This feature is available starting with Oracle Database 12c Release 1 (12.1.0.2)

It enables to force caching of all segments into buffer cache automatically(when the segments are accessed). With this option turned on even FULL scans or NOCACHE LOBs are loaded into buffer cache. In previous releases it was not guaranteed that a given segments will be cached unless you specified KEEP buffer.

When to use it:

• when you have enough memory to keep all segments in memory
• when you are limited by I/O system and response time

To enable force full database caching mode, use the following ALTER DATABASE command. It can be executed only when database is in mount mode:

ALTER DATABASE FORCE FULL DATABASE CACHING;

Status of the setting can be checked in the V$DATABASE view as shown:

SELECT FORCE_FULL_DB_CACHING FROM V$DATABASE;

Have a fun 🙂
Tomasz