Re: question about automatic undo management

I've tried to stress a 9.2.0.2 system which large numbers of transactions, but at present I've only managed to get transactions sharing an undo segment when it is no longer possible to create a new segment in the tablespace.

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Jonathan Lewis
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Howard J. Rogers wrote in message
<_VQX9.31337$jM5.80372_at_newsfeeds.bigpond.com>...


>

>Incidentally, do you know any details about the modified allocation

policy


>that automatic undo uses for transactions?  Allegedly, it goes

something


>like 'assign each transaction to its own segment, until you reach a

point


>where you feel it appropriate to start sharing existing ones'...

though a


>bit of testing this end (in an 8GB undo tablespace, so plenty of room

for


>growth!) has indicated times when transactions 1 to 10 are assigned

to their


>own pre-existing segments, transaction 11 shares an existing segment,

and


>transaction 12 causes a new segment to be created. Transaction 13

then


>started sharing again. So it's rather more complicated than Oracle

are


>letting on!

>