Berkeley DB Reference Guide: Transaction Subsystem
Configuring transactions
There is only a single parameter used in configuring transactions, the DB_TXN_NOSYNC flag. Setting the DB_TXN_NOSYNC flag when opening a transaction region (using either db_appinit or txn_open) changes the behavior of transactions to not synchronously flush the log during transaction commit.
This change will significantly increase application transactional throughput, however, it means that while transactions will continue to exhibit the ACI (atomicity, consistency and isolation) properties, they will not have D (durability), i.e., database integrity will be maintained but it is possible that some number of the most recently committed transactions may be undone during recovery instead of being redone.
