Re: BUG #19519: REPACK can fail due to missing chunk for toast value

On 09/07/2026 8:43 AM, Michael Paquier wrote:
> On Thu, Jul 09, 2026 at 08:17:06AM +0300, Konstantin Knizhnik wrote:
>> Changing `table_relation_fetch_toast_slice` signature breaks compatibility
>> with some extensions, for example duckdb.
>> I wonder if we can change only  `bool (*relation_fetch_toast_slice)(...,
>> bool missing_ok)` callback signature, but preserve signature of
>> `table_relation_fetch_toast_slice`, adding one more function
>> `table_relation_try_fetch_toast_slice`:
> Thanks for the input.
>
> Adding more functions implies to change the size of TableAmRoutine,
> which may be bad. For now I'd be tempted to just focus on how to fix
> the problem on HEAD in a way we are happy with. We could sort out an
> optional back-branch version as a second step.
> --
> Michael

Sorry, I do not suggest to extend TableAmRoutine - it will contain
single `relation_fetch_toast_slice` entry with new signature.

I suggest to add only new wrapper function
`table_relation_try_fetch_toast_slice`, preserving original
`table_relation_fetch_toast_slice`. It will preserve compatibility with
extensions (there are not using TableAmRoutine directly) and do not
extend TableAmRoutine.