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LOB pctversion vs retention definition

Michael ElkinMar 26 2009 — edited Mar 26 2009
I am trying to understand the difference between pctversion and retention definitions of LOB column.
I am using outline LOB (5.5Kb size) that is stored in ASSM tablespace with UNIFORM size .

If i create a LOB without any settings then default is RETENTION that is derived from UNDO_RETENTION of the instance.
In addition i can see in user_lobs PCTVERSION is set to 10 which is a default value.

The question is what definition is taken precedence RETENTION or PCTVERSION ?

What is the exact meaning of RETENTION inside the LOB definition , does it mean that previous LOB pages are not overwritten for the UNDO_RETENTION period of time ?

My application is running massive update commands against LOB column with very few select statemnets .
I see that my LOB Segment is growing and application is waiting for "enq HW contention" wait.

Thank you

Michael
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Locked on Apr 23 2009
Added on Mar 26 2009
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