Oracle Performance Tuning Mock Interview

Master 30 Oracle Performance Tuning interview questions covering SQL optimization, indexing strategies, and execution plans.

Question 15 of 30

Can you describe the purpose of an Oracle SQL execution plan?

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William Swansen

William Swansen has worked in the employment assistance realm since 2007. He is an author, job search strategist, and career advisor who helps individuals worldwide and in various professions to find their ideal careers.

While you are interviewing for a specific job that involves optimizing an Oracle database, you're likely to be asked questions about all the functions and components of the DBMS. Interviewers ask these types of questions to confirm that you have a complete understanding of the Oracle environment and can use all of the commands, variables, and other items within Oracle to tune and optimize the database. The interviewer may also ask you questions about related topics such as applications, storage, memory, and other components of a system that impact Oracle's performance.

William Swansen

It is virtually impossible to know every item, component, command, and issue impacting an Oracle database's performance. Interviewers know this and will not expect you to know everything. However, you are expected to know the most important things, the common issues you will encounter, and the commands used to execute common tasks required of an Oracle administrator. Reviewing these before the interview will help prepare you for the majority of questions you will be asked. It is perfectly acceptable to admit that you do not know an answer to an interviewer's question as long as you can describe how you would locate the information needed to perform the task they describe.

William Swansen

"The purpose of an oracle SQL execution plan is to create a road map of how Oracle DBAs execute SQL. This helps Oracle administrators structure the database, create the tables, and execute SQLs to provide the information and data needed by the users to perform their jobs."

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30Oracle Performance Tuning Interview Questions & Answers

General

1.In your opinion, what is performance tuning?

General

2.What are some of the different types of tuning you can perform in an Oracle environment?

General

3.What are some of the elements you can tune to optimize an Oracle database?

General

4.In the context of an Oracle database, what does an optimizer do?

Operational

5.Can you discuss the different types of optimizers you use?

Technical

6.Describe the init parameter used to make use of an Oracle database optimizer?

General

7.In your opinion, which optimizer is the best one for most Oracle database tuning?

Operational

8.What are some of the prerequisites needed to use an Oracle database optimizer?

Technical

9.What is the most direct way to collect statistics on a database table?

Technical

10.What is the difference between using compute and estimate?

Technical

11.Which optimizer mode does the data dictionary follow?

Technical

12.What command can you use if you want to see the statistics of an Oracle table?

Operational

13.What is the easiest way to collect statistics of a single user in Oracle Apps?

Operational

14.What commands would you use if you didn't know what SQL is currently being used by a session?

Operational

15.Can you describe the purpose of an Oracle SQL execution plan?

Technical

16.What would you do if you needed to get the index of a table and identify which column the index is on?

Operational

17.What method would you use if you want to see the trace files in an Oracle database?

Technical

18.What types of wait events can be tuned to improve the performance of an Oracle database?

Technical

19.If the database tablespace has a table with 40 extents, does it need to be tuned? What other issues can impact this?

Technical

20.How can you assure the appropriate separation of the segments of the tablespaces when installing an Oracle database?

Technical

21.What should you check first if you see multiple fragments in the SYSTEM tablespace?

Technical

22.How would you know that the SHARED_POOL_SIZE parameter needs to be increased?

Operational

23.What guidelines do you typically follow when sizing the database block size and multi-block read for an application that does a lot of full-table scans?

Technical

24.Can you explain the use of TKPROF and the initialization parameter which needs to be used to get full TKPROF output?

Technical

25.Is it a problem when you see that disk sorts are high when you run the v$sysstat command, and how would you correct this?

Technical

26.When should copy latches be increased, and what parameters are used to do this?

Technical

27.Where do you find the list of all the initialization parameters for your instance, and how do you know if they are the default settings?

Technical

28.Can you describe the hit ratio in the context of database buffers? Also, do you use the instantaneous or cumulative hit ratio for tuning?

Technical

29.Please discuss row chaining, how it happens, and how it can be reduced or corrected.

Operational

Oracle Performance Tuning Mock Interview

Can you describe the purpose of an Oracle SQL execution plan?

30Oracle Performance Tuning Interview Questions & Answers

1.In your opinion, what is performance tuning?

2.What are some of the different types of tuning you can perform in an Oracle environment?

3.What are some of the elements you can tune to optimize an Oracle database?

4.In the context of an Oracle database, what does an optimizer do?

5.Can you discuss the different types of optimizers you use?

6.Describe the init parameter used to make use of an Oracle database optimizer?

7.In your opinion, which optimizer is the best one for most Oracle database tuning?

8.What are some of the prerequisites needed to use an Oracle database optimizer?

9.What is the most direct way to collect statistics on a database table?

10.What is the difference between using compute and estimate?

11.Which optimizer mode does the data dictionary follow?

12.What command can you use if you want to see the statistics of an Oracle table?

13.What is the easiest way to collect statistics of a single user in Oracle Apps?

14.What commands would you use if you didn't know what SQL is currently being used by a session?

15.Can you describe the purpose of an Oracle SQL execution plan?

16.What would you do if you needed to get the index of a table and identify which column the index is on?

17.What method would you use if you want to see the trace files in an Oracle database?

18.What types of wait events can be tuned to improve the performance of an Oracle database?

19.If the database tablespace has a table with 40 extents, does it need to be tuned? What other issues can impact this?

20.How can you assure the appropriate separation of the segments of the tablespaces when installing an Oracle database?

21.What should you check first if you see multiple fragments in the SYSTEM tablespace?

22.How would you know that the SHARED_POOL_SIZE parameter needs to be increased?

23.What guidelines do you typically follow when sizing the database block size and multi-block read for an application that does a lot of full-table scans?

24.Can you explain the use of TKPROF and the initialization parameter which needs to be used to get full TKPROF output?

25.Is it a problem when you see that disk sorts are high when you run the v$sysstat command, and how would you correct this?

26.When should copy latches be increased, and what parameters are used to do this?

27.Where do you find the list of all the initialization parameters for your instance, and how do you know if they are the default settings?

28.Can you describe the hit ratio in the context of database buffers? Also, do you use the instantaneous or cumulative hit ratio for tuning?

29.Please discuss row chaining, how it happens, and how it can be reduced or corrected.

30.The ESTAT events report indicates that you are getting busy buffer waits. What method can you use to find out what is causing this?