Merge pull request #3245 from alphagov/change-linksets-pkey-3-populate-column

(ADR-009 PR 3) Populate link_set_content_id with rake task

Author: richardTowers

lib/tasks/add_link_set_content_id_to_links.rake

@@ -0,0 +1,36 @@
+desc "Add link_set_content_id to links"
+task :add_link_set_content_id_to_links, [:link_id] => [:environment] do |_t, args|
+  batch_size = 1000
+  link_id = args.fetch(:link_id, 0).to_i
+  total_updated = 0
+  link_set_links = Link.where.not(link_set_id: nil)
+  total_count = link_set_links.where(id: link_id...).count
+
+  loop do
+    max_link_id = link_set_links.where(id: link_id...)
+                                .order(id: :asc).limit(batch_size)
+                                .pluck(:id).last
+    break if max_link_id.nil?
+
+    puts "Processing link ids from #{link_id} to #{max_link_id}"
+
+    sql = <<-SQL
+      UPDATE links
+      SET link_set_content_id = link_sets.content_id
+      FROM link_sets
+      WHERE links.link_set_id IS NOT NULL AND links.link_set_id = link_sets.id
+      AND links.id BETWEEN ? AND ?
+    SQL
+
+    ActiveRecord::Base.connection.execute(
+      ActiveRecord::Base.sanitize_sql_array([sql, link_id, max_link_id]),
+    )
+
+    link_id = max_link_id + 1
+    total_updated += batch_size
+    puts "Processed #{total_updated} of #{total_count} links so far (#{(total_updated.to_f / total_count * 100).round(1)}%)"
+    sleep(0.1)
+  end
+
+  puts "Finished processing links. Total updated: #{total_updated}"
+end