Re: Remove xmin and cmin from frozen tuples

> [skip]

> happening in the bgwriter's inner loop.  Even more to the point, you
> can't do such changes without getting a superexclusive lock on the  
> page
> (not only locked, but no one else has it pinned), which is a real
> nonstarter for the bgwriter, both for performance and possible  
> deadlock
> issues.
Hi Tom,

I do not want to discuss in deep the place to do this job, it is  
really over my head.

But, you said you need a "super-exclusive lock", and I wonder if a  
wait-free algorithm would be good for pg in a general manner.

I have given some references about it already on the list.
http://archives.postgresql.org/pgsql-hackers/2005-02/msg00263.php

Cordialement,
Jean-Gérard Pailloncy