Atomicity means that, if any given data operation within a transaction cannot successfully complete, then none of the operations within the transaction are allowed to complete. An atomic change does not leave partial or ambiguous effects in the database. Changes to individual files are always atomic whether Transaction Logging and Transaction Durability are on or off. But transactions make it possible to group changes to multiple files into one atomic group. The atomicity of these multi-file transactions are assured by the MicroKernel only when using transactions in your application, and Transaction Logging or Transaction Durability is turned on.
In addition to these benefits, Transaction Durability guarantees that, in the event of a system crash, the data files will contain the full results of any transaction that returned a successful completion status code to the application prior to the crash.
In the interest of higher performance, Transaction Logging does not offer this guarantee. Whereas
Transaction Durability ensures that a completed transaction is fully written to the transaction log before the engine returns a successful status code, Transaction Logging returns a successful status code as soon as the logger thread has been signaled to flush the log buffer to disk.
Turn on Transaction Durability if at least one of your Pervasive PSQL applications requires that completed transactions across multiple data files be absolutely guaranteed to have been written to the data files under almost any circumstances.