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2022-09-19: Failing migrations on gstg

    • Closed Incident created by ops-gitlab-net @ops-gitlab-net

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    Summary for CMOC notice / Exec summary:

    1. Customer Impact: None
    2. Service Impact: ServiceDeploy-Node
    3. Impact Duration: 2022-09-19 11:15 UTC - 2022-09-19 19:18 UTC - (483min)
    4. Root cause: gitlab-org/gitlab!91074 (merged)

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    2022-09-19

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    Takeaways

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    Corrective Actions

    When we rename columns, we create a new column and duplicate all the indexes defined for the old column. Unfortunately, there is a special index definition (with SQL expressions as columns) within the iterations_cadences table which is not parseable by Rails and the migration fails here: https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/database/migration_helpers.rb#L1012

    The index definition (notice the columns part):

    pp ActiveRecord::Base.connection.indexes("iterations_cadences")
[#<ActiveRecord::ConnectionAdapters::IndexDefinition:0x00007fb2e03c95e8
  @columns=
   "automatic, duration_in_weeks, date((COALESCE(last_run_date, '1970-01-01'::date) + ((duration_in_weeks)::double precision * 'P7D'::interval)))",
  @comment=nil,
  @lengths={},
  @name="cadence_create_iterations_automation",
  @opclasses={},
  @orders={},
  @table="iterations_cadences",
  @type=nil,
  @unique=false,
  @using=:btree,
  @where="(duration_in_weeks IS NOT NULL)">,
]

    Fix

    Option 1:

    Only copy indexes which have their column list successfully parsed (add type check).

    Option 2:

    If the columns variable is a String, try to parse out the columns and decide if the column is part of the index definition

    Why we didn't catch it?

    Assumption: locally, we didn't run the migrations and post-migrations separately. According to the timestamps, on the local dev environment, the index is removed first after the rename_column_concurrently method is called.

    Order on local dev environment:

    1. db/post_migrate/20220913082728_drop_index_cadence_create_iterations_automation.rb
    2. db/migrate/20220913082930_rename_iterations_cadences_last_run_date_to_next_run_date.rb

    Order on staging:

    1. db/migrate/20220913082930_rename_iterations_cadences_last_run_date_to_next_run_date.rb
    2. Deploy new version of the app.
    3. db/post_migrate/20220913082728_drop_index_cadence_create_iterations_automation.rb

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