Top 18 features of Oracle 18c

"Oracle Database 18c" is the next iteration of Oracle Database 12c Release 2 ( Oracle has simply changed the product names to follow a yearly release pattern and to simplify of the patching process. Oracle 12c was basically focused on Multitenant, In-Memory, Sharding and making almost every operation online along with thousands of other features. Oracle Database 18c comes with lots of incremental improvements over Oracle 12c R2. Following is the list of top 18 features of Oracle 18c:

1. For Exadata and Real Application Clusters (RAC), Oracle Database 18c uses RDMA over the Infiniband connection to access the undo blocks in the remote instance to reduce significant amount of undo that needs to be transferred across the interconnect.

2. In-Memory in Oracle Database 18c also allows you to place data from external tables in the column store. Also It can now scan compression units in-parallel to double the speed of data read

3. From Oracle 18c, we can patch each nodes in Grid Infrastructure in a rolling fashion while the databases on that node remains available.

4. In Oracle 18c, users can define Shards using either the System Managed (hash) approach or by User defined (Range and List) approach.

5. Oracle 18c enables you to define regular snapshots of PDBs called Snapshot Carousel

6. Oracle 18c also introduces “Refreshable PDB Switchover”, to create a PDB which can be incrementally updated from MASTER PDB. Then we can switch MASTER PDB becomes the CLONE and the old CLONE becomes the MASTER.

7. Oracle 12c introduced a lot of online partition features. With Oracle 18c, we can MERGE PARTITIONS online and maintain the indexes.

8. APPROX_COUNT(), APPROX_SUM() and APPROX_RANK() are introduced with Oracle 18c, which can calculate 99% accurate results in very high speed.

9. Private temporary tables enables Oracle 18c users to create temporary database objects that are automatically dropped at the end of a transaction or a session.

10. A lot of machine learning algorithms in the R extensibility framework has been added in Oracle 18c directly inside of the database.

11. In Oracle Database SODA (Simple Oracle Document Access) API is added for PL/SQL lets PL/SQL programs create, read, update, delete operations on JSON documents

12. With Oracle 18c we can use database NOLOGGING when loading data into production databases without compromising the integrity of your Oracle Data Guard STANDBY databases.

13. In Oracle 18c, RECOVER command enable a standby database to catch up with changes made to the primary database with minimal manual intervention.

14. Various enhancements have been made in Oracle 18c to improve the robustness and fault tolerance of shard queries. Query explain plan has been enhanced to display information for all shards participating in the query.

15. We can now alter a Non-Partitioned table to hash partitioning or to range partitioning online using ALTER TABLE MODIFY PARTITION SQL.

16. On Oracle Exadata Database Machine, the cost of smart scans depends on the system statistics. SQL Tuning Advisor of Oracle 18c is enhanced for Exadata to consider system statistics of Exadata Machines.

17. In Oracle 18c, we can create schema only accounts, for object ownership without allowing user to log in to the schema.

18. DBMS_LOCK.SLEEP is depreciated in Oracle 18c and DBMS_SESSION.SLEEP is introduced, and is available with no additional grants needed.

One extra cherry on top
With Oracle 18c we can cancel a SQL of another session without killing that session using "ALTER SYSTEM CANCEL SQL 'SID, SERIAL'".

Related Articles:
- Oracle 18c Database - Autonomous Database Cloud
- Oracle Cloud Performance Benchmark by Accenture
- Oracle 12c Partitioning New Features - Top 10
- Oracle Database 12c R2 New Features for developers
- Oracle Database 12c R1 New Features for Developers
- JSON in Oracle Database 12c with Examples
- SQL Interview Question Answers


  1. This blog was... how do I say it? Relevant!! Finally I have found
    something that helped me. Thanks a lot!

  2. There is certainly a lot to find out about this topic. I like all of the points you made.

  3. Awesome Nimish .. Thanks alot .. !!

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  5. Nice post Nimish and also mentioning that 18c is not so big of a change but just an enhanced version of 12c