Greg Stark <gsstark@mit.edu> writes:
> On Sun, Aug 23, 2009 at 7:00 PM, Tom Lane<tgl@sss.pgh.pa.us> wrote:
>> But we don't use that while examining individual tuples, do we?
> We don't use the visibility map itself but we *do* use the page
> header's all visible bit. On a sequential scan we skip the visibility
> check for tuples on the page if the page header bit is set.
Urgh. I bet that's where the problem is then. Some path is failing
to clear that bit, or maybe there's a race condition that allows it
to become set incorrectly (ie right after somebody else adds a tuple).
regards, tom lane