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VDiff: Handle read only error #18999

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VDiff: Handle read only error #18999

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@twthorn twthorn commented Dec 5, 2025

Description

This error happens during VDiff and reparents, so we should catch it not fail to client/command status.

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  • "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

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vitess-bot bot commented Dec 5, 2025

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@vitess-bot vitess-bot bot added NeedsBackportReason If backport labels have been applied to a PR, a justification is required NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsIssue A linked issue is missing for this Pull Request NeedsWebsiteDocsUpdate What it says labels Dec 5, 2025
@github-actions github-actions bot added this to the v24.0.0 milestone Dec 5, 2025
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promptless bot commented Dec 5, 2025

📝 Documentation updates detected!

New suggestion: Add v24.0.0 changelog entry for VDiff reparent error handling improvement

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codecov bot commented Dec 5, 2025

Codecov Report

❌ Patch coverage is 66.66667% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.82%. Comparing base (d411dd0) to head (5f7d3e8).
⚠️ Report is 2 commits behind head on main.

Files with missing lines Patch % Lines
go/vt/vttablet/tabletmanager/vdiff/controller.go 33.33% 2 Missing ⚠️
Additional details and impacted files 
@@           Coverage Diff           @@
##             main   #18999   +/-   ##
=======================================
  Coverage   69.82%   69.82%           
=======================================
  Files        1610     1610           
  Lines      215303   215309    +6     
=======================================
+ Hits       150328   150341   +13     
+ Misses      64975    64968    -7

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timvaillancourt
timvaillancourt reviewed Dec 5, 2025
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go/vt/vttablet/tabletmanager/vdiff/controller.go
log.Infof("%s vdiff %s", action, ct.uuid)
if err := ct.start(ctx, dbClient); err != nil {
if isReadOnlyError(err) {
log.Warningf("VDiff %s stopped due to tablet becoming read-only, will retry on new primary", ct.uuid)
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@timvaillancourt timvaillancourt Dec 5, 2025

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@twthorn / @mattlord: I wonder if we should explain that this may be caused by a reparent, or is that too much information?

timvaillancourt
timvaillancourt approved these changes Dec 5, 2025
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@twthorn thanks, this LGTM 👍

@timvaillancourt timvaillancourt added Type: Enhancement Logical improvement (somewhere between a bug and feature) Component: VReplication Component: VTTablet and removed NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsWebsiteDocsUpdate What it says NeedsIssue A linked issue is missing for this Pull Request NeedsBackportReason If backport labels have been applied to a PR, a justification is required labels Dec 5, 2025
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@timvaillancourt timvaillancourt timvaillancourt approved these changes

@rohit-nayak-ps rohit-nayak-ps Awaiting requested review from rohit-nayak-ps rohit-nayak-ps is a code owner

@mattlord mattlord Awaiting requested review from mattlord mattlord is a code owner

@shlomi-noach shlomi-noach Awaiting requested review from shlomi-noach shlomi-noach is a code owner

@beingnoble03 beingnoble03 Awaiting requested review from beingnoble03 beingnoble03 is a code owner

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Component: VReplication Component: VTTablet Type: Enhancement Logical improvement (somewhere between a bug and feature)

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