18c is the new name of 12.2.0.2, In 2018 Oracle started to name the new DB versions represent the year the product was released on. I've already covered the top remarkable new features of 12.1 and 12.2.0.1 in a previous post: http://dba-tips.blogspot.com/2019/11/a-summary-of-remarkable-new-features-in.html
In this post I'll cover the top new features of 18c which are not much!
Miscellaneous Features:
Shadow lost write protection feature introduced to minimize data loss and the time required to repair a database due to lost Writes.
To Enable:
-- First: Create A shadow bigfile tablespace to store only system change numbers (SCNs) for tracked data files it will allocate 2% of the protected data:
SQL> CREATE BIGFILE TABLESPACE SHADOW_WRITE DATAFILE '/oradata/shadow_lwp1.dbf' SIZE 1G LOST WRITE PROTECTION;
-- Second: Enable the scope of protection:
[Database wise]
SQL> ALTER DATABASE ENABLE LOST WRITE PROTECTION;
[Tablespace wise]
SQL> ALTER TABLESPACE USERS ENABLE LOST WRITE PROTECTION;
[Datafile wise]
SQL> ALTER DATABASE DATAFILE '/oradata/dfile1.dbf' ENABLE LOST WRITE PROTECTION;
To Disable: [Use same above command but with DISABLE keyword]
SQL> ALTER DATABASE DISABLE LOST WRITE PROTECTION;
[Tablespace wise]
SQL> ALTER TABLESPACE USERS DISABLE LOST WRITE PROTECTION;
[Datafile wise]
SQL> ALTER DATABASE DATAFILE '/oradata/dfile1.dbf' DISABLE LOST WRITE PROTECTION;
SQL statement level KILL instead of killing the whole session:
Starting from 18c you can cancel the current running SQL Statement, leaving its session remain connected:
SQL> ALTER SYSTEM CANCEL SQL '<SID>, <SERIAL#>, <SQLID>';
i.e.
SQL> ALTER SYSTEM CANCEL SQL '20, 51142, 8vu7s907prbgr';
ORACLE HOME read-only mode:
Starting from 18c Oracle Home can be configured in a read-only mode, thus preventing creation or modification of files inside the Oracle home directory. A read-only Oracle home can be used as a software image that can be shared across multiple database servers.
How to implement this feature:
While installing a new Oracle Database software, choose software-only option, then configure it as a read-only Oracle home before you create the listener and the database.
Password File is now under ORACLE_BASE:
New location for Password file under $ORACLE_BASE/dbs instead of $ORACLE_HOME/dbs
Schema only accounts:
In Oracle 18c there is a new account type called schema only account, where it can hold objects but no one can log in to it:
SQL> create test no authentication;
or:
SQL> alter user test no authentication;
New Initialization Parameters:
OPTIMIZER_IGNORE_HINTS [Default is FALSE]
This will force the Optimizer to ignore all impeded hints.
OPTIMIZER_IGNORE_PARALLEL_HINTS [Default is FALSE]
Will force the Optimizer to ignore PARALLEL hints.
FORWARD_LISTENER
Forward all the incoming connection from REMOTE_LISTENER to a particular listener.
References:
https://apex.oracle.com/database-features
Stay tuned for the 19c new features post.
In this post I'll cover the top new features of 18c which are not much!
Miscellaneous Features:
Shadow lost write protection feature introduced to minimize data loss and the time required to repair a database due to lost Writes.
To Enable:
-- First: Create A shadow bigfile tablespace to store only system change numbers (SCNs) for tracked data files it will allocate 2% of the protected data:
SQL> CREATE BIGFILE TABLESPACE SHADOW_WRITE DATAFILE '/oradata/shadow_lwp1.dbf' SIZE 1G LOST WRITE PROTECTION;
-- Second: Enable the scope of protection:
[Database wise]
SQL> ALTER DATABASE ENABLE LOST WRITE PROTECTION;
[Tablespace wise]
SQL> ALTER TABLESPACE USERS ENABLE LOST WRITE PROTECTION;
[Datafile wise]
SQL> ALTER DATABASE DATAFILE '/oradata/dfile1.dbf' ENABLE LOST WRITE PROTECTION;
To Disable: [Use same above command but with DISABLE keyword]
SQL> ALTER DATABASE DISABLE LOST WRITE PROTECTION;
[Tablespace wise]
SQL> ALTER TABLESPACE USERS DISABLE LOST WRITE PROTECTION;
[Datafile wise]
SQL> ALTER DATABASE DATAFILE '/oradata/dfile1.dbf' DISABLE LOST WRITE PROTECTION;
SQL statement level KILL instead of killing the whole session:
Starting from 18c you can cancel the current running SQL Statement, leaving its session remain connected:
SQL> ALTER SYSTEM CANCEL SQL '<SID>, <SERIAL#>, <SQLID>';
i.e.
SQL> ALTER SYSTEM CANCEL SQL '20, 51142, 8vu7s907prbgr';
ORACLE HOME read-only mode:
Starting from 18c Oracle Home can be configured in a read-only mode, thus preventing creation or modification of files inside the Oracle home directory. A read-only Oracle home can be used as a software image that can be shared across multiple database servers.
How to implement this feature:
While installing a new Oracle Database software, choose software-only option, then configure it as a read-only Oracle home before you create the listener and the database.
Password File is now under ORACLE_BASE:
New location for Password file under $ORACLE_BASE/dbs instead of $ORACLE_HOME/dbs
Schema only accounts:
In Oracle 18c there is a new account type called schema only account, where it can hold objects but no one can log in to it:
SQL> create test no authentication;
or:
SQL> alter user test no authentication;
New Initialization Parameters:
OPTIMIZER_IGNORE_HINTS [Default is FALSE]
This will force the Optimizer to ignore all impeded hints.
OPTIMIZER_IGNORE_PARALLEL_HINTS [Default is FALSE]
Will force the Optimizer to ignore PARALLEL hints.
FORWARD_LISTENER
Forward all the incoming connection from REMOTE_LISTENER to a particular listener.
References:
https://apex.oracle.com/database-features
Stay tuned for the 19c new features post.
