FIX: Drop columns only after app has been deployed with updated code.

db/fixtures/001_categories.rb

@@ -23,3 +23,27 @@ if uncat_id == -1 || !Category.exists?(uncat_id)
   Category.exec_sql "INSERT INTO site_settings(name, data_type, value, created_at, updated_at)
            VALUES ('uncategorized_category_id', 3, #{category_id}, now(), now())"
 end
+
+# 60 minutes after our migration runs we need to exectue this code...
+duration = Rails.env.production? ? 60 : 0
+if Category.exec_sql("
+    SELECT 1 FROM schema_migration_details
+    WHERE EXISTS(
+      SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
+        WHERE table_schema = 'public' AND table_name = 'categories' AND column_name = 'uploaded_logo_id'
+      ) AND
+    name = 'AddUploadsToCategories' AND
+    created_at < (current_timestamp at time zone 'UTC' - interval '#{duration} minutes')
+  ").to_a.length > 0
+
+
+  Category.transaction do
+    STDERR.puts "Removing superflous category columns!"
+    %w[
+      logo_url
+      background_url
+    ].each do |column|
+      Category.exec_sql("ALTER TABLE categories DROP column IF EXISTS #{column}")
+    end
+  end
+end