Re: [HACKERS] Parser bug?

> Bruce Momjian wrote:
>   >> I think this is a bug in 6.4:
>   >> 
>   >> bray=> select rcname, rcsrc from pg_relcheck where rcrelid =
>   >> '115404'::oid and rcrelid in (select min(rcrelid) from pg_relcheck
>   >> group by rcname); ERROR:  parser: Subselect has too many or too
>   >> few fields.
>   >> 
>   >> The subselect only produces one column; so I think that the
>   >> error message is wrong.
>   >
>   >What is the GROUP BY doing?
> 
> This relates to the bug in pg_dump which messes up inherited constraints.
> 
> The object is to find which is the table in an inheritance hierarchy for
> which the check constraint is first defined, which must inevitably be the
> one with the lowest numbered oid.  The GROUP BY operates with the aggregate
> to return the low-numbered oid for each separate rcname.

Maybe I should be clearer.  You are grouping by a column that is not in
the target list.  If you try the subquery on its own, it should fail
with a better error message.

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