Make organization_id NOT NULL on oauth_applications table

Summary

Add a NOT NULL constraint to the organization_id column on the oauth_applications table after backfill and application code changes are complete.

Context

This is the final step in adding the sharding key to oauth_applications. After the column is added, backfilled, and application code is updated, we need to enforce the constraint.

Prerequisites

All of the following must be completed before this issue:

• organization_id column added to table
• Background migration to backfill existing records is complete
• Application code updated to set organization_id on creation
• Verification that all records have organization_id set

Implementation Steps

1. Validate Data Completeness

   • Query to confirm no NULL values exist:

     SELECT COUNT(*) FROM oauth_applications WHERE organization_id IS NULL;

   • Should return 0

2. Add NOT NULL Constraint

   • Create migration to add constraint
   • Use add_not_null_constraint helper for zero-downtime deployment
   • Validate constraint before finalizing

3. Update Schema Documentation

   • Update db/docs/oauth_applications.yml
   • Mark organization_id as required
   • Update sharding key documentation

4. Update Model Validations

   • Add validates :organization_id, presence: true to model
   • Ensure validation aligns with database constraint

Migration Example

class AddNotNullConstraintToOauthApplicationsOrganizationId < Gitlab::Database::Migration[2.2]
  disable_ddl_transaction!

  def up
    add_not_null_constraint :oauth_applications, :organization_id
  end

  def down
    remove_not_null_constraint :oauth_applications, :organization_id
  end
end

Validation

• Constraint successfully added in development
• Constraint successfully added in staging
• No errors in production deployment
• Model validations working correctly
• Cannot create application without organization_id

Rollback Plan

If issues are discovered:

1. Remove NOT NULL constraint
2. Investigate missing organization_id cases
3. Fix application code or backfill issues
4. Re-attempt constraint addition

Dependencies

• Blocked by: All previous oauth_applications organization_id issues
• Related: #553465 (closed)

References

• Adding NOT NULL constraints