Re: Incomplete Explain for delete

On Mon, Jun 22, 2015 at 11:47 AM, Ghislain ROUVIGNAC <ghr(at)sylob(dot)com> wrote:

> So I think explain needs an improvement as it does not show the real plan
> used when running the query.
>
> Instead of displaying:
> Delete on uniform (cost=0.000..4,489.270 rows=57,847 width=6)
> -> Index Scan using two on uniform (cost=0.000..4,489.270 rows=57,847
> width=6)
> Index Cond: ((bravo)::text = 'romeo'::text)
>
It should display something like this
> Delete on uniform (cost=0.000..4,489.270 rows=57,847 width=6)
> -> Index Scan using two on uniform (cost=0.000..4,489.270 rows=57,847
> width=6)
> Index Cond: ((bravo)::text = 'romeo'::text)
> -> Foreign Keys check
> -> Index Scan using ix_ref1 on referencing1 (cost= rows= width=)
> Index Cond: ...
> -> ...
> -> Index Scan using ix_refN on referencingN (cost= rows= width=)
> Index Cond: ...
>
>
The underlying limitation here is that the planner does not concern itself
with triggers.

​There is definitely room for improvement here but this complaint by itself
is not particularly influential to me.​ The black-box nature of functions
makes anything more detailed than "this table has triggers" difficult -
though maybe FK check triggers could be special-cased.

David J.