Performance Engineering Interview Questions #17

Performance Engineering Interview Questions 17

Following are the Performance Engineering Interview Questions Set #17. Q. 81 Is a high buffer cache hit ratio always indicative of good performance? Ans: Not necessarily. While a high hit ratio means most data requests are served from memory, it doesn’t account for inefficient queries or unnecessary data access patterns. It’s important to look at … Read more

Performance Engineering Interview Questions #16

Performance Engineering Interview Questions 16

Following are the Performance Engineering Interview Questions Set #16. Q. 76 Explain the “latch: cache buffers chains” wait event and its impact. Ans: This wait event indicates contention for cache buffer chain latches, which protect the hash chains of buffer headers in the buffer cache. High waits suggest hot blocks or heavy concurrent access to … Read more

Performance Engineering Interview Questions #15

Performance Engineering Interview Question 15

Following are the Performance Engineering Interview Questions Set #15. Q. 71 How can you reduce the ‘Buffer Busy Waits’ identified in the AWR report? Ans: It can be reduced by: Q. 72 What are wait events in Oracle, and why are they important for performance analysis? Ans: Wait events represent the time sessions wait for … Read more

Performance Engineering Interview Questions #14

Performance Engineering Interview Questions 14

Following are the Performance Engineering Interview Questions Set #14. Q. 66 What is the difference between ‘db file sequential read’ and ‘db file scattered read’ wait events? Ans: The ‘db file sequential read’ indicates single-block reads, often associated with index lookups whereas ‘db file scattered read’ involves multi-block reads, typically from full table scans or … Read more

AWR – Host CPU

AWR - Host CPU

In AWR, the ‘Host CPU’ table comes under the ‘Report Summary’ section. Refer to the below figure: The following metrics are available in the ‘Host CPU’ table of an AWR report: CPUs The number of CPUs is the product of the number of cores and threads available on the database server. Formula: CPU = Number … Read more

AWR – Wait Classes by Total Wait Time

In AWR, the ‘Wait Classes by Total Wait Time’ table comes under the ‘Report Summary’ section. Refer to the below figure: To analyse this section, firstly check for the ‘Wait Class’ column. If User I/O, System I/O and Others have moderate ‘Waits’ value then it is fine. But if ‘Concurrency’ under the wait class has … Read more