Interview Questions.

Q1. Why We Should Need To Open Database Using Resetlogs After Finishing Incomplete Recovery?

When we're appearing incomplete recovery it me we deliver database to past time or rewind period of time the use of exchange based, cancel based or time based totally recovery. These all restoration make database in earlier state of database. The ahead series range already available after performing recuperation, because of mismatching of this series numbers and previous kingdom of database, it needs to open database with new series variety of Redo log and archive logs.

Q2. I Am Working As Oracle Dba In 24/7 Running Large Production Database. Size Of Database Is Around 800 Gb. We Take Hot Backup Every Day Night. But One Day At Around four:00 Pm, By Mistake One Table Is Drop

If your database is strolling on Oracle 10g/11g/12c model then there is new function to be had known as Recycle bin. You can get better dropped table from user_recyclebin or dba_recyclebin.

Q3. Have You Faced Any Recovery Scenario? Explain How You Resolved It?

2 months lower back, a capability desk changed into dropped by using an application developer on our large 24/7 walking manufacturing database. Immediately he knowledgeable us. We have standby database for our manufacturing database. We checked that archives didn’t apply to standby database as much as dropped timing. We stopped archive applying on standby without delay and open database study simplest. Took export of dropped desk and imported in production database. After completing appropriate checking of table, once more we commenced archive applying in standby database for fresh.

Q4. What Are The Steps Involved In Instance Recovery?

Rolling forward to get better facts that has not been recorded in information documents but has been recorded within the on-line redo log, including the contents of rollback segments.

Rolling lower back tractions that have been explicitly rolled back or have now not been committed as indicated by using the rollback segments regenerated in step a.

Releasing any sources (locks) held by means of tractions in system on the time of the failure.

Resolving any pending distributed tractions present process a two-phase commit at the time of the example failure.

Q5. Archive Logs Are Being Generated Around 20gb In My Production Large Database. But One Day Almost Double Archives Were Generated. What Is The Reason Behind This? How Can I Check It?

There are plenty of reason behind increasing length of archives like If more database adjustments were achieved the use of batch jobs or any special assignment like merging 2 database or records and so forth. You can check out exact root reason the usage of allowing Log Minor application.

Q6. Does Incremental Checkpoint Recorded In Alert.Log? How To Disable It?

We can enable disable recording incremental checkpoint in alert.Log .We can permit/disable recording the usage of parameter log_checkpoints_to_alert=authentic/false.

Q7. What Are The Different Modes Of Mounting A Database With The Parallel Server?

Exclusive Mode If the primary example that mounts a database does so in specific mode, best that Instance can mount the database.

Parallel Mode if the primary instance that mounts a database is started in parallel mode, different times that are commenced in parallel mode can also mount the database.

Q8. What Is Partial Backup?

A Partial Backup is any working machine backup quick of a complete backup, taken while the database is open or shut down.

Q9. What Is Restricted Mode Of Instance Startup?

An example can be started in (or later altered to be in) confined mode so that when the database is open connections are limited handiest to those whose consumer accounts were granted the RESTRICTED SESSION device privilege.

Q10. In Continuation Above Scenario, Why I Should Need To Perform Recovery In Uat And Test Database Server? Can I Restore Backup In Production Database Server Too?

Yes. You can. It is not recommended due to the fact your production database is massive database and walking 24/7 surroundings. Restoration and recovery will take downtime. It is higher to perform recuperation and recovery technique on UAT or Test database.

Q11. Which Command I Should Need To Execute To Back Up Database Which Is Running On Noarchivelog Mode?

Shutdown on the spot. Because with out shutdown, we can't perform on-line backup of database, which walking on NOARCHIVELOG mode. We need to want to take bloodless backup of database. After easy shutdown database replica of all datafiles, manipulate files, redo log files, password document, and parameter documents.

Q12. What Is On-line Redo Log?

The On-line Redo Log is a fixed of  or extra on line redo files that document all committed adjustments made to the database. Whenever a traction is dedicated, the corresponding redo entries quickly shops in redo log buffers of the SGA are written to an online redo log report through the historical past method LGWR. The online redo log files are used in cyclical fashion.

Q13. What Is Log Switch?

The point at which ORACLE ends writing to one on line redo log record and starts offevolved writing to some other is referred to as a log transfer.

Q14. Can Full Backup Be Performed When The Database Is Open?

No.

Q15. In Continuation Of Above Scenario, Recycle Bin Doesn't Enable In My Database Then How To Recover My Table? How To Disable It?

Then you should want to restore backup in your UAT or take a look at database server and enable time primarily based restoration for applying all files before drop command execution. For an example, practice data up to a few:55 PM here.

Q16. What Is Incremental Checkpoint?

In incremental checkpoint procedure, CKPT procedure records lowest Low RBA to the manage report to maintain advancing the Buffer checkpoint Queue (BCQ) to make smooth and quickest Active Checkpoint Queue (ACQ).

Q17. What Is Archived Redo Log?

Archived Redo Log consists of Redo Log documents which have executed earlier than being reused.

Q18. What Is Full Backup?

A complete backup is an operating system backup of all facts files, on line redo log documents and manipulate document that constitute ORACLE database and the parameter.

Q19. What Are The Advantages Of Operating A Database In Archivelog Mode Over Operating It In No Archivelog Mode?

Complete database restoration from disk failure is possible most effective in ARCHIVELOG mode.

Online database backup is viable simplest in ARCHIVELOG mode.

Q20. What Are The Steps Involved In Database Shutdown?

Close the Database; Dismount the Database and Shutdown the Instance.

Q21. One Of My Control File Corrupted And I Am Unable To Start Database. Could You Tell Me How To Perform Recovery?

If certainly one of your manipulate record is missing or corrupted then we've 2 alternatives to get better it. Check alert.Log for genuine name and location of corrupted manipulate file. Delete it manually and replica from available rest of manage report and rename it and begin database. Another choice is delete corrupted manage report and dispose of call from parameter document/ spfile. After doing away with said manipulate report from spfile, start your database.

Q22. What Is Mirrored On-line Redo Log?

A mirrored online redo log includes copies of on line redo log files bodily located on separate disks; adjustments made to at least one member of the group are made to all participants.

Q23. Why Export/data Pump Backup Called As Logical Backup?

Export and datapump sell off record would not backup or include any bodily structure of database like datafile, manage record, redo log file, parameter document, password record. Instead of bodily structure, export sell off incorporates logical structure of database like definition of tablespaces, segments, schemas, statistics of segments and so on. Due to those reasons export and datapump sell off is known as as logical backup.

Q24. What Are The Steps Involved In Database Startup?

Start an example, Mount the Database and Open the Database.

Q25. How Can I Know My Require Table Is Available In Export Dump File?

Create index report of export sell off report the use of import with index document command. A text document can be producing with all table and index item name with quantity of rows. You can affirm your require desk object from this text file. If you are using datapump then there may be parameter known as "sqlfile" in impdp.

Q26. What Is The Complete Recovery?

During this restoration we're making use of all database adjustments the usage of archives log and make it to up to date. Complete healing may be completed full database stage or datafile degree or tablespace level. Main idea is to use all facts adjustments the usage of archive logs and convey database up to recent time.

Q27. What Is The Meaning Of Lgwr Sync And Lgwr Async In Log Archive Destination Parameter Of Standby Configuration?

When use LGWR with SYNC, it me once network I/O initiated, LGWR has to watch for completion of community I/O before write processing. LGWR with ASYNC me LGWR doesn’t wait to complete community I/O and persevering with write processing.

Q28. How Do You Recover From The Loss Of Data File If Database Is Running In Archive Log Mode?

We can carry out this healing in 2 methods. One is open database mode and every other is database mount mode. After taking offline lost datafile, we are able to bring database open and after that repair misplaced datafile from ultimate backup. After recuperation of datafile we are able to carry out datafile degree healing for applying archive logs and make it online. In database mount mode, we can restore datafile from backup and carry out datafile restoration the usage of "Recover datafile" command.