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When using AWS Aurora, a nullable column can be added to existing large (100k rows+?) tables without causing downtime. However, the migration may still timeout in GoCD - so please coordinate the release with DevOps.

  1. Make a new field addition in model with null=True.
  2. Generate the model-change migrations locally.
  3. Create a pull request containing the model change and newly-generated migrations.
  4. Merge the migration pull request.
  5. The release process will run the migration and add the nullable column to table.

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On AWS Aurora, indexes can be build on large tables without causing downtime, but this requires devops coordination as the migration may timeout in GoCD.

  1. Add the new index on model fields.
  2. Generate the model-change migrations locally.
  3. Make pull request containing the model change and newly-generated migrations.
  4. Merge the migration pull request.
  5. Release will run the migration and add the index to table.

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  •  Is there a primary key? How fast will the table grow? Should the primary key be a bigint (more than 4b rows)? In general, use the Django default generated auto incrementing id for a primary key.
  •  Is there a process for identifying and trimming expired rows? Is there an appropriate index that will prevent a full table scan during cleanup?
  •  What are the most common queries? Are there indexes to support them?
  •  Should there be unique constraints?

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