Re: pg_amcheck contrib application

> On Apr 23, 2021, at 11:29 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>
> On Fri, Apr 23, 2021 at 2:15 PM Mark Dilger
> <mark.dilger@enterprisedb.com> wrote:
>> Another difference I should probably mention is that a bunch of unrelated tests are failing with errors like:
>>
>>    toast value 13465 chunk 0 has size 1995, but expected size 1996
>>
>> which leads me to suspect your changes to how the size is calculated.
>
> That seems like a pretty reasonable suspicion, but I can't see the problem:
>
> -       expected_size = curchunk < endchunk ? TOAST_MAX_CHUNK_SIZE
> -               : VARATT_EXTERNAL_GET_EXTSIZE(ta->toast_pointer) -
> (endchunk * TOAST_MAX_CHUNK_SIZE);
> +       expected_size = chunk_seq < last_chunk_seq ? TOAST_MAX_CHUNK_SIZE
> +               : extsize % TOAST_MAX_CHUNK_SIZE;
>
> What's different?
>
> 1. The variables are renamed.
>
> 2. It uses a new variable extsize instead of recomputing
> VARATT_EXTERNAL_GET_EXTSIZE(ta->toast_pointer), but I think that
> should have the same value.
>
> 3. I used modulo arithmetic (%) instead of subtracting endchunk *
> TOAST_MAX_CHUNK_SIZE.
>
> Is TOAST_MAX_CHUNK_SIZE 1996? How long a value did you insert?

On  my laptop, yes, 1996 is TOAST_MAX_CHUNK_SIZE.

I'm not inserting anything.  These failures come from just regular tests that I have not changed.  I just applied your
patchand ran `make check-world` and these fail in src/bin/pg_amcheck  

—
Mark Dilger
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