Changes in This Release for Oracle Database Concepts

The following features are new in this release:

• In-Memory Column Store

  The In-Memory Column Store (IM column store) is an optional area in the SGA that stores whole tables, table partitions, and individual columns in a compressed columnar format. The database uses special techniques, including SIMD vector processing, to scan columnar data rapidly. The IM column store is a supplement to rather than a replacement for the database buffer cache.

  See "In-Memory Column Store".

• Automatic Big Table Caching

  This optional, configurable portion of the database buffer cache uses an algorithm for large tables based on object type and temperature. In single-instance and Oracle RAC databases, parallel queries can use the big table cache when the DB_BIG_TABLE_CACHE_PERCENT_TARGET initialization parameter is set to a nonzero value, and PARALLEL_DEGREE_POLICY is set to auto or adaptive. In a single-instance configuration only, serial queries can use the big table cache when DB_BIG_TABLE_CACHE_PERCENT_TARGET is set.

  See "Buffer I/O", and "Buffer Pools".

The following features are new in this release:

• Multitenant architecture

  The multitenant architecture capability enables an Oracle database to function as a multitenant container database (CDB). A CDB includes zero, one, or many customer-created pluggable databases (PDBs). A PDB is a portable collection of schemas, schema objects, and nonschema objects that appears to an Oracle Net client as a non-CDB. You can unplug a PDB from a CDB and plug it into a different CDB.

  See "Introduction to the Multitenant Architecture ".

• Multiprocess and multithreaded Oracle Database

  Starting with this release, Oracle Database may use operating system threads to allow resource sharing and reduce resource consumption.

  See "Multiprocess and Multithreaded Oracle Database Systems".