RE: RAC PARALLEL
Date: Fri, 14 Oct 2011 06:49:59 +0000
>> Can you please suggest as how the Top 5 Events suggest to go
>> fortuning the topmost SQL in "SQL Ordered by Reads"
The reason you need to look at the top few SQL statements "ordered by reads" is because your top 5 events are:
db file sequential read 32,512,212 200,101 8 69.58 User I/O
DB CPU 40,112 11.30
db file scattered read 2,123,189 29,289 13 10.51 User I/O db file parallel read 161,091 4,058 25 2.01 User I/O PX Nsq: PQ load info query 20,702 3,689 189 1.23 Other
69.59% of your wait (Sorry Cary!) events are db file sequential reads. A further 10.51% are db file scattered reads and 2.01% are db file parallel reads.
"Reads" is the clue, your top 5 wait events are predominantly "reads". So, you look for the SQL doing the most reads and tune them. And don't forget, the best way to tune an SQL statement is not to execute it - so, don't retrieve data unless you have to.
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