From: Kevin Lewis
Date: January 21 2009 5:37pm
Subject: Re: When you have a chance...
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 > Vladislav Vaintroub wrote:
 >
 > Interesting, I still do not get it, why we checking for uniqueness during
 > garbage collection? We have no possibility to report an error to user at
 > this stage.

No, these are two separate activities by separate threads.  Checking for 
uniqueness is done by a client thread doing an insert or update. 
Garbage Collection is being done outside a transaction by the scavenger, 
usually, and inside a transaction by releaseSavepoint.  But 
releaseSavepoint is not the problem because the base record is owned by 
the transaction doing it.  The problem is garbage collection by the 
scavenger, now running-a-muck more than before.