On Jan 23, 2013, at 4:03 AM, Gabriel Sobrinho wrote: > It makes sense! > > I have a debt entity in my application and payments this entity can happen > three or more times in parallel (stupid brazilian banks, don't ask me why > they do it). > > Since I have to keep a cache column of the paid value for the debt, I have 25 > workers (sidekiq) that can call `increment!(:paid_value, paid_value)` and it > should keep the total paid value. > > I'm not sure if it will be a problem to happen something like that: > > debt.paid_value > # => 100.0 > > debt.increment!(:paid_value, 100.0) > # => 300.0 > > We can have problems if other columns relies on that value. > > Let suppose I have another column called paid_interest and with the > paid_value, I get the total paid: > > debt.paid_value > # => 100.0 > > debt.paid_interest > # => 10.0 > > debt.total_paid > # => 110.0 > > debt.increment!(:paid_value, 100.0) > # => 300.0 > > debt.total_paid > # => 310.0 > > The paid_interest in this case is updated in another process. > > It's a contrived example but if that's the case, I will need to reload the > entire record to get the right total paid. > > At least some documentation telling that increment and increment! are subject > to race conditions is needed.
I believe the suggested solution in this case is to use optimistic locking (via a lock_version column) and then handle collisions manually. --Matt Jones -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To post to this group, send email to rubyonrails-core@googlegroups.com. To unsubscribe from this group, send email to rubyonrails-core+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en.
