[open] Performance of Database

Question

Hello Gurus
I have around 5 databases Dev01,Dev02,Dev03,Dev04,Dev05 in my server
To increase the performance of one Dev04 DB i decrease the resources(sga_max_size,shared_pool_size,db_cache_size) for other DBs and increase the resources of Dev04 DB upto maximun extended
But i am observered the performance of Dev04 DB is poor
Is there any suggestion/tricks to increase or decraese resources for DB to perform better
Thanks in advance

Answer 1

It would be a little tough to say what to do with the information that you have provided. The first most important missing part is the database version(4 digits). Alot has changed with the versions so what and why can be different based on it.
It would be required for you to see that what's happening on the Dev 4 db that its slow. The parameters , even though given generously doesn't gurantee that there would be a performance boost all the time. If there is a hard parse issue in the statements itself than it won't matter how much shared pool you allocate,it will eventually get filled up. Changing the parameter and expecting performance gain is called instance tuning and its highly unlikely that it would be of much use.
You have mentioned high resource utilization in the db. Did you check that in the system itself is not choked up due to resource crunch? There are commands like sar, top, vmstat which can help you in doing this. The objective is to remove anything over the o/s itself which is causing it.
Once you are done with this, you should come to the db and check which are the areas that may have beocme the contention point,for example, due to heavy parsing of the statemen aka hard parsing of the statements, cpu would be used veyr heavily. This may cause the resource crunch also. The best way to check this would be to generate STatspack or AWR report, depending on the version of your db. Generate that and post it here than it would be a little accurate to advice you over the performance gain.
HTH
Aman....