Alvaro Herrera <alvherre@commandprompt.com> writes:
> Tom Lane wrote:
>> I'm fairly sure this query is illegal per spec. There are ancient
>> discussions in the archives about whether aggregates in an UPDATE target
>> list can have a consistent interpretation or not. We never found one,
>> but never got around to disallowing it either. Maybe it's time. If you
>> try it with something like sum() you don't get a crash, but you do get
>> rather bizarre behavior.
> Yeah, I agree we should disallow it. For the curious, the bizarre behavior
> is
> alvherre=# update pk set id = count(id) ;
> ERROR: ctid is NULL
Hmm, what version are you testing? What I see is that it updates a
single one of the table rows :-(
I found the previous discussion (or one such, anyway):
http://archives.postgresql.org/pgsql-bugs/2000-07/msg00046.php
That message mentions "ctid is NULL" in the context of a join update,
but for the single-table case, all the versions I've tried seem to do
the other thing. It's pretty broken either way of course ...
regards, tom lane