On 11/27/13 14:11, Andres Freund wrote:
On 2013-11-27 13:56:58 +0200, Heikki Linnakangas wrote:
Afaics the likelihood of the issue occuring on non-all-visible pages is
pretty low, since they'd need to be skipped due to lock contention
repeatedly.
Hmm. If a page has its visibility-map flag set, but contains a tuple that
appears to be dead because you've wrapped around, vacuum will give a
warning: "page containing dead tuples is marked as all-visible in relation
\"%s\" page %u".
I don't think this warning is likely to be hit as the code stands -
heap_page_prune() et. al. will have removed all dead tuples already,
right and so has_dead_tuples won't be set.
It might be a good idea to add such a warning to heap_page_prune(). Or
also emit the warning in lazy_scan_heap() if heap_page_prune() returned > 0.
Independent from this, ISTM we should add a
else if (PageIsAllVisible(page) && all_visible)
to those checks.
Can you elaborate, where should that be added?
- Heikki
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
