Re: Implement targetlist SRFs using ROWS FROM() (was Changed SRF in targetlist handling) - Mailing list pgsql-hackers

Andres Freund <andres@anarazel.de> writes:
> On 2016-09-02 10:20:42 -0400, Tom Lane wrote:
>> ... ISTM all we
>> need is that the SRF be on the inside of the join, which is automatic
>> if it's LATERAL.

> Right. But there's nothing to force a lateral reference to be there
> intrinsically. I've added a "fake" lateral reference to the ROWS FROM
> RTE to the subquery, when there's none otherwise, but that's not
> entirely pretty.

Hm, do you get cases like this right:
select generate_series(1, t1.a) from t1, t2;

That would result in a lateral ref from the SRF RTE to t1, but you really
need to treat it as laterally dependent on the join of t1/t2 in order to
preserve the old semantics.  That is, you need to be laterally dependent
on the whole FROM clause regardless of which variable references appear.
        regards, tom lane