ORACLE 18C: 26 REMARKABLE NEW FEATURES OF ORACLE DATABASE 18C..!!
Now let’s take a look at the 18c new features which are important in our opinion.
1. Oracle Data Guard Multi-Instance Redo Apply Supports Use of Block Change Tracking Files for RMAN Backups
Multiple-Instance Redo Apply (also known as MIRA) now supports BCT (Block Change Tracking) backups. This is aneffective incremental backup method large database, and both master and slave are RAC, and the backup happens on the slave this kind of DB environment.
2. Automatic Correction of Non-logged Blocks at a Data Guard Standby Database
added two new standby logging modes (mainly to speed up the primary database loading data):
One is Standby Nologging for Data Availability, where the commit of a loading operation is delayed until all standbyhave applied data.
SQL> ALTER DATABASE SET STANDBY NOLOGGING FOR DATA AVAILABILITY;
One is Standby Nologging for Load Performance. This mode is similar to the previous one, but it will not send data when it encounters the network bottleneck during loading data. This guarantees the loading performance but may lose the datawhich can be obtained again from primary.
SQL> ALTER DATABASE SET STANDBY NOLOGGING FOR LOAD PERFORMANCE;
3. Shadow Lost Write Protection
Create a shadow tablespaces to provide data protection.With this feature you may not need ADG to provide additional lost write protection.
Do you notice that this feature like double write of the MySQL?
4. Backups from non-CDBs are usable after migration to CDB
The original non-CDB can be migrated as a PDB to the existing CDB with this new function.
5. Support for PDBs as Shards and Catalogs
finally, oracle shard could be a pdb.
However, it only supports a single pdb in a single cdb. What’s the point?
6. User-Defined Sharding Method
This feature once appeared in the beta version of 12.2 butcanceled in the official release. Now it got released again.
7. Consistency Levels for Multi-Shard Queries
Provides the MULTISHARD_QUERY_DATA_CONSISTENCY initialization parameter, to avoid SCN synchronization duringslicing across slices you can be set it before the execution
8. Manual termination of run-away queries
Now you can manually kill a statement without breaking the session:
ALTER SYSTEM CANCEL SQL.
ALTER SYSTEM CANCEL SQL ‘SID, SERIAL, @INST_ID, SQL_ID’;
(B) Big Data and Data Warehousing
9. Approximate Top-N Query Processing
Note: In 18c, APPROX_COUNT and APPROX_SUM were added to make full use of theAPPROX_RANK.
10. LOB support with IMC, Big Data SQL
the memory database start support LOB objects.
(C) Database Overall
11. Copying a PDB in an Oracle Data Guard Environment
Two new parameters have been added to facilitate the creation of PDBs in an ADG environment.
➢ One is STANDBY_PDB_SOURCE_FILE_DIRECTORY, which automatically finds the ADG data file path. (Note that before 18c, if you inserted a pdb into a standby environment,cdbwould need to manually copy the file to pdb’s OMF path)
➢ The other is STANDBY_PDB_SOURCE_FILE_DBLINK, which is used to automatically find the ADG file path when remote clone is used (Note: Before 18c, if you are a local clone, you do not need to copy the data file, but the remote clone requires manual copying).
12. PDB Lockdown Profile Enhancements
PDB lockdown profiles can now be created in application root and CDB root.You can now create another pdb lockdown profile based on a pdb lockdown profile.18c contains three default lockdown profiles: PRIVATE_DBAAS, SAAS, PUBLIC_DBAAS
13. Refreshable PDB Switchover
PDB refresh has always been known as the ADG for the poor, this feature is now getting much better in 18c. Switchover is supported. The switchover is divided into two scenarios outside the planned kernel plan.
Planed switchover: it can be cut back and used mainly to balance the load of the CDB