On Thu, Jan 10, 2013 at 11:45 AM, Amit Kapila <amit.kap...@huawei.com> wrote: > On Thursday, January 10, 2013 6:09 AM Josh Berkus wrote:
>> >> Surely VACUUM FULL should rebuild the visibility map, and make tuples >> in >> the new relation all-visible, no? > > I think it cannot made all visible. > How about if any transaction in SSI mode is started before Vacuum Full, > should it see all tuples. > We can definitely do better than what we are doing today and that should fix many use cases and rebuild the VM for large part of the table if not all. More precisely, in cluster.c we can see what does HeapTupleSatisfiesVacuum() returns for every tuple in a page. If there are only DEAD or LIVE tuples in a page, we can set the VM bit. We may need similar additional checks for LIVE tuples like we have in vacuum code path. But its certainly doable. I'd also suggested doing something similar for cases when a table is created and written in the same transaction. But that's more invasive. Thanks, Pavan -- Pavan Deolasee http://www.linkedin.com/in/pavandeolasee -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
