Re: INSERT...ON DUPLICATE KEY LOCK FOR UPDATE

On Tue, Nov 26, 2013 at 1:41 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
> Great. I'll let you know what I think.

So having taken a look at what you've done here, some concerns remain.
I'm coming up with a good explanation/test case, which might be easier
than trying to explain it any other way.

There are some visibility-related race conditions even still, with the
same test case as before. It takes a good while to recreate, but can
be done after several hours on an 8 core server under my control:

pg(at)gerbil:~/pgdata$ ls -l -h -a hack_log.log
-rw-rw-r-- 1 pg pg 1.6G Nov 27 05:10 hack_log.log
pg(at)gerbil:~/pgdata$ cat hack_log.log | grep visible
ERROR: attempted to update invisible tuple
ERROR: attempted to update invisible tuple
ERROR: attempted to update invisible tuple

FWIW I'm pretty sure that my original patch has the same bug, but it
hardly matters now.

--
Peter Geoghegan