Re: Optimze usage of immutable functions as relation

Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp> wrote:

> I had the following error with the following query.
> 
> =# explain select * from pg_stat_get_activity(NULL) a join log(100000.0) p on a.pid = p.p;
> ERROR:  no relation entry for relid 2
> 

I think that the problem is that RTE_VALUES is wrapped in a subquery by parser
while RTE_FUNCTION is not. Thus some additional processing is done by
pull_up_simple_subquery() for VALUES. What seems to make difference here is
the call of flatten_join_alias_vars() on the query targetlist, although
pull_up_simple_subquery() does it for other reasons.

Actually the comment about flatten_join_alias_vars() in
pull_up_simple_subquery() makes me think if it's o.k. that
pull_up_simple_function() sets rvcontext.need_phvs=false regardless strictness
of the function: I think PlaceHolderVar might be needed if the function is not
strict. (In contrast, pull_up_simple_values() does not have to care because
pull_up_simple_subquery() handles such cases when it's processing the owning
subquery).

-- 
Antonin Houska
Cybertec Schönig & Schönig GmbH
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