Oracle Performance Tuning Trivia Quiz!

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.