Oracle Database 12c R1 New Features - Multiple Indexes on the same column or set of columns

Oracle Database 12c R1 New Features - Multiple Indexes on the same column or set of columns

In DB releases prior to Oracle DB 12c, you could not create multiple indexes either on the same column or set of columns in any form. 

But now in DB 12c, you can have multiple indexes on the same column or set of columns as long as the index type is different. However, only one type of index is usable/visible at a given time. 

In order to test the invisible indexes, you need to set the optimizer_use_use_invisible_indexes=true.

Example:


SQL> CREATE TABLE EMP_RECORDS
  2  (EMP_NO number (5),
  3  EMP_NAME varchar2 (30),
  4  EMP_SAL number (6) INVISIBLE)
  5  /

SQL> alter session set optimizer_use_invisible_indexes = true;

Session altered.

SQL> CREATE INDEX EMP_IND1 ON EMP_RECORDS (EMP_NO, EMP_NAME);

Index created.

SQL> CREATE BITMAP INDEX EMP_IND2 ON EMP_RECORDS (EMP_NO, EMP_NAME) INVISIBLE;

Index created.

Related:

Oracle Database 12c R1 New Features - Invisible columns

Installing Oracle Database 12c R1 (12.1.0.1.0)

Installation of Oracle Database 12c R1 (12.1.0.1.0)

Installation of Oracle Database 12c R1 (12.1.0.1.0)

Run setup.exe from installer directory (This is on windows, similarly invoke installer on Linux environment)

Oracle Database 12c Release 1 Installer - Installing Database

Step 1: Configure security updates

Enter My Oracle Support Username / Password to receive security updates via My Oracle Support (optional)

Step 2: Download Software updates

Enter My Oracle Support credentials to download software updates for this installation (optional)

Step 3: Select Installation Option

i)  Create and configure a database (Select this option)
ii) Install database software only
iii)Upgrade an existing database 

Step 4: System Class

i) Desktop class (Choose this option)
ii)Server class

Step 5: Specify Oracle Home User

i) Use Existing Windows User
ii) Create New Windows USer 
iii)Use Windows Built-in account (Option chosen - No need to specify username or password)


Step 6: Typical Install Configuration

Enter Administrative password: 

Step 7: Prerequisite checks

Step 8: Summary

Step 9: Install

At the end of installation, you will see on screen 

The installation of Oracle Database was successful.

Your database configuration files have been installed in C:\app\ while other components selected for installation have been installed in C:\app\product\12.1.0\dbhome_1.  Be cautious not to accidentally delete these configuration files.

SQL> select instance_name, status, version, database_status from v$instance;

INSTANCE_NAME    STATUS       VERSION           DATABASE_STATUS
---------------- ------------ ----------------- -------------------------------------------------------

newdb12c         OPEN         12.1.0.1.0        ACTIVE


Deinstalling Oracle Database 12c:

Go to $DB_HOME/deinstall and execute deinstall script.

For eg:

C:\app\db12c\product\12.1.0\dbhome_1\deinstall>deinstall

Related:

Oracle Database 12c R1 New Features - Invisible columns

Oracle Database 12c R1 New Features - Multiple Indexes on the same column or set of columns