Re: The documentation for storage type 'plain' actually allows single byte header

Andres Freund <andres(at)anarazel(dot)de> writes:
> On 2023-01-15 16:40:27 -0500, Tom Lane wrote:
>> The documentation is correct, what is broken is the code. I'm not
>> sure when we broke it

> I've not thought through this fully. But after a first look, this might be
> hard to fix without incuring a lot of overhead / complexity.

It appeared to me that it was failing at this step in
ExecGetInsertNewTuple:

if (relinfo->ri_newTupleSlot->tts_ops != planSlot->tts_ops)
{
ExecCopySlot(relinfo->ri_newTupleSlot, planSlot);
return relinfo->ri_newTupleSlot;
}

ri_newTupleSlot has the tupdesc we want, planSlot is a virtual slot
that has the bogus tupdesc, and for some reason heap_form_tuple is
getting called with planSlot's tupdesc not ri_newTupleSlot's. I'm
not quite sure if this is just a thinko somewhere or there's a
deficiency in the design of the slot APIs.

The UPDATE path seems to work fine, btw.

regards, tom lane