On Tue, Mar 7, 2023 at 9:49 PM Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
"David G. Johnston" <david.g.johnston@xxxxxxxxx> writes:
> So I found where this difference in behavior is at least explicitly noted:
>/*
> * If it's a named composite type (or domain over one), find the typcache
> * entry and record the current tupdesc ID, so we can detect changes
> * (including drops). We don't currently support on-the-fly replacement
> * of non-composite types, else we might want to do this for them too.
> */
I'm not quite sure that that's related, really. That code is concerned
with detecting changes to an already-identified type (that is, type
OID NNN has different details now than it did before). It seemed to
me that Bryn's question was more about reacting to cases where a given
string of source code would resolve to a different type OID than it
did a moment ago.
Sorta, and now I see why %TYPE doesn't work but %ROWTYPE does - a change in the former is necessarily a new OID while a change to the later will have the same OID but a different internal structure that the type reference compiled into the function can leverage to be resolve its structure at runtime.
Of course, I went from almost clueless to this answer in just over an hour so it is possible I'm wrong. But it seems to fit so far.
David J.
