DBA Interview Questions

1. Explain how you would restore a database using RMAN to Point in Time?
   
2. How does Oracle guarantee data integrity of data changes?
   
3. Which environment variables are absolutely critical in order to run the OUI?
   
4. What SQL query from v$session can you run to show how many sessions are logged in as a particular user account?
   
5. Why does Oracle not permit the use of PCTUSED with indexes?
   
6. What would you use to improve performance on an insert statement that places millions of
   rows into that table?
   
7. What would you do with an "in-doubt" distributed transaction?
   
8. What are the commands you?d issue to show the explain plan for "select * from dual"?
   
9. In what script is "snap$" created? In what script is the "scott/tiger" schema created?
   
10. If you?re unsure in which script a sys or system-owned object is created, but you know it?s in a script from a specific directory, what UNIX command from that directory structure can you run to find your answer?
    
11. How would you configure your networking files to connect to a database by the name of DSS which resides in domain icallinc.com?
    
12. You create a private database link and upon connection, fails with: ORA-2085: connects to . What is the problem? How would you go about resolving this error?
    
13. I have my backup RMAN script called "backup_rman.sh". I am on the target database. My catalog username/password is rman/rman. My catalog db is called rman. How would you run this shell script from the O/S such that it would run as a background process?
    
14. Explain the concept of the DUAL table.
    
15. What are the ways tablespaces can be managed and how do they differ?
    
16. From the database level, how can you tell under which time zone a database is operating?
    
17. What?s the benefit of "dbms_stats" over "analyze"?
    
18. Typically, where is the conventional directory structure chosen for Oracle binaries to reside?
    
19. You have found corruption in a tablespace that contains static tables that are part of a database that is in NOARCHIVE log mode. How would you restore the tablespace without losing new data in the other tablespaces?
    
20. How do you recover a datafile that has not been physically been backed up since its creation and has been deleted. Provide syntax example.
    

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