Hi all I think I might've found an error in the documentation page for ActiveRecord lock_version API at http://api.rubyonrails.org/classes/ActiveRecord/Locking/Optimistic.html The document says "This locking mechanism will function inside a single Ruby process. To make it work across all web requests, the recommended approach is to add lock_version as a hidden field to your form" but I don't think this is true. The SQL statement has a WHERE clause that restrict updates only to the row the current ruby process/thread knows about. Therefore, even in a cluster of rails servers this scheme would work as long as ActiveRecord checks the number of rows updated to ensure it's 1 (it does). The statement about single ruby process and hidden form field is not present at http://guides.rubyonrails.org/active_record_querying.html#optimistic-locking (which I think is the correct version of the text). Is that something someone is willing to look at or can I help? Thanks Kevin Yeung -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-core+unsubscribe@googlegroups.com. To post to this group, send email to rubyonrails-core@googlegroups.com. Visit this group at http://groups.google.com/group/rubyonrails-core. For more options, visit https://groups.google.com/d/optout.