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Incidents/2025-05-09 Missing autocomplete indices

From Wikitech

document status: draft

Summary

Incident metadata (see Incident Scorecard)
Incident ID 2025-05-09 Missing autocomplete indices Start 2025-05-08 2:30 AM
Task T393663 End 2025-05-08 8:25 AM
People paged 0 Responder count 1
Coordinators David Causse Affected metrics/SLOs N/A
Impact Autocomplete (typeahead) search results were missing or stale

During the incident, users typing in the Wikipedia search bar did not get expected results.

Timeline

All times in UTC.

  • 2025-05-07 1554 Bking (Search Platform SRE) merges this patch as a part of our ongoing OpenSearch migration. As a result, the next day's daily job is cancelled and there is no opportunity for the job to fix the autocomplete results.
  • 2025-05-07 1832 User thesavagenorwegian opens this Phab task to report the problem.
  • 2025-05-08 0825 - Dcausse (Search Platform software engineer) routes traffic away from EQIAD. User impact stops.

Detection

Issue first detected by: The community, see this Phab task.

Relevant alerts: Did not fire

Conclusions

What went well?

  • We (Search Platform) already had a plan to route traffic away from EQIAD, so it was easy to implement.

What went poorly?

  • Several community members opened tickets, which suggests noticeable impact.

Where did we get lucky?

  • We (Search Platform) already had a plan to route traffic away from EQIAD, so it was easy to implement.

Actionables

Scorecard

Incident Engagement ScoreCard
Question Answer

(yes/no)

Notes
People Were the people responding to this incident sufficiently different than the previous five incidents? N/A
Were the people who responded prepared enough to respond effectively Y
Were fewer than five people paged? N/A
Were pages routed to the correct sub-team(s)? N/A
Were pages routed to online (business hours) engineers?  Answer “no” if engineers were paged after business hours. N/A
Process Was the "Incident status" section atop the Google Doc kept up-to-date during the incident? N/A
Was a public wikimediastatus.net entry created? N
Is there a phabricator task for the incident? Y
Are the documented action items assigned? N
Is this incident sufficiently different from earlier incidents so as not to be a repeat occurrence? Y
Tooling To the best of your knowledge was the open task queue free of any tasks that would have prevented this incident? Answer “no” if there are open tasks that would prevent this incident or make mitigation easier if implemented. N We could have reduced impact by coordinating the job removal with the datacenter switchover.
Were the people responding able to communicate effectively during the incident with the existing tooling? Y
Did existing monitoring notify the initial responders? N
Were the engineering tools that were to be used during the incident, available and in service? Y
Were the steps taken to mitigate guided by an existing runbook? N
Total score (count of all “yes” answers above) 5
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