Re: VACUUM and open transactions

[Joseph S <jks(at)selectacast(dot)net>]

The serializable transaction  *can't* see those rows, they were created 
and obsoleted after the start of the transaction.  The point of make the 
transaction serializable in the first place was to allow VACUUM to 
reclaim those rows.

Alvaro Herrera wrote:
> Joseph S wrote:
> > I realize this thread is old, but I just conducted an experiment with pg 
> > 8.0.10 and a transaction with a SERIALIZABLE isolation level does 
> > prevent VACUUM from reclaiming rows that were created and then obsoleted 
> >  in a subsequent transaction.
>
> Right.  This is expected.  VACUUM cannot remove them because the
> serializable transaction might still want to see those rows.  (I am
> assuming the serializable transaction is still running when the vacuum
> starts.  If that's not the case, please explain better).