lib/lockbox/migrator.rb in lockbox-0.4.6 vs lib/lockbox/migrator.rb in lockbox-0.4.7

@@ -114,9 +114,16 @@
         end
         yield records if records.any?
       end
     end
 
+    # there's a small chance for this process to read data,
+    # another process to update the data, and
+    # this process to write the now stale data
+    # this time window can be reduced with smaller batch sizes
+    # locking individual records could eliminate this
+    # one option is: relation.in_batches { |batch| batch.lock }
+    # which runs SELECT ... FOR UPDATE in Postgres
     def migrate_records(records, fields:, blind_indexes:, restart:, rotate:)
       # do computation outside of transaction
       # especially expensive blind index computation
       if rotate
         records.each do |record|