On Fri, Jul 1, 2016 at 10:09 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: >>> Ah, I see. So your suggestion is to do this job in lazy_scan_heap() >>> when scanning each block, and then to issue a WARNING and clear the >>> visibility map. Indeed that's better. I guess I need to take a closer >>> look at vacuumlazy.c. See attached for example, but that's perhaps not >>> something to have in 9.6 as that's more a micro-optimization than >>> anything else. >> >> Right, something like that. I think Andres actually wants something >> like this in 9.6, and I'm inclined to think it might be a good idea, >> too. I think there should probably be a test for >> all_visible_according_to_vm at the beginning of that so that we don't >> add more visibility map checks for pages where we already know the VM >> bit can't possibly be set. >> >> Other opinions on the concept or the patch? > > +1 on the idea. > > + PageClearAllVisible(page); > + MarkBufferDirty(buf); > > What is the need to clear the Page level bit, if it is already > cleared, doesn't '!all_frozen' indicate that?
No, I don't think so. I think all_frozen indicates whether we think that all tuples on the page qualify as fully frozen. I don't think it tells us anything about whether PD_ALL_VISIBLE is set on the page. -- 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