Skip incompatible migration entirely

db/migrate/20180812173710_copy_status_stats.rb

@@ -2,18 +2,19 @@ class CopyStatusStats < ActiveRecord::Migration[5.2]
   disable_ddl_transaction!
 
   def up
-    safety_assured do
-      Status.unscoped.select('id').find_in_batches(batch_size: 5_000) do |statuses|
-        execute <<-SQL.squish
-          INSERT INTO status_stats (status_id, reblogs_count, favourites_count, created_at, updated_at)
-          SELECT id, reblogs_count, favourites_count, created_at, updated_at
-          FROM statuses
-          WHERE id IN (#{statuses.map(&:id).join(', ')})
-          ON CONFLICT (status_id) DO UPDATE
-          SET reblogs_count = EXCLUDED.reblogs_count, favourites_count = EXCLUDED.favourites_count
-        SQL
-      end
-    end
+    # FIXME upserts don't work in PostgreSQL 9.4, so we're skipping this for now.
+    # safety_assured do
+    #   Status.unscoped.select('id').find_in_batches(batch_size: 5_000) do |statuses|
+    #     execute <<-SQL.squish
+    #       INSERT INTO status_stats (status_id, reblogs_count, favourites_count, created_at, updated_at)
+    #       SELECT id, reblogs_count, favourites_count, created_at, updated_at
+    #       FROM statuses
+    #       WHERE id IN (#{statuses.map(&:id).join(', ')})
+    #       ON CONFLICT (status_id) DO UPDATE
+    #       SET reblogs_count = EXCLUDED.reblogs_count, favourites_count = EXCLUDED.favourites_count
+    #     SQL
+    #   end
+    # end
   end
 
   def down