On Mon, Jun 27, 2016 at 5:56 PM, Michael Paquier <michael.paqu...@gmail.com> wrote: >> Under what circumstances would you wish to check only one page of a relation? > > What I'd like to be able to do is to stop scanning the relation once > one defective tuple has been found: if there is at least one problem, > the whole vm needs to be rebuilt anyway. So this function could be > wrapped in a plpgsql function for example. It is more flexible than > directly modifying this function so as it stops at the first problem > stopped.
I think most likely the best way to handle this is teach VACUUM to do PageClearAllVisible() and visibilitymap_clear() on any page where VM_ALL_FROZEN(onerel, blkno, &vmbuffer) && !all_frozen. This would go well with the existing code to clear incorrectly-set visibility map bits, and it would allow VACUUM (DISABLE_PAGE_SKIPPING) to serve the purpose you're talking about here, but more efficiently. -- 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
