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Good day,
I'm currently busy with a physical database design for a DSS db. The relevant data mart estimate size is +- 60G. I'm now planning the rollback segments, but get inconsistent information from documentation.
I read in different documents to have 4 rollback segments per concurrent transaction and rollback segment size should be 10% of largest table, etc.
In document "How to stop decrementing and start living" the author suggests a rollback table space should have between 1024 and 4096 extents with between 1/8 and 1/16 of extents as number of rollback segments in table space.
What is the ideal solution?
Thanks
Johan
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Hi,
The Normal way of designing the RBS is say for eg
if u need 10 RBS then 3 must be large enough to handle very large tables and 7 must be small for small transactions. If the transaction is complex then specify the rolback segment name so that u can assign that particular rbs to that transaction else oracle will dynamically allocate rbs so can face snapshot too old error.
See the transaction rate and design ur RBS
Shiva
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Hi,
The number of RBS for OLAP should be high and the size of RBS should be less.
For DSS, the number of RBS should be less but the size of the RBS should be large enough to hold the transaction without extends and wraps.
Better if you know that larger transaction assign them to a RBS of larger size. Set the optimal size of the RBS to 5 times greater than the size of (initial+next) extents to avoid too many shrinks.
If you need a script to detect RBS shrinks and wraps mail me,and I'll send it to you.
Best of Luck
[email protected]
