Re: Logical insert/update/delete WAL records for custom table AMs

On Thu, Nov 4, 2021 at 7:09 AM Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
>
> On Wed, 2021-11-03 at 11:25 +0530, Amit Kapila wrote:
> > You have modeled DecodeLogicalInsert based on current DecodeInsert
> > and
> > it generates the same change message, so not sure how exactly these
> > new messages will be different from current heap_insert/update/delete
> > messages?
>
> Is there a reason you think the messages should be different for heap
> versus another table AM? Isn't the table AM a physical implementation
> detail?
>

We have special handling for speculative insertions and toast
insertions. Can't different tableAM's have different representations
for toast or may be some different concept like speculative
insertions? Similarly, I remember that for zheap we didn't had
TransactionIds for subtransactions so we need to make some changes in
logical decoding to compensate for that. I guess similar stuff could
be required for another table AMs. Then a different table AM can have
a different tuple format which won't work for current change records
unless we convert it to heap tuple format before writing WAL for it.

--
With Regards,
Amit Kapila.