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
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
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
In AWR, the ‘Top 10 Foreground Events’ table comes under the ‘Report Summary’ section. Refer to the below figure: The following metrics are available in the ‘Top 10 Foreground Events’ table of an AWR report: DB CPU It shows the total wait time for DB CPU and waiting %. Referring to Figure 01, the total … Read more
Following are the Performance Engineering Interview Questions Set #13. Q. 61 How can lock contention be identified in an AWR report? Ans: High wait events like “enq: TX- row lock contention” or “enq: TM- contention” indicate lock waits. The “Segments by Row Lock Waits” section shows which segments are involved. Q. 62 What does the … Read more
Following are the Performance Engineering Interview Questions Set #12. Q. 56 What role does the buffer cache play in database performance? Ans: The buffer cache stores copies of data blocks read from the disk. A properly sized buffer cache reduces physical I/O by satisfying requests from memory, thus improving performance. Q. 57 How can you … Read more