On the 22nd of july, patchset 220.127.116.11 for Oracle 12c database was made generally available  for Linux x86-64 and Solaris.
This patchset includes the eagerly awaited In-memory option which promises an application transparent performance boost by using column-format data storage in memory.
Database In – Memory uses an In-Memory column store (IM column store), which is a new component of the Oracle Database System Global Area (SGA), called the In-Memory Area. Data in the IM column store does not reside in the traditional row format used by the Oracle Database; instead it uses a new column format.
The IM column store does not replace the buffer cache, but acts as a supplement, so that data can now be stored in memory in both a row and a column format.
Enabling a table to be a candidate for In-Memory can be as simple as executing:
ALTER TABLE sales INMEMORY
From the Oracle In-Memory option whitepaper:
With the introduction of Oracle Database In-Memory, a single database can now efficiently support mixed workloads, delivering optimal performance for transactions while simultaneously supporting real-time analytics and reporting. This is possible due to a unique “dual-format” architecture that enables data to be maintained in both the existing Oracle row format, for OLTP operations, and a new purely in-memory column format, optimized for analytical processing.
In-Memory also enables both datamarts and data warehouses to provide more ad-hoc analytics, giving end-users the ability to ask multiple business driving queries in the same time it takes to run just one now.
Embedding the in – memory column format into the existing Oracle Database software ensures that it i s f ully compatible with ALL existing features, and requires no changes in the application layer. Companies striving to become real-time enterprises can more easily achieve their goals , regardless of what applications they are running.
Looking forward to evaluate and test this new killer database option in the upcoming months, since we might be able to gain huge performance benefits for a Datawarehousing project.