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Re: DBA Claim: Increasing SGA will reusult in more CPU Activity. True or False?

 
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Eric Antunes
Honored Contributor

Re: DBA Claim: Increasing SGA will reusult in more CPU Activity. True or False?

Hi Nelson,

In this case, a good idea would be to use the formula twice - at day and at night - and calculate the average of those 2 numbers. If you can do this and give us some feedback it would be nice.

Best Regards,

Eric
Each and every day is a good day to learn.
Alzhy
Honored Contributor

Re: DBA Claim: Increasing SGA will reusult in more CPU Activity. True or False?

Eric, that's what others are leaning.. make statspak analysis during batch, during online and during hybrid operation periods and get NOT the average but the biggest cache requirement.

And that's what I am leaning too. We've money to burn, we can even grow the partition to double the RAM (128GB to 256GB) .. why not increase SGA significantly so during our problematic "hybrid" operation hours -- those DSS like queries and jobs are effectively addressed.

Your thoughts?
Hakuna Matata.
Eric Antunes
Honored Contributor

Re: DBA Claim: Increasing SGA will reusult in more CPU Activity. True or False?

Nelson,

Probably you will get more SGA requirements in the hybrid period but, as I said before, it is a good idea to check this within each period and tune the SGA accordingly for the most demanding period (yes, not the average as I said before...).

Executing the queries above or the one in Metalink Note 105813.1 - "SCRIPT TO SUGGEST MINIMUM SHARED POOL SIZE" you will get a minimum SGA. Add some overhead to it but don't overshoot it:

- An undersized SGA database will be poor in performance;

- An overshooted SGA database will more likely cause ORA-04031 errors due to high fragmentation (see Note 396940.1 - "FAQ: ORA-4031").

Finally, if you are on 10g, you may have advantages in using Automatic Shared Memory Management (SGA_TARGET parameter)...

Best Regards,

Eric Antunes
Each and every day is a good day to learn.
Eric Antunes
Honored Contributor

Re: DBA Claim: Increasing SGA will reusult in more CPU Activity. True or False?

Nelson,

One more thing. What is your shared_pool_reserved_min_alloc?

Best Regards,

Eric Antunes
Each and every day is a good day to learn.