If you need atomic sequencing and still want to use a paralell system you are gonna have to push that sequencing off onto a system capable of atomic sequencing. probably the easiest way is to write a stored procedure with a transaction in an rdbms. and do an executesql in your flow. Don't use a cache as MC says caches are not designed for transactional atomic stuff. Only use cache for actually caching stuff (you can get the value but its expensive and cheaper just to store for a bit in the cache. ... View more