oracle interview questions

1. what is the RU and RUR from oracle 18c.

From 18c onwards, instead of PSU patches, oracle introduces RU and RUR.
version format changed as   [MAJOR].[RU].[RUR].0.0 ex: 19.3.0.0.0

RU will be released quarterly similer to PSU, which changes the second digit in the version number like 19.2.0 to 19.3.0.

RUR also released same quarterly basis to augment the Updates with fixes for known regressions, it will change the third digit in the version number like 19.2.1 to 19.2.2

Lets say, your database is in version 19.4.0, now jan patch oracle will released as 19.5.0 and 19.4.1
 you can apply either 19.5.0 or 19.4.1

But RUR will be released maximum two times, so 19.4.0 can go upto 19.4.2, after that if you want to patch you should go to 19.6 or higher.(note: you can not go to 19.5 as its lower release than 19.4.2)

In my view choose to apply only RU to database quarterly, but finally DBA can decide what they want to follow based on their requirement.

2. what are oracle 19c new features.
3. PSU patches are going to be discontinue after moving to 19c?

Now PSU patches will be released only for 12.1 and 11gr2. to support old releases.
From 12.2 on words 18c and 19c oracle releases patches only in the form of RU and RUR.
For 12.2, for continuation oracle release RU and RUR with the same version number.
you can observer that in master patch release note (Doc ID 756671.1)

4. what is block change tracking and what is the use of it.
5. what is restore point and what are the situations we will use it.
6. can we export data using expdp in standby database when its in read only mode?.
7. how to import dumpfile without generating redo in database?.
8. what root.sh script will do while installing rdbms software.
9. what is the default location of listener and tnsnames.ora, can we change it?
10. How to find latest patch releases in oracle?

oracle will update latest patch releases in every quarter in the Master Note for Database Proactive Patch Program (Doc ID 756671.1)

11. How to find the OS version, bit version, kernal version... etc.

Below command list the details of the server.

hostnamectl status

output:
Static hostname: Ora_testmachine
         Icon name: computer-vm
           Chassis: vm
        Machine ID: XXXXXXXXXXXXXXXX
           Boot ID: XXXXXXXXXXXXXXXXXXXXX
    Virtualization: XXXXXXXXXXXXXXXX
  Operating System: Red Hat Enterprise Linux Server 7.5 (Maipo)
       CPE OS Name: cpe:/o:redhat:enterprise_linux:7.5:GA:server
            Kernel: Linux 3.10.0-862.9.1.el7.x86_64
      Architecture: x86-64

Alternatively we can use uname -a, but it will not give OS version.

12. Can we install oracle database in CentOS?

 Yes, CentOS also similer  to linux, we can install. advantage is, its Open source no licence cost.

13. what is the ASM power limit value.

Beginning with Oracle Database 11g Release 2(11.2.0.2), if the COMPATIBLE.ASM disk group attribute is set to 11.2.0.2 or higher, then the range of values is 0 to 1024.

14. How can we know ASM re-balance is going on in ASM instance.

We can use V$ASM_OPERATION view to check re-balance is going on or not. if below query displays any rows, we can say re-balance is in progress.


select * from V$ASM_OPERATION where STATE='RUN';