    -8     

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

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles

[rohit-nayak-ps]

Maybe in a future refactor, similar to the extraction into Lag(), you could extract the code to check if copy is in progress too into a utility function ...

[shlomi-noach]

Good idea. To do that I'd need to issue a query against copy_state. Or I can converge the two queries (vreplication+copy_state into one. I guess that would be wasteful for most of the time though.