Oracle Performance Tuning Trivia Quiz!
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Do you know about performance tuning in the Oracle databases? Take this "Oracle Performance Tuning trivia quiz" and assess yourself. Performance tuning is the process of administering an Oracle database to improve performance. Database tuning strives to maximize system resources used to perform work efficiently and rapidly. Do you think you can answer all these questions in the quiz below? Play this quiz and check your knowledge for the same. All the very best!
- 1.
What best describes the relationship between indexes and SQL performance?
- A.
Indexes are only used in special cases
- B.
Indexes are used to make table storage more efficient
- C.
Indexes rarely make a difference in SQL performance
- D.
Indexes exist solely to improve query speed.
Correct Answer
D. Indexes exist solely to improve query speed.Explanation
The sole purpose of indexes in any relational database management system is to reduce the access time for SQL statements. The SQL optimizer can detect when and indexes present, and use sophisticated algorithms in order to determine the fastest way of accessing the data. If indexes did not exist in a relational database the Oracle database SQL optimizer would have no choice except to read every single row in the table.Rate this question:
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- 2.
Which of the following is not an important Oracle tuning metric?
- A.
Buffer hit ratio
- B.
Library cache hit ratio
- C.
Full-table scans
- D.
Buffer busy waits
Correct Answer
C. Full-table scansExplanation
This is because some applications read most of a table, in which case a full-table scan is the fastest way to access the table. Which of the following is not an important Oracle tuning metric? A, B, and C are all important indicators of how well optimized the performance is for the database.Rate this question:
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- 3.
Why is searching for large-table full-table scans critical to SQL tuning?
- A.
They indicate an optimized execution plan.
- B.
They may be able to be tuned to use an index
- C.
The full-table scan should be normalized from the database design
- D.
A full-table scan is always sub-optimal.
Correct Answer
B. They may be able to be tuned to use an indexExplanation
Full-table scans can be critical to SQL tuning because they may be able to be tuned to use an index. By utilizing an index, the query can retrieve the required data more efficiently, resulting in improved performance. This approach is preferred over a full-table scan, which reads every row in the table and can be resource-intensive. Therefore, identifying the possibility of tuning the scan to use an index is essential for optimizing the execution plan and enhancing the overall SQL performance.Rate this question:
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- 4.
Which of the following tuning techniques will NOT reduce the disk I/O for an Oracle query?
- A.
Add blocks to the SGA buffer pool
- B.
Created a clustered table
- C.
Create tables with redundant columns from other tables
- D.
Run parallel query against the table
Correct Answer
D. Run parallel query against the tableExplanation
This is because a parallel query will not decrease the amount of disk I/O, but performance will improve because there are multiple processes reading the database blocks. Which of the following tuning techniques will NOT reduce the disk I/O for an Oracle query? A, B, and C are incorrect because their purpose is to reduce disk I/O for a query.Rate this question:
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- 5.
Which of the following database design features is most important to SQL performance?
- A.
Removal of data redundancy
- B.
The introduction of data redundancy
- C.
The introduction of non-first normal form relations
- D.
The introduction of SQL*Plus
Correct Answer
B. The introduction of data redundancyExplanation
The introduction of data redundancy is the most important database design feature for SQL performance because it allows for faster and more efficient data retrieval. By duplicating certain data elements across multiple tables, it reduces the need for complex joins and improves query performance. This redundancy also enables the use of denormalized tables, which can further enhance performance by reducing the number of table scans and disk I/O operations required. Overall, data redundancy can significantly improve the speed and efficiency of SQL queries, making it a crucial design feature for optimizing performance.Rate this question:
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- 6.
All else being equal, which of the following tuning tasks is least likely to provide an improvement in performance?
- A.
De-normalization of the logical tables
- B.
Eliminating full-table scans from SQL queries
- C.
Moving Oracle data files from hot disks onto cool disks
- D.
Adding additional storage to the SGA shared pool
Correct Answer
D. Adding additional storage to the SGA shared poolExplanation
The correct answer is D, adding additional storage to the shared pool. This is because the shared pool size will only help to speed-up loads of PL/SQL packages and SQL statements. Which of the following tuning tasks is least likely to provide an improvement in performance? A is incorrect because the de-normalization of logical tables can be a huge performance booster. B is incorrect because unnecessary full-table scans are often the cause of poor performance. C is incorrect because disk load balancing can make a huge positive impact on performance.Rate this question:
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- 7.
Which of the following is an important consideration when tuning an SQL statement?
- A.
The number of CPUs on the server
- B.
The degree of parallelism on the tables
- C.
The quality of the SQL optimization
- D.
The use of bitmap indexes
Correct Answer
C. The quality of the SQL optimizationExplanation
When tuning an SQL statement, the quality of the SQL optimization is an important consideration. This refers to how well the SQL statement is written and structured to efficiently retrieve the desired data. A poorly optimized SQL statement can result in slower performance and increased resource usage. Therefore, it is crucial to ensure that the SQL statement is optimized for maximum efficiency in order to improve query performance and overall system performance.Rate this question:
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- 8.
What areas of Oracle tuning have the most impact on system performance?
- A.
Logical design tuning
- B.
Physical design tuning
- C.
SGA tuning
- D.
SQL tuning
Correct Answer
A. Logical design tuningExplanation
This is because a good logical design will greatly minimize disk I/O, since less work is required to retrieve the desired information. What areas of Oracle tuning have the most impact on system performance? B is incorrect because physical tuning will only optimize tables that have already been designed. C is incorrect because SGA tuning has far less impact than design. D is incorrect because no amount of SQL tuning can compensate for a bad design.Rate this question:
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- 9.
Which of the following is an important feature of relational databases and SQL?
- A.
Independence of table relationships
- B.
High speed of SQL
- C.
Powerful GUI front-end
- D.
Easy to install and use
Correct Answer
A. Independence of table relationshipsExplanation
Relational databases and SQL have an important feature of independence of table relationships. This means that tables in a database can be related to each other through common fields, allowing for efficient and organized data storage and retrieval. This feature ensures data integrity and consistency by enforcing referential integrity constraints. It also allows for flexibility in modifying and updating the database structure without affecting the data stored in other tables. Overall, the independence of table relationships is a fundamental aspect of relational databases and SQL that enables efficient data management and analysis.Rate this question:
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- 10.
Identify the correct statement about the Active Session History (ASH) data.
- A.
A part of SGA memory is used to store ASH data as rolling buffer.
- B.
All ASH data in memory are flushed to disk by MMNL process whenever the buffer is full.
- C.
All ASH data in memory are flushed to disk by MMON in every 3 seconds.
- D.
None of the above
Correct Answer
A. A part of SGA memory is used to store ASH data as rolling buffer.Explanation
The correct statement about the Active Session History (ASH) data is that a part of the SGA memory is used to store ASH data as a rolling buffer. This means that the ASH data is continuously overwritten in the memory, allowing for a continuous capture of session activity. This rolling buffer approach helps in capturing and analyzing the recent session activity efficiently without consuming excessive memory resources.Rate this question:
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- 11.
In which case is the database buffer cache NOT used?
- A.
When physical I/Os are performed to read from data files
- B.
When the database writer process writes to the SYSTEM tablespace
- C.
When the server process writes sort data to the temporary tablespace
- D.
When the database writer process writes undo data to the undo tablespace
Correct Answer
C. When the server process writes sort data to the temporary tablespaceExplanation
The database buffer cache is used to store frequently accessed data blocks in memory, reducing the need for physical I/Os to read from data files. However, when the server process writes sort data to the temporary tablespace, it does not use the database buffer cache. This is because sort data is temporary and does not need to be stored in memory for future access. Instead, it is written directly to the temporary tablespace on disk.Rate this question:
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- 12.
Which statements are true about performance analysis by SQL Performance Analyzer?
- A.
It detects changes in SQL execution plans.
- B.
It produces results that can be used to create the SQL plan baseline.
- C.
It generates recommendations to run SQL Tuning Advisor to tune regressed SQL statements.
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
Performance analysis by SQL Performance Analyzer includes the detection of changes in SQL execution plans. It also produces results that can be used to create the SQL plan baseline. Additionally, it generates recommendations to run SQL Tuning Advisor to tune regressed SQL statements. Therefore, all of the given statements are true about performance analysis by SQL Performance Analyzer.Rate this question:
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- 13.
What indicates that the rate of writing data blocks to the disk is very slow?
- A.
Very high cache-hit ratio
- B.
Increasing number of free buffer waits
- C.
increasing number of buffer busy waits
- D.
Waits on latch: cache buffers chains event
Correct Answer
B. Increasing number of free buffer waitsExplanation
An increasing number of free buffer waits indicates that the rate of writing data blocks to the disk is very slow. When data blocks need to be written to the disk, but there are no free buffers available in the cache, the system has to wait for a buffer to become available. This wait time increases as the number of free buffer waits increases, indicating a slow rate of writing data blocks to the disk.Rate this question:
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- 14.
In which scenarios would you recommend using RAID level 5 as an option for database storage?
- A.
For a database with lower recovery (MTTR) overhead
- B.
For a database in which the applications primarily perform read operations and predominantly sequential I/O is performed
- C.
For a database in which performance is the primary goal of the database because applications are demanding in terms of I/O operations
- D.
None of the above
Correct Answer
B. For a database in which the applications primarily perform read operations and predominantly sequential I/O is performedExplanation
RAID level 5 is recommended for a database in which the applications primarily perform read operations and predominantly sequential I/O is performed. This is because RAID level 5 provides good read performance and can handle sequential I/O efficiently. It uses striping with distributed parity, which allows for data to be read from multiple disks simultaneously, improving read performance. Additionally, the distributed parity allows for data recovery in case of a disk failure, reducing the recovery overhead. Therefore, RAID level 5 is a suitable option for a database with a focus on read operations and performance.Rate this question:
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- 15.
Identify the reason why chained or migrated rows in a table cause performance degradation when you access them.
- A.
Because the ROWID changes for these rows
- B.
Because these rows make existing indexes invalid
- C.
Because it is not possible to use indexes to retrieve these rows
- D.
Because retrieving these rows requires more than one data block to be accessed
Correct Answer
D. Because retrieving these rows requires more than one data block to be accessedExplanation
Chained or migrated rows in a table cause performance degradation when accessed because retrieving these rows requires more than one data block to be accessed. This means that the database needs to perform additional I/O operations to retrieve the complete row, resulting in slower performance.Rate this question:
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- 16.
While configuring the snapshot data capture for your database, you have specified the snapshot level setting as 6.Which statistics would be captured by the Statspack report?
- A.
Resource limit
- B.
memory statistics
- C.
Optimizer execution plans
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
The correct answer is "All of the above". When the snapshot level setting is specified as 6, the Statspack report captures resource limit statistics, memory statistics, and optimizer execution plans. This means that all of these statistics will be included in the report, providing a comprehensive overview of the database's performance and resource usage.Rate this question:
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- 17.
During a proactive database performance monitoring routine, on examining the AWR report you find that log file sync appears among the top 5 wait events. What does this event indicate?
- A.
Frequent logfile switches are occurring.
- B.
Redo is generated faster than LGWR can write it out.
- C.
Frequent commits or rollbacks are taking place in the application.
- D.
Frequent incremental checkpoints are taking place in the database.
Correct Answer
C. Frequent commits or rollbacks are taking place in the application.Explanation
The "log file sync" event in the AWR report indicates that frequent commits or rollbacks are taking place in the application. This event occurs when a user session waits for a redo log buffer to be written to disk. In other words, it means that the application is frequently committing or rolling back transactions, causing the system to wait for the log buffer to be synchronized with the redo log files on disk. This can be a performance bottleneck and may indicate a need for optimization or tuning in the application.Rate this question:
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- 18.
You analyze an Automatic Database Diagnostic Monitor (ADDM) report to identify the component that contributes most to the database time. Which is the correct description of database time?
- A.
It is the sum of the CPU time of all nonidle sessions.
- B.
It is the sum of wait time and the CPU time of all nonidle sessions.
- C.
It is the time spent in processing the input/output (I/O) request by users.
- D.
It is the difference between the wait time and the CPU time of all nonidle sessions.
Correct Answer
B. It is the sum of wait time and the CPU time of all nonidle sessions.Explanation
The correct answer is that database time is the sum of wait time and the CPU time of all nonidle sessions. This means that it includes both the time spent waiting for resources and the time spent actively processing tasks. By considering both wait time and CPU time, the analysis can identify the component that contributes the most to the overall time spent by the database.Rate this question:
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- 19.
You enabled tracing for a session by executing the following command: SQL>SET AUTOTRACE TRACEONLY; You issued a SQL query in the same session. Which two statements are true?
- A.
Trace for the statement would be created without displaying the query output.
- B.
It generates a report on the execution path used by the SQL optimizer and the statement execution statistics.
- C.
Above A and B
- D.
It generates only the statement execution statistics without executing the query.
Correct Answer
C. Above A and BExplanation
The command "SET AUTOTRACE TRACEONLY" enables tracing for a session without displaying the query output. This means that the trace for the statement would be created, but the query result would not be shown. Additionally, this command generates a report on the execution path used by the SQL optimizer and the statement execution statistics. Therefore, both statements A and B are true.Rate this question:
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