> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Can anyone explain this failure? It still exists in CVS.
>
> >> update t1 set f2=count(*) from t2 where t1.f1=2 and t2.f1=t1.f1 ;
> >> ERROR: ExecutePlan: (junk) `ctid' is NULL!
>
> As I recall, discussion about fixing that problem trailed off because
> no one could explain what an aggregate means in UPDATE. My thought
> is we should probably forbid the construct entirely (SQL does).
> See previous discussion around 7/7/00.
Oh, so it is the aggregate. What threw me off is that both parts of the
WHERE clause are required to cause the failure, so I thought it was
something else.
I don't see a problem with aggregates in UPDATE, except when the updated
field is part of the WHERE clause, but even then, transaction semantics
should make it matter. I see the mailist thread now.
I will try and get it added to the TODO list so it is documented.
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill,
Pennsylvania19026
