I need to implement a feature for a rails site that will involve
reading and exporting most of my database.
I know this operation is going to take a while. That's fine-- I've got
delayed job for that.
What I'm worried about is the data changing during the running of the
job, and the resulting export being corrupted because of that.
My initial thought was to do all of the reads within a transaction.
However, I would also like to be running the reads concurrently.
ActiveRecord docs say that Transactions cannot be shared between
Connections, and Connections cannot be shared between Threads. So it
looks as though I am restricted to a single thread with this approach.
Any suggestions for a workaround? Is there another way to give the job
a consistent view of the data that doesn't involve transactions? Or is
there some alternative to ActiveRecord/Mysql out there that can
distribute transactions across threads?