Oracle 18c: 26 Remarkable new features of Oracle Database 18c..!!
Oracle 18c was released in 2018-02-16, and now available on Cloud and Engineered Systems，Adhering to Oracle’s Cloud first philosophy
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 an effective 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 standby have 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 data which 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 but canceled 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 during slicing 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.
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.
Unplanned switchover: mainly for the PDB master failure, do not switch the entire CDB.
14. PDB Snapshot Carousel
The pdb snapshot backup carousel, reserves 8 copies and is backed up every 24 hours by default.
ALTER PLUGGABLE DATABASE SNAPSHOT MODE EVERY 24 HOURS;
15. New Default Location of Oracle Database Password File
Note that the new password file path is already in ORACLE_BASE, not ORACLE_HOME.
16. Read-Only Oracle Home
You can use dbca or roohctl -enable to install read only oracle home.Run the orabasehomecommand to check if the current Oracle Home is read-only. If the output of this command is the same as $ORACLE_HOME, Oracle Home is read-write. If the output is ORACLE_BASE/homes/HOME_NAME, Oracle Home is read-only.
17. Online Merging of Partitions and Subpartitions
Supports online consolidation of partitions and the ONLINE keyword is required.
18. Concurrent SQL Execution with SQL Performance Analyzer
The SPA can run in parallel (by default, it is serial), helping you to complete the SPA test faster.
19. Automatic In-Memory
this feature evicts the infrequently accessed IM columns out of memory in the situation of memory insufficiency, based on the Heat Map.
20. Database In-Memory Support for External Tables
External tables support IM features.
21. Memoptimized Rowstore
There is a memoptimize pool area in the SGA. The size is set by the MEMOPTIMIZE_POOL_SIZE parameter. When fast lookup is turned on, the memory area can be used for quick search.
Open fast lookup, need to add keywords in the table statement:
fast lookup would be used based on the primary key query
Memoptimized Rowstore will greatly improve the high-frequency query based on the primary key in the Internet of Things.
(E) RAC and Grid
22. ASM Database Cloning
You can clone pdb based on ASM. Use the flex diskgroup to achieve.
23. Converting Normal or High Redundancy Disk Groups to Flex Disk Groups without Restricted Mount
We think use the Flex disk groups is great.
24. Integration of Active Directory Services with Oracle Database
Combined with Microsoft’s AD.
Before 18c, interaction with Oracle Enterprise User Security (EUS) was required. Now, you can use the centrally managed users (CMU) to mappiing the AD users and groups directly with the Oracle users and roles.
25. Add initialization parameters:
It’s worth mentioning OPTIMIZER_IGNORE_PARALLEL_HINTS. In a pure OLTP system, you can finally disable developers’ uncontrolled concurrency (often not writing concurrency). 🙂
Finally, it is no longer necessary to grant grants for dbms_lock separately.
Until here the article. Thanks for Reading!
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Post Author Bios:
Joel Pérez is an Expert DBA ( Oracle ACE Director, Maximum Availability OCM, OCM Cloud Admin. & OCM12c/11g ) with over 17 years of Real World Experience in Oracle Technology, specialised in design and implement solutions of: High Availability, Disaster Recovery, Upgrades, Replication, Cloud and all area related to Oracle Databases. International consultant with duties, conferences & activities in more than 50 countries and countless clients around the world. Habitual and one of leading writers of Technical Oracle articles for: OTN Spanish, Portuguese, English and more. Regular Speaker in worldwide Oracle events like: OTN LAD (Latin America), OTN MENA (Middle East & Africa), OTN APAC ( Asian Pacific), DTCC China, Oracle Code.. . Joel has always been known for being a pioneer in Oracle technology since the early days of his career being the first Latin American awarded as “OTN Expert” at year 2003 by Oracle Corp., one of the first “Oracle ACE” globally in the Oracle ACE Program at year 2004. He was honoured as one of the first “OCM Database Cloud Administrator” & Maximum Availability OCM in the world. Currently Joel works as Senior Cloud Database Architect in “Yunhe Enmo (Beijing) Technology Co.,Ltd”., company located in Beijing, China En.enmotech.com
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