Re: Lob chunk updates
- From: "Tanel Poder" <tanel.poder.003@xxxxxxx>
- To: "" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 17 Mar 2004 22:58:50 +0200
> Anyone notice this? 50 concurrent updaters for a
> table's LOB stored out-of-line are serialized on
> the HW enqueue, unless truncated.
Because of read consistency reasons, Oracle never overwrites the lobchunk upon
update, it stores a new copy in available space instead. The period how long
the old copies are retained before can be overwritten by other transactions
depends on your PCTVERSION or RETENTION settings on the lobsegment.
For a freshly created out-of-line lob this might cause lob segment growing (HWM
increases = HW enqueue gets) upon first updates, but should stabilize after a
while, when old chunks start to get overwritten.
If you're on 9i, start with checking RETENTION setting on your LOB segment.
Tanel.
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