Re: BUG #18722: Processing arrays with plpgsql raises errors

Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> writes:
> I didn't mean do it in all cases, I just meant the NullIfExpr case
> identified here. My point was that instead of modifying the evaluation
> code for EEOP_NULLIF to make it call
> MakeExpandedObjectReadOnlyInternal(), it would be easier to insert a
> EEOP_MAKE_READONLY step for the first argument of the EEOP_NULLIF
> step.

But then the NULLIF step would only have access to the R/O pointer,
no? We do want to pass on a R/W pointer to the output, if we got
one, to handle cases like
fconsumer(NULLIF(fproducer(...), ...), ...)
Admittedly that's a pretty edgy edge-case, but still we're leaving
money on the table if we don't do it. So I think we have to deal
with the issue within NULLIF.

regards, tom lane