Re: Set visibility map bit after HOT prune

On Thursday, December 20, 2012 6:14 AM Robert Haas wrote:
> On Wed, Dec 19, 2012 at 12:39 PM, Simon Riggs <simon@2ndquadrant.com>
> wrote:
> > The benefit of saying that only UPDATEs clean the block is that this
> > penalises only the workload making the mess, rather than everybody
> > cleaning up repeatedly over one messy guy.
> 
> Right, but there are plenty of situations where having everybody clean
> up after the messy guy is better than waiting around and hoping that
> Mom (aka vacuum) will do it.

If we see for similar situation in index, during index scan, it just marks
the tuple as DEAD without taking X lock and then during split (when it
already has X lock) it free's the actual space. 
So not sure if it's good idea to take X lock for cleanup during heap scan,
where write operation's happens more frequently and have better chance of
cleanup.

With Regards,
Amit Kapila.