IMU is one such introduction. It became standard issue starting with the initial Oracle Database 10g release. Oracle knows that for many customers, segment management and, in particular, creating read-consistent buffers, consumes significant computing resources: memory, CPU, and IO. So if the developers can reduce one or all of these consumables while improving performance, they are thrilled. IMU is wonderful, and it sets the stage for transforming other traditionally segment-based operations into in-memory alternatives.

* To allow a transaction to roll back so the database looks just as it did before the transaction started.

* By default, whenever a query starts and ends, the results will match what the database looked like when the query started.