On Thu, May 26, 2011 at 8:57 AM, Pavan Deolasee <pavan.deola...@gmail.com> wrote: > On Thu, May 26, 2011 at 4:10 PM, Pavan Deolasee > <pavan.deola...@gmail.com> wrote: >> On Thu, May 26, 2011 at 9:40 AM, Robert Haas <robertmh...@gmail.com> wrote: >> >>> Currently, I believe the only way a page can get marked all-visible is >>> by vacuum. But if we make this change, then it would be possible for >>> a HOT cleanup to encounter a situation where all-visible could be set. >>> We probably want to make that work. >>> >> >> Yes. Thats certainly an option. > > BTW, I just realized that this design would expect the visibility map > to be always correct or at least it should always correctly report a > page having dead line pointers. We would expect the index vacuum to > clean index pointers to *all* dead line pointers because once the > index vacuum is complete, other backends or next heap vacuum may > remove any of those old dead line pointers assuming that index vacuum > would have taken care of the index pointers. > > IOW, the visibility map bit must always be clear when there are dead > line pointers on the page. Do we guarantee that today ? I think we do, > but the comment in the source file is not affirmative.
It can end up in the wrong state after a crash. I have a patch to try to fix that, but I need someone to review it. (*looks meaningfully at Heikki, coughs loudly*) -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
