2021-03-18 Database degradation
Summary
Very similar to the previous related incidents (#3962 (closed) and #3875 (closed)) where the stats of the namespaces
table were in a state where they incurred expensive query plans leading to a generalized slowdown across the platform. Our current remediation of analyzing the namespaces
table mitigates the issue.
Investigation as to what preceded the degradation is ongoing.
Draft exec summary:
- Customer Impact: Latency of CI Runners, Sidekiq, and Web
- Customer Impact Duration: CI Runners (36 mins) Sidekiq (~60 minutes), Web (30 min)
- Current state: IncidentResolved
- Known cause: recurrence of #3875 (closed)
- True root cause: query plan of query in gitlab-org/gitlab#325133 (closed)
Timeline
View recent production deployment and configuration events (internal only)
All times UTC.
2021-03-18
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14:10
- @mwasilewski-gitlab declares incident in Slack.
Corrective Actions
Corrective actions should be put here as soon as an incident is mitigated, ensure that all corrective actions mentioned in the notes below are included.
- Rapid Action: Linear namespace queries gitlab-org&5296 (closed)
- Rapid Action: Work around Postgres 11 query planner bug gitlab-org&5617 (closed)
- Verify DB Rapid Action gitlab-org&5434 (closed)
- Infrastructure epic for corrective actions: &436 (closed)
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Incident Review
Summary
- Service(s) affected:
- Team attribution:
- Time to detection:
- Minutes downtime or degradation:
Metrics
Customer Impact
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Who was impacted by this incident? (i.e. external customers, internal customers)
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What was the customer experience during the incident? (i.e. preventing them from doing X, incorrect display of Y, ...)
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How many customers were affected?
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If a precise customer impact number is unknown, what is the estimated impact (number and ratio of failed requests, amount of traffic drop, ...)?
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What were the root causes?
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Incident Response Analysis
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How was the incident detected?
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How could detection time be improved?
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How was the root cause diagnosed?
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How could time to diagnosis be improved?
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How did we reach the point where we knew how to mitigate the impact?
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How could time to mitigation be improved?
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What went well?
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Post Incident Analysis
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Did we have other events in the past with the same root cause?
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Do we have existing backlog items that would've prevented or greatly reduced the impact of this incident?
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Was this incident triggered by a change (deployment of code or change to infrastructure)? If yes, link the issue.
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Lessons Learned
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Guidelines
Resources
- If the Situation Zoom room was utilised, recording will be automatically uploaded to Incident room Google Drive folder (private)