Re: scan on inheritance parent with no children in current session

On 2017/08/04 18:11, Ashutosh Bapat wrote:
> After that commit in session 1, we get an Append plan
> postgres=# explain verbose select * from parent;
>                             QUERY PLAN
> -------------------------------------------------------------------
>  Append  (cost=0.00..0.00 rows=1 width=4)
>    ->  Seq Scan on public.parent  (cost=0.00..0.00 rows=1 width=4)
>          Output: parent.a
> (3 rows)
> 
> I don't think this is an intentional change. Here's patch to fix it.
> The comment in the patch uses term "real child" in the context of
> comments about temporary children from other session and the comment
> at the end of the function where rte->inh is reset. May be we should
> move the second comment before setting has_child in the patch and use
> "real child" in the comment at the end to avoid repetition. But I want
> to first check whether we want this fix or we can live with the Append
> plan.

Good catch.  I agree that getting an Append node after that commit is
unintentional and we should fix so that we don't get an Append.  So, +1 to
your patch.  I looked at the patch and the code fix seems to do what we want.

Thanks,
Amit