FIX: 404 on old thumbnails

db/migrate/20130828192526_fix_optimized_images_urls.rb

@@ -0,0 +1,19 @@
+class FixOptimizedImagesUrls < ActiveRecord::Migration
+  def up
+    # `AddUrlToOptimizedImages` was wrongly computing the URLs. This fixes it!
+    execute "UPDATE optimized_images
+             SET url = substring(oi.url from '^\/uploads\/[^/]+\/_optimized/[0-9a-f]{3}/[0-9a-f]{3}/[0-9a-f]{11}')
+                    || '_'
+                    || oi.width
+                    || 'x'
+                    || oi.height
+                    || substring(oi.url from '\.\w{3,4}$')
+             FROM optimized_images oi
+             WHERE optimized_images.id = oi.id
+               AND oi.url ~ '^\/uploads\/[^/]+\/_optimized\/[0-9a-f]{3}/[0-9a-f]{3}/[0-9a-f]{11}\.';"
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end