The following features are new in this release:

• CDB fleet

  A CDB fleet is a collection of different CDBs that can be managed as one logical CDB.

  See "Administering a CDB Fleet".

• PDB snapshot carousel

  A PDB snapshot is a point-in-time copy of a PDB. The source PDB can be open read-only or read/write while the snapshot is created. You can create snapshots manually using the SNAPSHOT clause of CREATE PLUGGABLE DATABASE (or ALTER PLUGGABLE DATABASE), or automatically using the EVERY interval clause. When a PDB is enabled for snapshots, you can create multiple snapshots (point-in-time copies) of the PDB. The library of snapshots is called a PDB snapshot carousel. You can quickly clone a new PDB based on any snapshot in the carousel. In this way, you can perform point-in-time recovery to any snapshot in the carousel, or rapidly create a PDB by cloning any snapshot.

  See "User Interface for PDB Snapshot Carousel" and "Administering a PDB Snapshot Carousel".

• Logical partitioning

  A container map enables a session to issue SQL statements that are routed to the appropriate PDB, depending on the value of a predicate used in the SQL statement. The partitioning column in the map table does not need to match a column in the metadata-linked table. For example, if the table sales is enabled for the container map pdb_map_tbl, and if sales does not have the column used to partition pdb_map_tbl, then queries with the predicate CONTAINERS(sales) are still routed to the PDBs specified in the map table.

  See "Container Maps".

• Refreshable PDB switchover

  A refreshable clone PDB is a read-only clone that can periodically synchronize with its source PDB. You can reverse the roles, transforming the source PDB into the clone and the clone into the source. This technique can be useful for load balancing. Also, if the source PDB fails, then you can resume operations on the clone PDB, rendering a CDB-level Oracle Data Guard failover unnecessary.

  See "About Refreshable Clone PDBs" and "Switching Over a Refreshable Clone PDB".

• Lockdown profile enhancements

  You can create, alter, or drop lockdown profiles in application containers. Also, you can create lockdown profiles based on a static or a dynamic base profile.

  See "Overview of PDB Lockdown Profiles", "About Restricting PDB Users for Enhanced Security", and "Restricting Operations on PDBs Using PDB Lockdown Profiles".

• DBCA enhancements

  You can use DBCA to clone a local PDB or duplicate a CDB. Duplication is only supported in silent mode.

  See "About CDB Creation with DBCA" and "About Cloning a Local PDB".

• Usable backups of non-CDBs and relocated PDBs

  When you are cloning a non-CDB as a PDB or relocating a PDB, you can use the DBMS_PDB.EXPORTRMANBACKUP procedure to export RMAN backup metadata into the PDB dictionary. This metadata enables backups of the source non-CDB or PDB to be usable for restore and recovery of the target PDB.

  See "General Prerequisites for PDB Creation".

• RMAN duplication of a PDB to another CDB

  You can clone a PDB from a source CDB to an existing CDB that is open read/write.

  See "Techniques for Creating a PDB"

• Relocation of sessions during planned maintenance

  Application Continuity can drain database sessions during planned maintenance when the application submits a connection test, at request boundaries, and at good places to fail over. The relocation is transparent to applications. This feature is on by default for all maintenance operations invoked at the database service and PDB levels: stop service, relocate service, relocate PDB, and stop PDB.

  See "Managing Services for PDBs", "How PDB Relocation Works", and Oracle Real Application Clusters Administration and Deployment Guide.

• Copying a PDB in an Oracle Data Guard environment

  When performing a remote clone in a primary database, or plugging in a PDB in a primary database, you can set initialization parameters in a standby database that automates copying the data files for the newly created PDB.

  See "Cloning a Remote PDB: Basic Steps" and "Plugging In an Unplugged PDB".

• Parallel statement queuing at the PDB level

  You can configure parallel statement queuing for a PDB just as for a non-PDB using the PARALLEL_SERVERS_TARGET initialization parameter. At the PDB level, the default is based on the CPU_COUNT setting for the PDB. At the CDB level, the default value is the value of the PARALLEL_MAX_SERVERS initialization parameter.

  See "Utilization Limits for PDBs".

• Split mirror clone PDBs

  When a PDB resides in Oracle ASM, you can use a split mirroring technique to clone a PDB. The cloned PDB is independent of the original PDB. The principal use case is to rapidly provision test and development PDBs in an Oracle ASM environment.

  See "Creating a Split Mirror Clone PDB".