Re: Composite Datums containing toasted fields are a bad idea(?)

Andres Freund <andres@2ndquadrant.com> writes:
> On 2014-04-24 19:40:30 -0400, Tom Lane wrote:
>> * Because HeapTupleGetDatum might allocate a new tuple, the wrong thing
>> might happen if the caller changes CurrentMemoryContext between
>> heap_form_tuple and HeapTupleGetDatum.

> It's fscking ugly to allocate memory in a PG_RETURN_... But I don't
> really have a better backward compatible idea :(

It's hardly without precedent; see PG_RETURN_INT64 or PG_RETURN_FLOAT8 on
a 32-bit machine, for starters.  There's never been an assumption that
these macros couldn't do that.
        regards, tom lane