rules:
- id: ruby-rails-performance-indexes-are-beneficial
  patterns:
  - pattern-not-inside: |
      add_column $TABLE, $COLUMN, $TYPE, ...
      ...
      add_index $TABLE, $COLUMN, ...
  - pattern: |
      add_column $TABLE, $COLUMN, $TYPE, ...
  - metavariable-regex:
      metavariable: $COLUMN
      regex: (.*_id$)
  - metavariable-regex:
      metavariable: $TYPE
      regex: :integer|:bigint
  message: >-
    The $COLUMN column appears to be a foreign key. Would it benefit from
    an index? Having an index can improve performance.
  languages:
  - ruby
  severity: INFO
  metadata:
    category: performance
    technology:
    - rails
    references:
    - https://archive.is/i7SLO