| Considerations for SGA.. [message #56847] |
Wed, 30 April 2003 06:56  |
Naveen
Messages: 75
Registered: June 2001
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Member |
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Hi,
I am desiginging a new database. Is there anyway to estimate the size of SGA. What should be the optimum SGA. I know few steps to be followed to estimate the database size(estimating the table size, index etc). I would be thankful if some one could give me a link which delas with SGA and Database size estimation. I would like to know the real time process followed by you DBAs out there.
Thank you.
Naveen.
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| Re: Considerations for SGA.. [message #56848 is a reply to message #56847] |
Wed, 30 April 2003 07:59  |
Anand
Messages: 161
Registered: August 1999
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Senior Member |
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Ideally, SGA can't be more than 2/3rds of the total main memory in the system. SGA sizing can based on the following criterions:
1. Memory
2. No. of users expected to use the system
3. Volume of activity expected in the system...sorts, # of objects etc.
You need to design the Buffer pool, db_block_buffer, shared pool accordingly. There is no ideal number for these. The best way is to observe the performance for a couple of days and during peak time, and increase the size if performance is not good. No DBA sets all the values well in advance and starts the database. It's over a period of time. Load my differ over a period of time, volume may differ.
Even, too much of SGA can hamper the performance of the system.
Check out the metalink and asktom sites for expert opinions/technical notes
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