Re: pgsql: Teach verify_heapam() to validate update chains within a page.

On 2023-03-22 We 09:17, Robert Haas wrote:
> Teach verify_heapam() to validate update chains within a page.
>
> Prior to this commit, we only consider each tuple or line pointer
> on the page in isolation, but now we can do some validation of a line
> pointer against its successor. For example, a redirect line pointer
> shouldn't point to another redirect line pointer, and if a tuple
> is HOT-updated, the result should be a heap-only tuple.
>
> Himanshu Upadhyaya and Robert Haas, reviewed by Aleksander Alekseev,
> Andres Freund, and Peter Geoghegan.

This has apparently broken one case in the buildfarm, which now fails an
upgrade from REL9_2_STABLE because we run amcheck after the upgrade:

heap table "regression.public.xacttest", block 0, offset 1:
    non-heap-only update produced a heap-only tuple at offset 18
heap table "regression.public.xacttest", block 0, offset 2:
    non-heap-only update produced a heap-only tuple at offset 19
heap table "regression.public.xacttest", block 0, offset 4:
    non-heap-only update produced a heap-only tuple at offset 20
heap table "regression.public.xacttest", block 0, offset 5:
    non-heap-only update produced a heap-only tuple at offset 21
heap table "regression.public.wslot", block 0, offset 89:
    non-heap-only update produced a heap-only tuple at offset 95
heap table "regression.public.pslot", block 0, offset 95:
    non-heap-only update produced a heap-only tuple at offset 100
heap table "regression.public.pslot", block 0, offset 96:
    non-heap-only update produced a heap-only tuple at offset 101

I don't know if this is a bug in this commit or if the REL9_2_STABLE
repo is really broken.

cheers

andrew

--
Andrew Dunstan
EDB:https://www.enterprisedb.com