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Quick and probably easy question for the resident experts in the house!
I have just reconfigured my rollback segments, but I was wondering, are wraps good or bad? and is there a way of eliminating them?
Rich
Rich H
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If you imagine your rollback segments as a ring, with the head moving around the ring. When the head has moved around once that is a wrap. A high number of wraps indicate you shoud increase the size of your rollback segments, or allocate new ones. Wraps are not a problem unless the 'head' starts overwriting 'inactive in use' data' - that is data that is not part of an active insert/update etc, but is being read by a long running query for read consistency. If this happens you will get "SNAPSHOT TOO OLD " errors in the long running SQL. If this isnt happening then your wrapping is probably ok....
-B
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it seems to be better than the last time, now I have no WAITS or EXTENDS which I had few of before.
Rich H
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how can i know the no. of wraps in a rbs....
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use v$rollstat, that will provide you with most of the info. use v$rollname to get the rollback segments name.
Rich H
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