A publick rollback segment is available to all Database instances and is brought online when the database is started.( For more then one instances)
Whereas, a private rollback segment is available only to the instance that brings the rollback segment online.( For one instance only)
So a public rollback segment is a kind of public property that's why we need not to make an entry in init parameter of a single database's init.ora file.
Hope it helps
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I could imagine value for transactions_per_rollback_segment but what could be the value for transaction prameter at any point of time . ( i believe a transaction is said to be completed, when commit is issued ) does this mean that number of transactions = number of process / sessions connected to the instance ?
I could imagine value for transactions_per_rollback_segment but what could be the value for transaction prameter at any point of time .
One way to figure that out (in a big database) is to shedule a job run every 5' minute within say 24 hours. The job would execute a function which returns count(*) from v$transaction; and inserts the value amount in some temp table, call it T1. Then you can select avg(amount) from T1; This would give you the approximate/avg amount of transactions at a given point of time. You don't have to run the function every 5' in 24 hours. You may as well run it every minute within 2 hours or so.
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