Redo proofing cost migrations as strong migrations

[zachmargolis]

The migration I previously added failed when deployed in prod because adding a column with a default value causes a table rewrite. Here's literally what the gem told me to do:

          Adding a column with a non-null default causes the entire table to be rewritten.
          Instead, add the column without a default value, then change the default.
          
          class AddAcuantResultToProofingCosts < ActiveRecord::Migration[5.2]
            def up
              add_column :proofing_costs, :acuant_result_count, :integer
              change_column_default :proofing_costs, :acuant_result_count, 0
            end
          
            def down
              remove_column :proofing_costs, :acuant_result_count
            end
          end
          
          Then backfill the existing rows in the Rails console or a separate migration with disable_ddl_transaction!.
          
          class BackfillAddAcuantResultToProofingCosts < ActiveRecord::Migration[5.2]
            disable_ddl_transaction!
          
            def up
              ProofingCost.unscoped.in_batches do |relation| 
                relation.update_all acuant_result_count: 0
                sleep(0.01)
              end
            end
          end

[zachmargolis]

Normally I think it's bad to delete migrations? But since this failed to run in production, I think it's safe. Some local devs might be messed up if they already have the column

[mitchellhenke]

👍🏼