Incident Library
Applied filters ComponentSchema migrationClear allEvery case under the filters, with no sentence; newest first.
Suggested filters Search, and the values found in your words appear here.

Graph

  • Root cause
  • Component
  • Symptom
  • Contributing factor
  • Case

Cases8 cases

8 to 8 of 8

  1. IL-0391 GoCardless API requests timed out for about 15 seconds while a Postgres migration waited for an AccessExclusive lock
    GoCardless2015
    Symptoms

    Just after a planned Postgres schema migration started, GoCardless received alerts that API requests were timing out. The API was down for about 15 seconds, until the migration went through and the API came back.

    Lock contention or deadlockService outage
    Trigger

    A deploy with a schema migration that renamed the empty invoicing tables and dropped and recreated their foreign key constraints, which referenced some of the most heavily used tables.

    Root cause
    Faulty deployment
    Component
    DatabaseSchema migration
    Contributing factor
    Unverified assumption
    Detection

    Alerts about API requests timing out began just after the schema migration started.

    Lessons

    Avoiding renames of tables in use, table rewrites under an exclusive lock and expensive work while holding one was not enough for GoCardless: a short DDL statement can still cause downtime by waiting in the lock queue behind a long-running query. GoCardless recommends removing long-running queries and transactions from the application and running analytics on an asynchronously updated replica, setting log_min_duration_statement and log_lock_waits to find such queries, setting lock_timeout in migration scripts so a deploy aborts rather than taking the application down, splitting schema changes so locks are held for shorter times, and keeping Postgres up to date. Developers with a console on the production database can cause the same downtime by leaving a transaction open.

    View case
Check your cluster for this

These 8 cases involve Database and Schema migration. kubegap audits a Kubernetes cluster for gaps like these, read-only, from Claude Code or Codex; its checks cite public reports like the ones in this library.

Open kubegap

By root cause2

Software defect2 cases

Component
Database2Schema migration2
Contributing factor
Unverified assumption1No headroom1No staged rollout1
Organisation
Daangn1GitHub1
  1. IL-0451 Setting indexes INVISIBLE on Aurora MySQL 3.10 spiked CPU and ReadIOPS on all three readers but not on the writer
    Daangn2026
  2. IL-0385 GitHub MySQL read replicas hit a semaphore deadlock during a schema migration's table rename and kept crash-recovering
    GitHub2021

Faulty deployment6 cases

Component
Database6Schema migration6Database proxy and connection pooler1Liveness and readiness probes1
Contributing factor
No runbook2Unrepresentative staging2Unverified assumption1No configuration tests1Overlapping failures1Health check tied to a dependency1Missed in review1Gap in automated tests1
Organisation
CrowdWorks1GoCardless1Open Collective1Railway1Sentry1U.S. Department of Health and Human Services1
  1. IL-0570 Dropping an unused MySQL table stalled queries on its busy parent table and crowdworks.jp was hard to reach for a minute
    CrowdWorks2026
  2. IL-0369 Railway's backend API went down when a column migration waited on locks and replicas could not get database connections
    Railway2025
  3. IL-0554 A database migration used up Sentry US's Postgres connections, and the site and event ingestion were down for 22 minutes
    Sentry2024
  4. IL-0523 TANF-app production deployments were blocked for two months when a search-index migration ran out of database disk space
    U.S. Department of Health and Human Services2023
  5. IL-0524 An index migration locked Open Collective's whole Transactions table and degraded the service for nearly an hour
    Open Collective2023
  6. IL-0391 GoCardless API requests timed out for about 15 seconds while a Postgres migration waited for an AccessExclusive lock
    GoCardless2015