refactor license user seed script to use batches

db/scripts/seed_license_users.rb

@@ -3,18 +3,26 @@
 # heroku run:detached -e SLEEP_DURATION=0.5 --tail \
 #   rails runner db/scripts/seed_license_users.rb
 
+BATCH_SIZE     = ENV.fetch('BATCH_SIZE')     { 1_000 }.to_i
 SLEEP_DURATION = ENV.fetch('SLEEP_DURATION') { 1 }.to_f
 
-licenses = License.where_assoc_not_exists(:license_users)
-                  .where_assoc_exists(:user)
-                  .includes(:user)
+licenses_with_users = License.where_assoc_not_exists(:license_users)
+                             .where_assoc_exists(:user)
+                             .eager_load(
+                               :account,
+                               :user,
+                             )
 
-Rails.logger.info "Seeding #{licenses.count} license_users"
+Rails.logger.info "Seeding license_users for #{licenses_with_users.count} total licenses"
 
-licenses.find_each do |license|
-  Rails.logger.info "Seeding license_user for license=#{license.id} <> user=#{license.user_id}"
+licenses_with_users.find_in_batches(batch_size: BATCH_SIZE) do |licenses|
+  Rails.logger.info "Seeding batch of #{licenses.count} licenses"
 
-  license.users << license.user
+  licenses.each do |license|
+    Rails.logger.info "Seeding license_user for license=#{license.id} <> user=#{license.user_id}"
+
+    license.users << license.user
+  end
 
   sleep SLEEP_DURATION
 end