Popular interview questions for DBA

1. What are the differences between database designing and database modeling?
2. If the large table contains thousands of records and the application is accessing 35% of the table, which method do you use: index searching or full table scan?
3. In which situation whether peak time or off peak time you will execute the ANALYZE TABLE command. Why?
4. How to check to memory gap once the SGA is started in Restricted mode?
5. All the users are complaining that their application is hanging. How you will resolve this situation in OLTP?
6. If the SQL * Plus hangs for a long time, what is the reason?
7. Shall we create procedures to fetch more than one record?
8. How do you increase the performance of %LIKE operator?
9. You are regularly changing the package body part. How will you create or what will you do before creating that package?
10. How can you see the source code of the package?
11. Dual table explain. Is any data internally storing in dual table.
12. Lot of users are accessing select sysdate from dual and they getting some millisecond differences. If we execute SELECT SYSDATE FROM EMP; what error will we get. Why?
13. In exception handling we have some NOT_FOUND and OTHERS. In inner layer we have some NOT_FOUND and OTHERS. While executing which one whether outer layer or inner layer will check first?
14. What is mutated trigger, is it the problem of locks. In single user mode we got mutated error, as a DBA how you will resolve it?
15. Schema A has some objects and created one procedure and granted to Schema B. Schema B has the same objects like schema A. Schema B executed the procedure like inserting some records. In this case where the data will be stored whether in Schema A or Schema B?
16. What is bulk SQL?
17. How to do the scheduled task/jobs in Unix platform?
18. If the entire disk is corrupted how will you and what are the steps to recover the database?
19. How will you monitor rollback segment status?
20. List the sequence of events when a large transaction that exceeds beyond its optimal value when an entry wraps and causes the rollback segment to expand into another extend?
21. What is redo log file mirroring?
22. How can we plan storage for very large tables?
23. When will be a segment released?
24. What are disadvantages of having raw devices?
25. List the factors that can affect the accuracy of the estimate?
26. What is the difference between $$DATE$$ & $$DBDATE$$? - $$DBDATE$$ retrieves the current database date$$date$$ retrieves the current operating system.
27. How to prevent unauthorized use of privileges granted to a Role?
28. What is a deadlock and Explain?
29. What are the basic element of base configuration of an Oracle database?
30. What is an index and How it is implemented in Oracle database?
31. What is the use of redo log information?
32. What is a schema?
33. What is Parallel Server?
34. What is a database instance and Explain?
35. What is a datafile?
36. What is a temporary segment?
37. What are the uses of rollback segment?