atomic INSERT or UPDATE with activerecord

rubyonrails-talk
1

what i need: if :record is in the database -> upgrade his counter else create :record (with his counter on 1)

this should be done with an atomic operation, to avoid race conditions. What is the best way to do this with activerecord? I read about transactions, but as i understand a transaction acts on a single connection to the database.

2

incrementing the counter is simple enough - AR's increment_counter method basically does update foos set counter = counter + 1 where ...

To avoid duplicate records being created I'd create a unique index on whatever it is that identifies a record

Fred

3

This would be a single DB connection, so it seems like a good candidate for a transaction. What's the problem with doing that?

Best,

4

i think that multiple requests use multiple db connections, didn't they? This is obviously true having two database server in a multi- master configuration. I think that Frederick Cheung's solution should solve the problem anyway. thank you.