btrc-hub/backend/db/migrate/20260323192300_create_wiki_assets.rb

class CreateWikiAssets < ActiveRecord::Migration[8.0]
  def change
    create_table :wiki_assets, primary_key: [:wiki_page_id, :no] do |t|
      t.references :wiki_page, null: false, foreign_key: true, index: false
      t.integer :no, null: false
      t.string :alt_text
      t.column :sha256, 'binary(32)', null: false
      t.references :created_by_user, null: false, foreign_key: { to_table: :users }
      t.timestamps
    end

    add_index :wiki_assets, [:wiki_page_id, :sha256], unique: true

    add_column :wiki_pages, :next_asset_no, :integer, null: false, default: 1
  end
end