DD-Cache quality % is low after SHARED_POOL_SIZE increase

[Former Member]

Hi Basis Consultant,

My shared_pool_size value was 600 MB and the details in ST04

was:

Shared Pool

Size kb 638.976

DD-Cache quality % 79,1

SQL Area getratio % 95,6

pinratio % 98,7

reloads/pins % 0,0263

Now i changed the value to 850MB as SAP recommendations

and the details in ST04 is:

Shared Pool

Size kb 835.584

DD-Cache quality % 50,9

SQL Area getratio % 92,0

pinratio % 97,2

reloads/pins % 0,0511

My doubt is:

The value DD-Cache quality should not increase as i have changed the value ?

I know that this value should be > 90% and for this reason i am changing this value.

My oracle version is 9.2.0.6

Best Regards,

Fábio Karnik Tchobnian

[former_member204746 · Accepted solution]

wait a few hours, or better yet, a few days. Then check these stats again, they should improve.

If not, then maybe you have a lot of activity (maybe overnight) such as huge BW loads.

[Former Member]

Hi,

As Eric points out, you should always wait until your database has reached "cruising altitude" (e.g. after a full working day) before evaluating the efficiency of the Oracle shared pool or data cache. If you stick to that rule and still see a poor hit rate, then querying the Oracle views V$ROWCACHE, V$LIBRARYCACHE and V$SHARED_POOL_ADVICE will enable you to have a closer look at where the problem might be and whether extending the shared pool would help.

Regards,

Mark