anybody can tell me when does wrap means and when did it happen (v$rollstat) ?
See wraps happen when Rollback segment writes from one extent to the next available extent.Here the word (AVAILABLE EXTENT) is important as rollback segment will not allocate a new extent but it will write to the next existing extent.
When the next existing extent is being used by another transaction ,then RBS will allocate a new extent which is called a EXTEND.
Wrapping is more beneficial and advantageous since Oracle doesnot have to allocate a new extent.RBS will use the next extent if it is free.
e.g Ur Rollback segment is of following parameters
Transacation A is started and will use the extent no 1.The transaction is still running so it will go to the next extent i.e No2 ,if it is free.If it is free then it is called a wrap.
If it is not free and is used by some other transaction then RBS will allocate another extent and it calls it as extend.
In case of any help please be free to ask me at email@example.com
Rohit Nirkhe,Oracle DBA,OCP 8i
does that means if we notify lot of wraps, we don't really care.
but if we notice some extends, we need to figure out if rollback segment is too small.
am i right?
guru is on the way!!!!
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