Re: Odd, intermittent failure in contrib/pageinspect

Michael Paquier <michael(at)paquier(dot)xyz> writes:
> On Mon, Jan 18, 2021 at 05:47:40PM -0500, Tom Lane wrote:
>> So, do we have any other tests that are invoking a manual vacuum
>> and assuming it won't skip any pages? By this theory, they'd
>> all be failures waiting to happen.

> check_heap.sql and heap_surgery.sql have one VACUUM FREEZE each and it
> seems to me that we had better be sure that no pages are skipped for
> their cases?

It looks to me like heap_surgery ought to be okay, because it's operating
on a temp table; if there are any page access conflicts on that, we've
got BIG trouble ;-)

Poking around, I found a few other places where it looked like a skipped
page could produce diffs in the expected output:
contrib/amcheck/t/001_verify_heapam.pl
contrib/pg_visibility/sql/pg_visibility.sql

There are lots of other vacuums of course, but they don't look like
a missed page would have any effect on the visible results, so I think
we should leave them alone.

In short I propose the attached patch, which also gets rid of
that duplicate query.

regards, tom lane